Aspherical surface characterization method based on CGH lens zero position compensation detection light path

Abstract

The application relates to the technical field of optical aspheric surfaces, in particular to a non-spherical surface characterization method based on a CGH lens zero-position compensation detection light path, which is oriented to the detection of non-spherical surfaces, is based on a zero-position compensation detection principle, uses the light path tracing method, Snell's law, the diffraction principle and the equal optical path principle, uses the parameters required by a zero-position compensation detection system of an interferometer incident wave front, a compensator single CGH lens and a diffraction surface binary optical surface 2 to characterize the non-spherical surface shape, and according to a non-spherical surface type defined according to the characterization method, the non-spherical surface is called a zero-position non-spherical surface. The zero-position non-spherical surface has more flexible wave front modulation capacity, can realize the characterization of a continuous large-degree-of-freedom zero-position non-spherical surface shape with a curvature curve containing an inflection point, and can design a more compact optical system and improve the imaging quality of the optical system.

Description

Technical Field

[0001] This invention relates to the field of optical aspherical technology, and in particular to an aspherical characterization method based on the zero-position compensation detection optical path of a CGH lens. Background Technology

[0002] Optical aspherical surfaces are an important type of optical surface shape. Compared to spherical lenses, aspherical lenses can more precisely control the direction and focusing effect of light, thereby achieving higher optical performance and less imaging distortion, and are therefore used in a wide range of fields.

[0003] The manufacturing process of aspherical lenses typically includes three stages: design, fabrication, and inspection. In the design stage, aspherical representation is mostly design-oriented, aiming to modify the surface shape through mathematical description to increase the degrees of freedom for optimization, correct various aberrations in the system, and obtain the optimal design. After design and fabrication, aspherical inspection is used to verify whether the optical performance of the aspherical lens meets the design requirements and to determine its surface shape and errors. Among these methods, the zero-position compensation method is an effective method for inspecting the entire surface of aspherical lenses. The compensator required for this method generally needs to have a simple structure; otherwise, errors in the fabrication and assembly of the compensator will cause the zero-position compensation method to lose its inspection accuracy.

[0004] When using the zero-position compensation method as a detection method, the design of the compensator is closely related to the aspherical surface shape. However, since the aspherical lens is a common part of both the system optical path and the zero-position compensation detection optical path, and in actual production, the system optical path design and the zero-position compensation detection optical path design are carried out sequentially and unidirectionally, the zero-position compensation detection optical path design cannot provide feedback for the system optical path design, and the tolerance of the system optical path cannot be effectively utilized to optimize the zero-position compensation detection optical path. This means that even a tiny deviation in the aspherical surface shape can make the compensator structure extremely complex, rendering the zero-position compensation method infeasible. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem that in the prior art, since the design of aspherical surfaces precedes processing and testing, when using the zero-position compensation method for testing, the testing cannot provide feedback for the design, and the tolerance of the system's optical path structure cannot be effectively utilized to fine-tune the testing scheme, resulting in a very complex testing scheme in some cases and reduced testing accuracy.

[0006] To address the aforementioned technical problems, this invention provides an aspherical characterization method based on a CGH lens null-compensation detection optical path, comprising:

[0007] In a zero-position compensation detection system where the incident wavefront of the interferometer is set to a plane wave and the compensator is a single CGH lens, the aperture of the interferometer standard mirror is D, the wavelength of the detection light is λ, the phase of the diffraction surface of the single CGH lens compensator is φ, the diffraction order is M, the radius of curvature of the refractive surface is r, the center thickness of the single CGH lens compensator is d, the refractive index of the material of the single CGH lens compensator is n, and the distance between the single CGH lens compensator and the aspherical surface is L.

[0008] When the standard mirror of the interferometer detects parallel incident light rays, different heights and diffraction orders correspond to different points on the aspherical surface. Different diffraction plane directions correspond to different null aspherical surfaces. This optical path follows the principle of equal optical path, the principle of diffraction, and Snell's law. Therefore, after the light rays are reflected by the aspherical surface, they return along the original optical path, pass through a single CGH lens compensator, and are re-formed into a plane wave. Inside the interferometer, the plane wave interferes with the reference wave, thus reflecting the surface information of the aspherical surface being measured.

