Optical system for terahertz beam shaping

Abstract

The utility model discloses an optical system for terahertz wave beam shaping. The optical system comprises an off-axis parabolic mirror, a plurality of groups of microarray off-axis reflectors and an integral reflector which are sequentially arranged along a light path propagation path, wherein the off-axis parabolic mirror is used for reflecting and collimating a terahertz wave beam with a certain divergence angle into a parallel wave beam; the plurality of groups of microarray off-axis reflectors enable the parallel wave beams from the off-axis parabolic mirror to form a plurality of divergent sub-beams and the divergent sub-beams are incident to the integral reflector; and the integral reflector is used for reflecting, collimating and homogenizing the sub divergent beams into flat-topped beams. The optical system for terahertz wave beam shaping can form a uniform light field, and ensures that the shaped terahertz wave beam has good uniformity.

Description

Technical Field

[0001] The utility model belongs to the technical field of terahertz imaging, and in particular relates to an optical system for terahertz beam shaping. Background Art

[0002] Terahertz waves have the unique property of penetrating non-metallic and non-polar materials, which makes them have wide application potential in non-destructive testing, human security inspection, medicine, communications and other fields. Terahertz beam shaping technology is one of the basic technologies for terahertz wave applications, which directly affects the performance and application effect of terahertz imaging systems. The purpose of terahertz beam shaping is to shape the divergent Gaussian beam into a collimated and uniform light field, which plays an important role in the application of terahertz waves, especially in imaging, communication and sensing.

[0003] In the existing technology, terahertz beam shaping technology mainly adopts the following two methods:

[0004] Refractive beam shaping method: The divergent terahertz beam is shaped into a uniform light field using an optimized surface combination structure. The advantages of this method are simple structure and assembly. The disadvantages are that the material has large dispersion, the shaping effect is different at different frequencies, and the interference between the two mirrors is serious, which affects the imaging quality.

[0005] Diffraction beam shaping method: Use diffraction gratings or optical elements to shape the divergent terahertz beam into a uniform light field. The advantage of this method is that the structure is simple and easy to implement. The disadvantage is that the required optical components are large in size and difficult to integrate.

[0006] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0007] The utility model aims to provide an optical system for terahertz beam shaping, which can form a uniform light field and ensure that the shaped terahertz beam has good uniformity.

[0008] In order to achieve the above-mentioned object, a specific embodiment of the utility model provides an optical system for terahertz beam shaping, comprising off-axis parabolic mirrors, multiple groups of micro-array off-axis reflectors and an integrating reflector arranged in sequence along an optical propagation path;

[0009] Among them, the off-axis parabolic mirror is used to reflect and collimate the terahertz beam with a certain divergence angle into a parallel beam; multiple groups of the micro-array off-axis reflectors make the parallel beam from the off-axis parabolic mirror into multiple sub-divergent beams and incident on the integrating reflector; the integrating reflector is used to reflect, collimate and homogenize the sub-divergent beams into a flat-top beam.

[0010] In one or more embodiments of the present invention, the number of the microarray off-axis reflectors is two groups, each group of the microarray off-axis reflectors is integrated with a plurality of identical sub-mirror surfaces arranged in an array, and each of the sub-mirror surfaces is an off-axis parabolic mirror; each sub-mirror surface of the second group of the microarray off-axis reflectors is located at the focus of the corresponding sub-mirror surface of the first group of the microarray off-axis reflectors.

[0011] In one or more embodiments of the present invention, the off-axis parabolic mirror is made of an aluminum substrate or a stainless steel substrate; the microarray off-axis reflector is made of an aluminum substrate or a stainless steel substrate; the integrating reflector is made of an aluminum substrate or a stainless steel substrate.

[0012] In one or more embodiments of the present invention, a terahertz wave with a certain divergence angle is reflected and collimated into a parallel beam by the off-axis parabolic mirror, and the parallel beam is irradiated onto the first group of the microarray off-axis reflectors, reflected by the sub-mirrors of the first group of the microarray off-axis reflectors and divided into a plurality of focused sub-beams, and each sub-beam is focused by the corresponding sub-mirror onto the second group of the microarray off-axis reflectors corresponding to the sub-mirror, thereby being reflected and re-diverged to form a plurality of sub-divergent beams, and all the sub-divergent beams are incident on the integrating reflector, reflected by the integrating reflector and re-collimated to form a flat-top beam.

