CN120035785A - Endoscopic devices, calibration assemblies, endoscopes and imaging systems - Google Patents

Abstract

The invention relates to an endoscopic device (110) comprising a lens assembly (112) configured for imaging light in the visible and near infrared range, and being symmetrical about a first symmetry plane (120) perpendicular to an optical axis (114). The lens assembly (112) comprises six rod lenses (122) and two correction elements (124), each comprising a lens system (128) having a first lens (130) and a second lens (132). The first lens (130) is made of a first optic and the second lens (132) is made of a second optic. The first lens and the second lens have different abbe numbers, wherein the relative partial dispersions of the first lens and the second lens deviate in an opposite manner from the lens having normal dispersion. The lens assembly (112) further comprises a correction pair assembly (134) comprising two of the correction elements (124) that are symmetrical to each other about a second plane of symmetry (136) perpendicular to the optical axis (114).

Description

Endoscope device, correction pair assembly, endoscope, and imaging system

The present invention relates to an endoscopic device, in particular for hyperspectral and/or multispectral imaging, a correction pair assembly for a lens assembly of an endoscope, an endoscope and an imaging system with an endoscope.

Lens assemblies for endoscopes having a plurality of rod lenses are known from the prior art. Such a lens assembly is combined with an objective lens and an eyepiece lens. Light entering the objective lens from the object under observation may be transmitted through the lens assembly to the eyepiece. Thereby, the observed object can be imaged in a known manner.

In the field of endoscopy, endoscope apparatuses that generate multispectral or hyperspectral images are increasingly used. Multispectral or hyperspectral images have spectral dimensions in addition to the two spatial dimensions that conventional camera images have, for example. The spectral dimensions include a plurality of spectral bands (wavelength bands). Multispectral images and hyperspectral images differ substantially in the number and width of their spectral bands. In principle, such a system may also be suitable for performing fluorescence image acquisition.

Some imaging devices for producing such multispectral or hyperspectral images are known, especially in the context of medical applications. For example, DE 20 2014 010 558 U1 describes a device for recording hyperspectral images of a body examination region. In the device an input objective for producing an image in an image plane and a slit diaphragm in the image plane for defining a slit-shaped area in the image are arranged. The light passing through the diaphragm is fanned out by means of a dispersive element and collected by means of a camera sensor. Thus, the camera sensor can acquire a plurality of spectra in the longitudinal direction of the slit-shaped diaphragm, which spectra have respective assigned spatial coordinates. The described device is further configured for acquiring further spectra in a direction different from the longitudinal direction of the slit-shaped aperture along the longitudinal direction of the slit-shaped aperture. The method disclosed herein for generating multispectral or hyperspectral images is also referred to as the so-called push broom (Pushbroom) method.

In addition to push-broom methods, there are other methods for producing multispectral or hyperspectral images. In the so-called sweep (Whiskbroom) method, the examined region or also the object is swept in a point-by-point manner and a spectrum is acquired for each point. In contrast, in the gaze (Staring) method, multiple images with the same spatial coordinates are acquired. Here, spectral information is resolved using different spectral filters and/or illumination sources for each image. Furthermore, there are methods according to which a two-dimensional polychromatic image is decomposed by means of suitable optical elements (such as optical splitters, lenses and prisms) into a plurality of spectral single images, which are simultaneously detected on different detectors or detection areas. This is sometimes referred to as a snapshot method.

Multispectral and hyperspectral imaging devices are particularly suitable as endoscopic imaging devices, as described in DE 10 2020 105 458 A1. In this context, multispectral and/or hyperspectral imaging is an important field of application, for example for diagnosis and evaluation of the success or quality of surgery.

The multi-modality endoscopic device allows for the selective acquisition of white light images and/or multispectral images and/or fluorescence images and/or hyperspectral images.

It is advantageous or even necessary for the above-mentioned application situations to be able to transmit and image light in the visible and near infrared range. Multispectral or hyperspectral imaging is particularly widely used, for example, when capable of operating in the spectral range of about 450nm to 1000 nm. It is also advantageous for fluorescence imaging to have a broad spectral range, since this allows the same optical system to be used for both fluorescence and white light image acquisition. The latter generally reveals the anatomy observed more fully, so it is meaningful to combine it with a fluoroscopic image. In this regard, existing lens assemblies often fail to provide satisfactory imaging quality over a broad spectral range. Thus, in certain parts of the entire spectral range used, it is often necessary to operate with lower resolution or defective focusing.

Furthermore, it is often not satisfactory for the user to work with focus optimized for the near infrared range with out-of-focus in the visible range, since the image quality is subjectively considered to be inadequate at this time.

In practice, it is in many cases impractical for the user to make a subsequent adjustment of the focus of the used endoscopic device according to the respective observation mode. If the superimposed representation should be produced, for example, by superimposing a white light image and a fluorescence image, or a white light image and a hyperspectral image/multispectral image on each other, switching takes place automatically and at very short time intervals if necessary. Fluorescence imaging and multispectral imaging may be performed in real-time. Hyperspectral imaging is typically performed at least substantially in real time, with acquisition of a hyperspectral image dataset lasting, for example, a few seconds. However, all wavelengths are considered here when a single image acquisition is performed, so that a subsequent adjustment of the focus according to wavelength is impractical.

Based on the prior art, the present invention is based on the object that high quality endoscopic imaging can be achieved in a wide spectral range.

According to the invention, this object is achieved by an endoscopic device, a correction pair assembly for a lens assembly of an endoscope, an endoscope and an imaging system as described herein and defined in the claims.

An endoscopic device, in particular for hyperspectral and/or multispectral imaging, comprises a lens assembly defining an optical axis and configured for optically coupling an eyepiece to an objective lens. The lens assembly is configured for at least substantially equivalent light transmission and/or imaging in the visible and near infrared range, and in particular over a majority of the visible range and in the near infrared range, in particular for a given focus. The lens assembly is symmetrical about a first plane of symmetry perpendicular to the optical axis.

The lens assembly comprises at least six rod lenses and at least two correction elements, the correction elements together with the rod lenses defining an optical system, and the correction elements each comprise a lens system having at least a first lens and a second lens. The first lens is made of a first optic and the second lens is made of a second optic. The first lens and the second lens have different abbe numbers. The relative partial dispersion of the first lens and the relative partial dispersion of the second lens deviate in an opposite manner from the lens having normal dispersion. Furthermore, the lens assembly comprises at least one correction pair assembly comprising two of these correction elements, which are symmetrical to each other about a second plane of symmetry perpendicular to the optical axis.

The invention also relates to a correction pair assembly for a lens assembly of an endoscope, the correction pair assembly comprising at least two correction elements defining an optical axis and configured for defining an optical system together with a plurality of rod lenses, and the correction elements each comprising a lens system having at least a first lens and a second lens. The first lens is made of a first optic and the second lens is made of a second optic. The first lens and the second lens have different abbe numbers. The relative partial dispersion of the first lens and the relative partial dispersion of the second lens deviate in an opposite manner from the lens having normal dispersion. The correction elements are symmetrical to each other about a plane of symmetry perpendicular to the optical axis.

Features according to the invention can achieve high quality endoscopic imaging over a wide spectral range. The inventors have realized that in order to achieve high imaging quality over a wide spectral range, lens errors have to be solved in a very targeted way and that optical components have to be selected and combined appropriately for this purpose. By using pairs of correction elements and suitable symmetry in the lens assembly structure, chromatic aberration can be advantageously reduced, enabling images with high imaging quality to be acquired in the visible and near infrared range without requiring subsequent adjustment/adjustment of focus in terms of wavelength. Furthermore, the inventors have realized that especially for high quality multispectral or hyperspectral imaging, if possible, as high light intensities as possible should be present on the corresponding detection sensor device in the entire imaging spectral range. Furthermore, the use of a rod lens and an additional correction element enables the production of an endoscope or an endoscope shaft using conventional assembly methods, wherein an endoscope device or a lens assembly according to the invention is used. The lens system may be constructed using known method steps, with only the combined optical components differing from the existing lens assemblies.

The objective lens may comprise a lens system configured for enabling coupling in of light and transmitting the coupled in light to the lens assembly. The light coupled in is for example light that is returned and/or emitted by the object under observation. In particular, it may be returned illumination light and/or fluorescence light.

In some embodiments, the eyepiece is configured to supply light transmitted by the lens assembly to the image detection sensing device. The image detection sensor device may be a component of an imaging unit, in particular a multi-modality imaging unit, by means of which preferably multi-spectral imaging, hyperspectral imaging, white light imaging and/or fluorescence imaging are selectively performed.

The endoscopic device may be a component of an endoscope, in particular a medical endoscope. Typically, it may be a medical endoscopic device. In addition to the endoscopic device, the endoscope may include an eyepiece and/or an objective lens. Alternatively or additionally, the ocular and/or the objective may be part of an endoscopic device.

Multispectral imaging may particularly relate to imaging in which at least two, particularly at least three and in some cases at least five spectral bands can be detected and/or are to be detected independently of each other. The individual spectral bands of multispectral imaging may be defined by suitable and, if necessary, switchable optical filters. Hyperspectral imaging may particularly relate to imaging in which at least 20, at least 50 or even at least 100 spectral bands can be detected and/or are to be detected independently of each other. Hyperspectral imaging can be performed, for example, according to push-broom and/or swing-broom and/or gaze and/or snapshot principles.

The rod lenses may in particular be arranged with their longitudinal axes parallel to each other and/or to the optical axis of the lens assembly. Preferably, the longitudinal axis of the rod lens coincides with the optical axis. The rod lenses and correction elements may be arranged such that light transmitted and/or imaged by the lens assembly passes through all rod lenses and all correction elements.

In some embodiments, the lens assembly may have a length of at least 20cm, at least 30cm, or even at least 40 cm. The lens assembly may be rigid. In other words, the components of the lens assembly (e.g. the at least six rod lenses and the at least two correction elements), in particular all components of the lens assembly, are not movable relative to each other.

The endoscopic device may also include an eyepiece and/or an objective lens. The eyepiece and/or object may form an imaging optics system with the lens assembly.

