Analysis Method for Image Quality Influence of Optical System Based on Component Manufacturing Errors

Abstract

The present invention relates to the field of optical processing technology, and particularly to a method for analyzing the influence of component manufacturing errors on the image quality of an optical system, determining the structure of the optical system, and determining the ideal optical components to be analyzed in the optical system; based on the manufacturing error map corresponding to the ideal optical components, obtaining the corresponding actual optical components with error surfaces; replacing the ideal optical components with the actual optical components to obtain the actual optical system; determining the incident light rays incident on the actual optical system; after the incident light rays are transmitted through the actual optical system, outputting the corresponding outgoing light rays; based on the outgoing light rays, performing a ray trace analysis on the optical system of the actual optical components to obtain the corresponding ideal ray trace map and ideal spot diagram. The method provided by the present invention provides an analysis method for the influence of medium-frequency manufacturing errors that are not suitable for diffraction theory analysis on optical image quality, effectively reducing the uncertainty of the analysis.

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 relatively large 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, 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:

[0005] A method for analyzing the influence of component manufacturing errors on the image quality of an optical system, comprising:

[0006] S1: Determine the structure of the optical system and determine the ideal optical components in the optical system that need to be analyzed;

[0007] 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;

[0008] 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;

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] Further, in 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.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0016] 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

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] 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;

[0019] Figure 2 is a schematic diagram of the component system according to the embodiment of the present invention;

[0020] Figure 3 is a manufacturing error diagram according to the embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of calculating the outgoing light ray vector according to the embodiment of the present invention;

[0022] Figure 5 is the light trace curve described in the embodiment of the present invention;

[0023] Figure 6 is the actual light trace diagram described in the embodiment of the present invention;

[0024] Figure 7 is the actual point spread function diagram described in the embodiment of the present invention.

[0025] Explanation of reference numerals:

[0026] 1, image plane; 2, calculation starting plane; 3, parabolic reflecting surface. Detailed implementation manners

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present 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 only used to explain the present invention, rather than limiting the present invention.

[0028] 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.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are 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 limiting 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.

[0030] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "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 according to specific situations.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0032] As Figure 1 shown, the method for analyzing the image quality influence of an optical system based on component manufacturing errors according to an embodiment of the present invention includes:

[0033] S1: Determine the structure of the optical system and determine the ideal optical components in the optical system that need to be analyzed.

[0034] Among them, the optical system is determined according to actual needs and can be an off-axis three-mirror system, a Gauss objective lens, a coaxial two-mirror system, etc. After determining the optical system, the ideal optical components to be analyzed are determined according to the actual situation or research experience. For example, in an off-axis three-mirror optical system, the main consideration is the error of the primary mirror. It should be noted that the ideal optical components in the structure of the optical system are in a state without any errors.

[0035] 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;

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In some embodiments, in step S3, the outgoing light vector is calculated by Snell's law. Specifically: calculate the surface tangent slope of each optical component surface in the actual optical system; calculate the normal of the corresponding surface based on the surface 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 scratch surface is calculated based on the surface tangent slope, and then the outgoing light is calculated from the normalized normal and the incident light.

[0040] In some embodiments, step S3 further includes: determining the analysis field of view of the actual optical system, and determining the incident light rays 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 rays based on the analysis field of view; calculating the surface tangent slope of the surface; calculating the normal of the surface based on the surface tangent slope; and calculating the outgoing light rays from the normal and the incident light rays.

[0041] S4: Based on the outgoing light ray vectors obtained in step S3, perform a ray tracing analysis on the actual optical system obtained in step S3 to obtain the corresponding ideal ray tracing diagram and ideal spot diagram.

