Optical system image quality influence analysis method based on element manufacturing error

Abstract

The invention relates to the technical field of optical processing, in particular to an optical system image quality influence analysis method based on element manufacturing errors, and the method comprises the steps: determining the structure of an optical system, and determining an ideal optical element needing to be analyzed in the optical system; obtaining a corresponding actual optical element with an error surface based on the manufacturing error graph corresponding to the ideal optical element; replacing the ideal optical element with the actual optical element to obtain an actual optical system; determining incident light rays incident to the actual optical system; after incident light is transmitted by the actual optical system, corresponding emergent light is output; and based on the emergent light, performing light trace analysis on the optical system of the actual optical element to obtain a corresponding ideal light trace graph and an ideal point sequence graph. The method provided by the invention provides an analysis method for the influence of the manufacturing intermediate frequency error which is not suitable for diffraction theory analysis on the optical image quality, and the analysis uncertainty is effectively reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical processing, and particularly relates to a method for analyzing the influence of component manufacturing errors on the image quality of an optical system. Background Art

[0002] Currently, the influence of manufacturing errors on the imaging of optical systems is mostly processed using diffraction theory. Starting from the approximate equation of surface errors, the influence on wave aberration is analyzed, which in turn affects the pupil function and thus the point spread function. In this method, the functions of most manufacturing errors are unknown, and the calculation of the wavefront transmitted to the exit pupil is also based on ray tracing calculations. Moreover, for some medium-frequency errors with larger scales, diffraction theory cannot be used, resulting in some calculation errors and uncertainties. Summary of the Invention

[0003] In view of this, the present invention aims to provide a method for analyzing the influence of component manufacturing errors on the image quality of an optical system. By obtaining the surface equation and manufacturing error distribution of an optical component, combining the two to obtain an error surface, performing ray optical trace analysis on the actual optical system, then converting the ideal trace diagram into an ideal point spread diagram, and relying on the ideal point spread diagram for optical image quality evaluation. The method provided by the present invention provides an analysis method for the influence of manufacturing medium-frequency errors that are not suitable for diffraction theory analysis on optical image quality, effectively reducing the uncertainty of the analysis.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows: A method for analyzing the influence of component manufacturing errors on the image quality of an optical system, comprising: S1: Determine the structure of the optical system and determine the ideal optical components in the optical system that need to be analyzed; S2: Based on the manufacturing error map corresponding to the ideal optical component in step S1, obtain the corresponding actual optical component with an error surface; S3: Replace the ideal optical component with the actual optical component in step S2 to obtain the actual optical system; emit incident light rays to the actual optical system to obtain the corresponding exit light rays; S4: Based on the exit light ray vectors obtained in step S3, perform trace analysis on the actual optical system obtained in step S3 to obtain the corresponding ideal trace diagram and ideal point spread diagram.

[0005] Further, in step S2, the manufacturing error map is superimposed on the surface of the ideal optical component to obtain the actual optical component; the surface of the actual optical component on which the manufacturing error map is superimposed is the error surface.

[0006] Further, in step S3: calculate the surface tangent slope of each optical element in the actual optical system; calculate the normal of each surface based on the surface tangent slope; calculate the outgoing light ray of each surface from the normal of each surface and the incident light ray; the outgoing light ray of each surface is then used as the incident light ray of the next optical element in the actual optical system.

[0007] Further, in step S3, it also includes: determining the analysis field of view of the actual optical system and determining the incident light ray based on the analysis field of view.

[0008] Further, in step S4: calculate the straight-line equation where the outgoing light ray vector is located; determine the observation plane for ray tracing analysis according to the optical system; obtain the ideal ray trace diagram of the actual optical system based on the intersection of the straight-line equation and the observation plane; analyze the ideal point spread function based on the ideal ray trace diagram.

[0009] Further, during the process of analyzing the ideal point spread function based on the ideal ray trace diagram: judge the ray trace point of the chief ray entering the actual optical system; subtract the ideal ray trace diagram from the chief ray trace point to obtain the ideal point spread function.

[0010] Compared with the prior art, the present invention can achieve the following beneficial effects: The method for analyzing the influence of the image quality of an optical system based on the manufacturing error of components according to the present invention can analyze the influence of the error on the distribution of the ideal point spread function of the optical system only by relying on the topography of the manufacturing error and calculating its differential; the method provided by the present invention uses ray optics to obtain first-hand conclusions more directly compared with the existing methods, and is applicable to errors and curved surfaces of various scales. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a schematic flow chart of the method for analyzing the influence of the image quality of an optical system based on the manufacturing error of components according to the embodiment of the present invention; Figure 2 is a schematic diagram of the component system according to the embodiment of the present invention; Figure 3 is a manufacturing error diagram according to the embodiment of the present invention; Figure 4 is a schematic diagram for calculating the outgoing light ray vector according to the embodiment of the present invention; Figure 5 is a ray trace curve according to the embodiment of the present invention; Figure 6The actual light trace diagram described in the embodiments of the present invention; Figure 7 The actual point spread function diagram described in the embodiments of the present invention.