The endoscopic device may include a shaft in which the lens assembly is received and/or secured. In this case, the optical axis may be arranged parallel to and in particular coincident with the longitudinal axis of the shaft. In other words, the shaft, the rod lens and in particular the correction element may be arranged coaxially.

"Most of the wavelength range" especially means a preferably continuous wavelength range covering at least 60%, preferably at least 70%, particularly preferably at least 80% and preferably at least 90% of the reference wavelength range. In this context, the range, in particular, from 400nm to 750nm is understood to be the visible wavelength range. In this context, the term "near infrared range" relates in particular to wavelengths outside the visible wavelength range. In particular, for a given focus, the lens assembly may be configured for achieving at least substantially equivalent light transmission and/or imaging over a majority of the visible light range and over a majority of the range of at least 800nm to 1000 nm. In other words, for a given focus, the lens assembly may be configured for achieving at least substantially equivalent light transmission and/or imaging over a large part of the range of 480nm to 900nm and preferably over a large part of the range of 400nm to 1000 nm.

"At least substantially equivalent light transmission" is understood in particular to mean that, for all arbitrarily selectable pairs of intervals in the wavelength range mentioned, the average transmission in the wavelength range mentioned differs between these intervals by at most 30%, preferably at most 20%, particularly preferably at most 15% and preferably at most 10%, these intervals having a width of at most 100nm, at most 50nm or even at most 10nm. "at least substantially equivalent light transmission" may comprise that for all arbitrarily selectable pairs of wavelengths within the mentioned wavelength ranges the transmission within the mentioned wavelength ranges differs between these wavelengths by at most 30%, preferably at most 20%, particularly preferably at most 15% and preferably at most 10%. Here, "transmittance" refers in particular to the degree of transmittance, i.e. the quotient of the transmitted intensity and the incident intensity. Such information relates in particular to such light intensities whose transmittance is independent or at least substantially independent of intensity.

"At least substantially equivalent light transmission and imaging" means in particular that the lens assembly can be used both over a large part of the visible range and in the near infrared range. In other words, the lens assembly may be used in the visible and near infrared range, especially equivalently, for a given focus.

"Substantially equivalent light transmission" can be understood in particular as meaning that for all arbitrarily selectable pairs of intervals in the wavelength ranges mentioned, the average transmission in the wavelength ranges mentioned differs between these intervals by at most 30%, preferably by at most 20%, particularly preferably by at most 15% and preferably by at most 10%, these intervals have a width of at most 100nm, at most 50nm or even at most 10nm, and in particular the average transmission in these intervals is less than 95%, less than 90% or less than 85%. "at least substantially equivalent light transmission" may include that for all arbitrarily selectable pairs of wavelengths within the mentioned wavelength ranges the transmission within the mentioned wavelength ranges differs between these wavelengths by at most 40%, preferably at most 30%, particularly preferably at most 20% and preferably at most 10%, in particular the transmission is less than 95%, less than 90% or less than 85%. Furthermore, the term may comprise that there is at least one sub-region of the mentioned wavelength range in which the transmittance is more than 80%, more than 85% or even more than 90%. Here, "transmittance" refers in particular to the degree of transmittance, i.e. the quotient of the transmitted intensity and the incident intensity. Such information relates in particular to such light intensities whose transmittance is independent or at least substantially independent of intensity. In other words, an efficient optical transmission can be achieved over the entire wavelength range mentioned.

"Substantially equivalent photoimaging" can be understood in particular as meaning that for all arbitrarily selectable pairs of intervals within the wavelength range mentioned, the average RMS point radii differ between these intervals by at most 15 times, preferably by at most 10 times, particularly preferably by at most 5 times and preferably by at most 3 times, these intervals having a width of at most 100nm, at most 50nm or even at most 10nm, and in these intervals, in particular, the average RMS point radii ("RMS" stands for "root mean square") exceeds the diffraction limit. "substantially equivalent photoimaging" may include RMS spot radii differing by at most 15 times, preferably by at most 10 times, particularly preferably by at most 5 times and preferably by at most 3 times between the wavelengths, in particular the average RMS spot radii exceeding the diffraction limit in the case of the wavelengths, for all arbitrarily selectable pairs of wavelengths within the mentioned wavelength range. Furthermore, the term may include the presence of at least one sub-region of the mentioned wavelength range in which the RMS point diameter is below the diffraction limit. In other words, a sufficiently strongly focused light imaging can be achieved over the entire wavelength range mentioned.

The term "for a given focusing" especially means that the incidence of light into the lens assembly does not change, i.e. proceeds in the same way for different wavelengths. For example, if the lens assembly is combined with an objective lens and/or an eyepiece lens and focused, there is no change in focus for light transmission and imaging where the evaluation wavelengths are different. Such focusing may comprise a preset and/or presettable focus for a specific wavelength within the mentioned wavelength range, which focus then remains unchanged over the whole of the mentioned range.

The rod lens and/or the correction element may be designed as an at least substantially cylindrical, preferably cylindrical, object. The sides of the rod lens and/or the correction element may be in the shape of the sides of a cylinder. The front and/or rear surfaces of the rod lens and/or the correction element may be other than cylindrical in shape and may for example be convexly or concavely curved.

The rod lens is preferably elongated. The rod lens may have a length of at least 2 times, 3 times, 4 times, 5 times or even 6 times the diameter of the rod lens, for example. The rod lenses may be designed identically or differently. In some embodiments, the lens assembly may include a plurality of different rod lens types. These rod lens types may differ in their size, curvature, refractive behavior, coating, material, and/or other parameters.

Within the scope of the present disclosure, the term "lens" may relate to any lens material. In this regard, the "lens" should not be limited to silicate lenses or silicon-based lenses, although in some embodiments the first lens and/or the second lens may be silicate lenses or silicon-based lenses.

Within the scope of the present disclosure, the abbe number may be defined as:

ν_d＝(n_d-1)/(n_F-n_C),

Where n _d、n_F and n _C are the refractive indices of the relevant materials in the corresponding fraunhofer line (Fraunhoferlinie). For example, fraunhofer lines d, F and C have corresponding wavelengths of 587.56nm, 486.13nm and 656.27nm.

Alternatively, within the scope of the present disclosure, the abbe number may also be defined as:

ν_e＝(n_e-1)/(n_F'-n_C'),

Where n _e、n_F' and n _C' are the refractive indices of the relevant materials in the corresponding fraunhofer line. For example, fraunhofer lines e, F 'and C' have corresponding wavelengths of 546.07nm, 479.99nm and 643.85nm.

The above-mentioned relative partial dispersion may generally be a relative partial dispersion for two wavelengths x, y, which may be defined as follows:

P_x,y＝(n_x-n_y)/(n_F-n_C),

Where n _x and n _y represent refractive indices at wavelengths x and y. In particular, the above relative partial dispersions of the first lens and the second lens may be P _g,F, where g and F represent the corresponding fraunhofer lines. For example, fraunhofer lines g, F and C' have respective wavelengths of 435.83nm and 486.13nm.

A lens with normal dispersion is to be understood as a lens whose relative partial dispersion is linearly dependent on the abbe number, i.e. in particular a lens lying on a straight line in the v _d-P_x,y diagram, wherein the following relationship holds:

P_x,y＝a_x,y+b_x,y·ν_d,

Where a _x,y and b _x,y are dimensionless constants belonging to the partial dispersion determined by x and y. V _e can also be expressed in a similar manner. For P _g,F, these constants are known as a _g,F = 0.6438 and b _g,F = 0.001682. Such lenses are also commonly referred to as "normal lenses". It is distinguished in that light is dispersed in the same way, regardless of the spectral range.

In contrast, lenses that deviate from lenses with normal dispersion may exhibit different dispersion behavior in different spectral ranges, e.g., stronger or weaker dispersion in the short wave range than in the long wave range. Such lenses are sometimes referred to as lenses having anomalous dispersion.

It should be understood that these concepts should not be equivalent to the partially used concepts of normal and anomalous dispersion, the latter involving the fundamental dispersive behavior of the material, i.e. the refractive index increases with frequency ("normal dispersion") or decreases with frequency ("anomalous dispersion"). Instead, the lens characteristics described herein relate to different derivatives of dispersion at different wavelengths, if necessary, but they may have the same sign.

The relative partial dispersions of the first lens and the second lens deviate from the lens with normal dispersion in an opposite manner, in particular, in that in the v _d-P_x,y diagram the first lens is located on one side of the normal dispersion lens line and the second lens is located on a second side opposite the first side. Similarly, this may apply to the v _de-P_x,y chart. The deviation parameter Δp _x,y may be defined as follows:

ΔP_x,y＝(n_x-n_y)/(n_F-n_C)-a_x,y+b_x,y·ν_d。

v _e can also be expressed in a similar manner. The sign of the value of the deviation parameter Δp _x,y may be different for the first lens and the second lens.

The first lens may be at least largely and/or entirely comprised of the first optic. The second lens may be at least largely and/or entirely comprised of the second optic. "at least a majority" can mean at least 55%, preferably at least 65%, preferably at least 75%, particularly preferably at least 85% and very particularly preferably at least 95%, more precisely in particular in relation to the volume and/or mass of the object.

Preferably, the first lens and the second lens are arranged directly next to one another and in particular in contact with one another and/or are integrally formed with one another, for example optically bonded and/or glued.

The correction elements of the correction assembly may be arranged symmetrically to each other about the second plane of symmetry. The correction elements of the correction assembly can be designed identically and can, for example, merely be rotated relative to one another to produce symmetry. In other embodiments, the correction elements may be designed differently, but symmetrically to each other.

A simple optical structure is achieved in particular when the first plane of symmetry and the second plane of symmetry coincide. Thus, optical modeling for adjusting the lens assembly may be particularly easy to perform. In other embodiments, the first plane of symmetry and the second plane of symmetry may be spaced apart from each other along the optical axis.

In some embodiments, the lens assembly comprises at least one further correction pair assembly, wherein the further correction pair assembly comprises two further correction elements of the correction elements, the two further correction elements being symmetrical to each other about a third symmetry plane perpendicular to the optical axis. Thus, high imaging quality and imaging stability can be achieved. The further correction pair assembly may be designed to be identical to the correction pair assembly. Alternatively, these correction pair components may differ, for example, in the correction elements used and/or their relative positions and/or orientations.