[0009] In the zero-position compensation detection system model, the single CGH lens compensator takes the planar binary optical surface as the reference, the phase function of the diffraction surface is the rotationally symmetric binary optical surface 2, the detection light is incident as a plane wave, the single CGH lens compensator and the aspherical surface form a zero spherical aberration system, and the system follows the principle of equal optical path.

[0010] Based on the principle of equal optical path length, two detection rays are selected. One ray is the ray emitted from the center point of the diffraction surface, and the other ray is the parametric tracing ray, i.e., the off-axis ray. According to the parameters of the zero-position compensation detection system, the optical path length corresponding to the parametric tracing ray is determined, and the expressions of the two optical paths are combined to obtain the trajectory equation of the intersection point Q of the detection ray and the aspherical surface, i.e., the surface shape expression of the zero-position aspherical surface.

[0011] The zero-position aspherical surface is a rotationally symmetric surface, and its maximum effective aperture is determined by the actual light-transmitting aperture of the interferometer's standard mirror.

[0012] In one embodiment of the present invention, the phase function of the diffraction surface of the single CGH lens compensator is a rotationally symmetric binary optical surface 2. Considering only the change in its phase, the phase expression of the binary optical surface 2 is:

[0013]

[0014] Where N is the number of polynomial coefficients, ρ is the normalized radial aperture coordinate, and C i It is the coefficient of ρ raised to the power of 2i, and M is the diffraction order.

[0015] In one embodiment of the present invention, the binary optical surface 2 is a 2n-step structure, where n is determined based on the diffraction efficiency and the actual manufacturing difficulty.

[0016] In one embodiment of the present invention, the binary optical surface 2 is a 2n-step structure. When n=1, the first-order diffraction efficiency reaches 40.5%; when n=2, the first-order diffraction efficiency reaches 81.1%.

[0017] In one embodiment of the present invention, when the diffraction surface of the single CGH lens compensator faces the incident plane wave, the detection light is emitted parallel to the interferometer standard mirror and intersects the CGH surface at point A. The M-order diffraction light is emitted and intersects the back refraction surface at point B. After being refracted by the back surface, it intersects the aspherical surface at point Q. The incident height of the light at the interferometer standard mirror is set as h, which is used as a parameter of the aspherical surface shape. h is a continuous variable in the aperture range of the interferometer standard mirror [-D / 2, D / 2].

[0018] When all parameters in the zero-position compensation detection optical path are fixed, the detection light is incident at any height h, and the optical path from point A to point Q is the same. At this time, the trajectory function of point Q is the aspherical formula characterized by the front surface of the single CGH lens compensator being a binary optical surface 2.

[0019] According to the principle of equal optical path, two detection rays are selected. One ray is the ray emitted from the center point O1 of the diffraction surface of the single CGH lens compensator, and the path is: O1→O2→O; where O2 is the center vertex of the rear surface of the single CGH lens compensator, and O is the center vertex of the aspherical surface; the optical path of the on-axis ray is G0=n·d+L;

[0020] The other ray is the parametric tracing ray, i.e., the off-axis ray, with the path: A→B→Q. Based on the parameters of the zero-position compensation detection system, the corresponding optical path of the parametric tracing ray is determined to be... Among them l AB Let l be the distance between point A and point B. BM Let l be the distance between point M and point B, the intersection points of the refracted ray BQ on the optical axis. MQ Let M be the distance between the intersection point M and point Q of the refracted ray BQ on the optical axis;

[0021] According to the principle of equal optical path length, we have G0 = G1, and thus the distance between point M and point Q on the aspherical surface is...

[0022] With point O as the origin, and the front surface of the single CGH lens compensator in the zero-position compensation detection system being a binary optical surface 2, the trajectory equation of any point Q on the zero-position aspherical surface, i.e., the surface shape expression of the zero-position aspherical surface, is as follows:

[0023]

[0024] Where u′1 is the angle between the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, and l′1 is the distance from point M, the intersection of the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, to the vertex O2 of the rear surface of the single CGH lens compensator; the zero-position aspherical surface is a rotationally symmetric structure, and the maximum effective aperture is determined by the actual light-transmitting aperture of the standard spherical mirror of the interferometer.

