CN108168703B

CN108168703B - Fourier transform spectrometer based on optical switch array and manufacturing method

Info

Publication number: CN108168703B
Application number: CN201711380931.9A
Authority: CN
Inventors: 梁静秋; 梁中翥; 王维彪; 秦余欣; 吕金光; 孟德佳; 陶金
Original assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Current assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Priority date: 2017-12-20
Filing date: 2017-12-20
Publication date: 2019-12-13
Anticipated expiration: 2037-12-20
Also published as: CN108168703A

Abstract

a Fourier transform spectrometer based on an optical switch array and a manufacturing method thereof relate to the technical field of infrared spectrum detection and infrared spectrum analysis, and solve the problems of large size, heavy weight and the like caused by the adoption of a high-precision moving mirror driving mechanism of the traditional time modulation Fourier transform infrared spectrometer, and the problems of high price and the like caused by the adoption of a refrigeration type infrared area array detector of the space modulation Fourier transform infrared spectrometer. The invention utilizes an array phase reflector to perform distributed phase modulation on an incident light field, and utilizes an optical switch array to perform amplitude modulation on an emergent interference light field array so as to realize a spectrum instrument for step-by-step gating and detection. The invention can use the point detector to detect, not only further reduce the volume and weight, but also greatly reduce the cost.

Description

fourier transform spectrometer based on optical switch array and manufacturing method

Technical Field

the invention relates to the technical field of infrared spectrum detection and infrared spectrum analysis, in particular to an infrared interference spectrometer, and specifically relates to an infrared interference spectrometer for performing phase modulation and amplitude modulation on a light field by respectively using an array phase reflector and an optical switch array.

Background

the infrared interference spectrum technology is a scientific technology which is a great breakthrough and is developed rapidly in nearly half a century, and has the advantages of high sensitivity, accurate wave number, good repeatability and the like. By using the infrared interference spectrum technology, the molecular composition of the unknown object can be determined according to the intensity, the position and the shape of an absorption peak in the infrared spectrum of the unknown object, so that the type of the unknown object can be deduced. The Fourier transform infrared spectrometer is one kind of infrared interference spectrometer, and has obvious application advantages owing to the advantages of multiple channels, high flux, high precision, low stray light and the like. The Fourier transform infrared spectrometer can be generally divided into a time modulation type and a space modulation type, and the time modulation type adopts a moving mirror scanning structure, so that the high-precision moving mirror driving mechanism enables the system to have larger volume and weight, and certain limit is generated on the portable application of the system; the space modulation type adopts a refrigeration type infrared area array detector with higher price, and the spectral resolution is limited by the number of detector pixels, thereby limiting the application field of the instrument.

in recent years, with the appearance and development of some high-tech scientific and technical fields, such as scientific research and engineering application in the fields of resource exploration, environment monitoring, meteorological monitoring, life science, modern medicine and the like, the infrared interference spectrum instrument which is miniaturized, light-weighted, high in cost performance and capable of carrying out portable detection and online analysis has very urgent use requirements.

disclosure of Invention

the invention provides a Fourier transform spectrometer based on an optical switch array and a manufacturing method thereof, aiming at solving the problems of large size, heavy weight and the like caused by the adoption of a high-precision moving mirror driving mechanism of the traditional time modulation Fourier transform infrared spectrometer and solving the problems of high price and the like caused by the adoption of a refrigeration type infrared area array detector of a space modulation Fourier transform infrared spectrometer.

The Fourier transform spectrometer based on the optical switch array comprises a light source, a collimating mirror, a beam splitter, a plane mirror, an array phase mirror, an optical switch array, a focusing mirror and a point detector;

The light emitted by the light source is collimated into parallel light beams by the collimator, the parallel light beams are divided into two beams of coherent light with equal intensity by the beam splitter, one beam of light is reflected by the beam splitter and then incident on the planar reflector of the array phase reflector, and the other beam of light is incident on the planar reflector through the beam splitter; the array phase reflector performs distributed phase modulation on an incident light field penetrating through the beam splitter; the light field modulated by the array phase reflector and the light field reflected by the plane reflector are subjected to coherent superposition again through the beam splitter to form an interference light field; the optical switch array receives the interference light field step by step and obtains an interference pattern sequence after passing through a focusing lens and a point detector;

The array phase reflector performs airspace segmentation on an incident light field, each phase reflector unit corresponds to one light field segmentation unit, the light field segmentation unit corresponding to the phase reflector unit corresponds to a phase difference with a light field reflected by a corresponding area of the plane reflector when the light field interferes on the emergent surface of the beam splitter, the emergent light field is an interference light field array with spatial phase difference distribution, and each phase reflector unit corresponds to one interference light field unit in the interference light field array;

the emergent interference light field array is incident on an optical switch array, the optical switch array is composed of a plurality of optical switch units distributed in a two-dimensional space, and each optical switch unit corresponds to one interference light field unit in the interference light field array; controlling the on-off of the corresponding interference light field unit in the interference light field array by controlling the on-off of each optical switch unit, and realizing the gating of the interference light field corresponding to a certain phase difference in the interference light field array;

sequentially controlling the opening and closing of the corresponding optical switch units on the optical switch array according to the spatial distribution sequence of the phase modulation quantity on the array phase reflector, so that each interference optical field unit in the interference optical field array sequentially passes through the optical switch array according to the phase difference sequence; the interference light field units are sequentially collected by a detector according to the phase difference sequence, and finally an interference pattern sequence is formed;

the beam splitter is a light beam splitter with a grid edge structure and comprises grid edges, beam splitting windows and beam splitting films, the grid edges divide the beam splitter spatially to form a beam splitting window array, the beam splitting films are positioned on the upper surfaces of the beam splitting windows or the upper surfaces of the beam splitting windows and the grid edges, and the grid edges support the beam splitting films;

the width of the grid edges in the grid beam splitter in the transverse direction being that of the grid edges in the longitudinal directionThe width of the beam-splitting window in the transverse direction being greater than that in the longitudinal directionThe duty ratios of the beam splitting windows in the transverse direction and the longitudinal direction are the same;

The width range of the grid edge in the grid mesh beam splitter is 1nm-100cm, and the width range of the beam splitting window is 1nm-100 cm; the thickness range of the grid edges is 1nm-100cm, and the thickness range of the beam splitting window is 1nm-100 cm;

the section structure of the grid edges in the grid mesh beam splitter is a single-sided rectangle, a single-sided parallelogram, a single-sided trapezoid, a double-sided rectangle, a double-sided parallelogram or a double-sided trapezoid.

the manufacturing method of the Fourier transform spectrometer based on the optical switch array adopts a method of combining visible laser array calibration and infrared camera observation to carry out system integration, and comprises the following specific manufacturing steps:

Step one, calibrating a system optical axis by adopting a visible laser array, wherein the laser array has the same number NxN as the array phase reflector units, and the transverse and longitudinal intervals of each laser unit of the laser array are equal to the unit size a of the array phase reflector; all optical axes of the laser array are parallel by adjusting the position and the angle of a laser array source;

Inserting a 45-degree visible light splitting prism into a light path, dividing the laser array into two paths, enabling the transmitted laser beam and the laser array beam to be collinear by adjusting the position and the angle of the splitting prism, and enabling the reflected laser beam to be perpendicular to the laser array beam;

Placing the array phase reflector in a light path of a reflection laser array, enabling each laser beam in the light path of the reflection laser array to be incident to the central position of each reflector unit in the array phase reflector by adjusting the position and the angle of the array phase reflector, and enabling the light beam incident to the array phase reflector to return along the original path, so as to ensure that the array phase reflector is vertical to the optical axis of the laser array;

placing the plane reflector in the light path of the transmission laser array, and enabling each laser beam in the light path of the transmission laser array to be uniformly distributed on the plane reflector by adjusting the position and the angle of the plane reflector, wherein the light beam incident on the plane reflector returns along the original path, and the optical axes of the plane reflector and the laser array are ensured to be collinear;

rotating the visible light beam splitter prism by 90 degrees, turning the reflected laser beams by 180 degrees, placing the optical switch array in a new reflected laser beam light path, and enabling each laser beam incident on the optical switch array to be positioned at the central position of each optical switch unit of the optical switch array by adjusting the position and the angle of the optical switch array;