[0012] Explanation of reference numerals: 1, image plane; 2, calculation start plane; 3, parabolic reflector. Detailed implementation manners

[0013] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the following further details the present invention in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0014] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0015] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0016] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

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

[0018] As Figure 1As shown in the figure, the method for analyzing the image quality influence of an optical system based on component manufacturing errors according to the embodiments of the present invention includes: S1: Determine the structure of the optical system and determine the ideal optical components in the optical system that need to be analyzed.

[0019] Among them, the optical system is determined according to actual needs and can be an off-axis three-mirror, Gauss objective, coaxial two-mirror, etc. After determining the optical system, determine the ideal optical components that need to be analyzed according to the actual situation or research experience. For example, in an off-axis three-mirror optical system, the error of the primary mirror is mainly considered. It should be noted that the ideal optical components in the structure of the optical system are in a state without any errors.

[0020] S2: Based on the manufacturing error map corresponding to the ideal optical component in step S1, obtain the corresponding actual optical component with an error surface; In some embodiments, in step S2, the manufacturing error map is superimposed on the surface of the ideal optical component to obtain the actual optical component; the surface of the actual optical component on which the manufacturing error map is superimposed is the error surface.

[0021] It can be understood that after combining the surface of the ideal optical component with the manufacturing error maps generated under different process parameters, the corresponding actual optical component with an error surface is obtained.

[0022] S3: Replace the ideal optical component in step S2 with the actual optical component to obtain the actual optical system; emit incident light to the actual optical system to obtain the corresponding outgoing light. It can be understood that after the emitted incident light is transmitted through the actual optical system, the corresponding outgoing light is obtained.

[0023] In some embodiments, in step S3, the outgoing light vector is calculated by Snell's law, specifically: calculate the curvature tangent slope of the surface of each optical component in the actual optical system; calculate the normal of the corresponding surface based on the curvature tangent slope; calculate the outgoing light of each surface from the normal of each surface and the incident light; the outgoing light of each surface is then used as the incident light of the next optical component in the actual optical system, and so on for calculation. In a certain embodiment, the normalized normal of the knife mark surface is calculated based on the curvature tangent slope, and then the outgoing light is calculated from the normalized normal and the incident light.

[0024] In some embodiments, step S3 further includes: determining the analysis field of view of the actual optical system and determining the incident light based on the analysis field of view. It can be understood that at this time, step S3 includes: determining the analysis field of view of the actual optical system and determining the incident light based on the analysis field of view; calculating the curvature tangent slope of the surface; calculating the normal of the surface based on the curvature tangent slope; calculating the outgoing light from the normal and the incident light.

[0025] S4: Based on the outgoing ray vector obtained in step S3, perform a ray trace analysis on the actual optical system obtained in step S3 to obtain the corresponding ideal ray trace diagram and ideal spot diagram.

[0026] In some embodiments, in step S4: calculate the straight-line equation where the outgoing ray vector is located; determine the observation plane for ray trace analysis according to the optical system; obtain the ideal ray trace diagram of the actual optical system based on the intersection point of the straight-line equation and the observation plane; calculate the ideal spot diagram based on the ideal ray trace diagram. In the process of calculating the ideal spot diagram based on the ideal ray trace diagram: determine the ray trace points of the chief ray entering the actual optical system; subtract the ray trace points of the ideal ray trace diagram from those of the chief ray to obtain the ideal spot diagram. It should be noted that the ideal ray trace diagram and ideal spot diagram described in the present invention are different from the corresponding actual ray trace diagram and actual spot diagram in that the ideal ray trace diagram and ideal spot diagram do not consider aberration, while the corresponding actual ray trace diagram and actual spot diagram are obtained through actual calculation and contain aberration.

[0027] To clearly illustrate the method for analyzing the image quality influence of an optical system based on component manufacturing errors described in the embodiments of the present invention, an embodiment is provided.

[0028] Embodiment: S1: Determine the structure of the optical system and determine the ideal optical components in the optical system that need to be analyzed.