[0042] In some embodiments, in step S4: calculate the straight line equation where the outgoing light ray vectors are located; determine the observation plane for ray tracing analysis according to the optical system; obtain the ideal ray tracing diagram of the actual optical system based on the intersection points of the straight line equation and the observation plane; calculate the ideal spot diagram based on the ideal ray tracing diagram. In the process of calculating the ideal spot diagram based on the ideal ray tracing diagram: determine the ray tracing points of the chief ray entering the actual optical system; subtract the ray tracing points of the ideal ray tracing diagram and the chief ray to obtain the ideal spot diagram. It should be noted that the ideal ray tracing diagram and ideal spot diagram described in the present invention are different from the corresponding actual ray tracing diagram and actual spot diagram in that the ideal ray tracing diagram and ideal spot diagram do not consider aberration, and the corresponding actual ray tracing diagram and actual spot diagram are obtained by actual calculation and include aberration.

[0043] To clearly illustrate the method for analyzing the influence of component manufacturing errors on the image quality of an optical system described in the embodiments of the present invention, an embodiment is provided.

[0044] Embodiment:

[0045] S1: Determine the structure of the optical system and determine the ideal optical components in the optical system that need to be analyzed.

[0046] 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 rays in this optical system includes: parallel light propagates from the calculation starting surface 2 to reach the parabolic reflecting surface 3, and after reflection, 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 index is the actual ray tracing 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:

[0047] ;

[0048] where f represents the focal length of the parabolic reflector.

[0049] Since the surface of the reflector is a paraboloid and the paraboloid 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:

[0050] ;

[0051] S2: Based on the manufacturing error map corresponding to the ideal optical element in step S1, the actual optical element with an error surface is obtained. In this embodiment, the manufacturing error is specifically the periodic tool mark error.

[0052] 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 where 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 vertical red intercept line in

[0053] is the tool mark intercept line. Since the error surface is only periodic in the y direction, the error surface D(x,y) can be simplified as:

[0054] ;

[0055] where represents the tool mark intercept line, and the tool mark intercept line is as shown in Figure 4 . Figure 4 In TM , the abscissa represents the y coordinate of the surface of the actual optical element, and the ordinate is the manufacturing error P

[0056] S3: Replace the ideal optical element in step S2 with the actual optical element to obtain the actual optical system; emit incident light to the actual optical system to obtain the corresponding outgoing light.

[0057] Specifically, in step S3, the analysis field of view of the actual optical system is determined, and the incident light is determined 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 .

[0058] After determining the vector where the incident light is located , the vector where the outgoing light is located is calculated according to Snell's law. The specific process includes:

[0059] Calculating the curvature tangent slope of the surface of each optical element in the actual optical system is:

[0060] ;

[0061] Among them, is the derivative of the knife mark intercept line with respect to y.

[0062] Correspondingly, the surface tangent slope of each optical element in the optical system is:

[0063] ;

[0064] Based on the surface tangent slope , the normalized normal of the surface of each optical element in the actual optical system is calculated by the following formula as:

[0065] ;

[0066] Correspondingly, based on the surface tangent slope , the surface normalized normal of each optical element in the optical system is calculated by the following formula as:

[0067] .

[0068] From the normalized normal and the vector where the incident light ray is located , the vector where the outgoing light ray is located is calculated by the following formula

[0069] ;

[0070] Correspondingly, from the surface normalized normal and the vector where the incident light ray is located , the corresponding vector where the outgoing light ray is located is calculated by the following formula

[0071] .

[0072] 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, and so on for the calculation.

[0073] S4: Based on the outgoing light ray vector obtained in step S3, perform a ray tracing analysis on the actual optical system obtained in step S3 to obtain the corresponding ideal ray tracing diagram and ideal point spread function diagram.

[0074] In this embodiment, due to the properties of the parabolic mirror, the observation plane is selected to be the focal plane position O of the parabolic mirror z =- f (image plane 1 is the observation plane) for ray tracing analysis. Specifically:

[0075] Calculate the vector of the outgoing ray at any incident point (y0, z0) on the surface with tool marks The equation of the line where it lies:

[0076] ;

[0077] Correspondingly, calculate the vector of the outgoing ray at any incident point (y0, z0) on the surface of the ideal optical element The equation of the line where it lies:

[0078] .