Removing the visible light splitting prism, placing a beam splitter at the position of the visible light splitting prism, and adjusting the position and the angle of the beam splitter to enable each laser beam reflected to the array phase reflector to be positioned at the central position of each reflector unit and enable the light beam reflected by the array phase reflector to return along the original path;

Placing a collimating mirror in the front light path, and adjusting the position and the angle of the collimating mirror to ensure that the laser array is symmetrically distributed on the surface of the collimating mirror, and the laser beams reflected by the surface of the collimating mirror are also distributed in an opposite array on the source plane of the laser array, so as to ensure that the optical axis of the collimating mirror is parallel to the laser array;

Removing the laser array, placing the infrared light source in front of the collimating mirror, and enabling the infrared light source to be located on an object focus of the collimating mirror by adjusting the position of the infrared light source;

Placing an infrared camera on the optical switch array, turning on an infrared light source, setting all optical switch units of the optical switch array to be in an on state, adjusting the position of the infrared camera to enable the array phase reflector to clearly image on an area array detector of the infrared camera, adjusting the axial translation position of the plane reflector, and observing by using the infrared camera until an interference image appears;

Removing the infrared camera, placing a focusing mirror behind the optical switch array, placing the infrared area array detector on an image focal plane of the focusing mirror, and enabling light beams in each on state of the optical switch unit to be focused on the central position of the infrared area array detector by adjusting the position and the angle of the focusing mirror;

And step eleven, removing the infrared area array detector, placing the point detector on a focal plane of the focusing mirror, adjusting the position of the single-point detector, and fixing each device when the output signal of the detector is maximum to complete system manufacturing.

The invention has the beneficial effects that: the invention provides a Fourier transform spectrometer based on an optical switch array, which is a spectrometer for realizing step-by-step gating and detection by performing distributed phase modulation on an incident light field by using an array phase reflector and performing amplitude modulation on an emergent interference light field array by using the optical switch array. Compared with a time modulation Fourier transform infrared spectrometer, the high-precision movable mirror driving mechanism is not needed, compared with a space modulation Fourier transform infrared spectrometer, due to the fact that the optical switch array corresponding to the array phase reflector is introduced, the detector can be used for detecting, the size and the weight are further reduced, the cost is greatly reduced, the infrared spectrometer has the advantages of being small in size, light in weight, low in cost, good in portability and the like, and has important application value in the field of infrared spectrum detection and infrared spectrum analysis.

drawings

FIG. 1 is a schematic block diagram of a Fourier transform spectrometer based on an optical switch array according to the present invention;

FIG. 2 is a schematic structural diagram of an array phase mirror in a Fourier transform spectrometer based on an optical switch array according to the present invention;

FIG. 3 is a schematic diagram of a phase difference array formed by modulating an optical field with an array phase reflector in the optical switch array-based Fourier transform spectrometer according to the present invention;

FIG. 4 is a schematic diagram of the optical switch array in the Fourier transform spectrometer based on the optical switch array according to the present invention gating a certain optical field unit in the interference optical field array;

FIG. 5 is a schematic diagram of the step-by-step gating of the optical switch array to the interference optical field array in the Fourier transform spectrometer based on the optical switch array according to the present invention;

fig. 6a and 6b in fig. 6 are schematic diagrams of diffraction spots and detectors and front views of matching of diffraction spots and photosensitive surfaces of detectors in the fourier transform spectrometer based on the optical switch array according to the present invention, respectively;

FIG. 7 is a top view of a grating beam splitter in an infrared interference spectrometer based on a stepped phase mirror and an optical switch array according to the present invention;

FIG. 8 is a schematic diagram of horizontal and vertical grid rib configurations for ten kinds of grid splitters, wherein the left part of FIGS. 8a, 8c, 8e, 8g, 8i, 8k, 8m, 8o, 8q and 8s are front cross-sectional views of ten kinds of grid splitters; fig. 8b, 8d, 8f, 8h, 8j, 8l, 8n, 8p, 8r and 8t on the right part are left sectional views of corresponding main sectional views, respectively;

FIG. 9a to FIG. 9f are schematic cross-sectional views of a double-sided grating edge in FIG. 9;

FIG. 10 is a top view of a grating beam splitter structure;

FIG. 11 is a schematic diagram of horizontal and vertical grating structures of ten grating beam splitters, wherein FIG. 11a, FIG. 11c, FIG. 11e, FIG. 11g, FIG. 11i, FIG. 11k, FIG. 11m, FIG. 11o, FIG. 11q and FIG. 11s at the left part are front sectional views of ten grating beam splitters; 11b, 11d, 11f, 11h, 11j, 11l, 11n, 11p, 11r and 11t on the right side are left side sectional views corresponding to the main sectional views, respectively;

FIG. 12 is a schematic diagram of a process for making a wire-grid thin film beam splitter;

FIG. 13 is a schematic diagram of a fabrication process for a grating film splitter;

FIG. 14 is a schematic diagram of a process for obtaining an array phase mirror by two-dimensional multi-deposition of film layers;

FIG. 15 is a schematic diagram of a process for obtaining an array phase mirror by a two-dimensional multiple etching method;

FIG. 16 is a schematic diagram of a process for obtaining an array phase reflector by a hybrid method of one-dimensional etching and another-dimensional plating;

FIG. 17 is a schematic diagram of a process for fabricating a Fourier transform spectrometer based on an optical switch array according to the present invention.

Detailed Description

first embodiment, the first embodiment is described with reference to fig. 1 to 16, and the fourier transform spectrometer based on the optical switch array includes a light source 1, a collimator mirror 2, a beam splitter 3, a plane mirror 4, an array phase mirror 5, an optical switch array 6, a focusing mirror 7, and a point detector 8.

The light source 1 is located on the object focal plane of the collimating mirror 2, the divergent light beam emitted by the light source 1 becomes a parallel light beam after passing through the collimating mirror 2, and the beam splitter 3 splits the parallel light beam into two coherent light beams with equal intensity. The plane mirror 4 and the array phase mirror 5 are respectively located at the exit pupils of the collimator mirrors in the two perpendicular optical paths divided by the beam splitter 3, and are in mirror positions with respect to the beam splitter 3.

The light field reflected by the beam splitter 3 is incident on the array phase mirror 5 and is reflected back to the beam splitter 3 by the plane mirror 4; the light field transmitted by the beam splitter 3 is incident on the plane mirror 4, the array phase mirror 5 divides the incident light field into a plurality of localized light field units in the transverse space, and each light field unit corresponds to one phase mirror unit on the array phase mirror 5, so that the incident light field is modulated by the spatially distributed phase quantity corresponding to the array phase mirror 5 in the transverse space.

The light field modulated and reflected by the array phase mirror 5 and the light field reflected by the plane mirror 4 meet again via the beam splitter 3 and interfere. Because each phase mirror unit in the array phase mirror 5 corresponds to a phase modulation amount, when the array phase mirror 5 and the light field reflected by the plane mirror 4 are coherent, the emergent light field is an interference light field array with spatial phase difference distribution, and each interference light field unit corresponds to a phase mirror unit on the array phase mirror 5, so as to correspond to a fixed phase difference value.

The interference light field array modulated by the array phase reflector 5 is incident on the optical switch array 6, the optical switch array 6 is composed of a plurality of optical switch units distributed in a two-dimensional space, and each optical switch unit on the optical switch array 6 corresponds to one phase reflector unit on the array phase reflector 5, so as to correspond to one interference light field unit. When one of the optical switch units on the optical switch array 6 is in an open circuit state, the interference light field unit corresponding to the optical switch unit is allowed to pass through and is received by the point detector 8 through the focusing mirror 7.

therefore, each optical switch unit on the optical switch array 6 is sequentially opened and closed according to the phase arrangement sequence on the array phase reflector, so that each interference light field unit in the interference light field array sequentially passes through the optical switch array according to the phase difference sequence and is converged to the point detector 8 by the focusing mirror 7 to be sequentially received, and then an interference light intensity sampling sequence is obtained. Only one interference light field unit passes through at a certain moment, and the intensity of each interference light field unit is converged to a point detector by a focusing mirror to be received.