A high degree of flexibility in the design of the lens assembly and the wide variety of possibilities associated therewith for achieving high imaging quality can be achieved in particular when the second and third symmetry planes differ from the first symmetry plane. The second symmetry plane and the third symmetry plane may be coincident. Alternatively, it may be provided that the second plane of symmetry is different from the third plane of symmetry. These symmetry planes may be spaced apart from each other along the optical axis. In further embodiments, the first plane of symmetry and the third plane of symmetry may coincide with each other, but are different from the second plane of symmetry.

It is within the scope of the present disclosure that the planes of symmetry that are different from each other may be spaced apart from each other along the optical axis by a distance of at least 1cm, at least 2cm, at least 5cm, at least 10cm, or even at least 20cm.

It may also be provided that each of these correction elements comprises at least a third lens. In some embodiments, the third lens is made of the first lens and/or the second lens. In other embodiments, the third lens may also be made of a third lens different from the first lens and/or the second lens. In particular, the third lens may be different from a lens exhibiting normal dispersion in the sense of the present disclosure. The third lens may be composed at least largely and/or entirely of the first lens, the second lens or the third lens. Here, the second lens may be disposed between the first lens and the third lens. Preferably, the first lens, the second lens and the third lens are arranged directly in succession and in particular in contact with one another and/or are integrally formed with one another, for example optically bonded and/or glued.

In particular, the assembly effort and/or the number of components can be reduced when the correction elements are each formed integrally with the rod lens. In general, at least one of the correction elements may be integrally formed with at least one of the rod lenses. Herein, "integrally" includes both one-piece and one-piece. At least one lens of the associated correction element may be integrally formed with the associated rod lens. Preferably, all lenses of the associated correction element are integrally formed with the associated rod lens. For example, in these cases, the first lens may be disposed immediately adjacent to and/or optically bonded and/or adhered to the rod lens. The arrangement may also be vice versa such that the second lens is arranged next to the rod lens. The second lens may then also be arranged next to and/or optically bonded and/or glued to the first lens. In some embodiments, the correction element may be disposed on and/or bonded and/or adhered to the planar surface of the rod lens.

Furthermore, the correction pair assembly may comprise at least one aperture arranged in the region of the second plane of symmetry. Thereby, the aperture of the lens assembly can be conveniently positioned. In some variations, the second plane of symmetry intersects the aperture. In particular, the aperture has a smaller diameter than the rod lens and/or the correction element and/or the lens of the correction element. The information about the symmetry of the lens assembly may relate in particular to the parts of the lens assembly that do not contain an aperture (i.e. ignore an aperture). In other words, the lens assembly may be symmetrical without an aperture, but the aperture may be arranged off-center, for example. In principle, a plurality of apertures may also be provided. The apertures may be symmetrically arranged with respect to each other and/or each symmetrically formed with respect to one or any or all of the mentioned symmetry planes.

Depending on the design of the lens assembly or the optical system defining the rod lens and the correction element, at least one of the first lenses and/or at least one of the second lenses may be a convex lens. Alternatively or additionally, at least one of the first lenses and/or at least one of the second lenses may be a concave lens. The second lenses may be designed identically. The first lenses may be designed identically.

High image quality can be achieved especially over a large spectral range when the lens assembly is capable of achieving optical imaging in the range of 400nm to 1000nm, which optical imaging has an RMS point radius of at most 40 μm, preferably at most 35 μm and preferably at most 30 μm. This may mean in particular that for each arbitrarily selected interval within this range having a width of at most 50nm, preferably at most 40nm, particularly preferably at most 30nm and preferably at most 20nm, the average RMS point radii are each at most 40 μm, preferably at most 35 μm and preferably at most 30 μm. This may also mean that the RMS spot radius is at most 40 μm, preferably at most 35 μm and preferably at most 30 μm for each arbitrary wavelength.

In some embodiments, the lens assembly is capable of achieving diffraction-limited optical imaging in the range of 480nm to 1000 nm. In other words, the lens assembly may be designed to enable diffraction-limited optical imaging for each arbitrary wavelength in the range of 480nm to 1000 nm. Diffraction-limited optical imaging is distinguished, inter alia, by the fact that the calculated RMS point radius is less than or equal to the value defined by the diffraction limit.

Especially in the range of 480nm to 1000nm, the lens assembly may have a maximum RMS point radius of at most 8 μm, preferably at most 6 μm and preferably at most 4 μm. In other words, the RMS spot radius may be at most 8 μm, preferably at most 6 μm and preferably at most 4 μm for each arbitrary wavelength, in particular in the range of 480nm to 1000 nm.

The inventors have also recognized that conventional lens assemblies, while sometimes having good transmission in the visible range, exhibit significantly poorer transmission in the near infrared range. Thus, the usability of such conventional lens assemblies is significantly limited, especially for multispectral and hyperspectral applications, where imaging should also be performed in the near infrared range. Particularly when the rod lens and the correction element have antireflection surfaces that function in the visible light range and the near infrared range, high-quality imaging can be achieved in a wide spectral range. In other words, the anti-reflective surface may be designed such that the transmittance outside the visible light range remains at a higher level, rather than dropping off rapidly, although a slightly lower transmittance may be acceptable than an anti-reflective surface that optimizes the transmittance only in the visible light range. The anti-reflective surface may comprise a coating of the relevant optical element, such as an anti-reflective coating. Alternatively or additionally, the surface itself of the relevant optical element may also be treated, for example roughened on a microscopic and/or nanometric scale.

It may be especially proposed that the anti-reflective surfaces each give rise to an average reflectivity in the range of 400nm to 1000nm of at most 2%, preferably at most 1% and preferably at most 0.6%. Alternatively or additionally, it may be proposed that the antireflective surfaces each give rise to a maximum reflectivity in the range of 400nm to 1000nm of at most 3%, preferably at most 2% and preferably at most 1%.

The above-mentioned anti-reflection surface may be present on at least one surface of at least one optical element of the lens assembly, for example on at least one rod lens and/or on at least one correction element, such as on at least one of these lenses. Preferably, at least a number (preferably all) of the existing surfaces are provided with an anti-reflective surface.

The lens assembly may have an average transmittance in the range 400nm to 1000nm of at least 70%, preferably at least 80% and particularly preferably at least 85%. Alternatively or additionally, the lens assembly may have a minimum transmittance in the range of 400nm to 1000nm of at least 60%, preferably at least 70% and particularly preferably at least 80%. Thus, light transmission can be achieved over a wide spectrum through the entire lens assembly, so that light can be efficiently transmitted in the visible light range and the near infrared range.

The invention also relates to an endoscope having an endoscopic device according to the invention and/or having a correction pair assembly according to the invention. In some embodiments, the endoscope is configured to be inserted into a cavity (e.g., an artificial and/or natural cavity, such as a human interior, a body organ, tissue, etc.) for examination and/or visualization. The endoscope may also be configured to be insertable into a housing, shroud, well, duct, or another (especially man-made) structure for examination and/or observation.

Furthermore, the invention relates to an imaging system, in particular a medical imaging system. The imaging system includes an illumination device configured to provide illumination light in the visible and near infrared ranges. Furthermore, the imaging system comprises an endoscopic device according to the invention and/or an endoscope according to the invention. Furthermore, the imaging system comprises an imaging device having an image detection unit configured for detecting multispectral and/or hyperspectral image data. The image detection unit may comprise an image detection sensing device.

The imaging system may be multi-modal. In particular, the imaging system may be configured for selectively acquiring white light images and/or multispectral images and/or fluorescence images and/or hyperspectral images.

The image detection sensing device may be configured to detect light in the visible light range and the near infrared range. In some embodiments, the minimum detectable wavelength may be at most 500nm, at most 450nm, or even at most 400nm. In some embodiments, the maximum detectable wavelength may be at least 800nm, at least 900nm, or even at least 1000nm. The image detection sensing means may comprise, for example, at least one white light image sensor and at least one near infrared image sensor. In some embodiments, the imaging device includes a white light camera and/or a sensing device for detecting white light images. The imaging device may be configured for white light imaging. The anatomical image may be acquired by means of a white light camera and/or a sensing device for detecting white light images.

The image detection unit may have a filter unit with an optical observation filter. The filter unit may define a plurality of fluorescence modes defined by different observation filters. For example, different edge filters may be used which absorb/block the respective used spectrum of the relevant light-emitting element for excitation and at least substantially transmit only fluorescence. The observation filter blocking light in the first spectral range is then part of the filter unit. In some embodiments, the observation filter may also switch between a multispectral mode and a fluorescence mode.

The imaging device and in particular a certain optics and/or image detection sensing device may be configured for multispectral and/or hyperspectral imaging, in particular for detecting and/or generating multispectral and/or hyperspectral image data. Multispectral imaging or multispectral image data may in particular be imaging in which at least two, in particular at least three and in some cases at least five spectral bands can be detected and/or are to be detected independently of one another. Hyperspectral imaging or hyperspectral image data can mean here in particular imaging in which at least 20, at least 50 or even at least 100 spectral bands can be detected and/or are to be detected independently of one another. The imaging device may operate according to push-broom and/or swing-broom and/or gaze and/or snapshot principles.

For some applications, it may be advantageous to use high spectral resolution. Hyperspectral imaging is then interesting. Hyperspectral imaging can be combined with white light imaging. Thus, even if the detection of the spectrally resolved image data is only performed substantially in real time (i.e., for example, creating a spectrally resolved image takes several seconds), real-time observation can be performed by a white light image. For some applications, it may be advantageous to generate spectral image data in real time. This includes, for example, generating a spectrally resolved image in less than one second or even multiple times per second. Here, it may be expedient to employ multispectral imaging. In this case, a lower spectral resolution is traded for a higher image refresh rate if necessary. Depending on the application, it may be sufficient to consider only a few different spectral ranges and/or wavelengths (e.g., two, three, four, or typically less than ten). Here, additional white light imaging may be optionally omitted. The spectrally resolved image data, which is acquired in real time or provides a plurality of images per second, may also be used for monitoring purposes, wherein it is not necessary to create playable images for the user, but the image data may also be processed in the background.