[0079] Based on the line equation, obtain the ideal ray trace diagram of the actual optical system. In this embodiment, specifically, at the observation plane position O z =- f The ray trace distribution at this point, that is:

[0080] Correspondingly, substitute z = - f into the equation of the line where the outgoing ray vector lies to obtain the ray trace y corresponding to the surface of the ideal optical element Of ’ ;

[0081]

[0082] The above formula reflects the ideal situation of all rays at the focus of the paraboloid, that is, the incident light of all apertures converges at the focus of the paraboloid.

[0083] Substitute z = - f into the equation of the line where the outgoing ray vector lies to obtain the corresponding ray trace y Of :

[0084] ;

[0085] Substitute the derivative of the tool mark intercept , the focal length f = 200mm into the above formula, and at the same time let to obtain the ray trace y as shown in Figure 5 Of .

[0086] It can be seen from Figure 5 that the ray trace y Of appears to surround y Of ​​=0 (i.e., the optical trace is 0), the oscillation form of the purple line indicates that the optical trace reaching the focal plane is constantly oscillating and scanning around the origin of the ideal optical trace diagram, which shows that there will be an extended distribution of the ideal optical trace diagram in the y direction; in the x direction, it can be understood using the above formula. According to Figure 3 it can be seen that , where is a constant regarding the small change in the y direction. According to the above formula, the derivative effect completely disappears, and x Of is basically linear with . Therefore, a small offset of the optical trace in the x direction is generated, manifested as a small amount of dispersion in the x direction although there is dispersion. The actual optical 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 optical trace distribution can effectively explain the generation reason of the actual optical trace diagram.

[0087] Analyze the ideal point spread function based on the ideal optical trace diagram. Specifically, judge the optical trace point y of the chief ray entering the actual optical system Oc . In this embodiment, the incident position of the chief ray is y0 = 0, so there is:

[0088] ;

[0089] Subtract the ideal optical trace diagram y Of from the optical trace point y Oc to obtain the ideal point spread function spt, that is:

[0090] .

[0091] The origin of the ideal point spread function is the optical trace of the reference chief ray. For the system of this embodiment of the present invention, that is Figure 5 the intersection point of the red line and the oscillation line. It can be seen that its optical trace is at the bottom of the oscillation, that is, the optical trace of the chief ray , which indicates that on the ideal point spread function except for the optical traces of those rays are all in the positive direction of the optical trace of the chief ray, which will cause the ideal point spread function to be eccentrically distributed in the positive y direction.

[0092] The actual point spread function is obtained in the Zemax optical simulation software as shown in Figure 7 . Figure 7 In Figure 7It can be seen that the above formula for analyzing the distribution of the spot diagram can effectively explain the generation reason of the actual light trace diagram. As an important imaging index of the optical system, the actual spot diagram needs to be strictly constrained. The analysis model provided by this patent for the influence of manufacturing errors on the ideal spot diagram can quantitatively analyze the relationship between errors and the ideal spot diagram, and thus can be used for the precise constraint of the actual spot diagram to achieve good image quality.

[0093] It should be understood that various forms of processes shown above can be used, steps can be 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, and no limitation is made herein.

[0094] The above specific embodiments do not constitute a limitation on 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: Calculate the equation of the straight line on which the outgoing light obtained in step S3 lies; determine the observation surface for light trace analysis according to the optical system; Based on the intersection of the straight line equation and the observation surface, an ideal light trajectory diagram of the actual optical system is obtained; the light trajectory point of the main light entering the actual optical system is determined; and the ideal light trajectory diagram is subtracted from the light trajectory point to obtain an ideal point array diagram.

2. The optical system image quality impact analysis method based on component manufacturing error 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 method for analyzing the impact of optical system image quality based on component manufacturing errors 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.

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