The array phase mirror 5 and the plane mirror 4 described in the present embodiment are located at mirror positions with respect to the beam splitter 3, and the plane mirror 4 and one phase mirror unit of the array phase mirror 5 overlap in mirror image. The array phase mirror 5 is composed of a plurality of phase mirror units, and each phase mirror unit corresponds to a thickness value. Specifically, referring to fig. 2, with reference to the (0,0) th phase mirror unit 5-1 in the array phase mirror 5, with reference to the (0,0) th phase mirror unit 5-1, and with the thickness of the (1,0) th phase mirror unit 5-2 with respect to the (0,0) th phase mirror unit 5-1 being h, the thickness of the (2,0) th phase mirror unit with respect to the (0,0) th phase mirror unit is 2h, the thickness of the (3,0) th phase mirror unit with respect to the (0,0) th phase mirror unit is 3h, …, and the thickness of the (N-1,0) th phase mirror unit with respect to the (0,0) th phase mirror unit is (N-1) h; the thickness of the (0,1) th phase mirror unit with respect to the (0,0) th phase mirror unit is Nh, the thickness of the (1,1) th phase mirror unit with respect to the (0,0) th phase mirror unit is (N +1) h, and the thickness of the (2,1) th phase mirror unit with respect to the (0,0) th phase mirror unit is (N +2) h. By analogy, the thickness of the (m, n) -th phase mirror unit with respect to the (0,0) -th phase mirror unit is (nN + m) h. The thicknesses of the phase mirror units are sequentially increased by taking h as a step length along the m direction and are sequentially increased by taking Nh as a step length along the n direction. In order to effectively realize the sampling of the interference pattern, the thickness h is required to be less than or equal to lambda/4. Thus, setting the wave number of light as v, the phase modulation effect of the array phase reflector on the light field can be expressed as

In the formula, (x, y) is a coordinate point, j is an imaginary number, and rect () is a rectangular function;

The array phase mirror 5 according to the present embodiment modulates the phase of an incident light field by using the thickness change thereof, thereby introducing a phase difference array having spatial distribution to an interference light field. Specifically, referring to fig. 3, when the mirror position of the plane mirror 4 with respect to the beam splitter 3 coincides with the (0,0) th phase mirror unit 5-1 in the array phase mirror 5, the phase difference of the (0,0) th interference light field unit of the interference light field array 9 corresponding to the (0,0) th phase mirror unit 5-1 is 0, and the phase difference of the (1,0) th interference light field unit of the interference light field array 9 corresponding to the (1,0) th phase mirror unit 5-2 is 0the phase difference of the (2,0) th interference light field unit of the interference light field array 9 corresponding to the (2,0) th phase mirror unit isthe phase difference of the (3,0) th interference light field unit of the interference light field array 9 corresponding to the (3,0) th phase mirror unit isBy analogy, the (m, n) -th phase mirror unitThe phase difference of the (m, n) th interference light field unit of the corresponding interference light field array 9 isThereby, the phase difference array 10 is formed spatially distributed.

when the mirror position of the plane mirror relative to the beam splitter is equal to the (m) th mirror in the array phase mirror₀,n₀) When the phase mirror units are overlapped, then the (m) th₀,n₀) The phase difference of the interference light field unit corresponding to each phase reflector unit is 0, m₀+1,n₀) The phase difference of the interference light field unit corresponding to each phase reflector unit is(m) th₀-1,n₀) The phase difference of the interference light field unit corresponding to each phase reflector unit isBy analogy, the phase difference of the interference light field unit corresponding to the (m, n) -th phase reflector unit isBy controlling the superposition position of the mirror images of different phase reflector units in the plane reflector and the array phase reflector, different sampling modes such as single-side sampling, double-side sampling, small double-side sampling and the like of interference light intensity can be realized.

The optical switch array 6 according to the present embodiment is located in the interference light field modulated by the array phase mirror, and performs amplitude modulation on each interference light field unit to control gating. The optical switch array and the beam splitter form an angle of 45 degrees, in order to enable the light field emitted by the optical switch array 6 and the light field detected by the detector 8 to meet the Fourier transform relationship, the optical switch array 6 is positioned on the object space focal plane of the focusing mirror 7, and the detector 8 is positioned on the image space focal plane of the focusing mirror 7, so that the optimal receiving of energy is realized.

the optical switch array 6 can be implemented by using a liquid crystal spatial light modulator, and the specific implementation manner is that the liquid crystal spatial light modulator is divided into a plurality of liquid crystal spatial light modulation units, each liquid crystal spatial light modulation unit is used as an optical switch unit and corresponds to each interference light field unit one by one, and the amplitude modulation of the interference light field array is implemented by controlling the light transmission and the light non-transmission of each liquid crystal spatial light modulation unit.

Referring to fig. 4, the optical switch array 6 is formed by a plurality of optical switch units distributed in two-dimensional space, and the passing and blocking of the interference optical field unit 9-1 corresponding to the optical switch unit 6-1 in the interference optical field array 9 can be realized by controlling the opening and closing of the optical switch unit 6-1. In order to achieve efficient gating of the interference intensity array by the optical switch array, each optical switch element in the optical switch array needs to be matched with each phase mirror element in the array phase mirrors.

If the size of each optical switch unit in the optical switch array is b × b and the number of the optical switch units is M × M, the size of each optical switch unit in the optical switch array should satisfy the relationship b ≥ a, and the number of the optical switch units should satisfy the relationship M ≥ N. The amplitude modulation effect of the optical switch array 6 on the optical field can be expressed as

The optical switch array described in this embodiment performs distributed gating on each optical field unit in the interferometric optical field array, and is described with reference to fig. 5. When the interference light field array is incident on the optical switch array, the (m, n) th optical switch unit 6-1 in the optical switch array 6 is in an "on" state, and the rest of the optical switch units are in an "off" state, then the "on" state of the (m, n) th optical switch unit 6-1 transmits the interference light field unit 9-1 corresponding to the (m, n) th phase reflector unit of the array phase reflector and converges to the point detector 8 through the focusing mirror 7 for detection, and the "off" state of the rest of the optical switch units blocks the interference light field unit corresponding to the rest of the phase reflector units. At the next moment, the (m +1, n) th optical switch unit 6-2 in the optical switch array 6 is in an "on" state, and the other optical switch units are in an "off" state, then the "on" state of the (m +1, n) th optical switch unit 6-2 transmits the interference optical field unit 9-2 corresponding to the (m +1, n) th phase reflector unit of the array phase reflector and converges to the point detector 8 through the focusing mirror 7 for detection, and the "off" state of the other optical switch units blocks the interference optical field unit corresponding to the other phase reflector units. And each optical switch unit in the optical switch array 6 is sequentially opened and closed according to the thickness sequence of each reflector unit in the array phase reflector 5, so that interference light field units corresponding to different phase reflector units of the array phase reflector are sequentially received by the point detector at different moments according to the phase difference sequence, and an interference light intensity sampling sequence is obtained.