[0025] In one embodiment of the present invention, when the front surface of the single CGH lens compensator in the zero-position compensation detection system is a binary optical surface 2, the general form of the parametric expression for the zero-position aspherical surface is:

[0026]

[0027] In one embodiment of the present invention, when the diffraction surface of the single CGH lens compensator faces the aspherical surface, the detection light is emitted parallel to the interferometer standard mirror, intersecting the refractive surface at point A, and after refraction, intersecting the rear diffraction surface at point B. The M-order diffracted light is emitted and intersecting the aspherical surface at point Q. The incident height of the light at the interferometer standard mirror is set as h, which is used as a parameter of the aspherical surface shape. h is a continuous variable in the aperture range of the interferometer standard mirror [-D / 2, D / 2].

[0028] When all parameters in the zero-position compensation detection optical path are fixed, the detection light is incident at any height h, and the optical path from point A to point Q is the same. At this time, the trajectory function of point Q is the aspherical formula characterized by the rear surface of the single CGH lens compensator being a binary optical surface 2.

[0029] According to the principle of equal optical path, two detection rays are selected. One ray is the ray emitted from the center point O1 of the refractive surface of the single CGH lens compensator, and the path is: O1→O2→O; where O2 is the center vertex of the rear surface of the single CGH lens compensator, and O is the center vertex of the aspherical surface; the optical path of the on-axis ray is G0=n·d+L;

[0030] The other ray is the parametric tracing ray, i.e., the off-axis ray, with the path: A→B→Q. Based on the parameters of the zero-position compensation detection system, the corresponding optical path of the parametric tracing ray is determined to be... Among them l AB Let l be the distance between point A and point B. BM Let l be the distance between point M and point B, the intersection points of the refracted ray BQ on the optical axis. MQ Let M be the distance between the intersection point M and point Q of the refracted ray BQ on the optical axis;

[0031] According to the principle of equal optical path length, we have G0 = G1, and thus the distance between point M and point Q on the aspherical surface is...

[0032] With point O as the origin, and the rear surface of the single CGH lens compensator in the zero-position compensation detection system being a binary optical surface 2, the trajectory equation of any point Q on the zero-position aspherical surface, i.e., the surface shape expression of the zero-position aspherical surface, is as follows:

[0033]

[0034] Where θ′ m The angle between the refracted ray from the rear surface of the single CGH lens compensator and the optical axis is given by l′1, and l′1 is the distance from point M, the intersection of the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, to the vertex O2 of the rear surface of the single CGH lens compensator. The zero-position aspherical surface has a rotationally symmetric structure, and its maximum effective aperture is determined by the actual light-transmitting aperture of the standard spherical mirror of the interferometer.

[0035] In one embodiment of the present invention, when the rear surface of the single CGH lens compensator in the zero-position compensation detection system is a binary optical surface 2, the general form of the parametric expression for the zero-position aspherical surface is:

[0036]

[0037] The technical solution of the present invention has the following advantages compared with the prior art:

[0038] This invention discloses an aspherical characterization method based on a CGH lens null compensation detection optical path. Guided by the detection method, and based on the principles of null compensation detection and diffraction optics, it utilizes the parameters required for a null compensation detection system with an interferometer incident wavefront of a plane wave, a single CGH lens as the compensator, and a diffraction surface of a binary optical surface 2 to characterize the aspherical surface shape. This allows for the acquisition of relevant detection data during the optical system design phase, and enables the modulation and constraint of the characterization parameters of the null aspherical surface, i.e., the parameters required for the null compensator optical path, according to imaging requirements. This achieves the goal of balancing factors such as system imaging quality, aspherical surface structure, compensator, and the rationality of the detection optical path. It not only verifies the role of the null aspherical surface in the optical system but also effectively improves the feasibility of the null compensation method and reduces the difficulty of detecting the aspherical surface shape.

[0039] The aspherical characterization method based on the zero-position compensation detection optical path of the CGH lens provides more degrees of freedom for the phase of the binary optical surface 2 in the single CGH lens compensator. Compared with the aspherical characterization method based on the zero-position compensation detection optical path using a spherical mirror as the compensator, the zero-position aspherical has more flexible wavefront modulation capability. It can realize the characterization of the continuous large-degree-of-freedom zero-position aspherical surface shape with inflection points in the curvature curve, thereby enabling the design of a more compact optical system and improving the imaging quality of the optical system. Attached Figure Description

[0040] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0041] Figure 1 This invention provides a meridional cross-section optical path diagram of the zero-position compensation detection system when the incident wavefront of the interferometer is a plane wave and the front surface of the single CGH lens compensator is a binary optical surface 2.

