WO2023019826A1 - Aberration measurement system and aberration measurement method for optical imaging lens - Google Patents

Abstract

An aberration measurement system and aberration measurement method for an optical imaging lens. The aberration measurement system comprises a measurement module (1) and an analysis module (2); the measurement module (1) comprises a light source apparatus (3), an imaging target (4), a collimating lens (5), an imaging lens to be measured (6), a detection camera (8), and at least three different parallel flat plates (7); the light source apparatus (3) provides monochromatic or quasi-monochromatic uniform illuminating parallel outgoing light beams; the outgoing light beams illuminate the imaging target (4) in a transmissive mode; the collimating lens (5) collimates the light beams; the imaging lens to be measured (6) images the imaging target (4); different defocusing amounts are obtained by means of the parallel flat plates (7); the detection camera (8) collects images; and the wave aberration, the point diffusion function, and the modulation transfer function of the imaging lens to be measured (6) are calculated according to the collected images. The measurement of a traditional point diffusion function and a modulation transfer function can be achieved, the single aberration can also be measured, on-axis aberration and off-axis aberration can be measured, and the monochromatic aberration of different-wavelength imaging can also be measured.

Description

Aberration detection system and aberration detection method of optical imaging lens technical field

The invention relates to the field of optical imaging lens measurement, in particular to an aberration detection system and an aberration detection method of an optical imaging lens.

Background technique

Optical imaging lens is an essential part of machine vision system, which directly affects the quality of optical imaging. Ideally, an object point through an optical imaging lens looks like a diffractive Airy disk. But in actual imaging, the shape and position of the image are different from the ideal calculation results. This difference between the actual image and the ideal image is called aberration.

Aberration is an inherent characteristic of optical imaging lenses. To detect and analyze the aberration of the lens is an important content to test whether the lens meets the design and use requirements. Traditionally, aberrations are evaluated by detecting the lens point spread function or modulation transfer function, but with the development of new optical imaging technology, people pay more and more attention to the individual aberrations.

Invention Patent A discloses an optical lens aberration detection device. Specifically, the optical lens aberration detection device includes: a point light source, a lens fixing claw, a slit plate and a target paper, the lens fixing claw is located between the point light source and the target paper, and the slit plate is installed on the lens fixing claw facing the target paper One side of the slit plate is provided with a strip-shaped slit, the width of the strip-shaped slit is d, the length is nd, n is a positive number, and the target paper is provided with several horizontal lines and vertical lines. The formed grid also discloses an optical lens aberration detection method. However, in this scheme, it is considered that the aberration within the aperture of nd mm is less than λ/4, and the aberration is within an acceptable range, and λ is the wavelength of light. Therefore, this scheme can only qualitatively reflect the comprehensive size of aberrations, and cannot give quantitative results , and cannot detect single aberrations.

Invention Patent B proposes an imaging system aberration detection method and device. Specifically, the imaging system aberration detection method is applied to an aberration detector. The aberration detector includes a microlens array and a CCD detector. The microlens array is placed on the focal plane of the imaging system to be tested, and the CCD detector is placed on the On the focal plane of the microlens array, the microlens array is used to divide the complex amplitude of the light at the focal plane of the entrance pupil, so as to form a low-resolution image of the observation target at the CCD detector. This scheme uses the focal plane Hartmann wavefront sensor to replace the traditional Hartmann wavefront sensor, which has the ability to obtain the aberration of the imaging system with a large field of view in a single measurement, but it needs to use a complex and expensive Hartmann sensor, and it does not The method of detecting single aberration is given.

Therefore, in the prior art, it is generally only possible to detect the point spread function and the modulation transfer function, and lacks a solution capable of single-item aberration detection.

Therefore, there is an urgent need for a solution that can detect both the point spread function and the modulation transfer function, as well as single-phase aberration, so as to solve the above problems.

Contents of the invention

Based on the problems existing in the prior art, the present invention provides an aberration detection system and an aberration detection method of an optical imaging lens. The specific plan is as follows:

An aberration detection system for an optical imaging lens, comprising a detection module and an analysis module, the detection module including a light source device, an imaging target, a collimating lens, an imaging lens to be tested, a detection camera, and at least three different parallel plates;

Each part of the detection module is arranged in sequence according to the order of the light source device, the imaging target, the collimating lens, the imaging lens to be tested, the parallel plate and the detection camera, and each part Align the center with the common optical axis;

The light source device is used to provide monochromatic or quasi-monochromatic uniform illumination and parallel outgoing light beams;

The imaging target is located at the front focal plane of the collimating lens, and the outgoing light beam illuminates the imaging target in a transmission manner;

The collimating lens is used to collimate the beam passing through the imaging target;

The imaging lens to be tested is located at the rear side of the collimating lens, and is used for imaging the imaging target;

The parallel plate is located at the rear side of the imaging lens to be tested, and is used to adjust the axial position of the imaging surface of the imaging lens to be tested to obtain different defocus amounts;

The detection camera is located on the rear side of the parallel plate, and is used to acquire images under different defocus amounts;

The analysis module is used to solve the wave aberration of the imaging lens to be tested according to the collected image, decompose the wave aberration to obtain individual aberrations, and calculate a point spread function and a modulation transfer function.

In a specific embodiment, the detection module further includes a lens clamping adjustment device;

The lens clamping and adjusting device is used to clamp, adjust the position and fix the imaging lens to be tested, so that the imaging lens to be tested is coaxial with the common optical axis.

In a specific embodiment, the light source device includes a point light source, a first collimating lens, a narrow-band filter, a converging lens, a pinhole and a second collimating lens, and each part of the light source device is in accordance with the point The light source, the first collimating lens, the narrow-band filter, the converging lens, the pinhole and the second collimating lens are sequentially arranged, and the centers of each part are aligned with the common optical axis;

The point light source is located at the front focal point of the first collimating lens for providing divergent light beams;

The first collimating lens is used to collimate the divergent light beam into a first parallel light;

The narrow-band filter is used to filter out preset wavelength components in the first parallel light to obtain quasi-monochromatic light;

The converging lens is used for converging the quasi-monochromatic light to obtain a converging light beam;

The pinhole is located at the back focus of the converging lens for spatially filtering the converging light beam;

The pinhole is located at the front focal point of the second collimator lens, the light beam passing through the pinhole propagates as a quasi-spherical wave, and the monochromatic or quasi-monochromatic light beam is obtained after passing through the second collimating lens. Uniform illumination with parallel exit beams.