The focusing mirror 7 described in this embodiment is used to converge an interference light field corresponding to a certain phase mirror unit of the array phase mirror 5 onto the point detector 8 for collection. The focusing lens works in an infrared band and is made of infrared optical materials such as silicon, germanium, zinc selenide, zinc sulfide and the like. In order to realize the convergence of the focusing mirror 7 on the interference light fields corresponding to all the phase reflector units, the aperture of the focusing mirror 7 needs to be matched with the apertures of the array phase reflector 5 and the optical switch array 6, i.e. the aperture phi of the focusing mirror 7 should satisfy the relationship

referring to fig. 6, the detector 8 of the present embodiment is located at the image-space focal point of the focusing mirror 7, and the point detector 8 is made of indium antimonide (InSb) or mercury cadmium telluride (HgCdTe). The focal length of the focusing mirror 7 is set to be f, the size of the detector 8 is set to be dxd, the wavelength of the incident light wave is set to be lambda, the interference light intensity converged on the detector 8 is a diffraction spot 11 due to the influence of the aperture diffraction effect of each phase mirror unit of the array phase mirror 5 and each optical switch unit of the optical switch array 6, and the size of the diffraction spot is set to be 2 lambda f/b. Since the size of the detector 8 photosurface is limited, the light energy of the diffracted spot 11 needs to be focused into the detector 8 photosurface in order to suppress light energy from escaping the detector.

Thus, probethe size of the light sensitive surface of the detector 8 must be larger than or equal to the size of the interference light intensity diffraction spot 11, so that the size of the light sensitive surface of the detector 8 should satisfy the relationship

the beam splitter 3 described in this embodiment adopts a parallel plate structure in the infrared band, and is composed of a beam splitting plate and a compensation plate, where the beam splitting plate adopts an infrared optical material such as zinc selenide (ZnSe), potassium bromide (KBr), cesium iodide (CsI), etc. as a base material, or adopts a semiconductor material such as undoped silicon (Si), germanium (Ge), gallium arsenide (GaAs), etc. as a base material; the compensating plate is made of the same base material as the beam splitting plate. The flatness requirement of the two surfaces of the beam splitting plate and the compensation plate is less than or equal to lambda/20, the surface roughness requirement is less than or equal to 3nm, and lambda is the wavelength. For a substrate with high refractive index, the first surface is not required to be plated with a beam splitting film, and only the second surface is required to be plated with an antireflection film. For a low index substrate, it is only necessary to deposit a broadband beam splitting film on the first surface of the substrate to have a reflectivity close to 0.5. For the substrate with the middle refractive index, both the beam splitting film and the antireflection film need to be plated. When a silicon material with a high refractive index is used as the substrate of the semiconductor beam splitter, the silicon substrate material corresponds to a refractive index of 3.4, and the plating material may be selected from germanium and polyethylene or polypropylene. The difference in light intensity reflectivity for different polarization directions can be reduced by reducing the angle of incidence of the beam on the beam splitter. If the array phase reflector is provided with NXN phase reflector units, the size of each phase reflector unit is a x a, and the beam splitting plate and the compensating plate are arranged at 45 degrees with the direction of the optical axis, the size of the beam splitting plate and the compensating plate is

The beam splitter can also adopt a light and thin beam splitter with a grid edge structure, and the grid film beam splitter supports the beam splitting film by utilizing the grid structure. Because the beam splitting film is too thin to be self-supporting, the beam splitting film is supported by adopting a grid structure. The grid structure is made of semiconductor materials, and the beam splitting film is made of polyester films. Grid structure requires phase reflection with stepsthe structures of the mirrors match each other. The grating film beam splitter is arranged at an angle of 45 degrees with the optical axis of the system, and the size of each grid period of the grating film beam splitter is equal to that of each grid period according to the geometric parameters of the step phase reflector

Specifically, referring to FIGS. 7 and 8, in the embodiment, the grid structure of the grid film beam splitter is composed of grid ribs 3-1 and beam splitting windows 3-2, wherein the width of the grid ribs in the transverse direction is the width of the grid ribs in the longitudinal directionthe width of the beam-splitting window 3-2 in the transverse direction is larger than that in the longitudinal directionthe beam splitting window 3-2 has the same duty cycle in the lateral and longitudinal directions. Since the size of the beam splitting window determines the luminous flux of the system, the area of the beam splitting window 3-2 is much larger than the area of the grating edge 3-1. The projection of each beam splitting window 3-2 on the transverse step phase mirror 4 and the longitudinal step phase mirror 5 is located on the respective mirror unit, while the projection of each grating edge 3-1 on the transverse step phase mirror 4 and the longitudinal step phase mirror 5 is located at the intersection of the adjacent mirror units.

The number of grids in two different directions of the grid beam splitter is P and Q respectively, and P is equal to Q or P is not equal to Q; p corresponds to the direction of M of the step phase reflector, and M and P have a multiple relation; q corresponds to the N direction of the step phase reflector, and N and Q have a multiple relation.

The period of the grid mesh in the P direction is a '+ b', a 'is the single edge width in the P direction, and b' is the width of the single beam splitting window in the P direction. Wherein a ' 2 ═ a ' 3 ═ … ═ a ' P; a '1 and a' (P +1) can be the same as or different from other grid edges; b ' 1 ═ b ' 2 ═ … ═ b ' P. Total length of the grating beam splitter P direction: lp is a ' 1+ b ' 1+ a ' 2+ b ' 2+ … + a ' P + b ' P + a ' (P + 1).

the period of the grid mesh in the Q direction is c '+ d', c 'is the single edge width in the Q direction, and d' is the width of the single beam splitting window in the Q direction. Wherein c ' 2 ═ c ' 3 ═ … ═ c ' q; c '1 and c' (Q +1) can be the same as or different from other grid edges; d ' 1 ═ d ' 2 ═ … ═ d ' Q. Total length of grating beam splitter Q direction: LQ ═ c ' 1+ d ' 1+ c ' 2+ d ' 2+ … + c ' Q + d ' Q + c ' (Q + 1).

The widths a 'and c' of the edges of the grid beam splitter are 1nm-100cm, and the widths b 'and d' of the beam splitting windows are 1nm-100 cm; the thickness range of the edges of the grid mesh beam splitter is 1nm-100cm, and the thickness range of the beam splitting window is 1nm-100 cm. The addition or non-addition of the compensation plate can be selected according to specific parameters, and the structure and the material of the compensation plate can be the same as or different from those of the beam splitter.

The ten shapes of the grid beam splitter in fig. 8, the beam splitting windows and the grid edges of the grid beam splitter are of the same structure or different structures, and the beam splitting windows and the grid edges of fig. 8a, 8b, 8e, 8f, 8i, 8j, 8m, 8n, 8q, 8r are of the same structure or different structures; the beam splitting windows and the grid edges in fig. 8c, 8d, 8g, 8h, 8k, 8l, 8o, 8p, 8s, 8t are of a homogenous structure. In the grating beam splitter structure, the cross section of the grating edge structure can be rectangular (fig. 8i, fig. 8k, fig. 8m, fig. 8o), parallelogram (fig. 8a, fig. 8c, fig. 8e, fig. 8g), trapezoid (fig. 8q, fig. 8s), arc or other shapes. In the same grid beam splitter, the grid edges in the horizontal direction and the grid edges in the vertical direction can be in the same structural form or different structural forms.

In conjunction with fig. 9, in the grating beam splitter structure, the cross section of the grating edge structure may also be a double-sided rectangle (fig. 9a and 9b), a double-sided parallelogram (fig. 9c and 9d), a double-sided trapezoid (fig. 9e and 9f), or other shapes.

the present embodiment is described with reference to fig. 10, fig. 10 is a top view of a grating beam splitter structure, where 3-1 is a grating edge and 3-2 is a beam splitting window. The grid number of the grid beam splitter is Q, Q corresponds to the N direction of the step phase reflector, and N and Q have a multiple relation. The period of the grid bars in the Q direction is c '+ d', c 'is the single edge width in the Q direction, and d' is the width of a single beam splitting window in the Q direction. Wherein c ' 2 ═ c ' 3 ═ … ═ c ' Q; c '1 and c' (Q +1) can be the same as or different from other grid edges; d ' 1 ═ d ' 2 ═ … ═ d ' Q. Total length of grating beam splitter Q direction: LQ ═ c ' 1+ d ' 1+ c ' 2+ d ' 2+ … + c ' Q + d ' Q + c ' (Q + 1).