[0042] Figure 2 The present invention provides a meridional cross-section optical path diagram of the zero-position compensation detection system when the incident wavefront of the interferometer is a plane wave and the rear surface of the single CGH lens compensator is a binary optical surface 2. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0044] This invention provides an aspherical characterization method based on a plane wave and a single CGH lens zero-position compensation detection optical path with a binary optical surface 2 as the diffraction surface, guided by the detection method. It also defines a type of aspherical surface, which is called zero-position aspherical surface.

[0045] In a zero-position compensation detection system where the incident wave in the interferometer is a plane wave and the compensator is a single CGH lens, the aperture of the interferometer standard mirror is set to D, the wavelength of the detection light is λ, the phase of the diffraction surface of the single CGH lens compensator is φ, the diffraction order is M, the radius of curvature of the refractive surface is r, the center thickness of the single CGH lens compensator is d, the refractive index of the material of the single CGH lens compensator is n, and the distance between the single CGH lens compensator and the aspherical surface is L.

[0046] The interferometer's standard mirror detects parallel incident light rays. Different heights and diffraction orders correspond to different points on the aspherical surface, and different diffraction plane directions correspond to different null aspherical surfaces. This optical path follows the principle of equal optical path length, the principle of diffraction, and Snell's law. Therefore, after reflection from the aspherical surface, the light rays return along the original optical path, pass through a single CGH lens compensator, and are re-formed into a plane wave. Inside the interferometer, this wave interferes with the reference wave, thus reflecting the surface information of the measured aspherical surface.

[0047] In the zero-position compensation detection system model, the single CGH lens compensator uses a planar binary optical surface as a reference. The phase function of the diffraction surface is a rotationally symmetric binary optical surface 2. Considering only the phase change, the phase expression of binary optical surface 2 is:

[0048]

[0049] Where N is the number of polynomial coefficients, ρ is the normalized radial aperture coordinate, and Ci It is the coefficient of ρ raised to the power of 2i, and M is the diffraction order.

[0050] The binary optical surface 2 is not limited to two steps, but can be made into 2n steps, and the diffraction efficiency is related to the number of steps; the more steps, the higher the efficiency. For example, a binary optical surface 2 with two steps has a first-order diffraction efficiency of 40.5%, while a binary optical surface 2 with four steps has a first-order diffraction efficiency of 81.1%. However, as the number of steps increases, the manufacturing process becomes more complex. Therefore, the number of steps in the design can be determined based on the diffraction efficiency and the actual manufacturing difficulty.

[0051] The following section derives and calculates the aspherical surface shape for two cases: when the diffraction surface of the single CGH lens compensator faces the incident plane wave and when the diffraction surface of the single CGH lens compensator faces the aspherical surface.

[0052] Reference Figure 1 As shown, when the diffraction surface of the single CGH lens compensator faces the incident plane wave, the detection light is emitted parallel to the interferometer standard mirror and intersects the CGH surface at point A. The M-order diffraction light is emitted and intersects the back refraction surface at point B. After refraction by the back surface, it intersects the aspherical surface at point Q. The incident height of the light at the interferometer standard mirror is set as h, which is used as a parameter of the aspherical surface shape. h is a continuous variable in the aperture range of the interferometer standard mirror [-D / 2, D / 2].

[0053] When all parameters in the zero-position compensation detection optical path are fixed, the detection ray incident at any height h has the same optical path from point A to point Q. The trajectory function of point Q is the aspherical formula characterized by the front surface of the single CGH lens compensator being a binary optical surface 2. Its general parametric expression is:

[0054]

[0055] The detection ray is incident as a plane wave. The single CGH lens compensator and the aspherical surface form a zero-spherical-aberration system, which follows the principle of equal optical path length. Based on this principle, two detection rays are selected. One ray is the ray emitted from the center point O1 of the diffraction surface of the single CGH lens compensator, with the path: O1→O2→O. O2 is the center vertex of the rear surface of the single CGH lens compensator, and O is the center vertex of the aspherical surface. The optical path length of the on-axis ray is G0 = n·d + L.

[0056] The other ray is the parametric tracing ray, i.e., the off-axis ray, with the path: A→B→Q. Based on the parameters of the zero-position compensation detection system, the corresponding optical path of the parametric tracing ray is determined to be... Among them l AB Let l be the distance between point A and point B. BMLet l be the distance between point M and point B, the intersection points of the refracted ray BQ on the optical axis. MQ Let M be the distance between the intersection point M and point Q of the refracted ray BQ on the optical axis.