In a specific embodiment, the imaging target is provided with a target pattern;

The target pattern includes on-axis object points and off-axis object points located in the horizontal and vertical directions;

In the target pattern, the distance between any two adjacent object points in the horizontal and vertical directions satisfies the following conditions:

d≥10 ⁴ ×λ _max f

Wherein, d is the distance between object points, λ _max is the maximum imaging wavelength, and f is the focal length of the collimating lens.

In a specific embodiment, the on-axis object point is a circular hole set in the target center of the target pattern;

The off-axis object point is three circular holes arranged on the left, right, up, down, and left sides of the on-axis object point;

The spacing between any two adjacent circular holes in the horizontal and vertical directions is equal, and the spacing satisfies the following conditions:

Δd=0.0175×f

Wherein, Δd is the distance between two adjacent circular holes, and f is the focal length of the collimating lens.

In a specific embodiment, the root mean square deviation of the wavefront of the collimating lens to the reference sphere centered on the diffraction focus does not exceed λ/50, where λ is the imaging wavelength.

In a specific embodiment, the front and rear surfaces of the parallel plates are parallel to each other and perpendicular to the common optical axis;

The centers of the parallel plates are aligned with the common optical axis;

The parallel plates have uniform refractive index and transmit light.

In a specific embodiment, the detection module is provided with a first parallel plate, a second parallel plate and a third parallel plate, and the thickness of the first parallel plate, the second parallel plate and the third parallel plate is There is a difference in the refractive index;

The first parallel plate is used for clear imaging;

The second parallel plate is used for front defocus imaging;

The third parallel plate is used for post defocus imaging.

In a specific embodiment, the thickness of the first parallel plate is d ₁ and the refractive index is n ₁ ; the thickness of the second parallel plate is d ₂ and the refractive index is n ₂ ; the thickness of the third parallel plate is Thickness d ₃ , refractive index n ₃ ;

The first parallel plate, the second parallel plate and the third parallel plate meet the following conditions:

Wherein, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, and D is the exit pupil diameter of the imaging lens to be tested.

In a specific embodiment, the detection module is further provided with a turntable, the turntable is uniformly provided with openings along the circumference, and a plurality of parallel plates are fixedly connected to the turntable through the openings;

By rotating the turntable, free switching of the parallel plates is realized.

In a specific embodiment, the analysis device specifically includes:

According to the collected images, the wave aberration of the imaging lens to be tested is solved by using the optical imaging mathematical model and the optimization estimation algorithm, the wave aberration is decomposed to obtain each individual aberration, and the point spread function and the modulation transfer function are calculated;

The wave aberration includes on-axis aberration and off-axis aberration.

In a specific embodiment, the detection module detects the monochromatic aberration of the imaging lens under test at different imaging wavelengths by adjusting the wavelength of the outgoing light beam.

In a specific embodiment, the position of the detection camera on the detection module is fixed;

And/or, the detection camera is a high pixel resolution area array black and white camera.

An aberration detection method of an optical imaging lens, suitable for the aberration detection system described in any one of the above, comprising the following:

Monochromatic or quasi-monochromatic uniform illumination parallel outgoing beams are emitted through the light source device;

The outgoing light beam illuminates the imaging target in a transmission manner;

collimating the light beam passing through the imaging target through a collimating lens;

Imaging the imaging target through the imaging lens to be tested;

adjusting the axial position of the imaging surface of the imaging lens to be tested by replacing a plurality of different parallel plates to obtain different defocus amounts;

Obtaining collected images under different defocus amounts by a detection camera;

The wave aberration of the imaging lens to be tested is solved by the analysis module according to the collected image, the wave aberration is decomposed to obtain each individual aberration, and the point spread function and the modulation transfer function are calculated.

In a specific embodiment, the aberration detection system further includes a lens clamping adjustment device;

Before "a monochromatic or quasi-monochromatic uniform illumination parallel exit beam is emitted by a light source device", it also includes:

Installing the imaging lens to be tested on the lens clamping adjustment device;

adjusting the position of the imaging lens to be tested in the radial direction through the lens clamping adjustment device, so that the center of the lens is aligned with the common optical axis;

adjusting the position of the imaging lens to be tested in an axial position through the lens clamping adjustment device, so that the target image is clear;

Lock and fix the imaging lens to be tested.

In a specific embodiment, the aberration detection system includes a first parallel plate, a second parallel plate and a third parallel plate, and the first parallel plate, the second parallel plate and the third parallel plate are There are differences in thickness and refractive index;

Setting the first parallel plate for clear imaging, and acquiring N ₁ focal plane images through the detection camera;

The second parallel plate is set to perform front defocus imaging, and N ₂ front defocus images are obtained through the detection camera;

The third parallel plate is set to perform post-defocus imaging, and N ₃ post-defocus images are acquired by the detection camera.

In a specific embodiment, the thickness of the first parallel plate is d ₁ and the refractive index is n ₁ ; the thickness of the second parallel plate is d ₂ and the refractive index is n ₂ ; the thickness of the third parallel plate is Thickness d ₃ , refractive index d ₃ ;

The first parallel plate, the second parallel plate and the third parallel plate meet the following conditions:

Wherein, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, and D is the exit pupil diameter of the imaging lens to be tested.

In a specific embodiment, the N ₁ focal plane images are averaged to obtain the first image I ₁ ;

Performing normalization on the first image I ₁ to obtain a normalized focal plane image i ₁ , the normalized focal plane image i ₁ satisfies:

Averaging the N ₂ front defocused images to obtain a second image I ₂ ;

Perform normalization on the second image I ₂ to obtain a defocused image i ₂ before normalization, and the defocused image i ₂ before normalization satisfies:

Averaging the N ₃ post-defocus images to obtain a third image I ₃ ;

The third image _I3 is normalized to obtain a normalized defocused image _i3 , and the normalized defocused image _i3 satisfies:

Among them, (m,n) is the image pixel position.