The width c 'of the edge of the grating beam splitter ranges from 1nm to 100cm, and the width d' of the beam splitting window ranges from 1nm to 100 cm; the thickness range of the edge of the grating beam splitter is 1nm-100cm, and the thickness range of the beam splitting window is 1nm-100 cm. The addition or non-addition of the compensation plate can be selected according to specific parameters, and the structure and the material of the compensation plate can be the same as or different from those of the beam splitter.

The beam splitting window, the grid edge and the grid mesh beam splitter of the grid strip beam splitter are the same and can be of a homogeneous structure or a heterogeneous structure. In the grating beam splitter structure, the cross section of the grating edge structure can be rectangular, parallelogram, trapezoid or other shapes. In the same grid beam splitter, the grid edges in the horizontal direction and the grid edges in the vertical direction can be in the same structural form or different structural forms.

fig. 11 is a schematic diagram of the horizontal and vertical grating edge structures of 10 grating beam splitters. In the grating beam splitter structure, the cross section of the grating edge structure can also be a double-sided rectangle, a double-sided parallelogram, a double-sided trapezoid or other shapes.

In this embodiment, the grating materials in the grating beam splitter and the grating beam splitter may be selected from metal, non-metal inorganic materials or organic materials, or may be a mixture of several materials. Metals such as aluminum, copper, titanium, nickel, gold, etc., non-metallic materials such as aluminum oxide, ceramic, quartz, glass, calcium fluoride, zinc selenide, zinc sulfide, silicon, germanium, silicon dioxide, silicon nitride, etc., and organic materials having a supporting function. The beam splitting window material may be quartz, glass, calcium fluoride, magnesium fluoride, barium fluoride, lithium fluoride, zinc selenide, zinc sulfide, silicon, germanium, silicon dioxide, silicon nitride, polyimide, PMMA, aluminum, beryllium, a non-metallic inorganic material, or an organic material. Refractive, reflective, and absorptive materials in the range from X-rays to far infrared, or even wider wavelength ranges not proposed in this embodiment can be applied to the device.

this embodiment is described with reference to FIG. 12, where FIG. 12 is a process for fabricating a wire-grid thin film beam splitter; firstly, the grid structure is manufactured. The grating structure is manufactured by adopting a micro-optical-electro-mechanical-system (MOEMS) process, specifically, as shown in fig. 12, a semiconductor material such as undoped silicon (Si), germanium (Ge), gallium arsenide (GaAs) and the like is selected as a substrate, a layer of photoresist is firstly spin-coated on the semiconductor substrate material, as shown in fig. 12a, then a mask plate of a grating pattern is used for exposure and development, the photoresist at the position of a beam splitting window is removed, and the surface of the semiconductor substrate is exposed, as shown in fig. 12 b. And then removing the semiconductor substrate material at the position of the beam splitting window by adopting a wet etching or dry etching technology to form a hollow structure, as shown in fig. 12 c. Finally, the photoresist at the position of the grid edge is removed, so as to form a grid structure, as shown in fig. 12 d. Fixing the beam splitting window material on the grid structure, supporting the beam splitting window by using the grid edges, splitting the beam by using the beam splitting window, and finally finishing the manufacturing of the grid thin film beam splitter, as shown in fig. 12 e.

When the used beam splitting film is thick, a grid film beam splitter can be adopted, and the grid film beam splitter supports the beam splitting film by utilizing a grid structure. The grid structure is made of semiconductor materials, and the beam splitting film is made of polyester films. The grating structure needs to match the structure of the transversal step phase mirrors. The grating film beam splitter is arranged at an angle of 45 degrees with the optical axis of the system, and the size of each strip period of the grating film beam splitter is equal to that of each strip period of the grating film beam splitter according to the geometric parameters of the step phase reflector

Referring to fig. 13, which illustrates the present embodiment, fig. 13 is a schematic diagram of a process for manufacturing a grating thin film beam splitter, wherein the width of the beam splitting window is much larger than the width of the grating edge because the size of the beam splitting window determines the luminous flux of the system. The projection of each beam splitting window on the transverse step phase mirror 4 is located on each mirror cell, and the projection of each grating edge on the transverse step phase mirror 4 is located at the intersection of adjacent mirror cells.

for the grating film beam splitter, the grating structure is first fabricated. The grating structure is manufactured by adopting a micro-optical-electro-mechanical-system (MOEMS) process, non-doped semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs) and the like are selected as a substrate, a layer of photoresist is firstly spin-coated on the semiconductor substrate material as shown in figure 13a, then a mask plate with grating patterns is placed on the substrate which is spin-coated with the photoresist, the photoresist at the position of the beam splitting window is removed through exposure and development, and the surface of the semiconductor substrate at the position of the beam splitting window is exposed as shown in figure 13 b. And then, removing the semiconductor substrate material at the position of the beam splitting window by adopting a wet etching or dry etching technology to form a hollow structure, as shown in fig. 13 c. Finally, the photoresist at the position of the grid edge is removed, so as to form a grid structure, as shown in fig. 13 d. Fixing the polyester film on the grid structure, supporting the polyester film by using the grid edges, splitting the polyester film by using the beam splitting window, and finally completing the manufacture of the grid film beam splitter, as shown in fig. 13 e.

In this embodiment, the manufacturing method of the grid beam splitter can be divided into an integral manufacturing method and a split manufacturing method. The integrated manufacturing method 1: an ultra-precision machining method. The integrated material is cut, ground, polished and the like; the preparation method 2 comprises the following steps: the MEMS technology is adopted for manufacturing. And carrying out photoetching, dry etching, wet etching and other methods on the integrated material. For example, anisotropic etching method, RIE etching method, ICP etching and surface polishing modification method, etc. of single crystal material, and a fabrication method combining the related MEMS methods.

Example 1: the grid beamsplitter of fig. 8s was fabricated from a double-side polished (100) single crystal silicon wafer with high flatness and high parallelism. The preparation method comprises the following steps:

1. Growing or evaporating silicon dioxide, silicon nitride and other dielectric films or composite films on the surface of the cleaned double-side polished single crystal silicon to be used as masking films;

2. And directionally photoetching to expose the side groove pattern, and removing the masking film in the side groove pattern by etching to expose the surface of the monocrystalline silicon. Etching the side groove by using a monocrystalline silicon anisotropic etching solution, wherein the etching depth is equal to the final thickness of the beam splitting window; the shape of the side groove may be formed by arranging a plurality of rectangles or squares at a predetermined distance, in addition to the illustration.

3. And carrying out second photoetching to expose the beam splitting window pattern, and removing the masking film in the beam splitting window pattern through etching to expose the surface of the single crystal silicon. And removing the photoresist, and simultaneously corroding the side groove and the beam splitting window by using monocrystalline silicon anisotropic corrosive liquid until the corrosion depth of the side groove is 0, wherein the beam splitting window reaches the final thickness.

4. And removing the masking film, evaporating the beam splitting film, and finishing the preparation of the device.

example 2: the double-sided grating beam splitter with both the horizontal and vertical grating structures of fig. 9f can be fabricated by the above method, except that a double-sided masking film needs to be prepared, which is implemented by double-sided lithography and double-sided etching, and the upper and lower surface patterns are the same. And during the first photoetching, the sum of the etching depths of the side grooves on the upper surface and the lower surface is the final thickness value of the beam splitting window.

Example 3: the beam splitter with the structure of the grid mesh is manufactured in the shape of fig. 8k, and the material is a double-sided polished silicon wafer with high flatness and high parallelism. The manufacturing process flow is as follows:

1. Evaporating and plating an aluminum film or thermally grown silicon dioxide or evaporated silicon nitride and other metal films or medium films or composite films on the surface of the cleaned double-side polished monocrystalline silicon to serve as masking films;

2. And photoetching to expose the side groove pattern, and removing the masking film in the side groove pattern by etching to expose the surface of the monocrystalline silicon. Adopting an ICP (inductively coupled plasma) or RIE (reactive ion etching) technology to etch the side groove to a depth equal to the final thickness of the beam splitting window; besides the figure, the side groove shape can also be formed by arranging a plurality of rectangles or squares or circles or ellipses or other polygonal shapes according to a certain distance.