[0013] In one or more embodiments of the present invention, the optical system for terahertz beam shaping also includes multiple groups of plane mirrors, which are formed in sequence on the side of the integrating mirror away from the microarray off-axis mirror, and the multiple groups of plane mirrors are used to shorten the optical path of the integrating mirror and change the optical path direction of the flat-top beam.

[0014] In one or more embodiments of the present invention, the number of the plane mirrors is two groups, and the two groups of plane mirrors can shorten the optical path of the integrating reflector and emit the flat-top beam from the integrating reflector in a direction parallel to the optical path of the incident integrating reflector; the number of the plane mirrors is three groups, and the three groups of plane mirrors can emit the flat-top beam from the integrating reflector in a direction perpendicular to the optical path of the incident integrating reflector.

[0015] In one or more embodiments of the present invention, the reflective surfaces of the off-axis parabolic mirror, the micro-array off-axis reflector and the integrating reflector are coated with a gold film, a silver film or a high-reflective film.

[0016] In one or more embodiments of the present invention, the integrating reflector is an off-axis parabolic mirror.

[0017] The purpose of the utility model is to provide a terahertz beam shaping method, comprising:

[0018] An off-axis parabolic mirror is used to reflect and collimate the terahertz wave with a certain divergence angle into a parallel beam;

[0019] Using multiple groups of micro-array off-axis reflectors to split the parallel beam into multiple focused sub-beams and finally form multiple sub-divergent beams;

[0020] An integrating reflector is used to reflect, re-collimate and homogenize the plurality of sub-divergent light beams into a flat-top beam.

[0021] In one or more embodiments of the present invention, two groups of microarray off-axis reflectors are used to divide the parallel beam into a plurality of focused sub-beams and finally form a plurality of divergent sub-beams; each group of the microarray off-axis reflectors is integrated with a plurality of identical sub-mirrors arranged in an array, each of the sub-mirrors is an off-axis parabolic mirror, and each sub-mirror of the second group of the microarray off-axis reflectors is located at the focus of the corresponding sub-mirror of the first group of the microarray off-axis reflectors; the parallel beam is reflected and divided into a plurality of focused sub-beams by the sub-mirrors on the first group of the microarray off-axis reflectors, and each sub-beam is focused by the corresponding sub-mirror onto the second group of the microarray off-axis reflectors corresponding to the sub-mirror, so as to reflect and re-diverge the focused plurality of sub-beams to form a plurality of divergent sub-beams.

[0022] In one or more embodiments of the present invention, the terahertz beam shaping method further includes using multiple groups of plane reflectors to shorten the optical path of the integrating reflector and change the optical path direction of the flat-top beam.

[0023] Compared with the prior art, the optical system for terahertz beam shaping and the terahertz beam shaping method of the utility model can form a uniform light field and ensure that the shaped terahertz beam has good uniformity.

[0024] The optical system and terahertz beam shaping method of the utility model realize the collimation of the terahertz beam through an off-axis parabolic mirror, so that the beam can maintain a small diffusion angle during the propagation process, improve the collimation of the terahertz beam, make the shaped beam more stable and accurate, and help to improve the applicability of the system in different application scenarios.

[0025] The utility model discloses an optical system and a method for terahertz beam shaping, which reflect and shape the terahertz beam by integrating a micro-array off-axis reflector and an integrating reflector, so that the beam eventually forms a flat-top uniform light field.

[0026] The optical system and method for terahertz beam shaping of the utility model ensure that the terahertz beam can be accurately controlled during the shaping process through the synergistic effect of the off-axis parabolic mirror, the micro-array off-axis reflector and the integrating reflector, thereby finally forming a uniform light field.

[0027] The optical system and terahertz beam shaping method of the utility model use reflective optical elements in all components, and the surfaces are plated with gold film, silver film or high reflective film, which eliminates the interference caused by reflection between interfaces and improves the imaging quality compared with other refractive optical elements.