In a specific embodiment, an on-axis object point is set at the target center of the imaging target, and a plurality of off-axis object points are set around the on-axis object point;

For the on-axis object point:

Intercept the first on-axis sub-image i _1s of P×P pixels from the first preset position in the normalized focal plane image i ₁ , so that the on-axis object point is imaged on the first axis The center of the image i _1s , and the sub-image i _1s on the first axis does not include other object points;

Intercepting a sub-image i _2s on the second axis of P×P pixels from the first preset position in the defocused image i ₂ before normalization;

Intercepting a third-axis sub-image i _3s of P×P pixels from the first preset position in the normalized defocused image i ₃ ;

According to the optical imaging mathematical model, construct the mathematical model of the axial wave aberration estimation of the imaging lens to be tested:

φ ₁ ＝ min ^-1 [E(i _1s ,i _2s ,i _3s ,d 1 ,n ₁ ,d ₂ ,n _{2 ,} d ₃ ,n ₃ ,F,D,λ)]

Wherein, φ ₁ is the axial wave aberration, E is the objective function, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, D is the exit pupil diameter of the imaging lens to be tested, and d ₁ is the The thickness of the first parallel plate, n ₁ is the refractive index of the first parallel plate; d ₂ is the thickness of the second parallel plate, n ₂ is the refractive index of the second parallel plate; d ₃ is the The thickness of the third parallel plate, n ₃ is the refractive index of the third parallel plate;

Using an optimal estimation method to solve the on-axis wave aberration φ ₁ , and decompose the on-axis wave aberration φ ₁ to obtain each monomial wave aberration;

On-axis point spread function and modulation transfer function are calculated according to the on-axis wave aberration.

In a specific embodiment, for each of the off-axis object points:

The first off-axis sub-image i _1z of P×P pixels is intercepted from the second preset position in the normalized focal plane image i ₁ , so that the image of the off-axis object point is located in the first off-axis sub-image The center of the image i _1z , and the first off-axis sub-image i _1z does not include images of other object points;

intercepting a second off-axis sub-image i _2z of P×P pixels from the second preset position in the defocused image i ₂ before normalization;

Intercepting a third off-axis sub-image i _3z of P×P pixels from the second preset position in the normalized defocused image i ₃ ;

According to the optical imaging mathematical model, construct the mathematical model of the off-axis wave aberration estimation of the imaging lens to be tested:

φ ₂ ＝ min ^-1 [E(i _1z ,i _2z ,i _3z ,d 1 ,n ₁ ,d ₂ ,n _{2 ,} d ₃ ,n ₃ ,F,D,λ)]

Wherein, φ ₂ is an off-axis wave aberration, E is an objective function, λ is an imaging wavelength, F is the focal length of the imaging lens to be tested, D is the exit pupil diameter of the imaging lens to be tested, and d ₁ is the The thickness of the first parallel plate, n ₁ is the refractive index of the first parallel plate; d ₂ is the thickness of the second parallel plate, n ₂ is the refractive index of the second parallel plate; d ₃ is the The thickness of the third parallel plate, n ₃ is the refractive index of the third parallel plate;

Using an optimal estimation method to solve the off-axis wave aberration φ ₂ , and decompose the off-axis wave aberration φ ₂ to obtain individual monomial wave aberrations;

An off-axis point spread function and a modulation transfer function are calculated from the off-axis wave aberration.

In a specific embodiment, also include:

By adjusting the wavelength of the outgoing light beam, the monochromatic aberration of the imaging lens under test at different imaging wavelengths is detected.

The present invention has following beneficial effects:

The invention provides an aberration detection system and an aberration detection method of an optical imaging lens, which solves the disadvantage that a single aberration detection cannot be performed in the prior art. The detection accuracy of the aberration detection system is high, the operation is simple, and the detection cost is much lower than the traditional detection scheme. Different parallel plates are used to change the defocus amount, the defocus amount is accurate and unique, and there is no wear and tear, and the maintenance cost is low. The scheme provided by the present invention can not only realize the detection of traditional point spread function and modulation transfer function, but also can detect single aberration, realize the detection of on-axis aberration and off-axis aberration, and can also detect different wavelength imaging by adjusting the beam wavelength monochromatic aberration.

In order to make the above-mentioned objects, features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

1 is a schematic structural diagram of an aberration detection system according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of components of a detection module according to an embodiment of the present invention;

3 is a schematic structural diagram of a light source device according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of a target pattern according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of a light beam passing through a parallel plate according to an embodiment of the present invention;

Fig. 6 is a schematic diagram of the light beam passing through the parallel plate and falling on the detection camera according to the embodiment of the present invention;

Fig. 7 is a schematic diagram of a turntable according to an embodiment of the present invention;

Fig. 8 is a side view of the turntable of the embodiment of the present invention;

FIG. 9 is a flowchart of an aberration detection method according to an embodiment of the present invention.

Reference signs: 1-detection module; 2-analysis module; 3-light source device; 4-imaging target; 5-collimating lens; 6-imaging lens to be tested; 7-parallel plate; 8-detection camera; Clamping adjustment device; 31-point light source; 32-first collimating lens; 33-narrow band filter; 34-converging lens; 35-pinhole; 36-second collimating lens.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

This embodiment proposes an aberration detection system for an optical imaging lens, and the structural diagram of the aberration detection system is shown in Figure 1 of the specification. The specific plan is as follows:

The aberration detection system includes a detection module 1 and an analysis module 2. The analysis module 2 analyzes the image data collected by the detection module 1 to obtain the aberration of the imaging lens 6 to be tested.

Wherein, the detection module 1 is mainly composed of a light source device 3 , an imaging target 4 , a collimator lens 5 , a detection camera 8 and at least three different parallel plates 7 . The imaging lens 6 to be tested is located in the detection module 1 . In addition, the detection module 1 also includes a lens clamping adjustment device 9 . The components of the detection module 1 are shown in Figure 2 of the specification.

The light source device 3, the imaging target 4, the collimating lens 5, the imaging lens to be tested 6, the parallel plate 7, and the detection camera 8 are sequentially arranged centered on the common optical axis. The target 4, the collimating lens 5, the imaging lens 6 to be tested, the parallel plate 7, and the detection camera 8 are arranged in sequence, and the centers of each part are aligned with the common optical axis. The common optical axis in this embodiment is the optical axis of the detection module 1, which is arranged in the order of the light source device 3, the imaging target 4, the collimating lens 5, the imaging lens to be tested 6, the parallel plate 7, and the detection camera 8, and each composition The centers of the sections are traversed by a common optical axis.

It should be noted that the “sequentially arranged with the center aligned with the common optical axis” in this embodiment means that they are arranged in a specific order, and the central axes of the components are all passed through by the common optical axis.

