A system and method for center detection of a through-focus lens

Abstract

This invention relates to a center detection system and method for defocused lenses. The system comprises an optical system consisting of a light source module, a beam splitter, a lens holder, a first imaging module, and a second imaging module. The light source module, lens holder, beam splitter, and first imaging module are arranged sequentially along the direction of signal beam propagation, while the lens holder, beam splitter, and second imaging module are arranged sequentially along the direction of reflected beam propagation from the lens under test. Therefore, the light emitted by the light source module is transmitted through the lens under test and received by the first imaging module for Hartmann detection imaging of the lens. Simultaneously, the beam reflected by the lens under test is captured by the second imaging module and imaged to obtain a reflection information map. This system not only has the function of real-time identification of the optical center of the main lens and calculation of the lens refractive power parameters, but also imaging of the microstructure of the defocus area and markings printed on the lens surface, thereby realizing the function of identifying and marking the geometric center of the defocused lens microstructure.

Description

Technical Field

[0001] This invention relates to the field of lens parameter measurement technology, and more specifically, to a center detection system and method for defocused lenses. Background Technology

[0002] In the actual fitting and manufacturing process of defocus lenses, there are three key "center" concepts. The accuracy of their positions directly determines the wearing effect and control efficacy of the lens. These three "centers" are the optical center of the primary lens, the center of the lens design reference mark, and the geometric center of the microstructure in the defocus area. The optical center of the primary lens refers to the optical center point of the distance vision area of ​​the lens used for vision correction, which is usually formed during lens manufacturing. The center of the lens design reference mark refers to the mark made by the manufacturer on the lens surface, theoretically representing the geometric center of the distance vision area. The geometric center of the microstructure in the defocus area refers to the actual center of the microlens array or microstructure on the lens surface used to generate the defocus signal.

[0003] Ideally, the three center points mentioned above should perfectly coincide to ensure the precise implementation of the lens optical design. However, in actual production and application, significant deviations often occur. This is mainly because the printing process of the lens design reference marks inevitably introduces manufacturing errors, and the optical center of the primary lens (especially low-power lenses) is also prone to positioning deviations during processing. Moreover, most manufacturers cannot even accurately determine the actual geometric center of the defocus microstructure.

[0004] If the optical center of the primary lens deviates from the center of the design reference mark beyond the required range of the defocus lens center mark circle, it will seriously affect the clinical effectiveness of the defocus lens and easily cause side effects. Existing technologies disclose lens measurement schemes using focimeters or high-precision optical measuring instruments. However, focimeters can only detect the optical center of the far-field region of the defocus lens (i.e., the optical center of the primary lens) and the vertex power, thus failing to effectively evaluate the optical characteristics and geometric center position of the defocus microstructure region. While high-precision optical measuring instruments (such as schlieren and moiré interferometry) can perform imaging analysis on defocus lenses, their complex structure, high cost, and poor performance in real-time prism power detection hinder their widespread adoption in eyewear fitting centers and quality inspection institutions.

[0005] In summary, the existing technology lacks a testing and evaluation method that can simultaneously achieve multi-center positioning and microstructure detection of defocused lenses, while also being cost-effective and easy to operate, which poses a significant challenge to the quality control and accurate fitting of defocused lenses. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: how to overcome the technical defects of existing lens measurement schemes that cannot meet the requirements of multi-center positioning, microstructure detection, cost and ease of operation of defocused lenses. In order to overcome the above defects of the prior art, the present invention provides a defocused lens center detection system and method, specifically including a defocused lens center detection system and a defocused lens center detection method.

[0007] This invention provides a center detection system for defocused lenses, the center detection system comprising: The light source module is used to provide the signal beam; A lens holder is used to position the lens under test so that the lens under test is in the propagation path of the signal beam; The first imaging module is used to perform Hartmann detection imaging on the lens under test to obtain a spot array pattern; The second imaging module is used to image the reflected beam of the lens under test to obtain a reflection information map; A beam splitter is used to transmit the signal beam onto the lens under test and reflect the reflected beam from the lens under test toward the second imaging module. The light source module, the lens holder, the beam splitter, and the first imaging module are arranged sequentially along the propagation direction of the signal beam, while the lens holder, the beam splitter, and the second imaging module are arranged sequentially along the propagation direction of the reflected beam from the lens under test.

