CN209689751U - Fast illuminated spectrum imaging system based on micro reflector array - Google Patents

Abstract

The utility model discloses a snapshot type spectral imaging system based on a micro-mirror array. After the light from the object at infinity passes through the front imaging objective lens, the image is divided into a series of long and narrow rectangular sub-images by the micro-mirror array located at its focal plane. The direction is periodic, and a single period is composed of a series of rectangular concave spherical mirror arrays. Each concave spherical mirror has a two-dimensional rotation angle around the spatial dimension direction and the spectral dimension direction. The micromirror array simultaneously converges the incident The beam diverges, and then the divergent beam is collimated by the collimator to generate a pupil array, corresponding to each sub-pupil, and the corresponding spectroscopic imaging mirror group is set behind the collimator to obtain the two-dimensional spatial information and spectral information. The spectral imaging system provided by the utility model realizes the acquisition of a complete data cube of an object in one exposure, and is suitable for monitoring fast-changing and moving objects.

Description

Snapshot Spectral Imaging System Based on Micromirror Array

technical field

The utility model relates to the technical field of spectral imaging, in particular to a snapshot type spectral imaging system based on a microreflector array, which can be applied to the monitoring field of rapidly changing scenes and moving targets.

Background technique

Spectral imaging technology combines traditional imaging technology with spectral technology, and can simultaneously obtain spatial information and spectral information of objects, that is, the data cube of objects. a wide range of applications.

At present, push-broom spectral imaging instruments are widely used in spaceborne or airborne earth observation equipment. This type of instrument obtains spatial dimension information and spectral information in one direction under a single exposure, or obtains spatial dimension information in a second direction by means of the movement of a satellite platform or the flight along the track of an aircraft. The scanning motion of this type of instrument itself has high requirements on the accuracy and stability of the motion platform or scanning parts on which it is located, and is easily affected by the external environment, which increases the difficulty of instrument development. Due to the need for pushbrooming, the instrument itself cannot acquire a complete data cube within a single exposure. When such instruments acquire spectral information and images of fast-changing scenes and moving targets, the time required for the push-broom process makes it difficult to accurately acquire target images and spectral information.

In 2009, Tomasz S. Tkaczyk and others from the School of Bioengineering of Rice University in the United States proposed an image mapping spectral imaging technology, but the key device image mapper used in this technology is composed of a series of planar mirrors, and requires The objective lens is a telecentric system, which is not conducive to the miniaturization of the system volume.

Contents of the invention

Aiming at the deficiencies in the prior art, the utility model proposes a snapshot spectral imaging system that has no moving parts and can accurately acquire image information and spectral information of rapidly changing scenes or moving objects.

In order to achieve the purpose of the above invention, the technical solution adopted by the utility model is to provide a snapshot spectral imaging system based on a micro-mirror array, which includes a front imaging objective lens, a micro-mirror array, a collimating mirror, an array of light-splitting elements, an imaging mirror array and image plane; the micromirror array has periodicity in the spectral dimension direction, and a single period is composed of several sub-reflectors, the sub-reflectors are rectangular concave spherical reflectors, and the length of the concave spherical reflector is 10 ～30mm, width 60μm～160μm; each concave spherical mirror has a two-dimensional rotation angle around the direction of the space dimension and the direction of the spectrum dimension, the rotation angle around the direction of the space dimension is -10°～10°, and the rotation angle around the direction of the spectrum dimension The angle is -10°～10°, the two-dimensional rotation angles of each concave spherical mirror in a single cycle are different, and the two-dimensional rotation angles of the corresponding concave spherical mirrors in different cycles are the same; the front objective lens of the spectral imaging system The exit pupil is located at the focal point of the concave spherical mirror behind the lens group. After the incident light passes through the front imaging objective lens, the image is divided into a series of long and narrow rectangular sub-images by the micro-mirror array, and the incident light The converging beam diverges, the collimating mirror collimates the diverging beam, and then the beam is dispersed by the beam splitting element array to generate beams of different wavelengths, and the dispersed beam is imaged on the image plane by the imaging mirror array.

In the technical solution of the utility model, the front objective lens may be a transmission system or a reflection system; the collimating mirror may also be a transmission system or a reflection system.

Described light-splitting element array is made up of light-splitting element consistent with the number of sub-reflectors in the micro-mirror array and the array arrangement, and the light-splitting element is a prism or a grating; The number of mirrors and the array arrangement of imaging mirrors are consistent.

In a single period of the micro-mirror array, the number of sub-mirrors forming the array is 16-100; the number of sub-mirrors in the micro-mirror array is 32-300.

Compared with the prior art, the utility model has the advantages of:

1. The technical solution provided by the utility model can obtain a complete data cube of an object under a single exposure, and is suitable for monitoring rapidly changing scenes or moving objects.

2. The spectral imaging system has no moving parts, which avoids the influence of changes in external factors on the internal components of the system.