[0029] In this embodiment, it is determined that the optical system to be analyzed is a single-component system, and this optical system is specifically a parabolic reflector, as Figure 2 shown. The propagation process of light in this optical system includes: parallel light propagates from the calculation starting surface 2 to reach the parabolic reflecting surface 3, and after reflection, it converges to the image surface 1 at the focus of the parabolic reflecting surface 3. The system evaluation index is obtained according to the imaging result at the image surface 1. In this embodiment, the system evaluation indexes are the actual ray trace diagram and the actual spot diagram. It can be understood that the parabolic reflector is the ideal optical component that needs to be analyzed, and its surface equation z(x, y) is: ; where f represents the focal length of the parabolic reflector.

[0030] Since the surface of the reflector is a parabolic surface and the parabolic surface has rotational symmetry, the meridian plane of the parabolic reflector is directly selected for analysis, that is, the YoZ plane. The surface equation of the meridian plane of the parabolic reflector becomes: ; S2: Based on the manufacturing error diagram corresponding to the ideal optical component in step S1, obtain the corresponding actual optical component with an error surface. In this embodiment, the manufacturing error is specifically a periodic tool mark error.

[0031] In this embodiment, the manufacturing error map as shown in Figure 3 is superimposed on the surface of the ideal optical element to obtain the actual optical element. At this time, the side of the actual optical element on which the manufacturing error map is superimposed is the error surface, and the error surface D(x, y) = z(x, y) + P TM (x, y), where P TM (x, y) represents the equation of the manufacturing error map. Figure 3 The red cut line in the vertical direction in

[0032] Since the error surface has periodicity only in the y direction, the error surface D(x, y) can be simplified as: ; where represents the knife mark cut line, and the knife mark cut line as shown in Figure 4 where the abscissa represents the y coordinate of the surface of the actual optical element, and the ordinate is the manufacturing error P Figure 4 TM TM .

[0033] S3: Replace the ideal optical element with the actual optical element in step S2 to obtain the actual optical system; emit incident light to the actual optical system to obtain the corresponding outgoing light.

[0034] Specifically, in step S3, determine the analysis field of view of the actual optical system and determine the incident light based on the analysis field of view. In this embodiment, the analysis field of view is the 0 field of view, that is, the vector where the corresponding incident light is located .

[0035] After determining the vector where the incident light is located , calculate the vector where the outgoing light is located according to Snell's law. The specific process includes: Calculate the surface tangent slope of each optical element surface in the actual optical system as: ; where is the derivative of the knife mark cut line with respect to y.

[0036] Correspondingly, the surface tangent slope of each optical element surface in the optical system is: ; Based on the surface tangent slope , calculate the normalized normal of each optical element surface in the actual optical system through the following formula as: ; Correspondingly, based on the surface tangent slope , calculate the surface normalized normal of each optical element in the optical system through the following formula as: .

[0037] From the normalized normal and the vector where the incident light ray is located , calculate the vector where the outgoing light ray is located through the following formula : ; Correspondingly, from the surface normalized normal and the vector where the incident light ray is located , calculate the corresponding vector where the outgoing light ray is located through the following formula : .

[0038] The outgoing light ray of each surface is used as the incident light ray of the next optical element in the actual optical system, and the calculation is carried out in this way by analogy.

[0039] S4: Based on the outgoing light ray vector obtained in step S3, perform a ray trace analysis on the actual optical system obtained in step S3 to obtain the corresponding ideal ray trace diagram and ideal spot diagram.

[0040] In this embodiment, due to the properties of the parabolic mirror, select the observation plane as the focal plane position O z =- f (image plane 1 is the observation plane) to perform ray trace analysis. Specifically: Calculate the straight line equation where the vector 0 , z 0 ) of the outgoing light ray at any incident point (y on the knife-edge surface is located: ; Correspondingly, calculate the straight line equation where the vector 0 , z 0 ) of the outgoing light ray at any incident point (y on the surface of the ideal optical element is located: .

[0041] Based on the straight line equation, obtain the ideal ray trace diagram of the actual optical system. In this embodiment, specifically, the ray trace distribution at the observation plane position O z =- f is: Correspondingly, substitute z = - f into the vector In the straight line equation where it is located, the light trace y corresponding to the surface of the ideal optical element is obtained Of ’ ;

[0042] The above formula reflects the ideal situation of all light rays at the focus of the paraboloid, that is, the incident light of all apertures converges at the focus of the paraboloid.

[0043] Substitute z = - f into the straight line equation where the outgoing light ray vector is located, and the corresponding light trace y is obtained Of : ; Substitute the derivative of the knife mark intercept line , the focal length , f = 200mm into the above formula, and at the same time let , and the light trace y as shown in Figure 5 is obtained Of .

