Design method of extremely simple optical system with external entrance pupil

Abstract

The invention discloses a method for designing a very simple optical system with an external entrance pupil, and the method comprises the steps: determining the system parameters and performance indexes of the very simple optical system according to the imaging demands of a target imaging system; selecting proper types of optical elements and lens structure parameters according to the performance indexes, and designing an initial optical structure; according to the initial optical structure, performing preliminary design in optical design software, and setting a diaphragm position as a first surface of the optical system; the size of the diaphragm is adjusted according to system parameters so as to ensure that only proper light passes through the extremely simple optical system, and interference of large-angle light is reduced; and carrying out iterative optimization and performance evaluation on the diaphragm external optical system in optical design software, verifying whether the extremely-simple optical system meets the requirements of performance indexes, outputting the extremely-simple optical system meeting the performance indexes, and completing the design of the entrance pupil external extremely-simple optical system. According to the invention, the diaphragm is arranged in front, so that the complexity and aberration of the system are reduced, and the overall performance of the optical system is improved.

Description

Technical Field

[0001] The present invention relates to the field of optical design, and in particular to a design method for a minimalist optical system with an external entrance pupil. Background Art

[0002] With the continuous development of optical technology, optical systems are being used more and more widely in various fields, especially in imaging, sensing, detection and many other fields. How to simplify the design of the optical system while ensuring the imaging performance of the system has become a key factor in the design of the optical system. In the design of traditional optical systems, the entrance pupil is usually set inside the system, and the light is propagated and refracted through multiple optical elements. With the improvement of imaging quality and accuracy requirements, the design and optimization of optical systems has become more difficult. Especially in the design of minimalist optical systems, how to simplify the system structure and reduce the number of optical elements while maintaining high imaging quality has become a major challenge.

[0003] At present, although there are some optimization methods for the design of traditional optical systems, such as controlling aberrations through precise configuration and adjustment of optical elements, these methods often require complex initial structures and a large number of optical elements, which not only increases the complexity of the system, but also leads to higher costs and larger volumes, making it difficult for the system to meet the requirements of lightweight and compactness in some applications. In these design methods, the aperture is generally located inside the optical system, which will cause subsequent optical elements to process large-angle incident light, causing the system to produce irregular aberrations, which in turn affects the imaging quality. In order to reduce these aberrations, more optical elements or more precise optical designs are usually required, but this will further increase the design difficulty and manufacturing cost of the system. Summary of the invention

[0004] In view of the shortcomings of the prior art in optical system design, the present invention proposes a minimalist optical system design method with external entrance pupil. This method innovatively sets the aperture at the front end of the optical system to achieve external entrance pupil design, thereby effectively simplifying the system structure, reducing the number of optical components, optimizing the light beam incident conditions, and reducing irregular aberrations caused by large-angle incident light.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for designing a minimalist optical system with an external entrance pupil comprises the following steps:

[0007] S1: Determine the system parameters and performance indicators of the minimalist optical system according to the imaging requirements of the target imaging system;

[0008] S2: According to the performance index, select the appropriate type of optical elements and lens structure parameters, and design the initial optical structure;

[0009] S3: Performing a preliminary design in an optical design software according to the initial optical structure, and setting the aperture position to the first surface of the optical system;

[0010] S4: adjusting the size of the aperture according to the system parameters to ensure that only appropriate light passes through the minimalist optical system and reduce interference of large-angle light;

[0011] S5: The aperture external optical system constructed in step S4 is iteratively optimized and performance evaluated in the optical design software, and it is verified whether the minimalist optical system meets the requirements of the performance indicators, and the minimalist optical system that meets the performance indicators is output, thereby completing the design of the minimalist optical system with an external entrance pupil.

[0012] Furthermore, the system parameters include working band, working field of view and lens aperture size.

[0013] Furthermore, the types of the optical elements include refractive surfaces and diffractive surfaces, and the lens structural parameters include lens aperture, lens spacing, and lens material.

[0014] Furthermore, the size of the aperture is calculated by the system performance index. When the image-side F number F is known, 像 When the focal length of the system is f, the diameter D of the aperture is calculated by the following formula:

[0015]

[0016] Furthermore, in step S5, the aperture external optical system constructed in step S4 is input into the optical design software, parameters including lens curvature radius, lens thickness, and lens cone coefficient are set as variables, and optimized through operand constraints to ensure that the optical system meets the design specifications.