The image detection sensor device has in particular at least one image sensor. Furthermore, the image detection sensor device may also have at least two and preferably more image sensors, which may be arranged one after the other. Furthermore, the two and preferably more image detection sensors can have spectral detection sensitivities that are designed to be different from each other, so that, for example, the first sensor is particularly sensitive in the red spectral range, the second sensor is particularly sensitive in the blue spectral range, and the third sensor is relatively more sensitive than the other sensors. The image sensor may be designed, for example, as a CCD sensor and/or a CMOS sensor.

The image detection unit is especially configured for generating at least two-dimensional spatial image data. The image detection unit may have a spatial resolution such that the image detection unit provides a resolution of at least 100 pixels, preferably at least 200 pixels, preferably at least 300 pixels, and advantageously at least 400 pixels in at least two different spatial directions, respectively. The image data is preferably at least three-dimensional, wherein at least two dimensions are spatial dimensions and/or wherein at least one dimension is a spectral dimension. A plurality of spatially resolved images of the image region, which are respectively assigned to different spectral bands, can be acquired from the image data. The spatial information and spectral information of the image data may be formed in such a way that a respective spectrum is acquired for a plurality of spatial image points on the basis of this information.

In some embodiments, the image detection unit is configured for generating continuously updated image data. The image detection unit may for example be configured for generating image data substantially in real time, which for example comprises generating updated image data at least every 30 seconds, in some cases at least every 20 seconds and in some cases even at least every 10 seconds or at least every 5 seconds. Preferably, the image detection unit is configured for generating at least anatomical images and fluoroscopic images in real time and illustrations based on these images, for example at a frame rate of at least 5fps, at least 10fps, at least 20fps or even at least 30 fps.

The illumination device may be designed to be multi-modal and include a plurality of light-emitting elements independent of each other that can be selectively activated, the light-emitting elements being configured to emit light according to different emission spectra to provide illumination light.

The illumination device may include an optical interface for optically coupling to an endoscope. The lighting unit may be configured to provide illumination light to the optical interface. The lighting unit may be designed to be multi-modal and comprise a plurality of light emitting elements independent of each other, capable of being selectively activated, configured for emitting light according to different emission spectra to provide illumination light. The illumination unit may be operated in at least one multispectral mode in which the first set of light-emitting elements is at least temporarily activated, and in which the illumination unit provides illumination light for multispectral imaging. Furthermore, the illumination unit may be operated in at least one fluorescence mode in which the second group of light emitting elements is at least temporarily activated, and in which the illumination unit provides illumination light for fluorescence imaging. The light emitting elements may comprise at least one light emitting element comprised in both the first group and the second group.

Furthermore, a method of generating illumination light for an imaging device by means of an illumination device may be provided. Here, the illumination device comprises an optical interface for optically coupling the endoscope and an illumination unit configured for providing illumination light to the optical interface, wherein the illumination unit comprises a plurality of light emitting elements that are independent of each other and that can be selectively activated, the light emitting elements being configured for emitting light according to different emission spectra to provide illumination light. The method comprises the steps of at least temporarily activating a first set of light emitting elements to provide illumination light for multispectral imaging, and at least temporarily activating a second set of light emitting elements to provide illumination light for fluorescence imaging. At least one of the light emitting elements is at least temporarily activated both when the first set of light emitting elements is at least temporarily activated and when the second set of light emitting elements is at least temporarily activated.

The optical interface may be selectively disconnected and connected. Furthermore, the optical interface may be combined with a mechanical interface such that the optical connection is established, for example, automatically when the endoscope is mechanically coupled.

The light emitting element may comprise a single color LED (light emitting diode) and/or a laser diode. Furthermore, at least one of the light emitting elements may be a white LED or another white light source. In some embodiments, the lighting unit comprises at least one blue light emitting element, at least one red light emitting element, at least one dark red light emitting element and at least one near IR light emitting element (near IR light emitting element), which are in particular LEDs or laser diodes, respectively. Furthermore, the lighting unit may comprise at least one white LED or another white light source.

The first group may comprise at least two light emitting elements that emit light spectrally differently. When the multispectral mode comprises different states of a specific light-emitting element or a specific light-emitting element type, respectively, at least temporarily, high efficiency can be achieved in the case of multispectral imaging. In this way, illumination can be specifically performed in a specific spectral range, so that different spectral images can be detected. Different light emitting elements enabled in different states can be used as different support points for multispectral imaging. At least one of these support points may be selected in such a way that it is adapted to a characteristic point of the absorption spectrum of the physiologically relevant component, for example an equal absorption point of the hemoglobin oxygenation curve. Multispectral imaging may also include the use of suitable observation filters.

Furthermore, the second group may comprise at least two light emitting elements that emit light spectrally differently. The fluorescence mode may comprise different sub-modes and/or states in which a specific light emitting element or a specific light emitting element type, respectively, is at least temporarily enabled. In this way, excitation can be performed specifically in a specific spectral range, so that, for example, fluorescence imaging for a specific selected dye can be achieved. In other words, the at least one light emitting element simultaneously included in the first group and the second group may be used for both the multispectral mode and the fluorescence mode.

In some embodiments, the first group includes only some, but not all, light-emitting elements. Alternatively or additionally, in some embodiments, the second group includes only some, but not all, light emitting elements. In the multispectral mode, in particular, only the light-emitting elements of the first group are at least temporarily activated, while light-emitting elements not belonging to the first group are not activated. In the fluorescent mode, in particular only the light-emitting elements of the second group are at least temporarily activated, whereas light-emitting elements not belonging to the second group are not activated. In general, it is understood that the light emitting elements may comprise different light emitting element types and that in particular exactly one light emitting element is present in each of these different light emitting element types. It should be understood that there may also be a hybrid operating mode according to the invention, in which the modes mentioned are used in turn. For example, multispectral imaging and fluorescence imaging may be performed sequentially.

Especially when at least one light emitting element comprised in both the first and the second group emits light in the red spectral range, especially in the spectral range between 600nm and 680nm, e.g. 610nm and 650nm or 620nm and 660nm or 630nm and 670nm, a synergistic effect of using light source elements for different modes and the efficiency gains associated therewith can be achieved. The spectral range may be narrowband and the wavelength may include 660nm. A "narrow band-like" may comprise a spectral width of at most 80nm, in particular at most 40nm or even at most 20 nm. The at least one light emitting element may be configured to excite the absorbing dye in the red spectral range and provide illumination in the red spectral range for multispectral imaging.

In some embodiments, the illumination unit may operate in at least one white light mode in which the illumination unit provides illumination light for white light imaging. The illumination light for white light imaging may be broadband white light. Alternatively, the illumination light for white light imaging may include a plurality of narrow wavelength bands separated from each other, such as a blue band, a red band, and a dark red band. Herein, "dark red" should be understood in the sense of "longer than red wavelength" and refers to the spectral position, not the light intensity. The illumination light for white light imaging may be mixed by the light of different light emitting elements.

In white light mode, the third set of light emitting elements may be at least temporarily activated to provide illumination light for white light imaging. The light-emitting elements may here comprise at least one light-emitting element which is comprised in both the first group and/or the second group and the third group. In some cases, the third group may include only some, but not all, light-emitting elements. In white light mode, in particular, only the light-emitting elements of the third group are at least temporarily activated, while light-emitting elements not belonging to the third group are not activated. In other words, the lighting unit may comprise light emitting elements for one, two or all three of the above-described lighting modes. Thus, a plurality of light emitting elements can be used a plurality of times.

At least one light-emitting element comprised in the first and/or second and third group may simultaneously emit light in the red spectral range, in particular in the spectral range between 600nm and 680nm, for example 610nm and 650nm or 620nm and 660nm or 630nm and 670 nm. The advantage of using light emitting elements together is particularly pronounced when at least one red light emitting element can be used in all three modes.

At least one light-emitting element comprised in the first and/or second and third group may simultaneously emit light in the blue spectral range, in particular in the spectral range between 440nm and 480 nm. The at least one blue light emitting element may conveniently be used in both a fluorescent mode and a white light mode.

In general, as described above, the light emitting element may comprise at least one particularly blue light emitting element emitting light in a spectral range between 440nm and 480 nm. Further, as described above, the light emitting element may comprise at least one particularly red light emitting element emitting light in a spectral range between 600nm and 680nm, for example between 610nm and 650nm or between 620nm and 660nm or between 630nm and 670 nm. Alternatively or additionally, the light-emitting element may comprise at least one particularly dark red light-emitting element which emits light in the spectral range between 750nm and 790 nm. Alternatively or additionally, the light emitting element may comprise at least one especially near IR light emitting element emitting light in a spectral range between 920nm and 960 nm. Further, the light emitting element may include a white light emitting element. Particularly when there is at least one light emitting element in each of the above-described light emitting element types, respectively, a compact and versatile lighting unit can be provided. For example, in the fluorescent mode, blue and red light emitting elements may be used, and in the case where a dye is suitable, a dark red light emitting element may also be used as necessary. In the multispectral mode, dark red and near-IR luminescent light emitting elements may be used. In the white light mode, a white light emitting element may be used. In white light mode, the white light emitting element can be supplemented by a blue light emitting element and, if necessary, also a red light emitting element. In this way, the white light emitting element can be supplemented by means of the colored light emitting element, for example, by its structure, but in particular by the filters and optical elements of the lighting unit, providing a wavelength range of lower intensity. In addition, the colored light emitting element can be used to adjust the color temperature at the time of white light imaging.

In some embodiments, the second group includes a single light-emitting element and/or a single type of light-emitting element. For example, white light-emitting elements, red light-emitting elements and IR light-emitting elements can be provided, wherein reference is made in particular to the above values for the possible spectral ranges. Thus, the first group may for example comprise light emitting elements emitting red and IR light. The second group may comprise light emitting elements that emit IR light, in particular as the sole light emitting element or as the sole type of light emitting element.

