CN106595857A - Monochromatic light generating device - Google Patents

Abstract

The invention discloses a monochromatic light generating device, which at least includes an incident slit, a collimating mirror, a grating device, an imaging mirror and an exiting slit; the light entering from the incident slit enters the collimating mirror and is reflected as parallel light , incident to the grating device, the diffracted light generated by the grating device is received by the imaging mirror, and the diffracted light is converged to the exit slit, and emitted from the exit slit; the grating device includes at least two gratings arranged around the central axis, and the grating device can The central axis turns to switch the grating for receiving the collimated light generated by the collimating mirror. In the monochromatic light generating device of the present invention, the grating device includes at least two gratings distributed symmetrically about the central axis, and the grating device is rotated about the central axis to realize grating scanning and switch between different gratings, and to realize wide-band output; optimize the design of each grating Spectral resolution can be improved.

Description

A monochromatic light generating device

technical field

The invention relates to the technical field of optical instruments, in particular to a monochromatic light generating device.

Background technique

Referring to Fig. 1, a traditional grating monochromator includes an entrance slit 1, a collimating mirror 2, a grating 3, an imaging mirror 4 and an exit slit 5, and the specific structure is shown in the figure. The light entering from the incident slit 1 is transformed into parallel light by the collimating mirror 2, and then enters the grating 3, and is diffracted by the grating 3. However, for a monochromator device of this structure, broadband and high resolution are inherent contradictions, and broadband and high resolution cannot be realized at the same time.

Contents of the invention

The purpose of the present invention is to provide a monochromatic light generating device, which can realize wide-band output and improve spectral resolution.

To achieve the above object, the present invention provides the following technical solutions:

A monochromatic light generating device, comprising at least an incident slit, a collimator mirror, a grating device, an imaging mirror and an exit slit;

The light entering through the incident slit enters the collimating mirror, is reflected as parallel light, and enters the grating device, and the imaging mirror receives the diffracted light generated by the grating device and converges the diffracted light to the exit slit, and emitted from the exit slit;

The grating device includes at least two gratings arranged around the central axis, and the grating device can be rotated on the central axis to switch the grating used to receive the parallel light generated by the collimating mirror.

Optionally, at least two gratings are uniformly distributed along the circumferential direction.

Optionally, the grating constants of at least two gratings are sequentially increased by multiples.

Optionally, the grating device includes three gratings, and the three gratings are arranged in an equilateral triangle.

Optionally, a first reflector and a second reflector are also included;

The first reflecting mirror is used to reflect the light entering from the incident slit to the collimating mirror;

The second reflection mirror is used to reflect the converging light formed by the imaging mirror to the exit slit;

The first reflecting mirror, the collimating mirror, the grating device, the imaging mirror and the second reflecting mirror form a W-shaped optical path.

Optionally, the incident slit and the exit slit are arranged oppositely, and both have a preset offset distance.

Optionally, it also includes a filter device arranged on the light incident side of the exit slit for filtering out the secondary spectrum and stray light;

The filter device is a filter wheel, and the filter wheel is provided with holes uniformly distributed along the circumferential direction for installing filters, and the number of the holes is consistent with the number of the gratings.

Optionally, the central axis of the grating device deviates from the axis of symmetry between the central axis ray of the outgoing light of the collimator and the central axis ray of the incident light of the imaging mirror.

Optionally, a turntable and a worm gear are also included;

At least two gratings are installed on the turntable, arranged around the center of the turntable, and the turntable is driven to rotate by the worm gear.

Optionally, an optocoupler block is set at a preset position of the turntable, an optocoupler sensor is arranged on the housing of the grating device, and the optocoupler block is sensed by the optocoupler sensor to determine the position of the turntable. rotation position.

It can be known from the above technical solutions that the monochromatic light generation device provided by the present invention at least includes an incident slit, a collimating mirror, a grating device, an imaging mirror and an exiting slit. The light entering from the incident slit enters the collimating mirror, is reflected as parallel light, and enters the grating device. The diffracted light generated by the grating device is received by the imaging mirror, and the diffracted light is converged to the exit slit. shot out. In the monochromatic light generating device of the present invention, the grating device includes at least two gratings arranged around the central axis, and the grating device is rotated by the central axis to realize grating scanning and switch between different gratings, and to realize wide-band output; optimize the design of each grating Spectral resolution can be improved.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural representation of traditional grating monochromator;

2 is a schematic diagram of a monochromatic light generating device provided by an embodiment of the present invention;