[0017] Furthermore, the operands include EFFL, ENPP, and WFNO.

[0018] A minimalist optical system designed by a minimalist optical system design method with an external entrance pupil, wherein the aperture is located on the first surface of the entire optical system.

[0019] Furthermore, it includes a biconvex lens G1 with positive optical power, a meniscus lens G2 with negative optical power, and a sensor, which are arranged on the same optical axis from the object side to the image side. The aperture is located at the front surface of the biconvex lens G1, at the front end of the entire optical system, and is used to select the range of light beams participating in imaging of the optical system.

[0020] The beneficial effects of the present invention are as follows:

[0021] The minimalist optical system design method with external entrance pupil proposed in the present invention effectively reduces the aberration of the optical system and reduces the complexity of the system by setting the aperture at the front end of the optical system. The method optimizes the incident conditions of the light beam, limits the large-angle incident light, reduces the irregular aberration caused by light divergence, and thus significantly improves the imaging quality; the present invention can simplify the optical system design and improve the performance of the optical system while maintaining high imaging quality through the design of the front entrance pupil. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart of the method for designing a minimalist optical system with an external entrance pupil according to the present invention.

[0023] Figure 2 Schematic diagram of the structure of a minimalist optical system according to an embodiment of the present invention.

[0024] Figure 3 It is a spot diagram of the extremely simple optical system design result of an embodiment of the present invention in the visible light band of 486-656nm.

[0025] Figure 4 It is an MTF curve diagram of the minimalist optical system design result in the embodiment of the present invention in the visible light band of 486-656nm.

[0026] Description of reference numerals:

[0027] G1-first lens, G2-second lens, STO-aperture stop. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below based on the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become more clear. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] The minimalist optical system design method with an external entrance pupil disclosed in the present invention reduces the aberration of the optical system and improves the imaging quality by placing the aperture in front. The effect of placing the aperture in front is that, since the aperture aperture can select the range of light beams participating in the imaging of the optical system, the influence of large-angle incident light on the imaging quality can be reduced by limiting the aperture angle of the light, that is, controlling the incident angle of the light. By placing the aperture in front, the incident conditions of the light beam can be controlled, and the irregular aberrations caused by large aperture angle light passing through multiple optical elements can be effectively avoided. By setting the aperture in front of the system, the incident light beam has been constrained to a certain extent when passing through the optical element, so the probability of light beam being dispersed in the imaging area can be reduced, thereby improving the imaging quality and reducing the aberration caused by light dispersion. This design not only helps to reduce aberrations, but also reduces the requirements for optical elements by controlling the size and incident angle of the light beam. Especially in the design of a minimalist optical system, this design method helps to reduce the number and types of lenses, thereby simplifying the design of the optical system.

[0030] like Figure 1 As shown, the minimalist optical system design method with external entrance pupil of the present invention comprises the following steps:

[0031] Step 1: According to the imaging requirements of the target imaging system, determine the system parameters and performance indicators of the minimalist optical system; wherein the system parameters include the working band, the working field of view, and the lens aperture size, etc. In this embodiment, the working band is the visible light band of 486-656nm, the lens focal length is 70mm, and the lens aperture size is 20mm.

[0032] Step 2: According to the system performance indicators, select the appropriate type of optical elements and lens structure parameters, and design the initial optical structure. The optical system in this embodiment uses a two-piece minimalist lens structure, such as Figure 2 As shown, the structure includes a biconvex lens G1 with positive optical power, a meniscus lens G2 with negative optical power, and a sensor, which are arranged on the same optical axis from the object side to the image side.

[0033] Step 3: According to the initial optical structure, perform preliminary design in the optical design software, and set the aperture position to the first surface of the optical system. The aperture angle of the incident light is limited by the aperture in front, the beam incident condition of the system is optimized, and the aberration of the optical system is reduced. In this embodiment, the aperture is placed on the front surface of the biconvex lens G1, located at the front end of the entire optical system, and is used to select the range of the beam participating in the imaging of the optical system. By limiting the aperture angle of the light, the aperture can control the incident angle of the light, thereby reducing the impact of large-angle light on the imaging quality.