[0057] According to the principle of equal optical path length, we have G0 = G1, and thus the distance between point M and point Q on the aspherical surface is...

[0058] Therefore, with point O as the origin and the front surface of the single CGH lens compensator in the zero-position compensation detection system being a binary optical surface 2, the trajectory equation of any point Q on the zero-position aspherical surface, i.e., the surface shape expression of the zero-position aspherical surface, is as follows:

[0059]

[0060] Where u′1 is the angle between the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, and l′1 is the distance from point M, the intersection of the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, to the vertex O2 of the rear surface of the single CGH lens compensator. The zero-position aspherical surface has a rotationally symmetric structure, and its maximum effective aperture is determined by the actual light-transmitting aperture of the standard spherical mirror of the interferometer.

[0061] Reference Figure 2 As shown, when the diffraction surface of the single CGH lens compensator faces the aspherical surface, the detection light is emitted parallel to the standard mirror of the interferometer, intersecting the refractive surface at point A. After refraction, it intersects the back diffraction surface at point B. The M-order diffracted light is emitted and intersects the aspherical surface at point Q. The incident height of the light at the standard mirror of the interferometer is set as h, which is used as a parameter of the aspherical surface shape. h is a continuous variable in the aperture range of the standard mirror of the interferometer [-D / 2, D / 2].

[0062] When all parameters in the zero-position compensation detection optical path are fixed, the detection ray incident at any height h has the same optical path from point A to point Q. The trajectory function of point Q is the aspherical formula characterized by the rear surface of the single CGH lens compensator being a binary optical surface 2. Its general parametric expression is:

[0063]

[0064] The detection ray is incident as a plane wave. The single CGH lens compensator and the aspherical surface form a zero-spherical-aberration system, which follows the principle of equal optical path. According to the principle of equal optical path, two detection rays are selected. One ray is the ray emitted from the center point O1 of the refractive surface of the single CGH lens compensator, with the path: O1→O2→O. Among them, point O2 is the center vertex of the rear surface of the single CGH lens compensator, and point O is the center vertex of the aspherical surface. The optical path of the on-axis ray is G0=n·d+L.

[0065] The other ray is the parametric tracing ray, i.e., the off-axis ray, with the path: A→B→Q. Based on the parameters of the zero-position compensation detection system, the corresponding optical path of the parametric tracing ray is determined to be... Among them l AB Let l be the distance between point A and point B. BM Let l be the distance between point M and point B, the intersection points of the refracted ray BQ on the optical axis. MQ Let M be the distance between the intersection point M and point Q of the refracted ray BQ on the optical axis.

[0066] According to the principle of equal optical path length, we have G0 = G1, and thus the distance between point M and point Q on the aspherical surface is...

[0067] Therefore, with point O as the origin and the rear surface of the single CGH lens compensator in the zero-position compensation detection system being a binary optical surface 2, the trajectory equation of any point Q on the zero-position aspherical surface, i.e., the surface shape expression of the zero-position aspherical surface, is as follows:

[0068]

[0069] Where θ' m Let l'1 be the angle between the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, and l'1 be the distance from point M, the intersection of the refracted ray from the rear surface of the single CGH lens compensator and the optical axis, to the vertex O2 of the rear surface of the single CGH lens compensator. The zero-position aspherical surface has a rotationally symmetric structure, and its maximum effective aperture is determined by the actual light-transmitting aperture of the standard spherical mirror of the interferometer.

[0070] Compared to aspherical surfaces characterized by zero-position compensation detection optical paths using spherical mirrors as compensators, the zero-position aspherical surfaces described above have more flexible wavefront modulation capabilities. They can represent continuous, high-degree-of-freedom zero-position aspherical surface shapes with inflection points in their curvature curves, thereby enabling the design of more compact optical systems and improving the imaging quality of the optical systems.