The light source device 3 generates a monochromatic or quasi-monochromatic uniformly illuminating parallel outgoing light beam, and the parallel outgoing light beam illuminates the imaging target 4 in a transmission manner. The imaging target 4 is located at the front focal plane of the collimating lens 5 , the parallel outgoing light beam emitted from the collimating lens 5 passes through the imaging lens 6 to be tested, the converging light beam passes through the parallel plate 7 , and finally is imaged by the detection camera 8 .

In this embodiment, the variation of the defocus amount is realized by switching a variety of different parallel plates 7 . After the parallel plate 7 is replaced each time, the detection camera 8 takes pictures and collects images. According to the series of images collected, the wave aberration and individual aberrations are solved by using the optical imaging mathematical model and the optimal estimation algorithm, and the point spread function and modulation transfer function are calculated. Both on-axis and off-axis aberrations can be detected. . By adjusting the wavelength of the outgoing light source of the light source system, the monochromatic aberration of imaging at different wavelengths can also be detected.

Specifically, the light source device 3 is responsible for providing an imaging illumination source, and its main features include: (1) providing monochrome or quasi-monochrome uniform illumination and parallel exiting light source; (2) adjustable wavelength. By adjusting the wavelength of the outgoing light source, the monochromatic aberration of imaging at different wavelengths can be detected.

Preferably, the structure of a light source device 3 is shown in Fig. 3 of the specification. The light source device 3 includes a point light source 31 , a first collimator lens 32 , a narrow band filter 33 , a converging lens 34 , a pinhole 35 and a second collimator lens 36 . Each part in the light source device 3 is arranged in sequence according to the order of the point light source 31, the first collimating lens 32, the narrow band filter 33, the converging lens 34, the pinhole 35 and the second collimating lens 36, and the point light source 31, the first The centers of a collimating lens 32 , a narrow band filter 33 , a converging lens 34 , a pinhole 35 and a second collimating lens 36 are aligned with a common optical axis.

The point light source 31 is a wide-spectrum point light source 31 located at the front focus of the first collimator lens 32 for providing divergent light beams. The first collimating lens 32 collimates the diverging light beam into a first parallel light, and the first parallel light is approximately parallel light. The first parallel light passes through the narrow-band filter 33, and the narrow-band filter 33 can filter out the preset wavelength components of the first parallel light, so that the first parallel light becomes quasi-monochromatic light. The quasi-monochromatic light passes through the converging lens 34 and converges to obtain a converging light beam. A pinhole 35 is placed at the back focus of the converging lens 34 to spatially filter the converging beam. At the same time, the pinhole 35 is located at the front focal point of the second collimating lens 36, and the light beam passing through the pinhole 35 propagates forward as a quasi-spherical wave, and obtains a uniformly illuminated parallel light source after passing through the collimating lens.

Specifically, the imaging target 4 is located on the front focal plane of the collimating lens 5 and serves as the imaging target of the detection module 1 . The imaging lens 6 to be tested images the target, and the aberration of the imaging lens 6 to be tested is analyzed according to the imaging result.

Wherein, the imaging target 4 is provided with a target pattern. The imaging target 4 is a transmission type, and the target pattern is provided with on-axis object points and off-axis object points in the horizontal and vertical directions.

In the target pattern, the distance between any two object points satisfies the following conditions:

d≥10 ⁴ ×λ _max f

Wherein, d is the distance between object points, λ _max is the maximum imaging wavelength, and f is the focal length of the collimating lens 5 .

Preferably, the target pattern of an imaging target 4 is as shown in Fig. 4 of the specification. A circular hole set in the target center of the target pattern is used as the on-axis object point. The three circular holes set at the left, right, top, bottom, and bottom of the on-axis object point are used as off-axis object points. There is only one on-axis object point, and 12 off-axis object points.

The collimating lens 5 is located at the rear side of the imaging target 4 and is used for collimating the light beam passing through the imaging target 4 . The transmitted light from the center hole of the target is collimated into a parallel beam parallel to the optical axis, and the transmitted light from other circular holes is collimated into a parallel beam with a small angle relative to the optical axis, and then enters the imaging lens 6 to be tested. The functional characteristics of the collimating lens 5 include: the aberration is fully corrected, and its wave aberration is negligible compared with the wave aberration of the lens to be tested. Preferably, the root mean square deviation of the wavefront of the collimating lens 5 to the reference sphere centered on the diffraction focus shall not exceed λ/50, where λ is the imaging wavelength.

The imaging lens 6 to be tested is located at the rear side of the collimator lens 5 , and its position is adjusted and fixed by the lens clamping adjustment device 9 . The lens clamping and adjusting device 9 is used for clamping, adjusting the position and fixing the imaging lens 6 to be tested. The functional characteristics of the lens clamping adjustment device 9 include: (1) can clamp and fix lenses with different outer diameters; (2) can make the imaging lens 6 to be tested coaxial with the common optical axis of the detection module 1; (3) ) can adjust the position of the lens along the radial direction and axial direction of the detection module 1, align the center of the imaging lens 6 to be tested with the common optical axis of the detection module 1 through radial adjustment, and make the imaging lens 6 to be tested form an image through axial adjustment The image plane falls on the photosensitive surface of the detection camera 8 .

The parallel plate 7 is located at the rear side of the imaging lens 6 to be tested, and is used to adjust the axial position of the imaging plane of the imaging lens 6 to be tested. The front and rear surfaces of the parallel plate 7 are perpendicular to the common optical axis, and the centers of the front and rear surfaces of the parallel plate 7 are aligned with the detection common optical axis. When the imaging of the imaging lens 6 to be tested is imaging with a thin beam in the paraxial region, the parallel plate 7 will not affect the image formed by the imaging lens 6 to be tested, but only moves the imaging image plane along the optical axis by an axial direction. displacement. The axial displacement is related to the thickness of the plate.

As shown in Figure 5 of the specification, when there is no parallel plate 7, the parallel light beam will converge at a after passing through the lens, as shown by the dotted line in the figure; when the parallel plate 7 is added, the outgoing light passing through the plate is still parallel to the incident light , but an offset will occur, and this offset will eventually lead to an axial displacement of the beam convergence point b, as shown by the solid line in the figure. The distance between points a and b is the axial displacement. For thin beam imaging in the paraxial region, the axial displacement ΔL is only related to the thickness d and the refractive index n of the plate, ΔL=d(1-1/n).