Fig. 3 is a schematic diagram of a monochromatic light generating device provided by another embodiment of the present invention;

FIG. 4 is a schematic diagram of a filter wheel provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a comparison of light scanning performed by a coaxial arrangement and an off-axis arrangement of the grating device in the monochromatic light generating device of the embodiment of the present invention.

detailed description

In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

Aiming at the defect that the traditional grating monochromator cannot take into account both wide-band output and high resolution, the embodiment of the present invention provides a monochromatic light generating device, please refer to Figure 2, which at least includes an incident slit 10, a collimating mirror 11, and a grating device 12. Imaging mirror 13 and exit slit 14;

The light entering through the incident slit 10 enters the collimator mirror 11, is reflected as parallel light, and enters the grating device 12, and the imaging mirror 13 receives the diffracted light generated by the grating device 12, And converge the diffracted light to the exit slit 14, and emit from the exit slit 14;

The grating device 12 includes at least two gratings 120 arranged around the central axis, and the grating device 12 can rotate around the central axis to switch the grating for receiving the parallel light generated by the collimating mirror 11 .

Wherein, the collimating mirror 11 is used to convert the light entering through the incident slit 10 into parallel light, and make the parallel light incident to the grating device 12 .

The grating device 12 includes at least two gratings 120 arranged around the central axis. Parallel light is incident on the gratings of the grating device 12 and is diffracted by the diffraction surface of the grating. The generated diffracted light is received by the imaging mirror 13, and the diffracted light is converged to the exit slit 14, and emitted from the exit slit.

The monochromatic light generating device in this embodiment drives the grating device to rotate on the central axis, and the incident light scans the grating, and as the incident angle of the parallel light reaching the diffraction surface of the grating changes, different wavelengths of outgoing light are obtained; the grating device rotates on the central axis , the grating can be switched during scanning, which can realize broadband spectral output.

Therefore, in the monochromatic light generating device of this embodiment, the grating device includes at least two gratings arranged around the central axis, and the grating device rotates with the central axis to realize raster scanning and switch between different gratings, which can realize broadband spectral output; Grating optimization design improves spectral resolution.

The monochromatic light generating device of this embodiment will be further described below in combination with specific implementation methods.

Please refer to Fig. 2, in the monochromatic light generating device of this embodiment, the grating device 12 includes at least two gratings 120 arranged around the central axis (point O in the figure corresponds to the position of the central axis), and the gratings 120 are planar blazed gratings parallel to each other. Light is diffracted when incident on the diffraction surface of the grating.

The number of gratings 120 in the grating device 12 can be flexibly set according to usage requirements.

Preferably, at least two gratings 120 are evenly distributed along the circumferential direction, which facilitates the mechanical design of the device and the driving control of the gratings during scanning.

Preferably, the grating constants of the at least two gratings 120 are set to increase in multiples sequentially, so that the wavelength ranges of the light output by each grating have a multiple relationship. According to the raster scan equation:

Among them, δ represents the angle between the incident light and the diffracted light, φ represents the rotation angle of the grating, λ represents the light wavelength, and d represents the grating constant. By setting the grating constants of each grating to increase in multiples in turn, the angular scanning range required for each grating to output monochromatic light of the corresponding band is the same, which is convenient for mechanical design and electrical control, and also simplifies processing and assembly. .

In a specific implementation manner, the grating device 12 may be set to include three gratings 120 arranged in an equilateral triangle, as shown in FIG. 2 . By driving the grating device 12 to rotate, the scanning of the grating and the switching of the grating are realized to realize continuous spectrum output.

Among them, the grating constants of the three gratings 120 are sequentially increased by multiples. For example, the grating constants of the three gratings 120 are set to 2400gr/mm, 1200gr/mm, and 600gr/mm respectively, corresponding to output 280nm-560nm, 560nm-1120nm, 1120nm- Monochromatic light in the 2240nm band range, which cleverly divides the wide band of 280nm-2240nm into three bands in multiples.

Spectral resolution can be improved by optimally designing each grating. In this specific embodiment, each grating is optimally designed. The resolution of the first grating is better than 0.05nm at the wavelength of 420nm, the resolution of the second grating is better than 0.1nm at the wavelength of 840nm, and the resolution of the third grating is better than 0.1nm at the wavelength of 1680nm. Better than 0.2nm.