[0028] The utility model discloses an optical system for terahertz beam shaping and a terahertz beam shaping method, which realizes the uniformity of the light field, simplifies the system structure, improves the collimation of the terahertz wave, improves the performance stability, and improves the adaptability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a schematic structural diagram of an optical system for terahertz beam shaping in one embodiment of the utility model;

[0031] Figure 2 This is a schematic diagram of the structure of a micro-array off-axis reflector in an optical system for terahertz beam shaping in one embodiment of the utility model;

[0032] Figure 3 It is a light path diagram of a sub-mirror surface in a micro-array off-axis reflector structure in one embodiment of the utility model;

[0033] Figure 4 The design simulation results of terahertz beam shaping of the optical system for terahertz beam shaping in Example 1 of the utility model are as follows;

[0034] Figure 5 These are actual test data of terahertz beam shaping performed by the optical system for terahertz beam shaping in Example 1 of the utility model. DETAILED DESCRIPTION

[0035] 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 described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] As mentioned in the background technology, the existing terahertz beam shaping technology has some shortcomings in some aspects, including the following:

[0037] Inhomogeneous light field: Conventional terahertz beam shaping technology may lead to inhomogeneity in the light field, that is, the formed beam has an uneven brightness or intensity distribution in spatial distribution, which may affect the performance of imaging or communication systems.

[0038] Serious interference: Some existing technologies use complex optical elements or structures, which cause serious interference due to refraction and reflection between the air and material interface.

[0039] Collimation is difficult to achieve: In some systems, achieving high collimation of terahertz waves may be subject to certain limitations, resulting in a large propagation angle of the beam and difficulty in forming a precise light field.

[0040] Unstable performance: Some existing technologies may be affected by environmental factors or external interference, resulting in unstable performance of the shaped terahertz beam, especially in complex application scenarios.

[0041] Poor adaptability: Some systems may have poor adaptability to different beam shapes and find it difficult to meet diverse application requirements.

[0042] Based on this, the present application provides an optical system and a terahertz beam shaping method for terahertz beam shaping, which uses an off-axis parabolic mirror to reflect and collimate the divergent terahertz beam to obtain a parallel terahertz beam. The parallel terahertz beam is irradiated onto a microarray off-axis reflector, which reflects the collimated terahertz beam and then splits it into multiple focused sub-beams and focuses them onto another group of microarray off-axis reflectors, which reflects most of the sub-beams and re-diverges them and then incidents them onto an integrating reflector, which reflects and collimates them into a flat-top beam, thereby obtaining collimated light with a flat-top uniform light field.

[0043] The present application provides an optical system and a terahertz beam shaping method for terahertz beam shaping, which adopts a total reflection beam shaping method, eliminates interference between interfaces and absorption of refractive materials, has high energy utilization, good shaping effect, and high beam quality.

[0044] like Figure 1 As shown, an optical system for terahertz beam shaping in an embodiment of the utility model includes an off-axis parabolic mirror 10, a plurality of groups of micro-array off-axis reflectors 21 / 22 and an integrating reflector 30 which are sequentially arranged along the optical propagation path.

[0045] The off-axis parabolic mirror 10 is used to reflect and collimate the terahertz beam A with a certain divergence angle into a parallel beam B. Multiple groups of micro-array off-axis reflectors 21 / 22 make the parallel beam B from the off-axis parabolic mirror 10 form multiple sub-divergent beams C and incident on the integrating reflector. The integrating reflector 30 is used to collimate and homogenize the sub-divergent beams C into a flat-top beam D.

[0046] Specifically, the number of the micro-array off-axis reflectors 21 / 22 is two groups. Figure 2 As shown, each group of micro-array off-axis reflectors 21 / 22 is integrated with a plurality of identical sub-mirror surfaces 23 arranged in an array, and each sub-mirror surface 23 is an off-axis parabolic mirror. Each sub-mirror surface of the second group of micro-array off-axis reflectors 22 is located at the focus of the corresponding sub-mirror surface of the first group of micro-array off-axis reflectors 21, so as to re-reflect and disperse the multiple sub-beams reflected and focused by the first group of micro-array off-axis reflectors 21 into multiple sub-divergent beams, and then incident on the integrating reflector 30.

[0047] The first group of micro-array off-axis reflectors 21 divides the parallel beam B into focused sub-beams C1. The focused sub-beams C1 are reflected by the second group of micro-array off-axis reflectors 22 and then diverge again. After passing through the integrating reflector 30, a homogenized flat-top beam D is formed near the focus of the integrating reflector 30.