3. The spatial information and spectral information of the object can be obtained directly on the image plane of the spectral imaging system, without using algorithms for secondary settlement.

4. Compared with the image mapping spectral imaging technology proposed in the prior art, the segmentation unit adopted in the technology proposed by the utility model is an element with optical power, and the front objective lens is a non-telecentric system, which is beneficial to Reduce system volume.

Description of drawings

Fig. 1 and Fig. 2 are the optical path diagrams of the snapshot spectral imaging system based on the micromirror array provided by the embodiment of the present invention;

Fig. 3 is a schematic structural view of the front imaging mirror provided by the embodiment of the present invention.

FIG. 4 is a schematic structural diagram of a micromirror array provided by an embodiment of the present invention.

Fig. 5 is a schematic structural diagram of a collimating mirror provided by an embodiment of the present invention.

FIG. 6 is a schematic diagram of the pupil array provided by the embodiment of the present invention.

Fig. 7 is a graph of the modulation transfer function of the micromirror array-based snapshot spectral imaging system provided by the embodiment of the present invention.

FIG. 8 is a spot diagram of a snapshot spectral imaging system based on a micromirror array provided by an embodiment of the present invention.

In the figure, 1. Front imaging objective lens, 1-1. Biconvex lens in the front imaging mirror, 1-2. Positive meniscus lens in the front imaging mirror; 2. Micromirror array; 3. Collimating mirror , 3-1. The first biconvex lens, 3-2. The second biconvex lens, 3-3. The third positive meniscus lens, 3-4. The fourth biconvex lens, 3-5. Five negative meniscus lenses, 3-6. The sixth biconcave lens, 3-7. The seventh biconvex lens, 3-8. The eighth positive meniscus lens; 4. Pupil array, 4-1. Pupil; 5. Light splitting element array, 5-1. Light splitting element; 6. Imaging mirror array, 6-1. Imaging mirror; 7. Image plane.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the technical solution of the utility model is further elaborated.

Example 1

In this embodiment, the main parameters of the snapshot spectral imaging system are as follows:

Spectral range: 450~650nm;

Field of view: 2.38°×1.65°;

Spectral resolution: 20nm;

Focal length: 80mm;

Detector pixel: 13.5um×13.5um.

Referring to accompanying drawing 1 and 2, they are the light path diagrams of the snapshot type spectral imaging system based on the micromirror array provided by the utility model; Pupil array 4 , light splitting element array 5 , imaging mirror array 6 and image plane 7 . In the light-splitting element array 5, several light-splitting elements 5-1 are included, which are Amici prisms or gratings; in the imaging mirror array 6, several imaging mirrors 6-1 are included, which are doublet lenses, which include several imaging mirrors 6 -1. The light from an object at infinity reaches its rear focal plane through the front imaging objective lens 1; the micro-mirror array 2 located at the focal plane position divides the image into a series of long and narrow rectangular sub-images, and at the same time The incident converging light beam becomes a divergent light beam; the collimator 3 collimates the divergent light beam, and produces a pupil array 4 on the focal plane; the Amici prism 5-1 disperses the light beam to generate light beams of different wavelengths, and the imaging mirror 6 -1 Image the dispersed light beam to the image plane 7 to realize spectral imaging.

Referring to accompanying drawing 3, it is the structural representation of the front imaging mirror that present embodiment provides; It is positive meniscus lens 1-2. The front imaging mirror can also be a reflective system.

The micromirror array 2 has periodicity in the direction of the spectral dimension, and a single period is composed of a series of sub-reflectors. The length of the spherical reflector is 10-30mm, and the width is 60μm-160μm; the concave spherical reflector has a two-dimensional rotation angle around the direction of the space dimension and the direction of the spectrum dimension, and the rotation angle around the direction of the space dimension is -10°～10°. The rotation angle of the spectral dimension is -10°～10°, the two-dimensional rotation angles of each concave spherical mirror in a single cycle are different, and the corresponding concave spherical mirrors in different cycles have the same two-dimensional rotation angle. The light-splitting element 5-1 in the light-splitting element array 5 and the imaging mirror 6-1 in the imaging mirror array 6 correspond to the number and array arrangement of sub-mirrors in the micro-mirror array. The micro mirror array 2 may include 32-300 concave spherical mirrors.

Referring to Figure 4, it is a schematic diagram of the micromirror array provided in this embodiment. The micromirror array includes 2 cycles, and there are 16 blocks (4×4 array) in a single cycle with concave spherical reflectors with different two-dimensional rotation angles. mirror.

Referring to accompanying drawing 5, it is the collimating mirror structure schematic diagram that the present embodiment provides; Collimating mirror 3 has 8 spherical lenses to form, and the first is biconcave lens 3-1, the second biconvex lens 3-2, the third Positive meniscus lens 3-3, fourth biconvex lens 3-4, fifth negative meniscus lens 3-5, sixth biconcave lens 3-6, seventh biconvex lens 3-7, eighth Positive meniscus lens 3-8.