The monochromatic light generation device of this embodiment can eliminate the coma aberration of the center wavelength of the output band corresponding to each grating by reasonably setting the eccentricity angle of the collimating mirror 11 and the imaging mirror 13, thereby balancing the coma aberration of the edge wavelengths and making the whole The image quality of the output band is uniform. The eccentric angle of the collimating mirror refers to the angle between the normal of the reflective surface of the collimating mirror and the incident light of the collimating mirror; the eccentric angle of the imaging mirror refers to the included angle between the normal of the reflecting surface of the imaging mirror and the incident light of the imaging mirror.

Further, on the basis of the above content, the monochromatic light generating device of this embodiment optimizes the layout of the light path. Specifically, the monochromatic light generating device is further provided with a first reflector 15 and a second reflector 16 , please refer to FIG. 3 .

The first reflecting mirror 15 is used to reflect the light entering from the incident slit 10 to the collimating mirror 11; the second reflecting mirror 16 is used to reflect the converged light formed by the imaging mirror 13 to the collimating mirror 11. The exit slit 14; the first reflecting mirror 15, the collimating mirror 11, the grating device 12, the imaging mirror 13 and the second reflecting mirror 16 form a W-shaped optical path. This folded optical path is beneficial to the layout of the positions of the optical elements and the system structure, making the system compact.

Wherein, the incident slit 10 and the outgoing slit 14 are arranged oppositely, the outgoing slit 14 is located opposite to the incident slit 10 , and the two are set to have a preset offset distance. For example, the incident slit 10 and the exit slit 14 can be set to have an offset distance of 1/4 of the focal length, which is the focal length of the imaging mirror 13 . The misalignment of the incident slit 10 and the exit slit 14 can prevent stray light from directly emitting from the exit slit caused by the mismatch between the incident light and the numerical aperture of the monochromatic light generating device, and can effectively avoid stray light from the grating.

Further, the monochromatic light generating device is also provided with a filter device 17 on the light incident side of the exit slit 14 for filtering out the secondary spectrum and stray light.

The filter device 17 can adopt a filter wheel, which is a schematic diagram of a filter wheel provided in this embodiment with reference to FIG. 4 , and the filter wheel is provided with The holes 170 for the filter are installed, the number of the holes 170 is consistent with the number of the gratings.

Specifically, two laminates can be designed in each hole for installing optical filters. According to the working band of each grating in the device, a band-pass filter of the corresponding band is installed in each hole position, and a high-pass filter or a low-pass filter can also be used together.

Wherein, an optocoupler block can be arranged on the filter wheel 17, and the position of each filter can be determined by sensing the optocoupler block on the filter wheel by the optocoupler sensor. When working with different gratings, switch the corresponding filter to the working position to filter out the secondary spectrum and stray light, effectively improving the output noise ratio.

In a preferred implementation of the monochromatic light generating device of this embodiment, on the basis of the content of the above embodiment, the central axis of the grating device 12 deviates from the central axis of the light emitted by the collimating mirror 11 and the The symmetry axis of the central axis ray of the incident light of the imaging mirror 13 can be shown with reference to FIG. 2 and FIG. 3 . When designing the optical path of the monochromatic light generating device, in the propagation optical path of the collimating mirror 11, the grating device 12, and the imaging mirror 13, the center axis ray of the outgoing light of the collimating mirror 11 and the incident light of the imaging mirror 13 will be determined. The position of the symmetry axis of the axis ray.

In the monochromatic light generating device, the central axis of the grating device 12 and the symmetry axis of the central axis ray can be set to intersect, that is, the center point of the grating device 12 coincides with the symmetry axis of the central axis ray, but in the case of overlap, during the scanning process It will bring the effect of grating effective aperture loss and stray light. Referring to Fig. 5, (1) (2) (3) in the figure is that the center point of the grating device coincides with the axis of ray symmetry, and (4) (5) (6) is the center point of the grating device and the center axis Ray symmetry axis misalignment setting. In the figure, the grating device rotates clockwise. It can be seen from the comparison diagram that in the case of coaxiality, the larger the incident angle of the scanning light, the greater the loss of the effective aperture of the grating; There is little effective aperture loss near the minimum and maximum incident angles of light, and the collimated light can fully illuminate the grating at the angle corresponding to the middle wavelength.

Therefore, the monochromatic light generating device of this embodiment deviates from the symmetry axis between the central axis of the grating device and the central axis light of the collimator exit light and the central axis light of the imaging mirror 13 incident light, and can reduce the grating compared with the coaxial arrangement. The loss of effective aperture can ensure that when the central wavelength light of the corresponding band is output during the scanning process, the parallel light from the collimator can fully illuminate the grating, so that the aperture loss at the two edge wavelengths can be balanced during the scanning process, effectively reducing the overall Band stray light, the overall performance is greatly improved compared to the case of non-off-axis installation.