By changing the thickness d or the refractive index n of the parallel plate 7, the magnitude of the axial displacement ΔL can be changed. The position of the detection camera 8 is fixed, and the axial position of the imaging plane is changed by changing the parallel plate 7, so that the images acquired by the detection camera 8 will have different defocus. As shown in accompanying drawing 6 of the specification, the photosensitive surface of the detection camera 8 is located at b, and for the parallel plate 7 shown in the figure, the imaging surface of the lens is also at b, at this time, the camera can obtain a clear focal plane image; when the parallel plate is removed After 7, the imaging image plane is at a, and what the camera acquires at this time is a rear defocused image; when the parallel plate 7 is replaced so that the imaging image plane is behind b, what the camera acquires at this time is a front defocused image.

Therefore, the detection module 1 of this embodiment includes a series of parallel flat plates 7 to obtain in-focus images and out-of-focus blur images. The functional characteristics of the parallel plate 7 include: (1) the parallelism of the front and rear surfaces of the plate is high; (2) the thickness of the plate is accurately known; (3) the thickness of the plate is as thin as possible; (4) the refractive index of the plate material is uniform and transparent, preferably, The material of the parallel plate 7 is optical glass; (5) At least three different parallel plates 7 are included, corresponding to clear imaging, front defocused imaging, and rear defocused imaging.

The multiple parallel flat plates 7 in this embodiment vary in thickness and refractive index, wherein air is equivalent to a flat plate with a thickness of 0 or a refractive index of 1. These parallel plates 7 can be independent entities, and can also be a whole. Preferably, this embodiment proposes a structure for realizing plate replacement. The structural connection relationship between the turntable and the parallel plate 7 is shown in Figure 7 of the specification, and the side view of the turntable is shown in Figure 8 of the specification. The detection module 1 is provided with a turntable, and holes are evenly arranged on the turntable along the circumference, and different parallel flat plates 7 are covered on the holes and fixed; by rotating the turntable, the required flat plate enters the optical path to realize the freedom of the flat plate. switch.

In this embodiment, by introducing several images with known phase differences, using images and optical imaging models to construct an objective function, an optimization algorithm is used to find a wavefront that best fits the objective function as a detection wavefront. The phase difference selected in this embodiment is defocus, and phase difference wavefront detection is realized by collecting focal plane images and defocus images.

In this embodiment, the parallel flat plate 7 is used to achieve defocusing, and the required amount of defocusing can be obtained by replacing the parallel flat plate 7 . After all the parallel plates 7 are calibrated once, there is no need to calibrate in the future, the defocus amount is accurate and unique, and there is no wear and tear, and the maintenance cost is low. The traditional acquisition of the defocus amount is mainly realized by moving the detection camera 8 on a sliding rail or using multiple detection cameras 8 . Using slide rails to move the detection camera 8 needs to achieve high-precision linear motion, and the defocus amount is often not accurate enough, and it is easy to wear and tear after long-term use, which affects the accuracy. Using multiple detection cameras 8 requires precise registration of multi-camera images, which is difficult to operate and expensive.

Taking three parallel plates 7 as an example, the detection module 1 is provided with a first parallel plate, a second parallel plate and a third parallel plate, and the first parallel plate, the second parallel plate and the third parallel plate exist in thickness and refractive index. difference. Among them, the first parallel plate is used for clear imaging, the second parallel plate is used for front defocused imaging, and the third parallel plate is used for rear defocused imaging.

Assume that the thickness of the first parallel plate is d ₁ and the refractive index is n ₁ ; the thickness of the second parallel plate is d ₂ and the refractive index is n ₂ ; the thickness of the third parallel plate is d ₃ and the refractive index is n ₃ .

The first parallel plate, the second parallel plate and the third parallel plate meet the following conditions:

Wherein, λ is the imaging wavelength, F is the focal length of the imaging lens 6 to be tested, and D is the exit pupil diameter of the imaging lens 6 to be tested.

Specifically, the detection camera 8 is located at the rear side of the parallel plate 7, and is used for shooting and collecting images. The functional characteristics of the detection camera 8 include: (1) a high pixel resolution area array camera; (2) a high signal-to-noise ratio; (3) a black and white camera. The detection camera 8 has a fixed position in the system. After the parallel plate 7 is replaced each time, the detection camera 8 takes pictures and collects images.

The analysis module 2 uses the optical imaging mathematical model and the optimal estimation algorithm to solve the wave aberration and each single wave aberration according to the series of images collected, and calculates the point spread function and the modulation transfer function.

This embodiment provides an aberration detection system of an optical imaging lens, which can satisfy the detection of traditional point spread function and modulation transfer function, and can also meet the detection of single aberration, realizing on-axis aberration and off-axis aberration For the measurement, the monochromatic aberration of imaging at different wavelengths is detected by adjusting the wavelength of the exiting light source. The detection accuracy of the aberration detection system is high, the operation is simple, and the detection cost is much lower than the traditional detection scheme.

Example 2

This embodiment proposes an aberration detection method for an optical imaging lens. Embodiment 1 is used to propose an aberration detection system for an optical imaging lens. The flow chart of the aberration detection method is shown in the accompanying drawing. The specific plan is as follows:

101. Monochromatic or quasi-monochromatic uniform illumination parallel outgoing beams are emitted through the light source device;

102. The outgoing light beam illuminates the imaging target in a transmission manner;

103. Collimating the light beam passing through the imaging target through the collimating lens;

104. Imaging the imaging target through the imaging lens to be tested;

105. Adjust the axial position of the imaging surface of the imaging lens to be tested by replacing multiple different parallel plates to obtain different defocus amounts;

106. Obtaining collected images under different defocus amounts through the detection camera;

107. Solve the aberration of the imaging lens to be tested according to the collected image through the analysis module.

Before step 101, it also includes: installing the imaging lens to be tested on the lens clamping adjustment device; adjusting the position of the imaging lens to be tested in the radial direction through the lens clamping adjustment device, so that the center of the lens is aligned with the common optical axis; The clamping adjustment device adjusts the position of the imaging lens to be tested in the axial position, so that the target image is clear; the imaging lens to be tested is locked and fixed.

Exemplarily, the aberration detection system is provided with a first parallel plate, a second parallel plate and a third parallel plate, and the thickness and refractive index of the first parallel plate, the second parallel plate and the third parallel plate are different;

Set the first parallel plate for clear imaging, and obtain N ₁ focal plane images through the detection camera;

Set the second parallel plate for front defocus imaging, and acquire N ₂ front defocus images through the detection camera;

Set up the third parallel plate for post-defocus imaging, and acquire N ₃ post-defocus images through the detection camera.