[0071] The aforementioned aspherical characterization method based on the zero-position compensation detection optical path using a CGH lens is method-oriented and based on the principles of zero-position compensation detection and diffraction optics. It utilizes the parameters required for a zero-position compensation detection system with an interferometer incident wavefront of a plane wave, a single CGH lens as the compensator, and a binary optical surface 2 as the diffraction plane to characterize the aspherical surface shape. This allows for the acquisition of relevant detection data during the optical system design phase and enables the modulation and constraint of the characterization parameters of the zero-position aspherical surface—that is, the parameters required for the zero-position compensator optical path—according to imaging requirements. This achieves a balance between system imaging quality, aspherical surface structure, and the rationality of the compensator and detection optical path. This characterization method not only verifies the role of the zero-position aspherical surface in the optical system but also effectively improves the feasibility of the zero-position compensation method and reduces the difficulty of aspherical surface shape detection.

[0072] This method not only verifies the role of zero-position aspherical surfaces in optical systems, but also effectively improves the feasibility of the zero-position compensation method and reduces the difficulty of detecting aspherical surface shapes.

[0073] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0074] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0075] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0076] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0077] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An aspherical characterization method based on a CGH lens zero-position compensation detection optical path, characterized in that, include: In a zero-position compensation detection system where the incident wavefront of the interferometer is set to a plane wave and the compensator is a single CGH lens compensator, the aperture of the standard mirror of the interferometer is [missing information]. The detection wavelength is The phase of the diffraction surface of the single CGH lens compensator is Diffraction order is The radius of curvature of the refractive surface is The center thickness of the single CGH lens compensator is The refractive index of the material of the single CGH lens compensator is The distance between the single CGH lens compensator and the aspherical surface is ; When the standard mirror of the interferometer detects parallel incident light rays, different heights and diffraction orders correspond to different points on the aspherical surface. Different diffraction plane directions correspond to different null aspherical surfaces. This optical path follows the principle of equal optical path, the principle of diffraction, and Snell's law. Therefore, after the light rays are reflected by the aspherical surface, they return along the original optical path, pass through a single CGH lens compensator, and are re-formed into a plane wave. Inside the interferometer, the plane wave interferes with the reference wave, thus reflecting the surface information of the aspherical surface being measured. In the zero-position compensation detection system, the single CGH lens compensator takes the planar binary optical surface as the reference, the phase function of the diffraction surface is the binary optical surface 2 in the rotational symmetry formula, the detection light is incident as a plane wave, the single CGH lens compensator and the aspherical surface form a zero spherical aberration system, and the system follows the principle of equal optical path. Based on the principle of equal optical path length, two detection rays are selected. One ray is the ray emitted from the center point of the diffraction surface, and the other ray is the parametric tracing ray, i.e., the off-axis ray. According to the parameters of the zero-position compensation detection system, the optical path length corresponding to the parametric tracing ray is determined. Then, by combining the expressions for the two optical path lengths, the intersection point between the detection ray and the aspherical surface is obtained. The trajectory equation of a point, i.e., the surface shape expression of a user-defined zero-position aspherical surface; The zero-position aspherical surface is a rotationally symmetric surface, and its maximum effective aperture is determined by the actual light-transmitting aperture of the interferometer's standard mirror. The phase function of the diffraction surface of the single CGH lens compensator is the binary optical surface 2 in the rotationally symmetric formula. Considering only the change in its phase, the phase expression of the binary optical surface 2 is: ,in The number of polynomial coefficients. These are normalized radial aperture coordinates. yes of The coefficient of a power. It is the diffraction order; The binary optical surface 2 is Steps, among which The binary optical surface 2 is determined based on diffraction efficiency and the actual manufacturing difficulty; Steps, when At that time, the first-order diffraction efficiency reached 40.5%; when At that time, the first-order diffraction efficiency reached 81.1%.

