Large-aperture transmission wavefront measuring device based on coherence tomography and measuring method thereof

Abstract

The invention belongs to the field of transmission wavefront measurement, and particularly relates to a large-aperture transmission wavefront measurement device and method based on coherence tomography, and the device comprises a broadband light source which is used for emitting low-coherence light; the beam splitter is used for splitting the low-coherence light into reference light and measuring light, the reference light enters the reference plane mirror and is reflected back to the beam splitter through the reference plane mirror, and the measuring light enters the optical element to be measured and penetrates through the optical element to be measured; the reflecting element is arranged at the focus of the optical element to be measured and is used for reflecting the transmitted wavefront of the optical element to be measured back to the beam splitter to interfere with the reference light to form interference light; the grating is arranged in the beam combining direction of the beam splitter and is used for carrying out dispersion on the interference light; the converging lens is arranged in the dispersion direction of the grating and is used for converging the dispersion light; and the photoelectric detector is arranged at the focus of the converging lens and is used for receiving the dispersion light and demodulating the transmission wavefront of the optical element to be detected. The measuring device is simple in structure, small in size, low in cost and high in measuring precision.

Description

Technical Field

[0001] This invention belongs to the field of transmission wavefront measurement technology, and particularly relates to a large-aperture transmission wavefront measurement device and its measurement method based on coherence tomography. Background Technology

[0002] Currently, the transmission wavefront of optical components can be measured using two technical approaches: integrating spheres and collimators. Integrating spheres produce the most uniform light emission, but their size is also relatively large, and their aperture diameter is limited (an excessively large aperture diameter affects the uniformity of light emission). Furthermore, on a larger scale, large-aperture integrating spheres require multiple light sources, making it difficult to guarantee the uniformity and consistency of the coating inside the integrating sphere. This uniformity affects the final emitted light, and the large exit diameter of a large-aperture integrating sphere also affects its edge uniformity, resulting in a significant deviation from the consistency with the Lambertian radiator. Using collimators for response testing offers advantages such as controllable field of view and uniform energy distribution. However, for large-aperture optical components under test, the size of the collimator also increases, and manufacturing large-size collimators is costly, time-consuming, and difficult to move. Summary of the Invention

[0003] In view of this, the present invention aims to provide a large-aperture transmission wavefront measurement device and method based on coherence tomography, so as to solve the technical problem that existing transmission wavefront measurement techniques are not applicable to large-aperture optical elements.

[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A large-aperture transmission wavefront measurement device based on coherence tomography includes a broadband light source, a beam splitter, a reference plane mirror, a reflecting element, a grating, a converging lens, and a photodetector; among which, Broadband light sources are used to emit low-coherence light; A beam splitter is used to split low-coherence light into a reference beam and a measurement beam. The reference beam is incident on a reference plane mirror, and the measurement beam is incident on the optical element under test. A reference plane mirror is used to reflect the incident reference light back to the beam splitter; The reflective element is placed at the focal point of the optical element under test and is used to reflect the transmitted wavefront of the optical element under test back to the beam splitter, where it interferes with the reference light to form interference light. The grating is positioned in the beam-combining direction of the beam splitter to disperse the interference light; A converging lens is positioned along the dispersion direction of the grating to converge the dispersed light; A photodetector is positioned at the focal point of the converging lens to receive dispersed light and demodulate the transmitted wavefront of the optical element under test.

[0005] Furthermore, when the number of optical elements to be tested is at least two, the reflective elements are successively set at the focal point of the corresponding optical element to be tested.

[0006] Furthermore, the reflecting element is a plane mirror or a corner mirror.

[0007] Furthermore, the optical element under test is a lens.

[0008] A large-aperture transmission wavefront measurement method based on coherence tomography, implemented using the aforementioned large-aperture transmission wavefront measurement device based on coherence tomography, includes the following steps: S1: Emits low-coherence light through a broadband light source; S2: Low-coherence light is incident on the beam splitter and split into reference light and measurement light. The reference light is incident on the reference plane mirror and reflected back to the beam splitter. The measurement light is incident on and passes through the optical element under test, forming a transmitted wavefront, which is then converged to the reflecting element. The reflecting element reflects the transmitted wavefront back to the beam splitter. S3: The reference light and the transmitted wavefront interfere at the beam splitter to form interference light, which is then dispersed by the grating to form dispersed light. S4: The dispersed light is focused by the converging lens onto the target surface of the photodetector. After the optical signal is converted into an electrical signal, the transmitted wavefront of the optical element under test is demodulated using Fourier transform.

[0009] Furthermore, when there are at least two optical elements to be tested, the reflective element is placed at the focal point of each optical element to be tested in turn, and steps S1 to S4 are repeated to achieve tomographic measurement of the transmitted wavefront of the optical element to be tested.

[0010] Compared with the prior art, the measuring device of the present invention has a simple structure, small size, low cost and high measurement accuracy. Attached Figure Description

[0011] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the large-aperture transmission wavefront measurement device based on coherence tomography as described in the embodiment of the present invention; Figure 2 This is a schematic flowchart of the large-aperture transmission wavefront measurement method based on coherence tomography as described in an embodiment of the present invention.