The thickness of the first parallel plate is d ₁ and the refractive index is n ₁ ; the thickness of the second parallel plate is d ₂ and the refractive index is n ₂ ; the thickness of the third parallel plate is d ₃ and the refractive index is n ₂ ;

The first parallel plate, the second parallel plate and the third parallel plate meet the following conditions:

Among them, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, and D is the exit pupil diameter of the imaging lens to be tested.

Averaging the N ₁ focal plane images to obtain the first image I ₁ ;

Normalize the first image I ₁ to obtain a normalized focal plane image i ₁ , and the normalized focal plane image i ₁ satisfies:

Wherein, I ₁ is the first image, i ₁ is the normalized focal plane image, and (m, n) is the pixel position of the image.

Averaging the N ₂ previous defocused images to obtain the second image I ₂ ;

Normalize the second image I ₂ to obtain the defocused image i ₂ before normalization, and the defocused image i ₂ before normalization satisfies:

Among them, I ₂ is the second image, i ₂ is the defocused image before normalization, and (m,n) is the pixel position of the image.

Averaging the N ₃ rear defocused images to obtain a third image I ₃ ;

Normalize the third image I ₃ to obtain the normalized defocused image i ₃ , and the normalized defocused image i ₃ satisfies:

Wherein, I ₃ is the third image, i ₃ is the defocused image after normalization, and (m, n) is the pixel position of the image.

An on-axis object point is set at the target center of the imaging target, and multiple off-axis object points are set around the on-axis object point;

For an on-axis object point:

Intercept the first on-axis sub-image i _1s of P×P pixels from the first preset position in the normalized focal plane image i ₁ , so that the image of the on-axis object point is located in the center of the first-axis image i _1s , and the second The sub-image i _1s on one axis does not include other object points;

Intercepting a sub-image i _2s on the second axis of P×P pixels from the first preset position in the defocused image i ₂ before normalization;

Intercepting a sub-image i _3s on the third axis of P×P pixels from the first preset position in the defocused image i ₃ after normalization;

According to the mathematical model of optical imaging, a mathematical model for the estimation of axial wave aberration of the imaging lens to be tested is constructed:

φ ₁ ＝ min ^-1 [E(i _1s ,i _2s ,i _3s ,d 1 ,n ₁ ,d ₂ ,n _{2 ,} d ₃ ,n ₃ ,F,D,λ)]

Among them, _φ1 is the axial wave aberration, E is the objective function, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, D is the exit pupil diameter of the imaging lens to be tested, and _d1 is the thickness of the first parallel plate , n ₁ is the refractive index of the first parallel plate; d ₂ is the thickness of the second parallel plate, n ₂ is the refractive index of the second parallel plate; d ₃ is the thickness of the third parallel plate, n ₃ is the third parallel plate the refractive index;

Using the optimal estimation method to solve the on-axis wave aberration φ ₁ , and decompose the on-axis wave aberration φ ₁ to obtain the individual wave aberrations;

Calculate the on-axis point spread function and modulation transfer function from the on-axis wave aberration.

For each off-axis object point:

Intercept the first off-axis sub-image i _1z of P×P pixels from the second preset position in the normalized focal plane image i ₁ , so that the image of the off-axis object point is located in the center of the first off-axis sub-image i _1z , and The sub-image i _1z outside the first axis does not include images of other object points;

Intercepting a second off-axis sub-image i _2z of P×P pixels from a second preset position in the defocused image i ₂ before normalization;

Intercepting a third off-axis sub-image i _3z of P×P pixels from a second preset position in the defocused image i ₃ after normalization;

According to the mathematical model of optical imaging, a mathematical model for estimation of off-axis wave aberration of the imaging lens to be tested is constructed:

φ ₂ ＝ min ^-1 [E(i _1z ,i _2z ,i _3z ,d 1 ,n ₁ ,d ₂ ,n _{2 ,} d ₃ ,n ₃ ,F,D,λ)]

Among them, _φ2 is the off-axis wave aberration, E is the objective function, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, D is the exit pupil diameter of the imaging lens to be tested, and _d1 is the thickness of the first parallel plate , n ₁ is the refractive index of the first parallel plate; d ₂ is the thickness of the second parallel plate, n ₂ is the refractive index of the second parallel plate; d ₃ is the thickness of the third parallel plate, n ₃ is the third parallel plate the refractive index;

Use the optimal estimation method to solve the off-axis wave aberration φ ₂ , and decompose the off-axis wave aberration φ ₂ to obtain the individual wave aberrations;

Calculate the off-axis point spread function and modulation transfer function from the off-axis wave aberration.

For each imaging wavelength that needs to be measured, adjust the wavelength of the outgoing light source, and repeat the above steps. By adjusting the wavelength of the outgoing beam, the monochromatic aberration of imaging at different wavelengths is detected.

This embodiment proposes an aberration detection method for an optical imaging lens, which is applicable to the aberration detection system in Embodiment 1, not only can realize the detection of traditional point spread function and modulation transfer function, but also can detect single aberration, The detection of on-axis aberration and off-axis aberration can be realized, and the monochromatic aberration of different wavelength imaging can also be detected by adjusting the beam wavelength.

The invention provides an aberration detection system and an aberration detection method of an optical imaging lens, which solves the disadvantage that a single aberration detection cannot be performed in the prior art. The detection accuracy of the aberration detection system is high, the operation is simple, and the detection cost is much lower than the traditional detection scheme. Different parallel plates are used to change the defocus amount, the defocus amount is accurate and unique, and there is no wear and tear, and the maintenance cost is low. The scheme provided by the present invention can not only realize the detection of traditional point spread function and modulation transfer function, but also can detect single aberration, realize the detection of on-axis aberration and off-axis aberration, and can also detect different wavelength imaging by adjusting the beam wavelength monochromatic aberration.

Those of ordinary skill in the art should understand that each module or each step of the present invention described above can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed on a network formed by multiple computing devices. Optionally, they can be implemented with executable program codes of computer devices, so that they can be stored in storage devices and executed by computing devices, or they can be made into individual integrated circuit modules, or a plurality of modules in them Or the steps are fabricated into a single integrated circuit module to realize. As such, the present invention is not limited to any specific combination of hardware and software.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

The above disclosures are only some specific implementation scenarios of the present invention, however, the present invention is not limited thereto, and any changes conceivable by those skilled in the art shall fall within the protection scope of the present invention.