[0048] It can be understood that when the array of sub-mirrors in the micro-array off-axis reflector 21 / 22 is a rectangular array, the homogenized and shaped light spot is rectangular; when the array of sub-mirrors in the micro-array off-axis reflector 21 / 22 is a circular array, the homogenized and shaped light spot is circular.

[0049] refer to Figure 1 and Figure 3As shown, a terahertz wave with a certain divergence angle is reflected and collimated into a parallel beam A by an off-axis parabolic mirror 10, and the parallel beam A is irradiated onto a first group of microarray off-axis reflectors 21, and is reflected by the sub-mirrors on the microarray off-axis reflectors 21 and divided into a plurality of focused sub-beams C1. At the same time, each sub-beam is focused by the corresponding sub-mirror onto a second group of microarray off-axis reflectors 22 corresponding to the sub-mirror, thereby being reflected and re-diverged to form a plurality of sub-divergent beams C. All the sub-divergent beams C are incident on an integrating reflector 30, and are re-collimated and homogenized into a flat-top beam D by the integrating reflector 30.

[0050] Among them, the parallel beam A formed after the terahertz wave is reflected and collimated by the off-axis parabolic mirror 10 has a light intensity distribution with a strong center and weak edges, and the parallel beam A is divided into a plurality of focused sub-beams C1 after being reflected by the first group of micro-array off-axis reflectors 21, and then formed into a plurality of sub-divergent beams C after being reflected by the second group of micro-array off-axis reflectors 22. Each sub-divergent beam C has a light intensity distribution with a strong center and weak edges, and the edge of a sub-divergent beam C will gradually approach the central light intensity after the edge of the adjacent sub-divergent beam C is superimposed, and finally all the sub-divergent beams C are reflected by the integrating reflector 30, and then re-collimated and homogenized into a flat-top beam D, and the flat-top beam D has a uniform light field, ensuring that the shaped terahertz beam has good uniformity.

[0051] Since the focal length of the integrating mirror 30 is relatively long, in order to shorten the optical path length, the optical system for terahertz beam shaping of the present application also includes multiple groups of plane mirrors 41 / 42 / 43, which are formed in sequence on the side of the integrating mirror 30 away from the microarray off-axis mirrors 21 / 22. The multiple groups of plane mirrors 41 / 42 / 43 are used to shorten the focal length of the integrating mirror 30 and change the optical path direction of the flat-top beam D.

[0052] Exemplarily, the number of plane reflectors is two groups, and the two groups of plane reflectors 41 / 42 can emit the flat-top beam D from the integrating reflector in a direction parallel to the optical path of the incident integrating reflector. Alternatively, the number of plane reflectors is three groups, and the three groups of plane reflectors 41 / 42 / 43 can emit the flat-top beam D from the integrating reflector in a direction perpendicular to the optical path of the incident integrating reflector.

[0053] The optical path of the plane reflector is based on a pentaprism structure, which mainly utilizes two plane reflectors to shorten the optical path of the integrating reflector 30; the function of the last 45° plane reflector is to change the horizontal optical path into a vertical upward optical path, and the last plane reflector can be set according to the optical path requirements.

[0054] In the optical system for terahertz beam shaping of the present application, the integrating reflector 30 is also an off-axis parabolic mirror. The material of the off-axis parabolic mirror 10 is an aluminum material substrate or a stainless steel substrate. The material of the micro-array off-axis reflector 21 / 22 is an aluminum material substrate or a stainless steel substrate. The material of the integrating reflector 30 is an aluminum material substrate or a stainless steel substrate. The reflecting surfaces of the off-axis parabolic mirror 10, the micro-array off-axis reflector 21 / 22, and the integrating reflector 30 are all coated with a gold film, a silver film, or a high-reflection film.