3. And carrying out second photoetching to expose the beam splitting window pattern, and removing the masking film in the beam splitting window pattern through etching to expose the surface of the single crystal silicon. And removing the photoresist, and etching the side groove and the beam splitting window simultaneously by adopting an ICP (inductively coupled plasma) or RIE (reactive ion etching) technology until the etching depth reaches 0, wherein the beam splitting window reaches the final thickness.

example 4:

the double-sided grating beam splitter with both the transverse and longitudinal grating structures of fig. 9b can be manufactured by the above method, except that a double-sided masking film needs to be manufactured, and the upper and lower surface patterns are the same by double-sided lithography and double-sided etching. And during the first photoetching, the sum of the corrosion depths of the side grooves on the upper surface and the lower surface is the final thickness value of the beam splitting window.

Example 5:

The double-side polished (110) monocrystalline silicon wafer with the structure of the grid beam splitter manufactured in the shape of fig. 8o and made of high-flatness and high-parallelism materials is prepared. The manufacturing process flow is similar to that of the embodiment 1.

example 6:

for a double-sided grating prism beam splitter having a structure corresponding to the shape of the grating prism beam splitter as shown in fig. 8o, the material is the same as that in example 5, the manufacturing method is similar to that in example 5, except that a double-sided masking film needs to be prepared, the double-sided masking film is realized by double-sided lithography and double-sided etching, and the upper surface pattern and the lower surface pattern are the same. And during the first photoetching, the sum of the corrosion depths of the side grooves on the upper surface and the lower surface is the final thickness value of the beam splitting window.

the grid and grid beam splitter of other materials or structures can also be realized by the method, and can also be realized by alternately performing wet etching and dry etching of MEMS and two methods, and a single crystal material forming a required included angle with a certain conventional crystal direction can be adopted as a substrate in the manufacturing process to etch a structure with an inclination angle; the structure with the inclination angle can also be etched by an inclined rotation method; and a compensation pattern can be designed, so that the obtained structure is more accurate.

in the present embodiment, the following three methods can be selected: firstly, the beam splitting window and the grid edge can be selected to be made of the same or different materials, a grid edge structure is prepared on the surface of the beam splitting window with or without a supporting material, and the grid edge structure can realize the grid edge of various materials such as metal and nonmetal materials, semiconductor materials, organic matters and the like through MEMS technology, such as X-ray lithography, deep ultraviolet lithography, evaporation and lithography, stripping, electroforming and the like. By utilizing the flexibility of technologies such as X-ray photoetching and the like, the grid edge structure with various structural forms can be realized through controlling the beam angle. After the grid edges are manufactured, the supporting structure needs to be removed for the substrate with the beam splitting window supporting structure. And plating a beam splitting film to finish the manufacturing of the beam splitter.

Selecting the same or different materials for the beam splitting window and the grid edge, bonding the beam splitting window structure and the grid edge structure together, then forming the grid edge structure by using ultra-precision machining or MEMS technology, and then removing the adhesive on the surface of the beam splitting window and the beam splitting window support body. And plating a beam splitting film to finish the manufacturing of the beam splitter.

And thirdly, selecting the beam splitting window and the grid edges to be made of the same or different materials, respectively manufacturing the beam splitting window structure and the grid edge structure by using ultra-precision machining or MEMS technology, and then combining the beam splitting window structure and the grid edge structure together by using bonding or other connection modes.

In the present embodiment described with reference to fig. 14, the array phase mirrors may be made of glass or quartz (SiO)₂) Silicon (Si), germanium (Ge), gallium arsenide (GaAs) and other materials through a two-dimensional multi-film deposition method. Firstly, glass and quartz (SiO) are selected₂) Silicon (Si), germanium (Ge), gallium arsenide (GaAs) and the like as a substrate, removing the photoresist of half the width of the substrate by gluing, masking, exposing and developing to expose the substrate surface of half the width of the substrate, evaporating a film layer with a certain thickness by using a coating process such as electron beam evaporation or magnetron sputtering, and removing the photoresist and the film layer of the mask part to form a two-stage step structure in one direction, as shown in fig. 14 a. Then, glue spreading, masking, exposing and developing are carried out on the step structure in the direction again, a surface with half of the width of each step is exposed on each step, then, film deposition is carried out again by adopting a film coating process such as electron beam evaporation or magnetron sputtering, the thickness of the film is half of that of the film coated in the previous time, and then, the photoresist and the film on the mask part are removed, so that a four-level step structure is formed in the direction, as shown in fig. 14 b. The process is cycled in the direction, the width of each mask is half of the width of the previous mask, and the thickness of each film layer is half of the thickness of the previous film layer, so that the required step structure can be obtained in the direction. Then, in another direction, through gluing, masking, exposing and developing, the surface of the substrate is exposed by half of the length of the substrate, the film deposition is carried out by adopting the film coating process such as electron beam evaporation or magnetron sputtering, the thickness of the film is half of that of the film coated at the last time, and then the photoresist and the film at the mask part are removed, so that the surface of the substrate is coated with the photoresist and the film at the other directiona two-step structure is also formed in this direction as shown in fig. 14 c. Then, glue spreading, masking, exposing and developing are carried out again in the direction, so that the surface of each step in the direction is exposed by half of the length of the step, then, film deposition is carried out again by adopting film coating processes such as electron beam evaporation or magnetron sputtering, the thickness of the film is half of that of the film coated last time, and then, the photoresist and the film on the mask part are removed, so that a two-dimensional step structure is formed, as shown in fig. 14 d. And (3) circulating the process in the direction, wherein the width of each mask is half of the width of the previous mask, the thickness of each film layer is half of the thickness of the previous film layer, and finally the required array phase reflector is obtained.

referring to fig. 15, the present embodiment is described, in which the array phase mirrors are implemented by two-dimensional multiple etching on a substrate made of semiconductor materials such as silicon (Si), germanium (Ge), and gallium arsenide (GaAs); firstly, semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs) and the like are selected as a substrate, then photoresist with half the width of the substrate is removed through gluing, masking, exposure and development, the substrate surface with half the width of the substrate is exposed, wet etching or dry etching is adopted to etch the exposed substrate surface with a certain depth, then the photoresist of the masking part is removed, and a two-stage step structure is formed in the direction, as shown in fig. 15 a. Then, the substrate with two step structures is coated with glue, masked, exposed and developed again in the direction, the substrate surface with half of the step width is exposed on each step, then the exposed substrate surface is etched again by adopting wet etching or dry etching process, the etching depth is half of the last etching depth, and the photoresist of the mask part is removed, so that a four-level step structure is formed in the direction, as shown in fig. 15 b. The process is circulated in the direction, the width of each mask is half of the width of the previous mask, and the etching depth of each mask is half of the etching depth of the previous mask, so that the required step structure can be obtained in the direction. Then, in another direction, the photoresist with half the length of the substrate is removed through gluing, masking, exposure and development, the substrate surface with half the length of the substrate is exposed, the exposed substrate surface is etched by adopting a wet etching or dry etching process, the etching depth is half of the last etching depth, and then the photoresist of the masking part is removed, so that a two-stage step structure is also formed in the direction, as shown in fig. 15 c. Then, glue spreading, masking, exposing and developing are carried out again in the direction, each step in the direction is exposed out of the substrate surface with half of the step length, then, wet etching or dry etching technology is adopted again to etch the exposed substrate surface, the etching depth is half of the last etching depth, and then the photoresist of the mask part is removed, so that a two-dimensional step structure is formed, as shown in fig. 15 d. The process is cycled in the direction, the width of each mask is half of the width of the previous mask, and the depth of each etching is half of the depth of the previous etching, and finally the required array phase reflector is obtained.