In the above embodiments, the grating device 12 uses a turntable and a worm gear to install and fix the grating, at least two pieces of the grating are installed on the turntable, arranged around the center of the turntable, and the turntable is driven by the worm gear turn. Realize the switching and scanning between each grating.

Further in this embodiment, an optocoupler block 18 is set at the preset position of the turntable, an optocoupler sensor is arranged on the box of the grating device 12, and the optocoupler block 18 is sensed by the optocoupler sensor, To determine the rotational position of the turntable, thereby determine the rotational position of each grating, to ensure the accuracy of the scanning and switching of the grating during the working process.

During the scanning process of the monochromatic light generating device in this embodiment, each optocoupler sensor on the box senses the optocoupler block on the turntable to determine the initial position of the turntable, and calibrates the number of steps of the motor to control the worm gear to drive the turntable to rotate , scan to the required grating, and at the same time control the filter wheel to rotate and switch to the filter of the corresponding band, then the desired monochromatic light can be output.

In summary, the monochromatic light generating device of the present invention can realize wide-band output and improve spectral resolution through the improvement of the structure of the grating device; and the optical path structure is cleverly designed to optimize the optical performance of the system; in addition , The center of the grating device is deviated from the optical axis, which reduces the loss of the effective aperture of the grating during the scanning process, ensures the relative aperture of the system, effectively reduces stray light, and improves the overall performance of the system. The monochromatic light generating device of the invention has the characteristics of ingenious design, compact structure, low stray light, wide working band and high spectral resolution.

The monochromatic light generating device provided by the present invention has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (10)

1. a kind of monochromatic light generating device, it is characterised in that at least including entrance slit, collimating mirror, grating device, imaging lens and Exit slit；

The light entered by the entrance slit is incident to the collimating mirror, is reflected as directional light, incides the grating dress Put, by the imaging lens diffraction light that the grating device is produced is received, and diffraction light is converged to into the exit slit, by institute State exit slit injection；

The grating device include around central shaft arrangement at least two blocks gratings, the grating device can with central axis, To switch the grating for receiving the directional light produced by the collimating mirror.

2. monochromatic light generating device according to claim 1, it is characterised in that at least two blocks gratings are along the circumferential direction It is uniformly distributed.

3. monochromatic light generating device according to claim 2, it is characterised in that at least grating constant of two blocks of gratings Increased with multiple successively.

4. monochromatic light generating device according to claim 3, it is characterised in that the grating device includes three blocks of light Grid, three blocks of gratings are with equilateral triangle arrangement.

5. monochromatic light generating device according to claim 1, it is characterised in that also including the first speculum and the second reflection Mirror；

First speculum is used to for the light entered by the entrance slit to reflex to the collimating mirror；

Second speculum is used to for the converged light formed by the imaging lens to reflex to the exit slit；

First speculum, the collimating mirror, the grating device, the imaging lens and second speculum form W types Light path.

6. monochromatic light generating device according to claim 5, it is characterised in that the entrance slit and the exit slit It is oppositely arranged, and both have default bias distance.

7. monochromatic light generating device according to claim 1, it is characterised in that also including being arranged on the exit slit light Incident side, filtering apparatus for filtering second order spectrum and veiling glare；

The filtering apparatus be optical filter wheel, the optical filter wheel be provided with it is being distributed uniformly and circumferentially, for install filter The hole of mating plate, the quantity in the hole is consistent with the quantity of the grating.

8. the monochromatic light generating device according to any one of claim 1-7, it is characterised in that the center of the grating device Axle deviates the middle axial ray of the collimating mirror emergent light and the symmetry axis of the middle axial ray of the imaging lens incident light.

9. the monochromatic light generating device according to any one of claim 1-7, it is characterised in that also including turntable and worm gear snail Bar；

At least two blocks gratings are arranged on the turntable, around turntable center arrangement, by the worm and gear institute are driven State turntable rotation.

10. monochromatic light generating device according to claim 9, it is characterised in that arrange in the predeterminated position of the turntable Optocoupler catch, arranges optocoupler sensor on the grating device casing, is kept off by optocoupler described in the optocoupler sensor sensing Piece, to determine the rotation position of the turntable.