[0055] The working principle of the optical system for terahertz beam shaping in this application is as follows:

[0056] The terahertz wave source O or the terahertz wave source O provided with a waveguide horn antenna O1 emits a terahertz beam A with a Gaussian distribution and a certain divergence angle (the waveguide horn antenna O1 can emit the terahertz wave from the waveguide into the free space and form a beam with a certain divergence angle). The terahertz beam A is collimated after passing through the off-axis parabolic mirror 10. The off-axis parabolic mirror 10 has the function of collimating and homogenizing the divergent light into a flat-top beam, so the terahertz beam A with a certain divergence angle can be collimated into a parallel beam B. The collimated parallel beam B is irradiated onto the first group of micro-array off-axis reflectors 21. The micro-array off-axis reflector 21 is composed of a plurality of sub-mirrors, each of which is an off-axis parabolic mirror. Since the curvature radius and focal length of each sub-mirror are the same and they are distributed on an inclined plane, each sub-mirror will focus the incident light onto a plane parallel to the first group of microarray off-axis reflectors 21, thereby splitting the parallel beam B into multiple focused sub-beams C1. Each sub-beam C1 will continue to propagate and irradiate the second group of microarray off-axis reflectors 22 (having a plane parallel to the first group of microarray off-axis reflectors 21). Each sub-mirror of the second group of microarray off-axis reflectors 22 is located at the focus of the corresponding sub-beam C1, so each sub-beam C1 will be reflected by the second group of microarray off-axis reflectors 22. After all sub-beams C1 pass through the second group of microarray off-axis reflectors 22, they will re-diverge to form multiple sub-divergent beams C and be incident on the integrator reflector 30. The integrator reflector 30 has the function of collimating and homogenizing the sub-divergent beams into flat-top beams, so all sub-divergent beams C can be re-collimated and homogenized into flat-top beams D. After the integrating reflector 30 re-collimates and homogenizes all the sub-divergent light beams C into a flat-top beam D, the flat-top beam forms a light spot on the focal plane of the integrating reflector 30 .

[0057] The present application also provides a terahertz beam shaping method, comprising the following steps:

[0058] S1, an off-axis parabolic mirror is used to collimate the terahertz wave with a certain divergence angle into a parallel beam.

[0059] S2, multiple groups of micro-array off-axis reflectors are used to split the parallel beam into multiple focused sub-beams and finally form multiple sub-divergent beams.

[0060] S3, using an integrating reflector to re-collimate and homogenize the multiple sub-divergent light beams into a flat-top beam.

[0061] S4, multiple groups of plane mirrors are used to shorten the focal length of the integrating mirror and change the optical path direction of the flat-top beam.

[0062] Wherein, in step S2, two groups of microarray off-axis reflectors are used to divide the parallel beam into multiple focused sub-beams and finally form multiple sub-divergent beams. Each group of microarray off-axis reflectors is integrated with multiple identical sub-mirrors arranged in an array, each sub-mirror is an off-axis parabolic mirror, and each sub-mirror of the second group of microarray off-axis reflectors is located at the focus of the corresponding sub-mirror of the first group of microarray off-axis reflectors; the parallel beam is divided into multiple focused sub-beams by the sub-mirrors on the first group of microarray off-axis reflectors, and each sub-beam is focused by the corresponding sub-mirror onto the second group of microarray off-axis reflectors corresponding to the sub-mirror, so as to diverge the focused multiple sub-beams to form multiple sub-divergent beams.

[0063] Embodiment 1:

[0064] The terahertz source emits a Gaussian beam with a divergence angle of 17° from a waveguide horn antenna, which forms a collimated beam through an off-axis parabolic mirror (curvature radius of -200 mm, cone coefficient of -1, off-axis eccentricity of 200 mm, angle of 90°, and focal length of 200 mm). The collimated beam is incident on the first micro-array off-axis reflector (the curvature radius of each sub-mirror-micro off-axis parabolic mirror is -127 mm, the cone coefficient is -1, the off-axis eccentricity is 127 mm, the focal length is 127 mm, the spacing between sub-mirrors is 7×6.99 mm, the array scale is 17×17, the oblique section of the array is at an angle of 45° with the incident plane-the direction of the array is 45° with the incident direction, so that each sub-beam is emitted vertically), and the collimated beam is split into multiple focused sub-beams by each sub-mirror, and the focus of the sub-beam is located at the center of the sub-mirror of the second micro-array off-axis reflector. The surface parameters of each sub-mirror surface of the first micro-array off-axis reflector and the second micro-array off-axis reflector are the same. The sub-divergent beam emitted by the second micro-array off-axis reflector is focused on the integrating reflector, and the integrating reflector has a curvature radius of -1778mm, a cone coefficient of -1, an off-axis eccentric distance of 1778mm, an angle of 90°, and a focal length of 1778mm. The first plane reflector, the second plane reflector, and the third plane reflector are all gold-plated plane reflectors, and their main function is to change the direction of the optical path, shorten the optical path and the direction of the outgoing beam.