[0044] It can be seen from Figure 5 that the light trace y Of appears in the form of a purple line oscillation around y Of = 0 (that is, the light trace is 0), indicating that the light trace reaching the focal plane is constantly oscillating and scanning around the origin of the ideal light trace diagram, indicating that there will be an extended distribution of the ideal light trace diagram in the y direction; in the x direction, it can be understood by using the above formula again. According to Figure 3 it can be known that , where is a constant about the small change in the y direction. According to the above formula, its derivative effect completely disappears, and x Of is basically linearly related to , so the light trace in the x direction produces a small offset, manifested as a small dispersion in the x direction. The actual light trace diagram is obtained in the optical simulation software as shown in Figure 6 . It can be seen that the above formula for analyzing the light trace distribution can effectively explain the generation reason of the actual light trace diagram.

[0045] Analyze the ideal point spread function based on the ideal light trace diagram. Specifically, judge the light trace point y Oc of the chief ray entering the actual optical system. In this embodiment, the incident position of the chief ray is y 0 = 0, so there is: ; Compare the ideal light trace diagram y Of with the light trace point y OcTaking the difference, an ideal point spread function diagram spt is obtained, i.e.: .

[0046] The origin of the ideal point spread function diagram is the ray trace of the reference chief ray. For the system of the embodiment of the present invention, i.e., Figure 5 the intersection point of the red line and the oscillation line. It can be seen that its ray trace is at the bottom of the oscillation, i.e., the chief ray trace , which indicates that except for the ray traces of those rays on the ideal point spread function diagram are all in the positive direction of the chief ray trace, which will cause the ideal point spread function diagram to be eccentrically distributed in the positive y direction.

[0047] Obtain the actual point spread function diagram in the Zemax optical simulation software as Figure 7 shown. Figure 7 In the left side of it, 400 represents the scale of 400 μm, OBJ represents the field of view; IMA represents that the observation plane is the image plane, i.e., the focal plane of the paraboloid. From Figure 7 it can be seen that the above formula for analyzing the distribution of the point spread function diagram can effectively explain the generation reason of the actual ray trace diagram. As an important imaging index of the optical system, the actual point spread function diagram needs to be strictly constrained. The analysis model provided by this patent for the influence of manufacturing errors on the ideal point spread function diagram can quantitatively analyze the relationship between errors and the ideal point spread function diagram, and then can be used for the precise constraint of the actual point spread function diagram to achieve good image quality.

[0048] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps recited in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. This is not limited herein.

[0049] The above specific embodiments do not constitute a limitation to the protection scope of the present 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for analyzing the impact of optical system image quality based on component manufacturing errors, characterized in that: include: S1: Determine the structure of the optical system and determine the ideal optical element to be analyzed in the optical system; S2: Based on the manufacturing error map corresponding to the ideal optical element in step S1, a corresponding actual optical element with an error surface is obtained; S3: replacing the ideal optical element with the actual optical element in step S2 to obtain an actual optical system; emitting an incident light ray to the actual optical system to obtain a corresponding outgoing light ray; S4: Based on the outgoing light vector obtained in step S3, a light trace analysis is performed on the actual optical system obtained in step S3 to obtain a corresponding ideal light trace diagram and an ideal point array diagram.

2. The method for analyzing the impact of optical system image quality based on component manufacturing errors according to claim 1, characterized in that: In step S2, the manufacturing error map is superimposed on the surface of the ideal optical element to obtain the actual optical element; the surface of the actual optical element on which the manufacturing error map is superimposed is the error surface.

3. The optical system image quality impact analysis method based on component manufacturing error according to claim 1, characterized in that: In step S3: Calculating the surface tangent slope of the surface of each optical element in the actual optical system; Calculating a normal line of a surface of a corresponding optical element based on the slope of the curved surface tangent line; The outgoing light of each surface is calculated from the normal of each surface and the incident light; The outgoing light from each surface is then used as the incident light for the next optical element in the actual optical system.

4. The optical system image quality impact analysis method based on component manufacturing error according to claim 1, characterized in that: In step S3, it also includes: An analysis field of view of the actual optical system is determined, and the incident light is determined based on the analysis field of view.

5. The method for analyzing the impact of optical system image quality based on component manufacturing errors according to claim 1, characterized in that: In step S4: Calculate the equation of the straight line where the outgoing light is located; According to the optical system, determining an observation surface when performing light trace analysis; Based on the intersection of the straight line equation and the observation surface, an ideal light trace diagram of the actual optical system is obtained; The ideal spot diagram is analyzed based on the ideal light trace diagram.

6. The method for analyzing the impact of optical system image quality based on component manufacturing errors according to claim 5, characterized in that: In the process of analyzing the ideal spot diagram based on the ideal light trace diagram: Determining the light trace point of the principal light entering the actual optical system; The ideal point array diagram is obtained by subtracting the ideal light trace diagram from the light trace points.

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