[0034] Step 4: According to the system parameters, adjust the size of the aperture to ensure that only appropriate light passes through the minimalist optical system and reduce the interference of large-angle light. 像 When the focal length of the system is f, the diameter D of the front aperture can be calculated by the following formula:

[0035]

[0036] Otherwise, the aperture size is determined by the aperture size specified by the system performance specifications.

[0037] Step 5: Perform iterative optimization and performance evaluation on the constructed optical system with external aperture in the optical design software, and verify whether the minimalist optical system meets the performance indicators, output the minimalist optical system that meets the performance indicators, and complete the design of the minimalist optical system with external entrance pupil. In this embodiment, the calculated initial optical structure is input into the optical design software, and the lens curvature radius, surface spacing, lens material, etc. are set as variables, and optimized through operand constraints. In this embodiment, the focal length of the optical system is constrained by the EFFL operand, and the center and edge thickness of the glass and air are constrained by the MNCA, MXCA, MNCG, MXCG and other operands to ensure that the optical system meets the processing requirements and design indicators. The point diagram of the minimalist optical system designed in this embodiment in the visible light band of 486-656nm is shown as follows. Figure 3 As shown, the MTF curve of the minimalist optical system in the visible light band of 486-656nm is as follows Figure 4 As shown. Figure 3 It can be seen that the radius of each field of view point diagram is small. Figure 4 It can be seen that the MTF curve of the minimalist optical system decreases slowly, which proves that the optical system of this embodiment has small aberration and high imaging quality.

[0038] Those skilled in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention is described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions recorded in the above examples or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, etc. made within the spirit and principle of the invention shall be included in the protection scope of the invention.

Claims

1. A method for designing a minimalist optical system with an external entrance pupil, characterized in that: The following steps are involved: S1: Determine the system parameters and performance indicators of the minimalist optical system according to the imaging requirements of the target imaging system; S2: According to the performance index, select the appropriate type of optical elements and lens structure parameters, and design the initial optical structure; S3: Performing a preliminary design in an optical design software according to the initial optical structure, and setting the aperture position to the first surface of the optical system; S4: adjusting the size of the aperture according to the system parameters to ensure that only appropriate light passes through the minimalist optical system and reduce interference of large-angle light; S5: The aperture external optical system constructed in step S4 is iteratively optimized and performance evaluated in the optical design software, and it is verified whether the minimalist optical system meets the requirements of the performance indicators, and the minimalist optical system that meets the performance indicators is output, thereby completing the design of the minimalist optical system with an external entrance pupil.

2. The method for designing a minimalist optical system with an external entrance pupil according to claim 1, characterized in that: The system parameters include working band, working field of view and lens aperture size.

3. The method for designing a minimalist optical system with an external entrance pupil according to claim 1, characterized in that: The types of the optical elements include refractive surfaces and diffractive surfaces, and the lens structural parameters include lens aperture, lens spacing, and lens material.

4. The method for designing a minimalist optical system with an external entrance pupil according to claim 1, characterized in that: The size of the aperture is calculated by the system performance index. When the image side F number F is known, 像 When the focal length of the system is f, the diameter D of the aperture is calculated by the following formula:

5. The method for designing a minimalist optical system with an external entrance pupil according to claim 1, characterized in that: In the step S5, the aperture external optical system constructed in the step S4 is input into the optical design software, parameters including lens curvature radius, lens thickness, and lens cone coefficient are set as variables, and optimized through operand constraints to ensure that the optical system meets the design specifications.

6. The method for designing a minimalist optical system with an external entrance pupil according to claim 1, characterized in that: The operands include EFFL, ENPP, and WFNO.

7. A minimalist optical system designed by the minimalist optical system design method with external entrance pupil as claimed in any one of claims 1 to 6, characterized in that: The aperture is located on the first surface of the entire optical system.

8. The minimalist optical system according to claim 7, characterized in that: The optical system comprises a biconvex lens G1 with positive focal power, a meniscus lens G2 with negative focal power, and a sensor, which are arranged in sequence on the same optical axis from the object side to the image side. The aperture stop is located at the front surface of the biconvex lens G1, at the front end of the entire optical system, and is used to select the range of light beams participating in imaging of the optical system.

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