Claims (21)

1. An aberration detection system for an optical imaging lens, characterized in that it includes a detection module and an analysis module, and the detection module includes a light source device, an imaging target, a collimating lens, an imaging lens to be tested, a detection camera, and at least three different parallel plate;

   Each part of the detection module is arranged in sequence according to the order of the light source device, the imaging target, the collimating lens, the imaging lens to be tested, the parallel plate and the detection camera, and each part Align the center with the common optical axis;

   The light source device is used to provide monochromatic or quasi-monochromatic uniform illumination and parallel outgoing light beams;

   The imaging target is located at the front focal plane of the collimating lens, and the outgoing light beam illuminates the imaging target in a transmission manner;

   The collimating lens is used to collimate the beam passing through the imaging target;

   The imaging lens to be tested is located at the rear side of the collimating lens, and is used for imaging the imaging target;

   The parallel plate is located at the rear side of the imaging lens to be tested, and is used to adjust the axial position of the imaging surface of the imaging lens to be tested to obtain different defocus amounts;

   The detection camera is located on the rear side of the parallel plate, and is used to acquire images under different defocus amounts;

   The analysis module is used to solve the wave aberration of the imaging lens to be tested according to the collected image, decompose the wave aberration to obtain individual aberrations, and calculate a point spread function and a modulation transfer function.
2. The aberration detection system according to claim 1, wherein the detection module further comprises a lens clamping adjustment device;

   The lens clamping and adjusting device is used to clamp, adjust the position and fix the imaging lens to be tested, so that the imaging lens to be tested is coaxial with the common optical axis.
3. The aberration detection system according to claim 1, wherein the light source device comprises a point light source, a first collimator lens, a narrow-band filter, a converging lens, a pinhole, and a second collimator lens, and the light source Each part of the device is arranged in sequence according to the order of the point light source, the first collimating lens, the narrow-band filter, the converging lens, the pinhole and the second collimating lens, and each The centers of the parts are aligned with the common optical axis;

   The point light source is located at the front focal point of the first collimating lens for providing divergent light beams;

   The first collimating lens is used to collimate the divergent light beam into a first parallel light;

   The narrow-band filter is used to filter out preset wavelength components in the first parallel light to obtain quasi-monochromatic light;

   The converging lens is used for converging the quasi-monochromatic light to obtain a converging light beam;

   The pinhole is located at the back focus of the converging lens for spatially filtering the converging light beam;

   The pinhole is located at the front focal point of the second collimator lens, the light beam passing through the pinhole propagates as a quasi-spherical wave, and the monochromatic or quasi-monochromatic light beam is obtained after passing through the second collimating lens. Uniform illumination with parallel exit beams.
4. The aberration detection system according to claim 1, wherein a target pattern is arranged on the imaging target;

   The target pattern includes on-axis object points and off-axis object points located in the horizontal and vertical directions;

   In the target pattern, the distance between any two adjacent object points in the horizontal and vertical directions satisfies the following conditions:

   d≥10 ⁴ ×λ _max f

   Wherein, d is the distance between object points, λ _max is the maximum imaging wavelength, and f is the focal length of the collimating lens.
5. The aberration detection system according to claim 4, wherein the on-axis object point is a circular hole set at the target center of the target pattern;

   The off-axis object point is three circular holes arranged on the left, right, up, down, and left sides of the on-axis object point;

   The spacing between any two adjacent circular holes in the horizontal and vertical directions is equal, and the spacing satisfies the following conditions:

   Δd=0.0175×f

   Wherein, Δd is the distance between two adjacent circular holes, and f is the focal length of the collimating lens.
6. The aberration detection system according to claim 1, wherein the root mean square deviation of the wavefront of the collimating lens to the reference sphere centered on the diffraction focus does not exceed λ/50, where λ is the imaging wavelength.
7. The aberration detection system according to claim 1, wherein the front and rear surfaces of the parallel plates are parallel to each other and perpendicular to the common optical axis;

   The centers of the parallel plates are aligned with the common optical axis;

   The parallel plates have uniform refractive index and transmit light.
8. The aberration detection system according to claim 7, wherein the detection module is provided with a first parallel plate, a second parallel plate and a third parallel plate, the first parallel plate, the second parallel plate There are differences in thickness and refractive index from the third parallel plate;

   The first parallel plate is used for clear imaging;

   The second parallel plate is used for front defocus imaging;

   The third parallel plate is used for post defocus imaging.
9. The aberration detection system according to claim 8, wherein the thickness of the first parallel plate is d ₁ and the refractive index is n ₁ ; the thickness of the second parallel plate is d ₂ and the refractive index is n ₂ ; the thickness of the third parallel plate is d ₃ , and the refractive index is n ₃ ;

   The first parallel plate, the second parallel plate and the third parallel plate meet the following conditions:

   

   

   Wherein, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, and D is the exit pupil diameter of the imaging lens to be tested.
10. The aberration detection system according to claim 7, wherein the detection module is further provided with a turntable, the turntable is uniformly provided with openings along the circumference, and a plurality of the parallel plates are fixed through the openings connected to the turntable;

    By rotating the turntable, free switching of the parallel plates is realized.
11. The aberration detection system according to claim 1, wherein the analyzing device specifically comprises:

    According to the collected images, the wave aberration of the imaging lens to be tested is solved by using the optical imaging mathematical model and the optimization estimation algorithm, the wave aberration is decomposed to obtain each individual aberration, and the point spread function and the modulation transfer function are calculated;

    The wave aberration includes on-axis aberration and off-axis aberration.
12. The aberration detection system according to claim 1, wherein the detection module detects the monochromatic aberration of the imaging lens to be tested at different imaging wavelengths by adjusting the wavelength of the outgoing light beam.
13. The aberration detection system according to claim 1, wherein the position of the detection camera on the detection module is fixed;

    And/or, the detection camera is a high pixel resolution area array black and white camera.
14. An aberration detection method for an optical imaging lens, suitable for the aberration detection system according to any one of claims 1-13, characterized in that it comprises the following:

    Monochromatic or quasi-monochromatic uniform illumination parallel outgoing beams are emitted through the light source device;

    The outgoing light beam illuminates the imaging target in a transmission manner;

    collimating the light beam passing through the imaging target through a collimating lens;

    Imaging the imaging target through the imaging lens to be tested;