2. The aspherical characterization method based on the zero-position compensation detection optical path of a CGH lens according to claim 1, characterized in that, When the diffraction surface of the single CGH lens compensator faces the incident plane wave, the detection light is emitted parallel to the standard mirror of the interferometer and intersects the CGH surface. point, After the first diffraction order light rays are emitted, they intersect with the back refraction surface. The point, after refraction by the back surface, intersects the aspherical surface at... Point; set the incident height of the light ray at the standard mirror of the interferometer as... This is used as a parameter of the aspherical surface shape. Within the range of the standard mirror aperture of the interferometer The variables inside are continuous variables; When all parameters in the zero-position compensation detection system are fixed, the detection light beam travels at any height. Incident, by Click The optical path lengths are all the same at this point. The trajectory function of a point is the aspherical formula that characterizes the front surface of a single CGH lens compensator when it is a binary optical surface 2. Based on the principle of equal optical path length, two detection rays are selected, one of which is the center point of the diffraction surface of the single CGH lens compensator. The path of the emitted ray is: ;in, The point is the center vertex of the rear surface of the single CGH lens compensator. The point is the center vertex of the aspherical surface; the optical path length of the ray on the axis is... ; The other ray is a parametric tracing ray, i.e., an off-axis ray, with the following path: Based on the parameters of the zero-position compensation detection system, the optical path length corresponding to the parameter tracing ray is determined to be... ,in for Point and Distance between points To refract light Intersection on the optical axis Point and Distance between points To refract light Intersection on the optical axis Point and Distance between points; According to the principle of equal optical path length, we have ,get Points and non-spherical surfaces The distance between the points is ; by Point 1 is the origin of the coordinate system. In the zero-position compensation detection system, when the front surface of the single CGH lens compensator is a binary optical surface 2, any point on the zero-position aspherical surface... The trajectory equation, that is, the surface shape expression of the zero-position aspherical surface, is: ,in The angle between the refracted ray from the rear surface of a single CGH lens compensator and the optical axis. The intersection of the refracted ray from the rear surface of a single CGH lens compensator and the optical axis. Point to the vertex of the surface of the single CGH lens compensator The distance; the zero-position aspherical surface is a rotationally symmetric structure, and the maximum effective aperture is determined by the actual light-transmitting aperture of the interferometer standard mirror.

3. The aspherical characterization method based on the zero-position compensation detection optical path of a CGH lens according to claim 2, characterized in that, When the front surface of the single CGH lens compensator in the zero-position compensation detection system is a binary optical surface 2, the general form of the parametric expression for the zero-position aspherical surface is: .

4. The aspherical characterization method based on the zero-position compensation detection optical path of a CGH lens according to claim 1, characterized in that, When the diffraction surface of the single CGH lens compensator faces the aspherical surface, the detection light is emitted parallel to the standard mirror of the interferometer and intersects the refractive surface at... The point, after refraction, intersects with the back diffraction plane at... point, The diffracted rays are emitted and intersect the aspherical surface at... Point; set the incident height of the light ray at the standard mirror of the interferometer as... This is used as a parameter of the aspherical surface shape. Within the range of the standard mirror aperture of the interferometer The variables inside are continuous variables; When all parameters in the zero-position compensation detection system are fixed, the detection light beam travels at any height. Incident, by Click The optical path lengths are all the same at this point. The trajectory function of the point is the aspherical formula that represents the back surface of a single CGH lens compensator when the rear surface is a binary optical surface 2. Based on the principle of equal optical path length, two detection rays are selected, one of which is the center point of the refractive surface of the single CGH lens compensator. The path of the emitted ray is: ;in, The point is the center vertex of the rear surface of the single CGH lens compensator. The point is the center vertex of the aspherical surface; the optical path length of the ray on the axis is... ; The other ray is a parametric tracing ray, i.e., an off-axis ray, with the following path: Based on the parameters of the zero-position compensation detection system, the optical path length corresponding to the parameter tracing ray is determined to be... ,in for Point and Distance between points To refract light Intersection on the optical axis Point and Distance between points To refract light Intersection on the optical axis Point and Distance between points; According to the principle of equal optical path length, we have ,get Points and non-spherical surfaces The distance between the points is ; by Point 1 is the origin of the coordinate system. In the zero-position compensation detection system, when the rear surface of the single CGH lens compensator is a binary optical surface 2, any point on the zero-position aspherical surface... The trajectory equation, that is, the surface shape expression of the zero-position aspherical surface, is: in The angle between the refracted ray from the rear surface of a single CGH lens compensator and the optical axis. The intersection of the refracted ray from the rear surface of a single CGH lens compensator and the optical axis. Point to the vertex of the surface of the single CGH lens compensator The distance; the zero-position aspherical surface is a rotationally symmetric structure, and the maximum effective aperture is determined by the actual light-transmitting aperture of the interferometer standard mirror.

5. The aspherical characterization method based on the zero-position compensation detection optical path of a CGH lens according to claim 4, characterized in that, When the rear surface of the single CGH lens compensator in the zero-position compensation detection system is a binary optical surface 2, the general form of the parametric expression for the zero-position aspherical surface is: .

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