Referring to fig. 16, the present embodiment will be described, in which the array phase mirrors are formed by a hybrid method of one-dimensional etching and another one-dimensional plating on a substrate made of semiconductor materials such as silicon (Si), germanium (Ge), and gallium arsenide (GaAs); firstly, semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs) and the like are selected as a substrate, then photoresist with half the width of the substrate is removed through gluing, masking, exposure and development, the substrate surface with half the width of the substrate is exposed, wet etching or dry etching is adopted to etch the exposed substrate surface with a certain depth, then the photoresist of the masking part is removed, and a two-stage step structure is formed in one direction, as shown in fig. 16 a. Then, glue coating, masking, exposing and developing are carried out on the substrate with the two-stage step structure again in the direction, a surface with half of the step width is exposed on each step, the exposed substrate surface is etched by adopting a wet etching or dry etching process, the etching depth is half of the previous etching depth, and the photoresist of the mask part is removed, so that a four-stage step structure is formed in the direction, as shown in fig. 16 b. The process is circulated in the direction, the width of each mask is half of the width of the previous mask, and the etching depth of each mask is half of the etching depth of the previous mask, so that the required step structure can be obtained in the direction. Then, in another direction, through gluing, masking, exposing and developing, the surface of the substrate is exposed by half of the length, the film deposition is carried out by the coating process such as electron beam evaporation or magnetron sputtering, the thickness of the film is half of the last etching depth, and then the photoresist and the film at the mask part are removed, so that a two-stage step structure is also formed in the direction, as shown in fig. 16 c. Then, glue spreading, masking, exposing and developing are carried out again in the direction, so that the surface of each step in the direction is exposed by half of the length of the step, then, film deposition is carried out again by adopting a film coating process such as electron beam evaporation or magnetron sputtering, the thickness of the film is half of that of the film coated last time, and then, the photoresist and the film on the mask part are removed, so that a two-dimensional step structure is formed, as shown in fig. 16 d. And (3) circulating the process in the direction, wherein the width of each mask is half of the width of the previous mask, the thickness of each film layer is half of the thickness of the previous film layer, and finally the required array phase reflector is obtained. In the actual operation process, the etching process is circulated in one direction to form steps of a certain number of stages, and the film coating process is circulated in the other direction, so that the required array phase reflector structure can be finally obtained.

After the array phase reflector structure is obtained, a reflecting film layer made of high-reflectivity materials such as gold and aluminum is evaporated on the surface of the array phase reflector structure, and finally the array phase reflector is formed. The flatness requirement of each reflector unit of the array phase reflector is less than or equal to lambda/20, and the surface roughness requirement is less than or equal to 3 nm.

in a second embodiment, the present embodiment is described with reference to fig. 17, and the present embodiment is a method for manufacturing a fourier transform spectrometer based on an optical switch array according to the first embodiment, and performs system integration by using a method combining visible laser array calibration and infrared camera observation. The specific manufacturing process comprises the following steps:

(1) Firstly, a visible laser array is adopted to calibrate the optical axis of the system, the laser array has the same number NxN as the array phase reflector units, and the distance between each laser unit of the laser array in the transverse direction and the longitudinal direction is equal to the unit size a of the array phase reflector. And the positions and angles of the laser array sources are adjusted, so that the optical axes of the laser arrays are parallel.

(2) A45-degree visible light splitting prism is inserted into a light path to divide the laser array into two paths. The position and the angle of the beam splitter prism are adjusted, so that the transmitted laser beam is collinear with the laser array beam, and the reflected laser beam is perpendicular to the laser array beam.

(3) The array phase reflector is placed in a light path of the reflection laser array, and the position and the angle of the array phase reflector are adjusted, so that each laser beam in the light path of the reflection laser array is incident to the central position of each reflector unit in the array phase reflector, and the light beam incident on the array phase reflector returns along the original path, and the array phase reflector is ensured to be vertical to the optical axis of the laser array, as shown in fig. 17 a.

(4) The planar reflector is placed in the light path of the transmission laser array, and the position and the angle of the planar reflector are adjusted, so that all laser beams in the light path of the transmission laser array are uniformly distributed on the planar reflector, and the light beams incident on the planar reflector return along the original path, and the optical axes of the planar reflector and the laser array are ensured to be collinear, as shown in fig. 17 b.

(5) The visible light splitting prism is rotated by 90 °, so that the reflected laser beam is turned by 180 °. The optical switch array is placed in the new reflected laser beam path, and the position and angle of the optical switch array are adjusted so that each laser beam incident on the optical switch array is located at the center of each optical switch unit of the optical switch array, as shown in fig. 17 c.

(6) and removing the visible light beam splitter prism, and placing the parallel flat plate beam splitter, the grid mesh film beam splitter or the grid strip film beam splitter at the position of the visible light beam splitter prism. Because the flat plate beam splitter, the grid mesh film beam splitter or the grid strip film beam splitter works in an infrared band and only reflects and does not transmit the visible laser array, the flat plate beam splitter, the grid mesh film beam splitter or the grid strip film beam splitter is adjusted by utilizing a reflection light path. For the parallel flat plate beam splitter, the position and the angle of the parallel flat plate beam splitter are adjusted, so that each laser beam reflected to the array phase reflector is positioned at the central position of each reflector unit, and the light beam reflected by the array phase reflector returns along the original path. For the grid film beam splitter, the position and the angle of the grid film beam splitter are adjusted, so that each laser beam of the laser array is incident to the central position of each grid window of the grid film beam splitter, meanwhile, the light beam reflected to the array phase reflector is positioned at the central position of each reflector unit, and the light beam reflected by the array phase reflector returns along the original path. For the grating thin film beam splitter, by adjusting the position and angle of the grating thin film beam splitter, the laser beams of each row of the laser array are incident to the central line position of the long axis of each grating window of the grating thin film beam splitter, and meanwhile, the light beam reflected to the array phase mirror is positioned at the central position of each mirror unit, and the light beam reflected by the array phase mirror returns along the original path, as shown in fig. 17 d.

(7) The collimating mirror is placed in the front light path, and the collimating mirror transmits infrared rays and reflects visible light, so that the laser array is symmetrically distributed on the surface of the collimating mirror by utilizing the characteristic and adjusting the position and the angle of the collimating mirror, and laser beams reflected by the surface of the collimating mirror are also distributed in an array on the source plane of the laser array, so that the optical axis of the collimating mirror is parallel to the laser array, as shown in fig. 17 e.

(8) And removing the laser array, placing the infrared light source in front of the collimating mirror, and adjusting the position of the infrared light source to enable the infrared light source to be positioned on the object focus of the collimating mirror.

(9) After placing the infrared camera in the optical switch array, the infrared light source is turned on, and all the optical switch units of the optical switch array are set to an on state. And adjusting the position of the infrared camera to enable the array phase reflector to clearly image on the area array detector of the infrared camera. The axial translation position of the plane mirror is then adjusted and observed with an infrared camera until an interference image appears, fig. 17 f.

(10) Removing the infrared camera, placing the focusing mirror behind the optical switch array, placing the infrared area array detector on the image focal plane of the focusing mirror, and adjusting the position and angle of the focusing mirror to make the light beams in each "on" state of the optical switch unit focus on the central position of the infrared area array detector, as shown in fig. 17 g.