    Adjust the axial position of the imaging image plane of the imaging lens to be tested by changing a plurality of different parallel plates to obtain different defocus amounts;

    Obtaining collected images under different defocus amounts by a detection camera;

    The wave aberration of the imaging lens to be tested is solved by the analysis module according to the collected image, the wave aberration is decomposed to obtain individual aberrations, and the point spread function and modulation transfer function are calculated.
15. The aberration detection method according to claim 14, wherein the aberration detection system further comprises a lens clamping adjustment device;

    Before "a monochromatic or quasi-monochromatic uniform illumination parallel exit beam is emitted by a light source device", it also includes:

    Installing the imaging lens to be tested on the lens clamping adjustment device;

    adjusting the position of the imaging lens to be tested in the radial direction through the lens clamping adjustment device, so that the center of the lens is aligned with the common optical axis;

    adjusting the position of the imaging lens to be tested in an axial position through the lens clamping adjustment device, so that the target image is clear;

    Lock and fix the imaging lens to be tested.
16. The aberration detection method according to claim 14, wherein the aberration detection system comprises a first parallel plate, a second parallel plate and a third parallel plate, the first parallel plate, the second parallel plate There are differences in thickness and refractive index between the flat plate and the third parallel flat plate;

    Setting the first parallel plate for clear imaging, and acquiring N ₁ focal plane images through the detection camera;

    The second parallel plate is set to perform front defocus imaging, and N ₂ front defocus images are obtained through the detection camera;

    The third parallel plate is set to perform post-defocus imaging, and N ₃ post-defocus images are acquired by the detection camera.
17. The aberration detection method according to claim 16, wherein the thickness of the first parallel plate is d ₁ and the refractive index is n ₁ ; the thickness of the second parallel plate is d ₂ and the refractive index is n ₂ ; the thickness of the third parallel plate is d ₃ , and the refractive index is n ₃ ;

    The first parallel plate, the second parallel plate and the third parallel plate meet the following conditions:

    

    

    Wherein, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, and D is the exit pupil diameter of the imaging lens to be tested.
18. The aberration detection method according to claim 17, wherein averaging the N ₁ focal plane images to obtain the first image I ₁ ;

    Performing normalization on the first image I ₁ to obtain a normalized focal plane image i ₁ , the normalized focal plane image i ₁ satisfies:

    

    Averaging the N ₂ front defocused images to obtain a second image I ₂ ;

    Perform normalization on the second image I ₂ to obtain a defocused image i ₂ before normalization, and the defocused image i ₂ before normalization satisfies:

    

    Averaging the N ₃ post-defocus images to obtain a third image I ₃ ;

    The third image _I3 is normalized to obtain a normalized defocused image _i3 , and the normalized defocused image _i3 satisfies:

    

    Among them, (m,n) is the image pixel position.
19. The aberration detection method according to claim 18, wherein an on-axis object point is arranged at the target center of the imaging target, and a plurality of off-axis object points are arranged around the on-axis object point;

    For the on-axis object point:

    Intercept the first on-axis sub-image i _1s of P×P pixels from the first preset position in the normalized focal plane image i ₁ , so that the on-axis object point is imaged on the first axis The center of the image i _1s , and the sub-image i _1s on the first axis does not include other object points;

    Intercepting a sub-image i _2s on the second axis of P×P pixels from the first preset position in the defocused image i ₂ before normalization;

    Intercepting a third-axis sub-image i _3s of P×P pixels from the first preset position in the normalized defocused image i ₃ ;

    According to the optical imaging mathematical model, construct the mathematical model of the axial wave aberration estimation of the imaging lens to be tested:

    φ ₁ ＝ min ^-1 [E(i _1s ,i _2s ,i _3s ,d 1 ,n ₁ ,d ₂ ,n _{2 ,} d ₃ ,n ₃ ,F,D,λ)]

    Wherein, φ ₁ is the axial wave aberration, E is the objective function, λ is the imaging wavelength, F is the focal length of the imaging lens to be tested, D is the exit pupil diameter of the imaging lens to be tested, and d ₁ is the The thickness of the first parallel plate, n ₁ is the refractive index of the first parallel plate; d ₂ is the thickness of the second parallel plate, n ₂ is the refractive index of the second parallel plate; d ₃ is the The thickness of the third parallel plate, n ₃ is the refractive index of the third parallel plate;

    Using an optimal estimation method to solve the on-axis wave aberration φ ₁ , and decompose the on-axis wave aberration φ ₁ to obtain each monomial wave aberration;

    On-axis point spread function and modulation transfer function are calculated according to the on-axis wave aberration.
20. The aberration detection method according to claim 19, wherein, for each of the off-axis object points:

    The first off-axis sub-image i _1z of P×P pixels is intercepted from the second preset position in the normalized focal plane image i ₁ , so that the image of the off-axis object point is located in the first off-axis sub-image The center of the image i _1z , and the first off-axis sub-image i _1z does not include images of other object points;

    intercepting a second off-axis sub-image i _2z of P×P pixels from the second preset position in the defocused image i ₂ before normalization;

    Intercepting a third off-axis sub-image i _3z of P×P pixels from the second preset position in the normalized defocused image i ₃ ;

    According to the optical imaging mathematical model, construct the mathematical model of the off-axis wave aberration estimation of the imaging lens to be tested:

    φ ₂ ＝ min ^-1 [E(i _1z ,i _2z ,i _3z ,d 1 ,n ₁ ,d ₂ ,n _{2 ,} d ₃ ,n ₃ ,F,D,λ)]

    Wherein, φ ₂ is an off-axis wave aberration, E is an objective function, λ is an imaging wavelength, F is the focal length of the imaging lens to be tested, D is the exit pupil diameter of the imaging lens to be tested, and d ₁ is the The thickness of the first parallel plate, n ₁ is the refractive index of the first parallel plate; d ₂ is the thickness of the second parallel plate, n ₂ is the refractive index of the second parallel plate; d ₃ is the The thickness of the third parallel plate, n ₃ is the refractive index of the third parallel plate;

    Using an optimal estimation method to solve the off-axis wave aberration φ ₂ , and decompose the off-axis wave aberration φ ₂ to obtain individual monomial wave aberrations;

    An off-axis point spread function and a modulation transfer function are calculated from the off-axis wave aberration.
21. The aberration detection method according to claim 14, further comprising:

    By adjusting the wavelength of the outgoing light beam, the monochromatic aberration of the imaging lens under test at different imaging wavelengths is detected.

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