[0065] In the above scheme, the arrangement of the first plane reflector and the second plane reflector can realize that the flat-top beam from the integrating reflector is emitted in a direction parallel to the optical path of the incident integrating reflector, and the optical path of the integrating reflector is shortened. When a third plane reflector is added, the flat-top beam from the integrating reflector can be emitted in a direction perpendicular to the optical path of the incident integrating reflector.

[0066] The size of the homogenized light spot in the above-mentioned embodiment 1 is 100×100 mm.

[0067] refer to Figure 4 As shown, Figure 4 The design simulation results of terahertz beam shaping of the optical system for terahertz beam shaping in Example 1 of the utility model are shown, wherein (a) represents the light field amplitude distribution at the focal plane of the integrating reflector, indicating that the optical system for terahertz beam shaping of the present application forms a Gaussian beam into a rectangular homogenized beam, and (b) and (c) represent the amplitude distribution in the center X direction and the amplitude distribution in the Y direction, respectively.

[0068] refer to Figure 5 As shown, Figure 5 The actual test data of terahertz beam shaping performed by the optical system for terahertz beam shaping in Example 1 of the utility model, wherein (a) indicates that the amplitude is relatively uniform within the area of ​​±13 mm, (b) and (c) respectively represent the amplitude distribution in the center X direction and the amplitude distribution in the Y direction.

[0069] pass Figure 4 and Figure 5 It can be seen that the optical system for terahertz beam shaping of the utility model finally achieves the goal of homogenization.

[0070] Embodiment 2:

[0071] The terahertz source emits a Gaussian beam with a divergence angle of 17° from a waveguide horn antenna, which passes through an off-axis parabolic mirror (curvature radius of -120 mm, cone coefficient of -1, off-axis eccentricity of 120 mm, angle of 90°, and focal length of 120 mm) to form a collimated beam. The collimated beam is incident on the first micro-array off-axis reflector (the curvature radius of each sub-mirror - micro-off-axis parabolic mirror is -76.2mm, the cone coefficient is -1, the off-axis eccentric distance is 76.2mm, the focal length is 76.2mm, the spacing between the sub-mirrors is 4×4mm, the array scale is 17×17, the oblique section of the array is at a 45° angle to the incident plane - the direction of the array is 45° to the incident direction, so that each sub-beam is emitted vertically), and the collimated beam is split into multiple focused sub-beams by each sub-mirror. The focus of the sub-beam is located at the center of the sub-mirror of the second micro-array off-axis reflector. The surface parameters of each sub-mirror of the first micro-array off-axis reflector and the second micro-array off-axis reflector are the same. The sub-divergent beam emitted by the second micro-array off-axis reflector is focused on the integrating reflector, the curvature radius of the integrating reflector is -1143mm, the cone coefficient is -1, the off-axis eccentric distance is 1143mm, the angle is 90°, and the focal length is 1143mm. The first plane reflector, the second plane reflector, and the third plane reflector are all gold-plated plane reflectors, and their main function is to change the direction of the optical path, shorten the optical path and the direction of the outgoing beam.

[0072] In the above scheme, the arrangement of the first plane reflector and the second plane reflector can realize that the flat-top beam from the integrating reflector is emitted in a direction parallel to the optical path of the incident integrating reflector, and the optical path of the integrating reflector is shortened. When a third plane reflector is added, the flat-top beam from the integrating reflector can be emitted in a direction perpendicular to the optical path of the incident integrating reflector.

[0073] The size of the homogenized spot in the above-mentioned embodiment 2 is 60×60 mm.

[0074] Compared with the prior art, the optical system and terahertz beam shaping method of the utility model for terahertz beam shaping ensure that the terahertz beam can be accurately controlled during the shaping process through the synergistic effect of the off-axis parabolic mirror, the micro-array off-axis reflector and the integrating reflector, and finally form a uniform light field, ensuring that the shaped terahertz beam has good uniformity. Compared with traditional technologies, it helps to improve the uniformity of the light field after shaping, and has obvious advantages for imaging and communication applications.