An advantageous arrangement of light emitting elements may be achieved in particular when the lighting unit comprises at least one cross beam splitter by means of which light can be deflected from the opposite input side to the output side, wherein at least one of the light emitting elements is arranged at the opposite input side of the cross beam splitter, respectively. In some embodiments, two or even more crossed beam splitters may be provided, which are arranged optically one after the other. The at least one cross beam splitter may comprise two beam splitter elements, the transmissivity of which is adapted to the respective assigned light emitting element. The beam splitter elements each comprise, in particular, notch filters such that they each reflect in a narrow spectral band, rather than transmit. The spectral position and/or width of the corresponding recess may be adapted to the spectral range of the respective assigned light emitting element such that the light of that light emitting element is deflected, but the light of the other light emitting elements is at least substantially transmitted.

In some embodiments, the light emitting elements may include at least four narrowband-emitting monochromatic light emitting elements, each having a different spectral range, and at least one broadband-emitting white light emitting element. In this respect, reference is also made to the embodiments described above with respect to the colored light emitting elements.

In particular, a combination of a wide functionality, a compact construction and a fully utilized synergistic effect when using light emitting elements can be achieved when the lighting unit can be operated in at least one hyperspectral mode, in which a plurality of light emitting elements are activated, the emission spectrum of which together covers a spectral range of at least 450nm to 850nm, and in which the lighting unit provides illumination light for hyperspectral imaging. This may especially relate to all light emitting elements.

It will be appreciated that polarization filters suitable for the optical filters mentioned herein may be used, especially in the case of laser diodes. Furthermore, in particular in the case of laser diodes, at least one cross beam splitter can be used, the beam splitter element of which is provided with a polarization filter. Thus, selective transmission can be achieved by combining different polarizations.

The device and the system according to the invention and the method according to the invention should not be limited to the above-described applications and embodiments. In particular, to meet the manner of operation described herein, these devices, systems, and methods may have numbers that differ from the number of individual elements, components, and units and method steps mentioned herein. Furthermore, values within the limits mentioned in the value ranges given in this disclosure are also to be regarded as published and disposable.

In particular, it is pointed out that all the features and characteristics described in relation to the device, however also the routes, can be usefully transferred to the method and can be used in the sense of the invention and are regarded as commonly disclosed. Otherwise, the same applies. It is intended that structural features mentioned in relation to the method, i.e. device-related features, may also be considered as well, claimed and as well within the scope of the device claims.

Hereinafter, the present invention is exemplarily described with the aid of the drawings. The figures, description and claims contain combinations of features. Conveniently, the person skilled in the art may also consider these features alone and use them in combination reasonably within the scope of the claims.

If more than one example of an object is present, reference numerals are provided for only one of the examples in the drawings and the description if necessary. The description of this example may be correspondingly transferred to other examples of the object. If objects are named, inter alia, by means of words (e.g. first, second, third object, etc.), these words are used for naming and/or assigning objects. Thus, for example, a first object and a third object may be included, but no second object is included. However, with the aid of the words, it is also possible to additionally deduce the number and/or order of the objects.

In the drawings:

FIG. 1 shows a schematic illustration of an imaging system having an illumination device, an endoscope with an endoscope device, and an image detection device;

FIG. 2 shows a schematic illustration of a lens assembly of an endoscopic device according to prior art;

FIG. 3 shows a schematic illustration of line pattern imaging performed with a lens assembly according to the prior art;

FIG. 4 shows a graph of wavelength dependence on RMS point radius for a lens assembly according to the prior art;

FIG. 5 shows a schematic illustration of a first endoscopic device;

FIG. 6 shows a schematic illustration of a calibration pair assembly of the first endoscopic device;

FIG. 7 shows a chart illustrating selection of lenses for correction of a pair of components;

FIG. 8 shows a schematic illustration of a second endoscopic device;

FIG. 9 shows a schematic illustration of a calibration pair assembly of a second endoscopic device;

FIG. 10 shows a schematic illustration of a third endoscopic device;

FIG. 11 shows a schematic illustration of a calibration pair assembly of a third endoscopic device;

FIG. 12 shows a schematic illustration of line pattern imaging performed with a first endoscopic device, a second endoscopic device, or a third endoscopic device;

FIG. 13 shows a graph of wavelength dependence of RMS point radius for a first endoscopic device, a second endoscopic device, or a third endoscopic device;

FIG. 14 shows a schematic illustration of a lens assembly having an anti-reflective surface;

FIG. 15 shows a schematic graph illustrating different reflectance curves;

FIG. 16 shows a schematic graph illustrating different transmittance curves;

fig. 17 shows a schematic illustration of a lighting device 150, and

Fig. 18 shows a schematic transmission curve of a beam splitter element of an illumination device.

Fig. 1 shows a schematic illustration of an imaging system 148. The imaging system 148 is an endoscopic imaging system. The imaging system 148 may be a medical imaging system. In the present case, the imaging system 148 is a multispectral and/or hyperspectral endoscopic imaging system.

The imaging system 148 includes an illumination device 150, an endoscopic device 110, and an imaging device 152 having an image detection unit 154. The image detection unit 154 is configured to detect multispectral and/or hyperspectral image data. To this end, the image detection unit 154 includes a suitable image detection sensing device 158, which is only shown by way of example.

The image detection sensing device 158 may comprise a CMOS or CCD sensor, not shown. The image detection sensing device 158 and associated optics may be arranged in a push-broom assembly as necessary. In other embodiments, a swipe assembly, a gaze assembly, and/or a snapshot assembly are used. Different methods for hyperspectral imaging and parts required therefor are published in Journal of Biomedical Optics journal of biomedical optics 18 (10), professional articles "Review of ACHIEVEMENTS AND CHALLENGES in biomedical engineering: review of spectral imaging: achievements and challenges" at month 10 of 100901,2013 and in Journal of Biomedical Optics journal of biomedical optics 19 (1), professional articles "MEDICAL HYPERSPECTRAL IMAGING: a Review of medical hyperspectral imaging: review" at month 1 of 010901,2014.

In other embodiments, as described above, the image detection unit 154 may also be multispectral. For example, multiple spectral ranges may be observed by filters that can be selectively introduced into the object beam path and/or by sequentially illuminating at different wavelengths.

The endoscopic device 110 is part of an endoscope 146. The endoscope 146 may include a portion of an image detection unit 154. The endoscopic device 110 includes a shaft 160. Shaft 160 is configured to house a lens assembly configured to direct imaging light from endoscopic device 110 and/or distal end 162 of shaft 160 to proximal end 164 of endoscopic device 110 and/or shaft 160. This will be further discussed below. The shaft 160 may be rigid. In particular, endoscope 146 is a rigid endoscope and/or endoscope device 110 is an endoscope device for a rigid endoscope.

Fig. 2 shows a schematic illustration of a lens assembly 212 of an endoscopic device 210 according to prior art. The endoscopic device 212 includes an eyepiece 216 and an objective lens 218. The lens assembly 212 couples an eyepiece 216 to an objective lens 218 in a known manner. Light collected from objective lens 218 may be transmitted through lens assembly 212 to eyepiece 216. Thereby, imaging can be generated.

The lens assembly 212 includes a plurality of rod lenses 222. The lens assembly 212 is primarily configured to transmit and image light in the visible range (e.g., in the range of 450nm to 750 nm).

Fig. 3 shows a schematic illustration of an image of a line pattern performed with a lens assembly 212 according to the prior art. FIG. 4 shows a graph of wavelength dependence with respect to the RMS point radius of lens assembly 212. As can be seen, the RMS spot radius is small in the medium wavelength range and even below the diffraction limit plotted with the dashed line in fig. 4. If the line pattern is imaged, an image shown in the middle of fig. 3 results here in a medium wavelength range, for example for light with a wavelength of between 486nm and 656 nm. A clear line pattern image can be obtained here, since the lens assembly 212 images well within this range. However, due to lens errors, especially chromatic aberration, a clear image cannot be obtained for both smaller and larger wavelengths. Within these ranges, the RMS point diameter is significantly larger, which results in unclear imaging. This is illustrated on the left side of fig. 3, illustratively for a wavelength range of 400nm to 500nm, and on the right side, illustratively for a wavelength range of 800nm to 1000 nm. In particular in the near infrared range, i.e. in the last-mentioned range, the imaging quality is rather low and thus the geometric features cannot be imaged precisely.

Accordingly, the conventional endoscope apparatus 210 is mainly applied to the visible light range. If the endoscopic device is used for white light imaging, for example, roughly corresponding to a combination of the cases on the left side and in the middle of fig. 3, the imaging quality may be sufficient. However, if imaging is also to be performed in the near infrared, the quality may not be sufficient to obtain convincing image data from which, for example, anatomical features of the examined anatomy of the patient cannot be assessed.

Fig. 5 shows a schematic illustration of a first endoscopic device 110 according to the present disclosure. The first endoscope apparatus 110 may be used in the visible light range and the near infrared range. The endoscopic device 110 includes a lens assembly 112, an eyepiece 116, and an objective lens 118. Here, they are arranged in the shaft 160 shown in fig. 1. The lens assembly 112 optically couples the eyepiece 116 to the objective lens 118. Thus, light may be substantially equivalently transmitted and imaged through the lens assembly 112, at least in the range between 480nm and 1000nm, preferably in the range between 400nm and 1000 nm.

The lens assembly 112 includes six rod lenses 122. In addition, the lens assembly 112 includes two correction elements 124. The lens assembly 112 defines an optical axis 114. The rod lens 122 and the correction element 124 are coaxially arranged about the optical axis 114. In the illustrated case, the rod lens 122 and the correction element 124 each have a circular cross-section centered on the optical axis 114.

The lens assembly 112 is symmetrical about a first plane of symmetry 120. The first plane of symmetry 120 is perpendicular to the optical axis 114.

The two correction elements 124 are part of or constitute a correction pair assembly 134. The two correction elements 124 of the correction pair assembly 134 are symmetrical to each other about a second plane of symmetry 136. In this embodiment, the second plane of symmetry 136 corresponds to the first plane of symmetry.

The correction assembly 134 is shown in more detail in fig. 6. Each of the correction elements 124 of the correction pair assembly 134 includes a first lens 130, a second lens 132, and a third lens 142. These lenses form a lens triplet. The first lens 130, the second lens 132, and the third lens 142 are integrally formed, for example, by adhesion and/or optical bonding. Together they form a lens system 128.