[0012] Explanation of reference numerals in the attached figures: 1. Broadband light source; 2. Beam splitter; 3. Reference plane mirror; 4. Reflecting element; 5. Grating; 6. Converging lens; 7. Photodetector; 8. Optical element under test. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0015] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0016] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] like Figure 1As shown, this invention provides a large-aperture transmission wavefront measurement device based on coherence tomography, including a broadband light source 1, a beam splitter 2, a reference plane mirror 3, a reflective element 4, a grating 5, a converging lens 6, and a photodetector 7. The broadband light source 1 emits low-coherence light; the beam splitter 2 splits the low-coherence light into a reference light and a measurement light, with the reference light incident on the reference plane mirror 3 and the measurement light incident on the optical element under test 8; the reference plane mirror 3 reflects the incident reference light back to the beam splitter 2; the reflective element 4 is located at the focal point of the optical element under test 8 and reflects the transmission wavefront of the optical element under test 8 back to the beam splitter 2, interfering with the reference light to form interference light; the grating 5 is located in the beam combining direction of the beam splitter 2 and disperses the interference light; the converging lens 6 is located in the dispersion direction of the grating 5 and converges the dispersed light; the photodetector 7 is located at the focal point of the converging lens 6 and receives the dispersed light and demodulates the transmission wavefront of the optical element under test 8.

[0019] The number of optical elements 8 to be tested is at least two, and the number of reflective elements 4 is the same as the number of optical elements 8 to be tested. Each reflective element 4 is set at the focal point of the corresponding optical element 8 to be tested, and the transmitted wavefront of each optical element 8 to be tested is reflected back to the beam splitter 2 and interfered with the reference light, so as to achieve tomographic detection of the transmitted wavefront of multiple optical elements 8 to be tested.

[0020] In one specific embodiment of the present invention, the reflecting element 4 is a plane mirror or a corner mirror, and the optical element to be tested 8 is a lens.

[0021] like Figure 2 As shown, this invention also provides a large-aperture transmission wavefront measurement method based on coherence tomography, implemented using the aforementioned large-aperture transmission wavefront measurement device based on coherence tomography, comprising the following steps: S1: Emits low-coherence light through a broadband light source; S2: Low-coherence light is incident on the beam splitter and split into reference light and measurement light. The reference light is incident on the reference plane mirror and reflected back to the beam splitter. The measurement light is incident on and passes through the optical element under test, forming a transmitted wavefront, which is then converged to the reflecting element. The reflecting element reflects the transmitted wavefront back to the beam splitter. S3: The reference light and the transmitted wavefront interfere at the beam splitter to form interference light, which is then dispersed by the grating to form dispersed light. S4: The dispersed light is focused by the converging lens onto the target surface of the photodetector. After the optical signal is converted into an electrical signal, the transmitted wavefront of the optical element under test is demodulated using Fourier transform.

[0022] When there are at least two optical elements under test, the reflective element is first moved to the focal point of one optical element under test A, and steps S1 to S4 are executed to measure the transmitted wavefront of optical element A. Then the reflective element is moved to the focal point of another optical element under test B, and steps S1 to S4 are executed to measure the transmitted wavefront of optical element B. In this way, the transmitted wavefront of each optical element under test is measured step by step, and tomographic transmission wavefront measurement is achieved for multiple optical elements under test.

[0023] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0024] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A large-aperture transmission wavefront measurement device based on coherence tomography, characterized in that, It includes a broadband light source, beam splitter, reference plane mirror, reflective element, grating, converging lens, and photodetector; among which, Broadband light sources are used to emit low-coherence light; A beam splitter is used to split low-coherence light into a reference beam and a measurement beam. The reference beam is incident on a reference plane mirror, and the measurement beam is incident on the optical element under test. A reference plane mirror is used to reflect the incident reference light back to the beam splitter; The reflective element is placed at the focal point of the optical element under test and is used to reflect the transmitted wavefront of the optical element under test back to the beam splitter, where it interferes with the reference light to form interference light. The grating is positioned in the beam-combining direction of the beam splitter to disperse the interference light; A converging lens is positioned along the dispersion direction of the grating to converge the dispersed light; A photodetector is positioned at the focal point of the converging lens to receive dispersed light and demodulate the transmitted wavefront of the optical element under test.

2. The large-aperture transmission wavefront measurement device based on coherence tomography according to claim 1, characterized in that, When there are at least two optical elements to be tested, the reflective elements are successively placed at the focal point of the corresponding optical element to be tested.

3. The large-aperture transmission wavefront measurement device based on coherence tomography according to claim 1 or 2, characterized in that, The reflecting element is a plane mirror or a corner mirror.

4. The large-aperture transmission wavefront measurement device based on coherence tomography according to claim 1, characterized in that, The optical element under test is a lens.

5. A method for measuring large-aperture transmission wavefronts based on coherence tomography, implemented using the large-aperture transmission wavefront measurement device based on coherence tomography as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1: Emits low-coherence light through a broadband light source; S2: Low-coherence light is incident on the beam splitter and split into reference light and measurement light. The reference light is incident on the reference plane mirror and reflected back to the beam splitter. The measurement light is incident on and passes through the optical element under test, forming a transmitted wavefront, which is then converged to the reflecting element. The reflecting element reflects the transmitted wavefront back to the beam splitter. S3: The reference light and the transmitted wavefront interfere at the beam splitter to form interference light, which is then incident on the grating and dispersed to form dispersed light. S4: The dispersed light is focused by the converging lens onto the target surface of the photodetector. After the optical signal is converted into an electrical signal, the transmitted wavefront of the optical element under test is demodulated using Fourier transform.

6. The large-aperture transmission wavefront measurement method based on coherence tomography according to claim 5, characterized in that, When there are at least two optical elements to be tested, the reflective element is placed at the focal point of each optical element to be tested in turn, and steps S1 to S4 are repeated to achieve tomographic measurement of the transmitted wavefront of the optical element to be tested.

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