[0075] The optical system and terahertz beam shaping method of the utility model for terahertz beam shaping adopt a relatively simple optical structure of an off-axis parabolic mirror, a micro-array off-axis reflector and an integrating reflector. Compared with complex structures such as photonic crystals and liquid crystal optical elements, the design of the system is simpler, the complexity of the entire system is reduced, and it is expected to reduce costs and improve maintainability.

[0076] The optical system and terahertz beam shaping method of the utility model realize the collimation of the terahertz beam through an off-axis parabolic mirror, so that the beam can maintain a small diffusion angle during the propagation process, improve the collimation of the terahertz beam, make the shaped beam more stable and accurate, and help to improve the applicability of the system in different application scenarios.

[0077] The utility model discloses an optical system and a method for terahertz beam shaping, which reflect and shape the terahertz beam by integrating a micro-array off-axis reflector and an integrating reflector, so that the beam eventually forms a flat-top uniform light field.

[0078] The optical system and terahertz beam shaping method of the utility model use reflective optical elements for all components, and the surfaces are plated with gold films. Compared with other refractive optical elements, the interference caused by reflection between interfaces is eliminated, and the imaging quality is improved.

[0079] The optical system for terahertz beam shaping and the terahertz beam shaping method of the utility model improve the performance stability of the terahertz beam after shaping, so that the system has better stability under different environments and interference conditions, which helps to improve the reliability and applicability of the system.

[0080] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0081] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An optical system for terahertz beam shaping, characterized in that: It includes off-axis parabolic mirrors, multiple groups of micro-array off-axis reflectors and integrating reflectors which are sequentially arranged along the optical propagation path; Among them, the off-axis parabolic mirror is used to reflect and collimate the terahertz beam with a certain divergence angle into a parallel beam; multiple groups of the micro-array off-axis reflectors enable the parallel beam from the off-axis parabolic mirror to form multiple sub-divergent beams and incident on the integrating reflector; the integrating reflector is used to reflect, collimate and homogenize the sub-divergent beams into a flat-top beam.

2. The optical system for terahertz beam shaping according to claim 1, characterized in that: The number of the micro-array off-axis reflectors is two groups, each group of the micro-array off-axis reflectors is integrated with a plurality of identical sub-mirrors arranged in an array, and each of the sub-mirrors is an off-axis parabolic mirror; Each sub-mirror surface of the second group of micro-array off-axis reflectors is located at the focus of the corresponding sub-mirror surface of the first group of micro-array off-axis reflectors.

3. The optical system for terahertz beam shaping according to claim 2, characterized in that: A terahertz wave with a certain divergence angle is reflected and collimated into a parallel beam by the off-axis parabolic mirror, and the parallel beam is irradiated onto the first group of the microarray off-axis reflectors, and is reflected by the sub-mirrors of the first group of the microarray off-axis reflectors and divided into a plurality of focused sub-beams. At the same time, each sub-beam is focused by the corresponding sub-mirror onto the second group of the microarray off-axis reflectors corresponding to the sub-mirror, so as to be reflected and re-diverged to form a plurality of sub-divergent beams, and all the sub-divergent beams are incident on the integrating reflector, and are reflected and re-collimated by the integrating reflector to be homogenized into a flat-top beam.

4. The optical system for terahertz beam shaping according to claim 1, characterized in that: The optical system for terahertz beam shaping also includes multiple groups of plane mirrors, which are sequentially formed on the side of the integrating mirror away from the microarray off-axis mirror. The multiple groups of plane mirrors are used to shorten the optical path of the integrating mirror and change the optical path direction of the flat-top beam.

5. The optical system for terahertz beam shaping according to claim 4, characterized in that: The number of the plane reflectors is two groups, and the two groups of plane reflectors can shorten the optical path of the integrating reflector and emit the flat-top beam from the integrating reflector in a direction parallel to the optical path of the incident integrating reflector; The number of the plane reflectors is three groups, and the three groups of plane reflectors can emit the flat-top beam from the integrating reflector in a direction perpendicular to the optical path of the incident integrating reflector.

6. The optical system for terahertz beam shaping according to claim 1, characterized in that: The integrating reflector is an off-axis parabolic mirror.

7. The optical system for terahertz beam shaping according to claim 1, characterized in that: The reflecting surfaces of the off-axis parabolic mirror, the micro-array off-axis reflecting mirror and the integrating reflecting mirror are all plated with a gold film, a silver film or a high-reflection film.

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