The first lens 130 is made of a first optic and the second lens 132 is formed of a second optic. The first lens and the second lens are selected in such a way that they deviate from lenses with normal dispersion in the opposite way. This is schematically shown in fig. 7. Fig. 7 shows a graph plotting the relative partial dispersion P _g,F as a function of the abbe number v _d. The solid lines define those points where lenses with normal dispersion are located. For this purpose, reference is made in particular to the embodiments described above with respect to lenses having normal and anomalous dispersions. In this diagram, the first lens and the second lens are located at the positions shown by the two black dots in fig. 7. The first lens is located to the right of the line with a larger abbe number and is offset in a first direction from a lens having normal dispersion. The second lens is located to the left of the line with a smaller abbe number and is offset from the lens with normal dispersion in a second direction opposite to the first direction.

For example, the first lens has an abbe number v _d of 63.66, a refractive index n _D of 1.61800, and a dispersion n _F-n_C of 0.009758. For example, the second lens has an abbe number v _d of 42.41, a refractive index n _D of 1.63775, and a dispersion n _F-n_C of 0.015038. Thus, the two lenses are intentionally chosen to be different and are intentionally offset from normal dispersion in the opposite manner. Thus, the lens assembly 112 can provide high quality imaging over a wide spectral range.

In the present embodiment, the third lens 142 is also made of the first lens.

The first lens 130 is a concave lens. The second lens 132 is a convex lens. The third lens 142 is a concave lens. Illustratively, the first lens 130 has a radius of curvature of-6 mm. Further, the second lens 132 has a radius of curvature of 6mm, for example. Further, the third lens 142 has a radius of curvature of 90mm, for example.

The correction pair assembly 134 has an aperture 144, which is arranged in the region of the second plane of symmetry 136. The aperture 144 has a smaller diameter than the rod lens 112 and the correction element 124.

Fig. 8 shows a schematic illustration of a second endoscopic device 110' according to the present disclosure. In order to be able to distinguish better, the reference numerals of this embodiment are provided with quotation marks. Unless otherwise indicated, reference is also made to the above statements in principle to existing components. The second endoscopic device 110' may be used in the visible light range and the near infrared range. The second endoscopic device 110 "includes a lens assembly 112', an eyepiece 116', and an objective lens 118'. Here, they are arranged in the shaft 160 shown in fig. 1. Lens assembly 112' optically couples eyepiece 116' to objective lens 118'. Thus, light may be substantially equivalently transmitted and imaged through the lens assembly 112' at least in the range between 480nm and 1000nm, preferably in the range between 400nm and 1000 nm.

The lens assembly 112 'includes ten rod lenses 122'. In addition, the lens assembly 112 'includes six correction elements 124'. Lens assembly 112 'defines an optical axis 114'. The rod lens 122' and the correction element 124' are coaxially arranged about the optical axis 114'. In the illustrated case, the rod lens 122' and the correction element 124' each have a circular cross-section centered on the optical axis 114'.

The lens assembly 112 'is symmetrical about a first plane of symmetry 120'. The first plane of symmetry 120 'is perpendicular to the optical axis 114'.

Two of these correction elements 124 'are part of or constitute the correction pair assembly 134'. The two correction elements 124' of the correction pair assembly 134' are symmetrical to each other about a second plane of symmetry 136 '. In this embodiment, the second plane of symmetry 136' corresponds to the first plane of symmetry.

The other two pairs of correction elements 124' form the other two correction pair assemblies 138', 168', respectively. The other two pairs of correction elements are symmetrical to each other about the third plane of symmetry 140 'and the fourth plane of symmetry 166', respectively. The third plane of symmetry 140' and the fourth plane of symmetry 166' are perpendicular to the optical axis 114', respectively.

The two additional correction pair assemblies 138", 168" are symmetrically arranged and/or formed about the first plane of symmetry 120 ". Further, as described above, the correction pair assembly 134 "is symmetrical about the first plane of symmetry 120". Thus, in this embodiment, the six correction elements 124 "are symmetrically arranged about the first plane of symmetry 120".

The correction pair assembly 134' is shown in more detail in fig. 9. Each of these correction elements 124 'of the correction pair assembly 134' includes a first lens 130 'and a second lens 132'. The first lens 130 'and the second lens 132' are integrally formed, for example, by adhesion and/or optical bonding. Together they form a lens system 128'.

The first lens 130 'is made of a first optic and the second lens 132' is formed of a second optic. The first lens and the second lens are selected in such a way that they deviate from lenses with normal dispersion in the opposite way. In this regard, reference is made again to fig. 7.

For example, the first lens has an abbe number v _d of 42.41, a refractive index n _D of 1.63775, and a dispersion n _F-n_C of 0.015038. For example, the second lens has an abbe number v _d of 63.33, a refractive index n _D of 1.61800, and a dispersion n _F-n_C of 0.009758. Thus, the two lenses are intentionally chosen to be different and are intentionally offset from normal dispersion in the opposite manner. Thus, the lens assembly 112' can provide high quality imaging over a wide spectral range.

The first lens 130' is a convex lens. The second lens 132' is a concave lens. Illustratively, the first lens 130' has a radius of curvature of 12 mm. Further, the second lens 132' illustratively has a radius of curvature of-4.8 mm.

The correction pair assembly 134' has an aperture 144' which is arranged in the region of the second plane of symmetry 136 '. The aperture 144' has a smaller diameter than the rod lens 112 and the correction element 124.

In the present embodiment, the correction elements 124 'are formed integrally with the rod lenses 122', respectively. For example, the correction element is glued and/or optically bonded to the particularly planar end face of the associated rod lens 122'.

On the side opposite to the respective correction element 124', a further lens 172' is arranged, which is part of the rod lens 122 '. The additional lens is glued and/or optically bonded to the substrate of the rod lens 122'. In the present case, the base body of the rod lens 122' is made of a lens having an abbe number v _d of 50.19 and a refractive index n _D of 1.62658. The base of the rod lens 122' has a flat end surface. The further lens 172' is made of a lens having an abbe number v _d of 49.34, a refractive index n _D of 1.74320 and a dispersion n _F-n_C of 0.015063. The further lens 172' is a concave lens and has an exemplary radius of curvature of 13.7 mm.

Fig. 10 shows a schematic illustration of a third endoscopic device 110 "according to the present disclosure. In order to be able to distinguish better, the reference numerals of this embodiment are provided with two quotation marks. Unless otherwise indicated, reference is also made to the above statements in principle to existing components. The third endoscopic device 110″ may be used in the visible light range and the near infrared range. The third endoscopic device 110 "includes a lens assembly 112", an eyepiece 116", and an objective lens 118". Here, they are arranged in the shaft 160 shown in fig. 1. Lens assembly 112 "optically couples eyepiece 116" to objective lens 118". Thus, light may be substantially equivalently transmitted and imaged by the lens assembly 112″ at least in the range between 480nm and 1000nm, preferably in the range between 400nm and 1000 nm.

The lens assembly 112 "includes six rod lenses 122". In addition, lens assembly 112 "includes four correction elements 124". Lens assembly 112 "defines an optical axis 114". The rod lens 122 "and the correction element 124" are coaxially arranged about the optical axis 114". In the illustrated case, the rod lens 122 "and the correction element 124" each have a circular cross-section centered on the optical axis 114".

The lens assembly 112 "is symmetrical about a first plane of symmetry 120". The first plane of symmetry 120 "is perpendicular to the optical axis 114".

Two of these correction elements 124 "are part of or constitute the correction pair assembly 134". The two correction elements 124 "of the correction pair assembly 134" are symmetrical to each other about a second plane of symmetry 136 ". The second plane of symmetry 136 "is different from the first plane of symmetry 120". The second plane of symmetry 136 "is perpendicular to the optical axis 114".

The other two of these correction elements 124 "are part of or constitute an additional correction pair assembly 138". The two correction elements 124 "of the further correction pair assembly 138" are symmetrical to each other about a third plane of symmetry 140 ". The third plane of symmetry 140 "is different from the first plane of symmetry 120" and different from the second plane of symmetry 136". The third plane of symmetry 140 "is perpendicular to the optical axis 114".

The correction pair assembly 134 "and the further correction pair assembly 138" are symmetrically arranged and/or formed about the first plane of symmetry 120 ". In this embodiment, it can be provided that no correction pair component is present in the region of the first plane of symmetry 120″.

The correction pair assembly 134 "is shown in more detail in fig. 11. Each of the correction elements 124 "of the correction pair assembly 134" includes a first lens 130", a second lens 132", and a third lens 142". These lenses form a lens triplet. The first lens 130", the second lens 132", and the third lens 142 "are integrally formed, for example, by adhesive and/or optical bonding. Together they form a lens system 128".

The first lens 130 "is made of a first optic and the second lens 132 is formed of a second optic. The first lens and the second lens are selected in such a way that they deviate from lenses with normal dispersion in the opposite way. In this regard, reference is made again to fig. 7.

For example, the first lens has an abbe number v _d of 59.71, a refractive index n _D of 1.53996, and a dispersion n _F-n_C of 0.009120. For example, the second lens has an abbe number v _d of 63.33, a refractive index n _D of 1.61800, and a dispersion n _F-n_C of 0.009758. Thus, the two lenses are intentionally chosen to be different and are intentionally offset from normal dispersion in the opposite manner. Thus, the lens assembly 112 "can provide high quality imaging over a wide spectral range.

In the present embodiment, the third lens 142″ is made of a third lens different from the first lens and the second lens. For example, the third lens has an abbe number v _d of 47.11, a refractive index n _D of 1.67003, and a dispersion n _F-n_C of 0.014380.

The first lens 130 "is a convex lens. The second lens 132 "is a concave lens. The third lens 142″ is a convex lens. Illustratively, the first lens 130 "has a radius of curvature of 8.5 mm. Further, the second lens 132″ has a radius of curvature of-7.8 mm, by way of example. Further, the third lens 142″ has a radius of curvature of 82mm, by way of example.

The correction pair assembly 134 "has an aperture 144" that is disposed in the region of the second plane of symmetry 136 ". The aperture 144 "has a smaller diameter than the rod lens 112" and the correction element 124".