(11) And removing the infrared area array detector, placing the single-point detector on the focal plane of the focusing mirror, and adjusting the position of the single-point detector to fix each device when the output signal of the detector is maximum, so as to complete system integration, as shown in fig. 17 h.

it should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. The basic elements of an optical switch array based fourier transform spectrometer based on the above description can be modified or changed in other different ways without departing from the scope of the present disclosure, as long as the function is not changed, and all embodiments need not be exhaustive. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The Fourier transform spectrometer based on the optical switch array comprises a collimating mirror (2), a beam splitter (3), a plane reflecting mirror (4), an array phase reflecting mirror (5), an optical switch array (6), a focusing mirror (7) and a point detector (8);

the light emitted by the light source (1) is collimated into parallel light beams through the collimating mirror (2), the parallel light beams are divided into two beams of coherent light with equal intensity through the beam splitter (3), one beam of light is reflected by the beam splitter (3) and then incident on the array phase reflector (5), and the other beam of light is incident on the plane reflector (4) through the beam splitter (3); the array phase reflector (5) performs distributed phase modulation on an incident light field penetrating through the beam splitter (3); the light field modulated by the array phase reflector and the light field reflected by the plane reflector are subjected to coherent superposition again through the beam splitter to form an interference light field; the optical switch array (6) receives the interference light field in a space step-by-step manner, and obtains an interference pattern sequence after passing through a focusing mirror (7) and a point detector (8);

It is characterized in that;

The array phase reflector (5) performs spatial domain segmentation on an incident light field, each phase reflector unit corresponds to one light field segmentation unit, the light field segmentation unit corresponding to the phase reflector unit corresponds to a phase difference when the light field reflected by the area corresponding to the plane reflector (4) interferes on the emergent surface of the beam splitter (3), the emergent light field is an interference light field array with spatial phase difference distribution, and each phase reflector unit corresponds to one interference light field unit in the interference light field array;

the emergent interference light field array is incident on an optical switch array (6), the optical switch array is composed of a plurality of optical switch units distributed in a two-dimensional space, and each optical switch unit corresponds to one interference light field unit in the interference light field array; controlling the on-off of the corresponding interference light field unit in the interference light field array by controlling the on-off of each optical switch unit, and realizing the gating of the interference light field corresponding to a certain phase difference in the interference light field array;

Sequentially controlling the opening and closing of the corresponding optical switch units on the optical switch array (6) according to the spatial distribution sequence of the phase modulation quantity on the array phase reflector, so that each interference optical field unit in the interference optical field array sequentially passes through the optical switch array (6) according to the phase difference sequence; the interference light fields are sequentially collected by a detector according to the phase difference sequence, and finally an interference pattern sequence is formed;

the beam splitter (3) is a light beam splitter with a grid edge structure and comprises grid edges, beam splitting windows and beam splitting films, the grid edges divide the beam splitter spatially to form a beam splitting window array, the beam splitting films are positioned on the upper surfaces of the beam splitting windows or the upper surfaces of the beam splitting windows and the grid edges, and the grid edges support the beam splitting films;

The cross section structure of the grid edges in the grid mesh beam splitter is a single-sided rectangle, a single-sided parallelogram, a single-sided trapezoid, a double-sided rectangle, a double-sided parallelogram or a double-sided trapezoid;

Step one, calibrating a system optical axis by adopting a visible laser array, wherein the laser array has the same number NxN as the array phase reflector units, and the transverse and longitudinal intervals of each laser unit of the laser array are equal to the unit size a of the array phase reflector (5); all optical axes of the laser array are parallel by adjusting the position and the angle of a laser array source;

placing the array phase reflector (5) in a light path of a reflection laser array, enabling each laser beam in the reflection laser array light path to be incident to the central position of each reflector unit in the array phase reflector by adjusting the position and the angle of the array phase reflector (5), and enabling the light beam incident to the array phase reflector to return along the original path, so as to ensure that the array phase reflector is vertical to the optical axis of the laser array;

Placing the plane reflector (4) in the light path of the transmission laser array, and enabling each laser beam in the light path of the transmission laser array to be uniformly distributed on the plane reflector by adjusting the position and the angle of the plane reflector, wherein the light beam incident on the plane reflector returns along the original path, and the optical axes of the plane reflector and the laser array are ensured to be collinear;

rotating the visible light beam splitter prism by 90 degrees, turning the reflected laser beams by 180 degrees, placing the optical switch array in a new reflected laser beam light path, and enabling each laser beam incident on the optical switch array to be positioned at the central position of each optical switch unit of the optical switch array by adjusting the position and the angle of the optical switch array (6);

2. the optical switch array based fourier transform spectrometer of claim 1, wherein; the beam splitter is manufactured by adopting an ultra-precise machining method and an MOEMS technology;

the preparation process by adopting the ultra-precise machining method comprises the following steps: obtaining grid edges and beam splitting windows on a substrate through an integrated cutting, grinding and polishing technology, and then integrally evaporating and plating a beam splitting film to finish the preparation of a device;

the preparation of the beam splitter by adopting the MOEMS technology is realized by the following steps:

Step one, monocrystalline silicon is selected as a substrate, and a masking film is prepared on the surface of the monocrystalline silicon;

Step two, directional photoetching is carried out, the masking film in the side groove graph is removed through an etching method, and the side groove graph is exposed; etching the side groove by using the monocrystalline silicon anisotropic etching solution, wherein the etching depth of the side groove is equal to the final thickness of the beam splitting window;

step three, carrying out second photoetching, removing the masking film in the beam splitting window graph through etching, and exposing the beam splitting window graph; adopting monocrystalline silicon anisotropic etching liquid to etch the side groove and the beam splitting window simultaneously, wherein the etching depth is up to the etching thickness of the side groove being 0, and the beam splitting window reaches the final thickness;

And step four, removing the masking film on the surface of the grid edge, and integrally evaporating the beam splitting film to finish the preparation of the beam splitter.

3. The optical switch array-based fourier transform spectrometer of claim 1, wherein the thickness of the (1,0) th phase mirror unit is set as h, and the thickness of the (m, n) th phase mirror unit is (nN + m) h, based on the (0,0) th phase mirror unit in the array phase mirror (5); when the mirror image position of the plane mirror (4) relative to the beam splitter (3) is superposed with the (0,0) th phase mirror unit in the array phase mirror (5), the phase difference of the interference light field unit corresponding to the (m, n) th phase mirror unit is 4 pi v (nN + m) h, and v is the wave number of the light wave;

When the mirror position of the plane mirror (4) relative to the beam splitter (3) and the (m) th mirror in the array phase mirror (5)₀,n₀) When the phase mirror units are overlapped, the phase difference of the interference light field unit corresponding to the (m, n) th phase mirror unit is

4. the optical switch array based fourier transform spectrometer of claim 1, wherein only one optical switch cell of the optical switch array (6) is in an on state and the rest of the optical switch cells are in an off state at a specific time, and the amplitude modulation formula of the optical switch array (6) to the optical field is:

the phase modulation formula of the array phase reflector to the incident light field is as follows:

5. the optical switch array-based fourier transform spectrometer of claim 1, wherein the on state of the (m, n) th optical switch cell in the optical switch array (6) transmits the interference optical field cell corresponding to the (m, n) th phase mirror cell of the array phase mirror, and the off state of the rest of the optical switch cells blocks the interference optical field cell corresponding to the rest of the phase mirror cells.

6. The optical switch array-based fourier transform spectrometer of claim 1, wherein the size of each phase mirror unit in the array phase mirror (5) is set to a x a, the number of arrays of the array phase mirror units is set to N x N, the size of each optical switch unit in the optical switch array (6) is set to b x b, and the number of arrays is set to M x M, then the size of each optical switch unit satisfies b ≦ a, and the number of arrays of optical switch units satisfies M ≧ N.

7. the optical switch array-based fourier transform spectrometer of claim 1, wherein the array phase mirror (5) is composed of a plurality of phase mirror units, each phase mirror unit corresponds to a thickness value, the thicknesses of the phase mirror units are sequentially increased by taking h as a step length along m direction and are sequentially increased by taking Nh as a step length along n direction, and the thickness h is less than or equal to λ/4; the planeness of each reflector unit of the array phase reflector (5) is less than or equal to lambda/20, and the surface roughness is less than or equal to 3 nm.

8. the fourier transform spectrometer based on the optical switch array according to claim 1, wherein the focal length of the focusing mirror (7) is f, the size of the point detector is d x d, the wavelength of the light wave is λ, and the size of the light-sensitive surface diffuse spot of the point detector (8) is 2 λ f/b; the size of the photosensitive surface of the point detector (8) satisfies

9. the method for manufacturing the fourier transform spectrometer based on the optical switch array as claimed in claim 1, wherein the system integration is performed by a method combining visible laser array calibration and infrared camera observation, and the specific manufacturing steps are as follows: