Method for solving the optimal misalignment angle of error elements in rotating element optical systems

Abstract

The present invention relates to the field of optical processing technology, and more particularly to a method for determining the optimal misalignment angle of an error element in a rotating element optical system. The method comprises: obtaining the surface error of the element, loading the error into optical design software for system imaging analysis, and determining the optical performance index of interest; repeating the imaging analysis while varying the relative angle of the element placement, and recording the values ​​of the optical performance index of interest. The angle with the optimal performance value is the optimal placement angle. The method provided by the present invention allows a large amount of debugging work to be completed at the simulation level, significantly reducing on-site adjustment time.

Description

Technical Field

[0001] The present invention belongs to the field of optical processing technology, and in particular relates to a method for solving the optimal misalignment angle of an error element in a rotating element optical system. Background Art

[0002] Existing aberration adjustment mainly includes two aspects: optimization based on optical design and adjustment, and adaptive optics technology. In the aberration adjustment method based on optimization of optical design and adjustment, aberrations are reduced by optimizing the parameters and layout of optical elements during the optical system design stage. For example, image quality is improved by optimizing optical elements. In the aberration adjustment method of adaptive optics technology, imaging quality is optimized by real-time measurement and correction of wavefront aberrations. Its system is usually more complex and the adjustment cost is high. Specifically, the "Research on Telescope System Adjustment Method Based on Aberration Correction" published in "Applied Optics" and the "Design and Implementation of Secondary Mirror Adjustment in a Hyperbolic Optical System" published in "Applied Optics" provide a framework based on aberration adjustment methods. However, in actual adjustment, new problems caused by manufacturing errors need to be considered, because the processing errors of rotational optical elements will destroy the rotational symmetry of the elements and show obvious directionality, thereby introducing additional aberrations.

[0003] Existing aberration adjustment provides the allowable misalignment of an ideal optical system. However, when actual components have manufacturing errors, their surface shape has obvious directionality, which will introduce additional misalignment. This patent discloses a simulation method to determine the placement misalignment angle of the directional surface shape of each actual rotary optical component, eliminating the need for on-site debugging and reducing a large amount of adjustment time. Summary of the Invention

[0004] In light of this, the present invention aims to provide a method for determining the optimal misalignment angle of error elements in rotating element optical systems. This method obtains element surface errors, loads these errors into optical design software for system imaging analysis, and determines the optical performance indicators of interest. The imaging analysis is repeated by varying the relative angles of the element placement, and the values ​​of the optical performance indicators of interest are recorded. The angle with the optimal performance value is the optimal placement angle. This method allows the bulk of debugging work to be completed at the simulation level, significantly reducing on-site setup time.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] A method for solving the optimal misalignment angle of an error element in a rotating element optical system, comprising:

[0007] S1: Determine the optical system with a rotational optical element and obtain the real surface image of the rotational optical element;

[0008] S2: constructing an optical simulation model of the optical system of step S1, and loading the real surface image obtained in step S1 onto the corresponding rotational optical element in the optical simulation model;

[0009] S3: Based on the optical simulation model obtained in step S2, the rotary optical element is rotated to obtain current optical simulation models corresponding to different rotation angles, and optical analysis is performed on the current optical simulation model;

[0010] S4: Determine the optimal misalignment angle of the rotational optical element based on the analysis result obtained in step S3.

[0011] Furthermore, the process of rotating the rotary optical element in step S3 includes:

[0012] For the optical simulation model I A rotary optical element, I ≥2:

[0013] Control i Each rotary optical element rotates successively to the corresponding rotation angle, i= 1 , 2 ,...,I ;

[0014] When i When the first rotary optical element completes one rotation, the i- The corresponding rotation angle of a rotary optical element is i- During the rotation of the 1-rotation optical element, the I To i Each rotary optical element continues to rotate according to the corresponding rotation angle.

[0015] In the i The first rotary optical element completes the j i The number of rotations of the rotary optical element in the optical simulation model is l Expressed as:

[0016] ;

[0017] in, N q represents the total number of rotations of the qth rotary optical element, ;

[0018] Until the 1 After a rotary optical element completes one rotation, I Each rotary optical element completes the operation of rotating according to the corresponding rotation angle. At this time, a total of Rotation of sub-rotational optical elements;

[0019] After each rotation of the rotary optical element, an optical analysis is performed on the current optical simulation model.

[0020] Furthermore, step S3 also includes:

[0021] Determine the rotation range of each rotary optical element;

[0022] According to the rotation range of each rotary optical element, the number of rotations of each rotary optical element and the rotation angle of each rotation are determined.

[0023] Furthermore, the process of performing optical analysis on the current optical simulation model in step S3 includes:

[0024] Setting optical performance indicators for optical analysis;

[0025] According to the optical performance index, a corresponding optical simulation model performance index test is performed on the current optical simulation model to obtain a corresponding optical performance index value.

[0026] Furthermore, in step S4:

[0027] Taking the optimal optical performance index value among the optical performance index values ​​obtained in step S3;

[0028] Under the optimal optical performance index value, the rotation angle of each rotational optical element is the optimal misalignment angle of each rotational optical element.

[0029] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0030] The present invention creates a method for solving the optimal misalignment angle of the error element in the rotating element optical system, which is aimed at determining the optimal relative placement angle of a rotational optical element with manufacturing errors in the system. The present invention takes into account the destruction of the rotational symmetry of the optical element by the directionality of the surface error of the rotational optical element, and thus the impact on the imaging quality of the optical system. Therefore, after the spatial adjustment is completed, some fine-tuning of the rotation amount should be performed on the directionality of the surface shape to achieve the optimal image quality. This part of the adjustment work is completed at the simulation level, which greatly reduces the on-site adjustment time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0032] Figure 1A schematic flow chart of a method for determining the optimal misalignment angle of an error element in a rotating element optical system according to an embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram of the optical system according to an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of the error map and the corresponding characteristic directions described in the embodiment of the present invention;

[0035] Figure 4 Schematic diagram of optical analysis when the rotation angle is 0~2π / 6 according to an embodiment of the present invention;

[0036] Figure 5 Schematic diagram of optical analysis when the rotation angles are 3π / 6 and 4π / 6 according to an embodiment of the present invention;

[0037] Figure 6 Schematic diagram of optical analysis when the rotation angles are 5π / 6 and π according to an embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 1. First reflector; 2. Second reflector. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 and do not constitute a limitation of the present invention.

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0045] like Figure 1 As shown, the method for solving the optimal misalignment angle of the error element in the rotating element optical system according to the embodiment of the present invention includes:

[0046] S1: Determine the optical system with a rotational optical element and obtain the actual surface shape of the rotational optical element.

[0047] The optical system is selected based on the actual situation and can include a Cooke three-part objective, a Gaussian objective, or a coaxial mirror. After the optical system is finalized, the rotational optical element within the system is processed, and the actual surface shape of the processed rotational optical element is measured using an interferometer. The optical properties of rotationally symmetric optical elements remain unchanged when rotated about the element's central axis, and this is typically only achieved under ideal conditions. Manufacturing errors in actual components inevitably destroy rotational symmetry, resulting in directional surface shape.

[0048] S2: Construct an optical simulation model of the optical system of step S1, and load the real surface image obtained in step S1 onto the corresponding rotational optical element in the optical simulation model.

[0049] In a certain embodiment, the process of loading the real surface shape diagram obtained in step S1 onto the corresponding rotational optical element in the optical simulation model includes: adding corresponding elements of the real surface shape diagram and the surface of the corresponding rotational optical element; writing the result of the addition into a grid vector height file, and loading the grid vector height file as the surface of the optical element into the optical simulation model.

[0050] S3: Based on the optical simulation model obtained in step S2, the rotary optical element is rotated to obtain current optical simulation models corresponding to different rotation angles, and optical analysis is performed on the current optical simulation model.

[0051] In some embodiments, step S3 includes:

[0052] Determine the rotation range of each rotary optical element;

[0053] Determining the number of rotations of each rotary optical element and the rotation angle of each rotation according to the rotation range of each rotary optical element;

[0054] For the optical simulation model I A rotary optical element, I ≥2:

[0055] Control i Each rotary optical element rotates successively to the corresponding rotation angle, i= 1 , 2 ,...,I ;

[0056] When i When the first rotary optical element completes one rotation, the i- The corresponding rotation angle of a rotary optical element is i- During the rotation of the 1-rotation optical element, the I To i Each rotary optical element continues to rotate according to the corresponding rotation angle.

[0057] In the i The first rotary optical element completes the j i The number of rotations of the rotary optical element in the optical simulation model is l Expressed as:

[0058] ;

[0059] in, N q Indicates the qThe total number of rotations of the rotary optical element, ;

[0060] Until the 1 After a rotary optical element completes one rotation, I Each rotary optical element completes the operation of rotating according to the corresponding rotation angle. At this time, a total of Rotation of sub-rotational optical elements;

[0061] After each rotation of the rotary optical element, an optical analysis is performed on the current optical simulation model.

[0062] In one embodiment, taking the light of the incident optical simulation model as a reference, along the propagation direction of the light, I The rotational optical elements are marked in sequence, that is, the first rotational optical element that the light irradiates is marked as the first rotational optical element, the second rotational optical element that the light irradiates is marked as the second rotational optical element, and so on. The last rotational optical element that the light irradiates is marked as the second rotational optical element. I Rotary optical element.

[0063] For example, there are three rotary optical elements in the optical simulation model (i.e. I =3), the three rotational optical elements are marked as the first rotational optical element, the second rotational optical element and the third rotational optical element along the propagation direction of the light. The rotation range of the three rotational optical elements is [0, 2π], and the rotation times of the three rotational optical elements are 3, 4 and 5 respectively, that is, N 1=3, N 2=4 and N 3=5, the three rotational optical elements rotate uniformly each time, that is, the rotation angles of the three rotational optical elements each time are 2π / 3, 2π / 4 and 2π / 5 respectively.

[0064] For the three rotational optical elements in the optical simulation model, the third rotational optical element is controlled to rotate successively by the corresponding rotation angle 2π / 5; when the third rotational optical element completes one round of rotation (i.e., completes N 3 = 5 rotations), control the second rotary optical element to rotate the corresponding rotation angle 2π / 4; repeat the rotation process of the third rotary optical element and the second rotary optical element until the second rotary optical element completes one round of rotation (i.e., completes N 2 = 4 rotations), the first rotary optical element is controlled to rotate by the corresponding rotation angle 2π / 3. During a certain rotation process, when the first rotary optical element rotates by an angle of 2π / 3, that is, j 1=1, the second rotation type optical element has rotated 2 angles and is at the third angle, that is,j 2=3, the third rotation optical element has completed 2 rotations and is at the second angle, that is, j 3=2, the number of rotations of the rotary optical element l for:

[0065] ;

[0066] It should be noted that in the multiplication In the equation, when a>b, its value is defined as 1.

[0067] Repeat the rotation process of the 3rd, 2nd and 1st rotary optical elements until the 1st rotary optical element completes one rotation (i.e. completes the rotation of the optical element). N 1 = 3 rotations), the three rotational optical elements finish rotating. At this time, the optical simulation model has a total of 60 rotations of the rotational optical elements, namely:

[0068] .

[0069] In one embodiment, the rotation angle of the rotational optical element is determined with reference to the direction of the eigenvector on the real surface diagram of each rotational optical element. That is, the rotation angle of each rotational optical element is the angle through which the eigenvector on the real surface diagram of the rotational optical element rotates when the rotational optical element rotates.

[0070] After each rotation of the rotary optical element, an optical analysis is performed on the current optical simulation model.

[0071] In some embodiments, the process of performing optical analysis on the current optical simulation model includes:

[0072] Set the optical performance index for optical analysis. The performance index of the optical simulation model in the present invention can be a point diagram index, a wave aberration index, a point spread function index, etc. The selection of the index is based on the optical system to be analyzed and the actual needs. The present invention does not limit the selection of the optical simulation model performance index.

[0073] According to the optical performance index, the current optical simulation model is subjected to a corresponding optical simulation model performance index test to obtain a corresponding optical performance index value. In one embodiment, this process can be expressed as:

[0074] K l ( k )∈{( K (1), K (2),..., K (k))| K ( 1 )∈ Ω SPT , K (2)∈ Ω wave ,..., K ( k )∈ Ω PSF};

[0075] in, k Indicates the number of optical performance index values, K l ( k ) indicates that the optical simulation model occurs l After the first rotation of the rotary optical element, the optical simulation model is k Optical performance index values, Ω SPT Indicates the value space of the dot chart indicator, Ω wave represents the value space of wave aberration index, Ω PSF Represents the value space of the point spread function indicator.

[0076] S4: Determine the optimal misalignment angle of the rotational optical element based on the analysis result obtained in step S3.

[0077] In some embodiments, step S4 includes:

[0078] The optimal optical performance index value among the optical performance index values ​​obtained in step S3 is taken; under the optimal optical performance index value, the rotation angle of each rotational optical element is the optimal misalignment angle of each rotational optical element. In one embodiment, the process can be expressed as:

[0079] ;

[0080] in, J =[ j 1, j 2,..., j I ] represents the sequence vector of the optimal misalignment angle, A function representing the optimal angle number when the optimal optical performance index value is obtained. The selection criteria for the optimal optical performance index value are adaptively adjusted according to the selected optical performance index. For example, when the optical performance index is the point spread function peak intensity index, the optimal optical performance index value at this time is the maximum value of the point spread function peak intensity index.

[0081] In the present invention, the process of steps S2 to S4 occurs in simulation software, such as Zemax software. The present invention completes a large amount of such adjustment work at the simulation level, greatly reducing the time for on-site micro-adjustment.

[0082] In order to clearly illustrate the method for solving the optimal misalignment angle of the error element in the rotating element optical system described in the embodiment of the present invention, an embodiment is provided.

[0083] Example: A method for solving the optimal misalignment angle of the error element in the rotating element optical system based on Zemax software, combined with Figure 1 , the method provided in this embodiment specifically includes:

[0084] S1: Determine the optical system with a rotational optical element and obtain the actual surface shape of the rotational optical element.

[0085] In this embodiment, the optical system to be analyzed is determined as follows: Figure 2 As shown, the rotary optical elements to be analyzed are the circularly symmetrical first reflector 1 and the second reflector 2. The first reflector 1 and the second reflector 2 are processed, and the error diagrams of the reflector surface of the first reflector 1 are obtained by using an interferometer. f Error diagram of the mirror surface of the second reflector 1 and the second reflector 2 f 2, that is, 1≤ i ≤2, I =2. Figure 3 As shown, Figure 3 (a) shows the error diagram of the mirror surface of the first mirror 1 f 1 and its eigenvector , Figure 3 (b) shows the error diagram of the mirror surface of the second mirror 2 f 2 and its eigenvector .

[0086] S2: Construct an optical simulation model of the optical system of step S1, and load the real surface image obtained in step S1 onto the corresponding rotational optical element in the optical simulation model.

[0087] In this embodiment, the process of loading the real surface shape diagram obtained in step S1 onto the corresponding rotational optical element in the optical simulation model includes: adding corresponding elements of the real surface shape diagram and the surface of the corresponding rotational optical element; writing the result of the addition into a grid vector height file, and loading the obtained grid vector height file as the surface of the first reflector 1 and the second reflector 2 into the optical simulation model.

[0088] S3: Based on the optical simulation model obtained in step S2, the rotary optical element is rotated to obtain current optical simulation models corresponding to different rotation angles, and optical analysis is performed on the current optical simulation model.

[0089] In this embodiment, step S3 includes:

[0090] S31: Determine the rotation range of each rotary optical element; specifically, the maximum rotation angle Θ=π, and correspondingly, the rotation range of the first reflector 1 and the second reflector 2 is [0,π];

[0091] S32: Determine the number of rotations of each rotary optical element and the rotation angle of each rotation according to the rotation range of each rotary optical element; Specifically, since the system has only two optical elements, we only need to care about the relative position between the first reflector 1 and the second reflector 2, so we only need to rotate one of the reflectors and set the total number of rotations. N =7, for the error graph f i At this time, the feature direction Rotatable angle θ j ∈linspace(0, Θ , N )=linspace(0,π,7)={0,π / 6,2π / 6,3π / 6,4π / 6,5π / 6,π};

[0092] S33: Control the second reflector 2 to rotate successively by corresponding rotation angles until the second reflector 2 completes one rotation (i.e., completes N=7 rotations);

[0093] After each rotation of the rotary optical element, an optical analysis is performed on the current optical simulation model.

[0094] In this embodiment, one optical analysis is performed on the current optical simulation model, namely k =1, the optical analysis performed is point spread analysis, and the point spread function index is obtained, that is, K l (1)= K l ∈ Ω PSF .

[0095] S4: Determine the optimal misalignment angle of the rotational optical element based on the analysis result obtained in step S3.

[0096] In this embodiment, the point spread function index K obtained in step S3 is taken lThe optimal point spread function peak intensity index in , that is, taking the maximum value of the 7 point spread function peak intensity indices, namely:

[0097] ;

[0098] The optical analysis results are as follows Figures 4 to 6 As shown, at this time, the rotation angle corresponding to the peak intensity index of the optimal point diffusion function is θ1=0, which is the optimal rotation angle. That is, for the system of this embodiment, the relative optimal misalignment angle of the two rotating elements is 0.

[0099] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0100] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for determining the optimal misalignment angle of an error element in a rotating element optical system, characterized in that: include: S1: Determine the optical system with a rotational optical element and obtain the real surface image of the rotational optical element; S2: constructing an optical simulation model of the optical system of step S1, and loading the real surface shape diagram obtained in step S1 onto the corresponding rotational optical element in the optical simulation model, the process comprising: adding the real surface shape diagram and the surface of the corresponding rotational optical element by corresponding elements; writing the result of the addition into a grid sag file, and loading the grid sag file as the surface of the optical element into the optical simulation model; S3: Based on the optical simulation model obtained in step S2, the rotational optical element is rotated to obtain current optical simulation models corresponding to different rotation angles, and optical analysis is performed on the current optical simulation model. The process includes: setting optical performance indicators for optical analysis; performing corresponding optical simulation model performance indicator tests on the current optical simulation model according to the optical performance indicators to obtain corresponding optical performance indicator values. This process is expressed as: K l ( k )∈{( K (1), K (2),..., K (k))| K ( 1 )∈ Ω SPT , K (2)∈ Ω wave ,..., K ( k )∈ Ω PSF}； in, k Indicates the number of optical performance index values, K l ( k ) indicates that the optical simulation model occurs l After the first rotation of the rotary optical element, the optical simulation model is k Optical performance index values, Ω SPT Indicates the value space of the dot chart indicator, Ω wave represents the value space of wave aberration index, Ω PSF Represents the value space of the point spread function indicator; S4: Determine the optimal misalignment angle of the rotational optical element based on the analysis result obtained in step S3; in step S4: take the optimal optical performance index value among the optical performance index values ​​obtained in step S3; under the optimal optical performance index value, the rotation angle of each rotational optical element is the optimal misalignment angle of each rotational optical element.

2. The method for determining the optimal misalignment angle of an error element in a rotating element optical system according to claim 1, wherein: The process of rotating the rotary optical element in step S3 includes: For the optical simulation model I A rotary optical element, I ≥2: Control i Each rotary optical element rotates successively to the corresponding rotation angle, i= 1 , 2 ,...,I ; When i When the first rotary optical element completes one rotation, the i- The corresponding rotation angle of a rotary optical element is i- During the rotation of the 1-rotation optical element, the I To i Each rotary optical element continues to rotate according to the corresponding rotation angle. In the i The first rotary optical element completes the j i When the optical element rotates, the number of rotations of the rotary optical element in the optical simulation model is l Expressed as: ； in, N q Indicates the q The total number of rotations of the rotary optical element, ; Until the first rotational optical element completes one rotation, all the rotational optical elements complete the operation of rotating according to the corresponding rotation angle. At this time, the optical simulation model has a total of The rotation of the rotary optical element; After each rotation of the rotary optical element, an optical analysis is performed on the current optical simulation model.

3. The method for determining the optimal misalignment angle of an error element in a rotating element optical system according to claim 1, wherein: Step S3 also includes: Determine the rotation range of each rotary optical element; According to the rotation range of each rotary optical element, the number of rotations of each rotary optical element and the rotation angle of each rotation are determined.

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