In the present case, no apertures are arranged in the region of the further correction pair assembly 138″. However, in other embodiments, instead of or in addition to the aperture 144' of the first correction pair assembly 134", an aperture is arranged in the region of the further correction pair assembly 138".

Fig. 12 shows a schematic illustration of line pattern imaging performed with the first endoscopic device 110, the second endoscopic device 110', or the third endoscopic device 110 ". In comparison to the line pattern imaging performed with the lens assembly according to the prior art described above, a relatively sharp line pattern imaging can be achieved in the entire spectral range between 400nm and 100 nm. By a combination of appropriately selected lenses and a design and arrangement of correction elements or correction pairs components, high quality imaging over a wide spectral range is achieved.

Fig. 13 shows a graph of wavelength dependence of RMS point radius for a first endoscopic device 110, a second endoscopic device 110', or a third endoscopic device 110 ". The diffraction limit is plotted as a dashed line. As can be seen, the RMS point diameter is below the diffraction limit in at least one range between 480nm and 1000 nm. At the blue edge in the range 400nm to 1000nm, the RMS spot diameter increases but is less than 25 μm. It follows that the high quality imaging of the line pattern shown in fig. 12 is obtained for different spectral ranges.

Fig. 14 shows a schematic illustration of a lens assembly 112 having an anti-reflective surface 170. Such an anti-reflective surface 170 may be used in any of the embodiments described above. Fig. 15 shows a schematic graph illustrating different reflectivity curves. These two dashed lines illustrate conventional coatings that are optimized to function in the visible range or slightly beyond. Although lower reflectivity can be achieved in the visible range, reflectivity rises sharply in the red or near infrared range. Such an anti-reflective surface is only conditionally suitable for multispectral imaging, hyperspectral imaging, combined white light imaging and fluorescence imaging or other imaging that should be able to image in a broad spectral range.

This can be seen in particular also from fig. 16, which shows a schematic diagram illustrating different transmittance curves. These transmittance curves were calculated for a lens assembly that illustratively included 30 surfaces. These surfaces are each provided with an anti-reflection surface which exhibits a reflectivity curve shown in dashed lines in fig. 15. Due to the large number of surfaces, losses at the respective surfaces accumulate and the transmittance drops rapidly in the red or near infrared range.

In contrast, anti-reflective surfaces may be used in the endoscopic devices 110, 110', 110″ described above, which are characterized by the curves illustrated in solid lines in fig. 15 and 16. It can be seen that here, in the range between 400nm and 1000nm, the reflectivity may be higher than the value of the surface optimized for the visible range, but at a lower level over the whole range. Specifically, the reflectance is at most 1% over the entire range. This results in a transmittance here again at a higher level over the entire range of at least 75%.

As mentioned above, these endoscopic devices have significant advantages, especially when the endoscopic devices 110, 110', 110 "are used for imaging in which a broad spectral range is observed, or at least a range of wavelengths distributed over a broad spectral range is observed. It may therefore be convenient to use a lighting device 150, preferably multi-modal, that is applicable in a broadband situation. This is described in exemplary detail below. However, it should be understood that the endoscopic devices 110, 110', 110 "may also be combined with other suitable illumination devices.

As described above, the lighting device 150 may be multi-modal. The illumination device 150 may operate in different illumination modes in which the illumination device provides light for different imaging modes. Here, the illumination device 150 may operate in three basic modes, i.e., a multispectral mode, a fluorescent mode, and a white light mode. Likewise, the imaging device 152 may be operated in different modes of operation, in particular also at least in a multispectral mode, a fluorescent mode and a white light mode. In the corresponding operating mode of the imaging device 152, the modes of the illumination device 150 match each other.

Fig. 17 shows a schematic illustration of a lighting device 150. The lighting unit 18 comprises a plurality of light emitting elements 20, 22, 24, 26, 28 that can be activated independently of each other. The light emitting elements are configured to emit light according to different emission spectra to provide illumination light, i.e. the respective emission spectra differ between the light emitting elements.

The light-emitting elements 20, 22, 24, 26, 28 are designed as LEDs, for example. Specifically, the first light emitting element 20 is designed as a red LED, the second light emitting element 22 as a dark red LED, the third light emitting element 24 as a blue LED, and the fourth light emitting element 26 as a near IR-LED. The colored light emitting elements 20, 22, 24, 26 emit light in narrow bands, for example, emission peaks at approximately wavelengths 660nm (first light emitting element 20), 770nm (second light emitting element 22), 460nm (third light emitting element 24), and 940nm (fourth light emitting element 26), respectively.

Furthermore, a fifth light-emitting element 28 is provided, which is here a white light-emitting element, for example a white light LED. The fifth light emitting element 28 emits light in a spectral range of about 400nm to 700nm, for example. In other embodiments, laser diodes may also be used, particularly as colored light emitting elements.

Depending on the illumination pattern, some of the light emitting elements 20, 22, 24, 26, 28 are at least temporarily activated, while other light emitting elements 20, 28, 24, 26, 22 may not be used in the respective illumination pattern.

Here, the first group includes the first light emitting element 20 and the fourth light emitting element 26. The first group may also include light-emitting elements 22 and/or light-emitting elements 24. The first group is for multispectral imaging, in which the light-emitting elements 20, 26 and, if necessary, 22 and 24 contained therein are used as support points, respectively. In the multispectral mode, for example, the first light-emitting element 20 is first used to illuminate and capture an image. Then, the fourth light emitting element 26 is used to illuminate and collect an image. These images are based on reflection, i.e. the observation of light reflected back by the object to be imaged, respectively. By means of these two different support points, spectroscopic information about the object to be imaged can be acquired. For example, a particular tissue type, perfusion status, tissue structure, etc. may be evaluated in this manner.

Further, the second group includes a first light emitting element 20, a second light emitting element 22, and a third light emitting element 24. The second group is used for illumination during fluorescence imaging. In this case, for example, objects colored with appropriately selected dyes can be observed in a targeted manner. It is also possible to introduce different dyes into different tissue types or the like that are observed simultaneously. By specifically exciting a specific dye, the dye is excited to fluoresce. Fluorescence is then imaged. The first light emitting element 20 is for example suitable for exciting cyanine 5.5 (Cy 5.5) dyes. The second light emitting element 22 is adapted to excite indocyanine green (ICG) dyes. The third light emitting element 24 is adapted to excite a fluorescein dye.

Further, the third group includes a fifth light emitting element 28. In the present embodiment, the third group further includes the first light emitting element 20 and the third light emitting element 24. The third group is used to provide illumination for white light imaging. For this purpose, the white light of the fifth light-emitting element 28 can be mixed with the light of a specific colored light-emitting element, so that spectral losses can be compensated and/or the color temperature can be specifically adjusted.

It can be seen that some of the light emitting elements 20, 22, 24, 26, 28 are assigned to groups, illustratively a first light emitting element 20 is assigned to all three groups and a third light emitting element 24 and, if necessary, a second light emitting element 22 is assigned to the second and third groups.

Alternatively or additionally, it may also be proposed that some or all of the light emitting elements 20, 22, 24, 26, 28 are applied in hyperspectral mode. Then, a broad excitation spectrum is generated. Thus, in combination with a suitable hyperspectral detector, spectral information about the object to be imaged can be detected over the entire visible spectrum and the near IR spectrum. To this end, the imaging device 14 may include a push broom assembly as a hyperspectral detector. In other embodiments, a swipe assembly, a gaze assembly, and/or a snapshot assembly are used. The imaging device 14 may be a hyperspectral imaging device. Different methods for hyperspectral imaging and parts required therefor are published in Journal of Biomedical Optics journal of biomedical optics 18 (10), professional articles "Review of ACHIEVEMENTS AND CHALLENGES in biomedical engineering: review of spectral imaging: achievements and challenges" at month 10 of 100901,2013 and in Journal of Biomedical Optics journal of biomedical optics 19 (1), professional articles "MEDICAL HYPERSPECTRAL IMAGING: a Review of medical hyperspectral imaging: review" at month 1 of 010901,2014.

The illumination unit 18 comprises two crossed beam splitters 30, 32. These cross beam splitters comprise an output side 42, 44, an input side 37, 41 opposite the output side 42, 44, and two input sides 34, 36, 38, 40 opposite each other, respectively. All input sides 34, 36, 37, 38, 40, 41 direct incident light to corresponding output sides 42, 44. The output side 42 of the first crossover beam splitter 30 is oriented toward the input side 41 of the second crossover beam splitter 32. The output side 44 of the second crossover beam splitter 32 is directed toward the optical interface 16. The two cross beam splitters 30, 32 are preferably arranged coaxially to each other and/or coaxially to the optical interface.

The illumination unit 18 may comprise suitable optical elements, such as lenses and/or mirrors not shown. Illustratively, a plurality of lenses 78, 80, 82, 84, 86, 88 are shown in fig. 17. For example, a lens 78 is assigned to the optical interface 16 and couples light from the output side 44 of the second cross beam splitter 32 into the optical interface 16. Furthermore, one lens 80, 88, 84, 86, 82 may be assigned to each of the light emitting elements 20, 22, 24, 26, 28, respectively. Particularly high compactness can be achieved in particular if the light-emitting elements 20, 28, 24, 26, 22 are each arranged without a mirror in between on the input side 34, 40, 37, 38, 36 of the at least one cross beam splitter 30, 32. The light emitting elements 20, 22, 24, 26, 28 may then be very close to the at least one crossed beam splitter 30, 32.

The crossed beam splitters 30, 32 include two beam splitter elements 90, 92, 94, 96, respectively. These beam splitter elements may in principle be partially transparent such that light from all input sides 34, 36, 37, 38, 40, 41 is deflected to the respective output sides 42, 44. In this embodiment, the beam splitter elements 90, 92, 94, 96 are selectively light transmissive. This is further elucidated with reference to fig. 3. The beam splitter elements 90, 92, 94, 96 may be filters that reflect only within a defined range, while having high transmittance in other ranges. In fig. 18, transmission curves 98, 100, 102, 104 of the beam splitter elements 90, 92, 94, 96 of the two crossed beam splitters 30, 32 are shown. Each of the colored light emitting elements 20, 22, 24, 26 or each of the opposing input sides 34, 36, 38, 40 is assigned one of the beam splitter elements 90, 92, 94, 96. The beam splitter elements 90, 92, 94, 96 are here selected in such a way that they each reflect in the wavelength range of the light emitted by the assigned light-emitting element 20, 22, 24, 26, but in addition are substantially transmissive. To this end, notch filters may be used in the medium wavelength range, which may illustratively have transmission spectra 100 and 102. At the spectral edges, instead of notch filters, high-pass or low-pass filters may also be used, see transmission spectra 98 and 104.

The light of the fifth light emitting element 28 is spectrally cut down due to the specific transmission spectra 98, 100, 102, 104 of the crossed beam splitters 30, 32. The light blocked by the beam splitters 30, 32 can thus be expediently supplemented in the manner already mentioned by means of the light-emitting elements 20 and 24 (and if necessary 22 and/or 26). This can be supplemented in particular by the fact that the beam splitters 30, 32 absorb and/or reflect light of the fifth light-emitting element 28 in these spectral ranges, but do not transmit to the optical interface 16 in any case. The complementary light-emitting elements 20, 24 and, if appropriate, 22 are preferably operated at a low power or at an adapted power. Here, the purpose may be to at least substantially restore the original spectrum of the fifth light emitting element 28.

In some embodiments, the fifth light-emitting element 28 may alternatively be a green light-emitting element, or in general, a colored light-emitting element that emits light primarily in the spectral range transmitted by the at least one beam splitter 30, 32. For example, in such an embodiment, the fifth light emitting element 26 may be an LED having a light emission peak at about 530 nm. For this purpose, green laser diodes are also taken into account. It can be provided here that in white light mode color mixing is possible and that, in particular, rather than using a separate white light source (e.g. a white light LED), white light is produced by targeted mixing of the individual light-emitting elements.

It will be appreciated that such green light emitting elements may also be used in fluorescence mode in the case of suitable dyes. Alternatively or additionally, it may be used in a multispectral mode.

The lighting units 18 define a common light path 54 into which light emitted by the light emitting elements 20, 22, 24, 26, 28 can be coupled. The common optical path 54 extends from the output side 44 of the second crossover beam splitter 32 to the optical interface. Here, the common light path 54 is arranged coaxially with the fifth light emitting element 26.

In the embodiment shown, the light-emitting elements 20, 26 of the first group are arranged such that light emitted from the light-emitting elements 20, 26 originates from the respective light-emitting element 20, 26 until the optical interface 16 accordingly passes through an at least substantially equidistant optical path. The light emitting elements 20, 26 of the first group each have a light emitting surface 56, 58. The light emitting surfaces 56, 62 are equidistantly arranged about the common light path 54. This is achieved in that the two light-emitting elements 20, 26 are arranged at equal distances from their assigned beam splitter 32 (here, the second beam splitter 32 is illustrated in the example), in particular at equal distances from the opposite input sides 38, 40 of the beam splitter. Here, the light is coupled from the cross beam splitter 32 into a common light path 54.

The beam splitters 30, 32 are in particular arranged such that the light emitting surfaces 56, 64, 26, 28, 58 of the light emitting elements 20, 22, 24, 60, 62 are arranged equidistantly with respect to their assigned cross beam splitters 30, 32, respectively.

By using crossed beam splitters 30, 32, the lighting unit 18 or the lighting device 12 has a high degree of compactness with respect to the light emitting elements 20, 22, 24, 26, 28 that can be used together for different modes. Furthermore, by equidistant placement it is achieved that no spectral shift occurs when the imaging device 14 or its light guide is rotated relative to the optical interface 16.

It will be appreciated that a different number of light emitting elements 20, 22, 24, 26, 28 and/or a different number of crossed beam splitters 30, 32 may be used. The use of crossed beam splitters 30, 32 has proven to be particularly convenient. However, in other embodiments, other types of beam splitters and/or other optical elements may be used in order to couple light of the light emitting elements 20, 22, 24, 26, 28 into the optical interface 16.

List of reference numerals

110. Endoscope apparatus

112. Lens assembly

114. Optical axis

116. Eyepiece lens

118. Objective lens

120. A first plane of symmetry

122. Rod lens

124. Correction element

126. Optical system

128. Lens system

130. First lens

132. Second lens

134. Correction assembly

136. Second plane of symmetry

138. Correction assembly

140. Third plane of symmetry

142. Third lens

144. Orifice

146. Endoscope with a lens

148. Imaging system

150. Lighting device

152. Image forming apparatus

154. Image detection unit

156. Display device

158. Image detection sensing device

160. Shaft lever

162. Distal end

164. Proximal end

166. Fourth plane of symmetry

168. Correction assembly

170. Antireflection surface

172. Lens

Claims (22)

1. An endoscopic device (110), in particular an endoscopic device for hyperspectral and/or multispectral imaging, comprising a lens assembly (112), the lens assembly defining an optical axis (114) and being configured for optically coupling an eyepiece (116) to an objective lens (118), wherein the lens assembly (112) is configured for achieving substantially equivalent light transmission and imaging for a given focus over a majority of the visible light range and in the near infrared range, wherein the lens assembly (112) is symmetric about a first symmetry plane (120) perpendicular to the optical axis (114), and wherein the lens assembly (112) comprises: at least six rod lenses (122); At least two correcting elements (124), which together with the rod lens (122) define an optical system (126), and each of the correcting elements includes a lens system (128) having at least a first lens (130) and a second lens (132), wherein the first lens (130) is made of a first lens and the second lens (132) is made of a second lens, wherein the first lens and the second lens have different Abbe numbers, and wherein the relative partial dispersion of the first lens and the relative partial dispersion of the second lens deviate from a lens with normal dispersion in opposite ways; and at least one correcting pair assembly (134), which includes two correcting elements in the correcting element (124), and the two correcting elements are symmetrical to each other about a second symmetry plane (136) perpendicular to the optical axis (114). 2. The endoscopic device (110) according to claim 1, wherein the first plane of symmetry (120) and the second plane of symmetry (136) are consistent. 3. An endoscopic device (110) according to claim 1 or 2, wherein the lens assembly (112) includes at least one additional correction pair assembly (138), wherein the additional correction pair assembly (138) includes two additional correction elements in the correction element (124), and the two additional correction elements are symmetrical to each other about a third symmetry plane (140) perpendicular to the optical axis (114). 4. The endoscopic device (110) according to claim 3, wherein the second symmetry plane (136) and the third symmetry plane (140) are different from the first symmetry plane (120). 5. The endoscopic device (110) according to one of the preceding claims, wherein the correction elements (124) each comprise at least a third lens (142), which is made of the first lens. 6. The endoscopic device (110) according to one of the preceding claims, wherein the correction elements (124) are each formed integrally with the rod lenses (122). 7. The endoscopic device (110) according to one of the preceding claims, wherein the calibration pair component (134) comprises at least one opening (144) which is arranged in the region of the second plane of symmetry (136). 8. The endoscopic device (110) according to one of the preceding claims, wherein the second lens (132) is a convex lens. 9. The endoscope device (110) according to any one of claims 1 to 7, wherein the second lens (132) is a concave lens. 10. The endoscopic device (110) according to one of the preceding claims, wherein the lens assembly (112) is capable of optical imaging in the range of 400nm to 1000nm, the optical imaging having an RMS spot radius of at most 40μm, preferably at most 35μm and preferably at most 30μm. 11. The endoscopic device (110) according to any of the preceding claims, wherein the lens assembly (112) is capable of diffraction-limited optical imaging in the range of 480 nm to 1000 nm. 12. The endoscopic device (110) according to one of the preceding claims, wherein the lens assembly (112) has a maximum RMS spot radius of at most 8 μm, preferably at most 6 μm and preferably at most 4 μm. 13. The endoscopic device (110) according to one of the preceding claims, wherein the rod lens (122) and the correction element (124) have antireflection surfaces (164) which are effective in the visible light range and the near infrared range. 14. The endoscopic device (110) according to claim 13, wherein the anti-reflection surfaces (164) each cause an average reflectivity of at most 2%, preferably at most 1% and preferably at most 0.6% in the range of 400 nm to 1000 nm. 15. The endoscopic device (110) according to claim 13 or 14, wherein the anti-reflection surface (164) each causes a maximum reflectivity of at most 3%, preferably at most 2% and preferably at most 1% in the range of 400 nm to 1000 nm. 16. The endoscopic device (110) according to one of the preceding claims, wherein the lens assembly has an average transmission in the range of 400 nm to 1000 nm of at least 70%, preferably at least 80% and particularly preferably at least 85%. 17. The endoscopic device (110) according to one of the preceding claims, wherein the lens assembly has a minimum transmittance in the range of 400 nm to 1000 nm of at least 60%, preferably at least 70% and particularly preferably at least 80%. 18. The endoscopic device (110) according to one of the preceding claims, further comprising the eyepiece (116) and/or the objective lens (118). 19. A correction pair assembly (134) for a lens assembly (112) for an endoscope (146), the correction pair assembly comprising at least two correction elements (124), the correction elements defining an optical axis (114) and being configured to define an optical system (126) together with a plurality of rod lenses (122), and the correction elements each comprising a lens system (128) having at least a first lens (130) and a second lens (132), wherein the first lens (130) is made of a first lens and the second lens (132) is made of a second lens, wherein the first lens and the second lens have different Abbe numbers, and wherein the relative partial dispersions of the first lens and the second lens deviate in opposite ways from a lens having normal dispersion; wherein the correction elements (124) are symmetrical to each other about a symmetry plane (120, 132, 140, 166) perpendicular to the optical axis. 20. The calibration pair assembly (134) according to claim 19, further comprising an orifice (144) which is arranged in the region of the symmetry plane (120). 21. An endoscope (146) having an endoscopic device (110) according to one of claims 1 to 18 and/or a correction pair assembly (134) according to claim 19 or 20. 22. An imaging system (148), comprising: an illumination device (150), configured to provide illumination light in the visible light range and the near infrared range; an endoscopic device (110) according to one of claims 1 to 18 and/or an endoscope (146) according to claim 21; and an imaging device (152), the imaging device having an image detection unit (154), configured to detect multispectral and/or hyperspectral image data.