Referring to accompanying drawing 6, it is the pupil array of the snapshot spectral imaging system, corresponding to the concave spherical mirror, there are 16 sub-pupils 4-1 in a 4×4 array.

In the spectral imaging system provided by the utility model, since the exit pupil of the front objective lens 1 is positioned at the focal point of the concave spherical reflector behind the mirror group, the microreflection array 2 is used as a field mirror to image the exit pupil of the front objective lens to infinity, The collimating mirror 3 images the exit pupil to its rear focal plane. Since the two-dimensional rotation angles of the concave spherical mirrors on the micromirror array 2 are different, the reflection directions of the light rays are different from the mirrors. Finally, after the collimating mirror 3 A pupil array 4 is formed on the focal plane, and then imaged to an image plane 7 through a light splitting element array 5 and an imaging mirror array 6 to realize spectral imaging.

The imaging method is as follows: the light from the object at infinity reaches the rear focal plane through the front imaging objective lens 1; the micro-mirror array 2 at the focal plane position divides the image into a series of long and narrow rectangles The sub-image diverges the incident converging beam at the same time; the collimating mirror 3 collimates the diverging beam, the beam splitting element 5-1 disperses the beam to generate beams of different wavelengths, and the imaging mirror 6-1 images the dispersed beam to the image plane 7.

Referring to accompanying drawing 7, it is the modulation function transfer curve diagram of the snap-shot spectral imaging system that the present embodiment provides, at the Nyquist rate 37.04lp/mm place, each field of view transfer function is close to the diffraction limit, and the lowest value is higher than 0.3, the image quality is good.

Referring to accompanying drawing 8, it is a spot diagram of the snapshot spectral imaging system provided by this embodiment. It can be seen from the figure that under each field of view, the spot diagram of the system is within a single detector pixel and within the Airy disk, and the imaging quality of the system is good.

Claims (7)

1. a kind of fast illuminated spectrum imaging system based on micro reflector array, it is characterised in that: it includes preposition image-forming objective lens (1), micro reflector array (2), collimating mirror (3), beam splitter array (5), imaging lens array (6) and as plane (7)；Described Micro reflector array (2) has periodically in spectrum dimension direction, and signal period forms array, sub- reflection by several sub- reflecting mirrors Mirror is rectangular-shaped concave spherical mirror, and a length of 10~30mm of concave spherical mirror, width is 60 μm~160 μm；Each concave spherical surface is anti- Penetrate mirror have around space dimension direction and spectrum dimension direction Two Dimensional Rotating angle, around space dimension direction rotation angle be -10 °~ 10 °, the rotation angle around spectrum dimension direction is -10 °~10 °, the Two Dimensional Rotating angle of each concave spherical mirror in signal period Difference, the Two Dimensional Rotating angle of corresponding concave spherical mirror is identical in different cycles；The spectrum imaging system it is preposition The emergent pupil of image-forming objective lens (1) is located at the focal point of its microscope group rear concave spherical mirror, and incident ray passes through preposition image-forming objective lens It (1) by image cutting is a series of long and narrow rectangle subgraphs through micro reflector array (2), and simultaneously by incident remittance after Optically focused misconvergence of beams, collimating mirror (3) collimate divergent beams, then light beam dispersion is generated different wave length through beam splitter array (5) Light beam, the light beam after dispersion is imaged in as plane (7) by imaging lens array (6).

2. a kind of fast illuminated spectrum imaging system based on micro reflector array according to claim 1, it is characterised in that: Preposition image-forming objective lens (1) are transmissive system or reflecting system.

3. a kind of fast illuminated spectrum imaging system based on micro reflector array according to claim 1, it is characterised in that: Collimating mirror (3) is transmissive system or reflecting system.

4. a kind of fast illuminated spectrum imaging system based on micro reflector array according to claim 1, it is characterised in that: The beam splitter array (5) is by the quantity and the consistent light splitting of array arrangement with micro reflector array (2) neutron-reflecting mirror Element (5-1) composition, beam splitter (5-1) are prism or grating.

5. a kind of fast illuminated spectrum imaging system based on micro reflector array according to claim 1, it is characterised in that: The imaging lens array (6) is by the quantity and the consistent imaging lens of array arrangement with micro reflector array (2) neutron-reflecting mirror (6-1) composition.

6. a kind of fast illuminated spectrum imaging system based on micro reflector array according to claim 1, it is characterised in that: In the signal period of micro reflector array (2), the sub- number of mirrors for forming array is 16~100.

7. a kind of fast illuminated spectrum imaging system based on micro reflector array according to claim 1, it is characterised in that: Sub- number of mirrors in micro reflector array (2) is 32~300.