[0008] The defocused lens center detection system disclosed in this invention employs a geometric optics imaging method. It comprises an optical system consisting of a light source module, a beam splitter, a lens holder, a first imaging module, and a second imaging module. These components are arranged sequentially along the signal beam propagation direction, while the lens holder, beam splitter, and second imaging module are arranged sequentially along the reflected beam propagation direction of the lens under test. Therefore, the light emitted from the light source module is transmitted through the beam splitter and then incident on the lens under test. After further transmission through the lens, it is received by the first imaging module, which performs Hartmann detection imaging on the lens. Simultaneously, the beam reflected by the lens is captured and imaged by the second imaging module to obtain a reflection information map. This optical system creatively integrates a dual-mode detection mechanism of Hartmann detection and reflection imaging. Specifically, the first imaging module acquires a spot array map through Hartmann detection, enabling high-precision capture of wavefront aberrations within the lens, thus accurately determining the optical center of the lens. Conversely, the second imaging module captures reflected beams from the lens surface, clearly identifying the physical contours and markings of the lens under test, achieving microstructure detection in the defocused area, and accurately locking the geometric center of the lens. By comparing and analyzing the two sets of data, the offset between the optical center and the geometric center (i.e., "optical center offset") can be precisely quantified, yielding equivalent prism power parameters. This meets the requirements for multi-center positioning and microstructure detection of defocused lenses, solving the problem that a single detection method cannot simultaneously address both internal optical performance and external physical characteristics.

[0009] Furthermore, the system disclosed in this invention utilizes a beam splitter to construct an ingenious common-path structure: the signal beam is transmitted through the beam splitter to illuminate the lens under test, while the reflected beam from the lens is reflected by the beam splitter to the second imaging module. This design ensures a high degree of coaxiality between the detection beam and the reflected imaging optical path, effectively avoiding measurement errors caused by optical path strays or mechanical vibrations, greatly improving the stability and anti-interference capability of the optical system, guaranteeing the reliability of measurement data and the accuracy of optical center positioning, thus ensuring reliable positioning while meeting the multi-center positioning requirements of defocused lenses.

[0010] Furthermore, the entire inspection process requires no complex physical contact or disassembly of the lens; simply placing the lens on the lens holder allows for simultaneous scanning of the optical and geometric centers, making operation simple. Compared to traditional manual visual alignment or item-by-item inspection methods, the system of this invention achieves automated, real-time data acquisition and analysis, significantly shortening the inspection cycle. This not only reduces labor costs but also avoids the risk of lens scratches due to improper human operation, making it particularly suitable for large-scale industrial production and quality control of defocused lenses.

[0011] Finally, this invention uses fewer optical components, and the components it relies on are inexpensive, thus meeting the need for cost reduction. Furthermore, the sequential arrangement of the light source module, lens holder, beam splitter, and imaging module along the beam propagation direction results in a linear or right-angled optical path, leading to a compact structure and small footprint. This modular and integrated layout simplifies equipment installation and debugging, and facilitates subsequent maintenance and calibration, providing a practical and efficient solution for high-precision center detection of defocused lenses.

[0012] In one possible implementation, the light source module comprises components arranged sequentially along the propagation direction of the signal beam: A light source used to provide a signal beam; A collimating lens is used to collimate the signal beam into parallel light and direct it toward the beam splitter.

[0013] The light emitted by the light source is collimated by the collimating lens to form parallel light. This parallel light is then transmitted through the beam splitter and incident on the lens, making both the reflected and transmitted light from the lens tend to be parallel. This ensures that the outline of the lens under test is clear during the test, thereby further improving the physical outline and marking clarity of the lens under test and making the center positioning of the lens under test clear.

[0014] In one possible implementation, the light source is a monochromatic laser light source to improve the spatial resolution of wavefront measurement and increase the center detection efficiency of the lens.

[0015] In one possible implementation, the first imaging module includes components arranged sequentially along the propagation direction of the signal beam: The Hartmann aperture, consisting of a two-dimensional array of microlenses, is used for wavefront spatial sampling of the signal beam transmitted from the lens under test. Camera 1 is used to acquire the wavefront spatial sampling results of the Hartmann aperture to obtain a spot array map.

[0016] The Hartmann aperture is a metal plate with multiple regularly arranged small holes. When a beam of light with aberrations (i.e., distortion of the signal beam wavefront due to the placement of the lens under test) passes through it, it is split into multiple small sub-beams. These sub-beams form a series of light spots on the receiving screen of camera one, located behind its focal plane, forming a light spot array. The light spot array reveals a wealth of optical information about the lens under test, providing a basis for assessing its qualification and microstructure, and also providing a basis for measuring the lens's optical power and center offset.

[0017] In one possible implementation, the second imaging module comprises components arranged sequentially along the propagation direction of the reflected beam from the lens under test: An imaging lens is used to focus and image the reflected light beam from the lens under test. Camera 2 is used to receive and record the light spot image formed by the focusing imaging of the imaging lens, so as to obtain the reflection information map.

[0018] Natural light and the signal beam transmitted through the beam splitter are incident on the lens under test. After being reflected by the lens under test, the light is focused onto camera one through the imaging lens to obtain a reflection information map. By using the center position of the light spot and the imaging position of the marked point on the reflection information map, the geometric center of the lens design reference mark position and the microstructure part of the defocus area can be extracted, thereby completing the center detection.

[0019] In one possible implementation, the beam splitter is tilted at an angle of 45° to achieve a 90° deflection of the signal beam and the reflected beam.

[0020] In one possible implementation, the center detection system further includes a data processing unit for obtaining the spot position offset caused by the lens under test based on the spot array map obtained by the first camera; and simultaneously extracting the center of the lens design reference mark and the geometric center of the microstructure in the defocus area based on the reflection information map obtained by the second camera. This allows for the reconstruction of the phase distribution of the incident wavefront and the marking of the optical center.

[0021] Another technical solution of the present invention is to provide a method for center detection of a defocused lens, comprising the following steps: S1: Place the central detection system in a bright environment, cause the light source module to emit a signal beam, and obtain a light spot array through the first imaging module. Figure 1 ; S2: Place the lens under test on the lens holder and obtain the light spot array through the first imaging module. Figure 2 ; S3: By comparing the light spot array Figure 2 With light spot array Figure 1 The position offset of the light spot caused by the lens under test is obtained, and the refractive power of the lens under test is calculated using the position offset of the light spot. S4: The reflected beam of the lens under test is imaged by the second imaging module to obtain a reflection information map; S5: Extract the center of the lens design reference mark and the geometric center of the microstructure in the defocus area based on the reflection information map, and calculate the equivalent prism power of the tested lens using the deviation distance between the two and the refractive power obtained in step S3.

[0022] The center detection method for defocused lenses disclosed in this invention not only calculates the refractive power of the lens through spot offset, but also innovatively introduces a second imaging module. By analyzing the lens's own reflection information, it extracts and calculates the deviation distance between the lens design reference mark and the geometric center of the microstructure in the defocused area, thereby deriving the equivalent prism power. This method, which combines refractive power and prism power detection, provides a comprehensive and accurate evaluation method for defocused lenses, especially those with complex microstructures. It effectively fills the gap in existing technologies where it is difficult to simultaneously and accurately detect the core optical parameters of such lenses on the same machine and in the same batch. It can simultaneously meet the needs of multi-center positioning, microstructure detection, cost, and ease of operation for defocused lenses.

[0023] In one possible implementation, the formula for calculating the refractive power obtained in step S3 is as follows; In the formula, This represents the refractive power of the lens being tested. This represents the offset of the light spot position. Represents a light spot array Figure 1 The distance from the center of the specified spot to the reference optical axis is displayed above. Represents a light spot array Figure 2 The distance from the center of the specified light spot to the reference optical axis shown above. This represents the distance from the Hartmann aperture to camera one. This represents the distance from the tested lens to the Hartmann stop.

[0024] In one possible implementation, the formula for calculating the equivalent prism power in step S5 is: In the formula, This represents the equivalent prism power of the tested lens. It represents the deviation distance between the center of the lens design benchmark mark and the geometric center of the microstructure in the defocus area. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the center detection system for a defocused lens disclosed in an embodiment of the present invention; Figure 2 This is a light spot array diagram obtained by the camera in the embodiments of the present invention; Figure 3 This is a schematic diagram of refractive error calculation disclosed in the embodiments of the present invention; Figure 4 This is a reflection information map obtained by camera 2 as disclosed in the embodiments of the present invention; Figure 5The image processing result of the reflection information map disclosed in the embodiments of the present invention; Figure 6 This is an enlarged view of the positioning results of the center of the lens design reference mark and the geometric center of the microstructure in the defocus area disclosed in the embodiments of the present invention. Figure 7 This is a flowchart of the method disclosed in the embodiments of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1. Light source module, 1.1. Light source, 1.2. Collimating lens, 2. Lens support, 3. Lens under test, 4. First imaging module, 4.1. Hartmann aperture, 4.2. Camera 1, 5. Second imaging module, 5.1. Imaging lens, 5.2. Camera 2, 6. Beam splitter. Detailed Implementation

[0027] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0028] In the description of the embodiments of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "electrical connection" and "establishing an electrical connection relationship" should be interpreted broadly, that is, it should be understood that two or more parties have an electrical relationship, which can be achieved through a wire, a radio connection, or a combination of both; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0029] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0030] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] See Figures 1 to 7 This embodiment discloses a center detection system for defocused lenses. Figure 1This is a schematic diagram of the central detection system, including a light source module 1, a lens holder 2, a first imaging module 4, a second imaging module 5, a beam splitter 6, and a data processing unit. The light source module 1 provides the signal beam. The light source module 1, lens holder 2, beam splitter 6, and first imaging module 4 are arranged sequentially along the direction of the signal beam propagation, while the lens holder 2, beam splitter 6, and second imaging module 5 are arranged sequentially along the direction of the reflected beam propagation from the lens 3 under test. The data processing unit is electrically connected to both the first imaging module 4 and the second imaging module 5. The entire central detection system needs to be placed in a well-lit environment during measurement.

[0032] See Figure 1 In this embodiment, the light source module 1 includes a light source 1.1 and a collimating lens 1.2 arranged sequentially along the propagation direction of the signal beam. The light source 1.1 is used to provide the signal beam. The light source 1.1 is a monochromatic laser light source; in this embodiment, a green light source, i.e., a green LED, is used. The collimating lens 1.2 is used to collimate the signal beam into parallel light and direct it toward the beam splitter 6. To enhance the parallel light formation effect, in this embodiment, the light source 1.1 is positioned on the object-side focal plane of the collimating lens 1.2. The collimating lens 1.2 can be a convex lens or a collimating lens tube.

[0033] See Figure 1 In this central detection system, the beam splitter 6 is used to transmit the signal beam onto the lens under test 3 and reflect the reflected beam from the lens under test 3 towards the second imaging module 5. For example... Figure 1 As shown, in this embodiment, the tilt angle of the beam splitter 6 is 45°, thereby achieving vertical separation of transmitted light and reflected light. Furthermore, to ensure uniform reflection and transmission, this embodiment employs a semi-reflective, semi-transparent reflective lens.

[0034] See Figure 1 In this central detection system, the first imaging module 4 is used to perform Hartmann detection imaging on the lens 3 under test to obtain a spot array pattern. For example... Figure 1 As shown, in this embodiment, the first imaging module 4 includes a Hartmann stop 4.1 and a camera 4.2 arranged sequentially along the signal beam propagation direction. The Hartmann stop 4.1 is composed of a two-dimensional array of microlenses, such as... Figure 3 As shown in (a), each microlens corresponds to a sub-aperture, used for wavefront spatial sampling of the signal beam transmitted from the lens under test 3. Camera 4.2 is a high-resolution two-dimensional image sensor used to acquire the wavefront spatial sampling results of the Hartmann stop 4.1 to obtain a spot array pattern. Figure 2 and Figure 3 (b) shows a spot pattern of a lens, in which multiple distinct spots are visible.

[0035] Thus, the light emitted from light source 1.1 passes sequentially through collimating lens 1.2, beam splitter 6, and the measured lens 3, and is finally transmitted through Hartmann aperture 4.1 and imaged onto the two-dimensional image sensor, i.e., camera 4.2, forming a shape as shown below. Figure 2 or Figure 3 The light spot matrix shown can be used to calculate parameters such as lens diopter, spherical power, cylindrical power, and prism power.

[0036] In this central testing system, the lens holder 2 is used to place the lens under test 3 so that it is positioned on the propagation path of the signal beam. To ensure that the lens under test 3 can be accurately positioned on the propagation path of the signal beam and precisely aligned with the Hartmann stop 4.1 in the system in the X, Y, and Z directions, the lens holder 2 used in this embodiment has a three-dimensional adjustment function to achieve precise alignment of the lens and the Hartmann stop in the X, Y, and Z directions.

[0037] Specifically, the lens holder 2 includes a lens mounting platform, an X-axis adjustment mechanism, a Y-axis adjustment mechanism, and a Z-axis adjustment mechanism. The X-axis adjustment mechanism uses a precision linear guide with a fine-tuning threaded joint structure. Rotating the X-axis adjustment knob drives the lens mounting platform to move horizontally along the X-axis. The precision linear guide uses high-rigidity, low-friction materials (such as precision linear bearings or crossed roller guides) to ensure smooth movement and no backlash error. The Y-axis adjustment mechanism is a combination of a vertically arranged precision lead screw and a slider, used to adjust the lens's height in the Y-axis (vertical direction). The lead screw uses a ball screw or a ground trapezoidal lead screw, combined with a high-precision nut pair, to ensure high linearity and stability of vertical movement. The Z-axis adjustment mechanism uses a tilt angle adjustment design. Through two sets of orthogonally arranged wedge blocks or a precision rotary table structure, it achieves minute angle adjustments (pitch / yaw) of the lens around the X / Y axes. The adjustment method is either to drive the wedge blocks to slide relative to each other by rotating the Z-axis adjustment knob, or to achieve precise rotation of the rotary table through a worm gear mechanism. Each adjustment shaft is equipped with a locking screw, which can lock the mechanism after adjustment to prevent lens displacement due to vibration or temperature changes.

[0038] The main body of the lens holder 2 is made of high-strength aluminum alloy or Invar steel, and undergoes precision machining and heat treatment, resulting in high thermal and dimensional stability. The bottom of the lens holder 2 can be equipped with standard optical platform mounting holes, compatible with M6 / M8 threads or magnetic bases, facilitating rapid integration into existing optical systems.

[0039] To achieve precise alignment, the lens mounting position on the lens mounting platform is equipped with a high-precision planar reference, which is pre-calibrated with the reference plane of the Hartmann aperture 4.1 using a laser interferometer to ensure the accuracy of the initial reference position. Alternatively, a grating ruler or capacitive displacement sensor can be installed on the lens mounting surface for real-time position feedback, forming a closed-loop control system to further improve alignment accuracy and repeatability. Simultaneously, the lens mounting position on the lens mounting platform has a reserved adapter interface to accommodate lenses of different diameters, allowing for flexible configuration by changing the adapter ring.

[0040] See Figure 1 , Figure 4 , Figure 5 and Figure 6 In this central detection system, the second imaging module 5 is used to image the reflected beam of the lens 3 under test to obtain a reflection information map; such as Figure 1 As shown, in this embodiment, the second imaging module 5 includes an imaging lens 5.1 and a second camera 5.2 arranged sequentially along the propagation direction of the reflected beam from the lens under test 3. The imaging lens 5.1 can be a focusing lens or a focusing barrel, used to focus and image the reflected beam from the lens under test 3. The second camera 5.2 is located at the image-side focal plane of the imaging lens 5.1, used to receive and record the light spot image formed by the focused imaging of the imaging lens 5.1, in order to obtain a reflection information map.

[0041] Thus, when the signal beam, combined with external illumination or ambient light (or only external illumination), irradiates the tested lens 3, the reflected light from the surface of the tested lens 3 is reflected by the beam splitter 6 and focused by the imaging lens 5.1, ultimately forming an image in the camera 5.2, resulting in a reflection information map with a circular outline. Figure 4 This is the corresponding black and white image.

[0042] See Figure 3 , Figure 4 , Figure 5 and Figure 6 In this central detection system, the data processing unit is electrically connected to both camera 4.2 and camera 5.2. It is used to obtain the position offset of the light spot caused by the tested lens 3 based on the light spot array diagram obtained by camera 4.2; and simultaneously extract the center of the lens design reference mark and the geometric center of the microstructure in the defocused area based on the reflection information diagram obtained by camera 5.2. For example... Figure 3 As shown, in determining the spot position offset, the reference optical axis is first selected, i.e. Figure 3 As shown by the dashed cross in (b), the symmetrical center line in the figure is specifically selected as the reference optical axis. Subsequently, the light spot array diagram is obtained without the tested lens 3, i.e., the light spot array. Figure 1 and acquire the light spot array Figure 1The distance from the center of the specified light spot to the reference optical axis is shown above. Finally, the light spot array diagram is obtained when the lens under test 3 is placed, i.e., the light spot array. Figure 2 And extract the light spot array Figure 2 The distance from the center of the specified light spot to the reference optical axis is displayed above. The difference between the two distances obtained above is the light spot position offset.

[0043] Next, see Figure 4 , Figure 5 and Figure 6 The method used to determine the two centers is as follows: First, the reflection information map is binarized to convert it into a black and white image, such as... Figure 4 As shown. Subsequently, the boundary circle between light and dark areas on the black and white image is extracted by least-squares circle fitting or curve approximation. The interior of this circle represents the microstructure of the defocused region of the tested lens 3, as shown. Figure 4 As shown. Finally, the center of the fitted circle is extracted, as shown. Figure 5 and Figure 6 As shown, the center of the "+" mark represents a circle, and the center of this circle is the geometric center of the microstructure of the defocus area of ​​the tested lens 3. The black dot next to it is the imaging position of the lens design reference mark, that is, the center of the lens design reference mark position.

[0044] See Figure 7 The following further discloses a method for using the center detection system of the defocused lens in this embodiment, namely, the center detection method of the defocused lens, which includes the following steps: S1: Place the central detection system in a bright environment, and make the light source module 1 emit a signal beam. The beam is then captured by the camera 4.2 in the first imaging module 4 to obtain the light spot array pattern when the lens under test 3 is not placed. Figure 1 .

[0045] S2: The lens 3 to be tested is placed on the lens holder 2, and the light spot array pattern when the lens 3 to be tested is placed is obtained through the camera 4.2 in the first imaging module 4. Figure 2 .

[0046] S3: By comparing the light spot array Figure 2 With light spot array Figure 1 The position offset of the light spot caused by the lens 3 under test is obtained, and the refractive power of the lens 3 under test is calculated using the position offset of the light spot.

[0047] In this embodiment, step S3 includes the following steps: S31: Select the reference optical axis and specify the spot center. See also Figure 3 (b) Specifically, the center line of symmetry of the light spot array pattern is selected as the reference optical axis, as shown in the figure. Figure 3 The dashed crosshairs are shown in (b). Meanwhile, see also... Figure 2 Since the light spot array diagram shows multiple light spots, the center of any one light spot can be selected as the designated light spot center, or the average position of the centers of multiple light spots can be selected as the designated light spot center.

[0048] S32: Based on the light spot array Figure 1 Obtain the first reference distance. The light spot array diagram without the tested lens 3, i.e., the light spot array. Figure 1 The display shows the position of the specified spot center and the position of the reference optical axis. The distance from the specified spot center to the reference optical axis is calculated and used as the first reference distance.

[0049] S33: Based on the light spot array Figure 2 Obtain the second reference distance. The light spot array diagram when the tested lens 3 is placed, i.e., the light spot array. Figure 2 The display shows the position of the specified spot center and the position of the reference optical axis. Due to the involvement of the tested lens 3, the position of the specified spot center will change. Calculate the spot array. Figure 2 The distance from the center of the specified spot to the reference optical axis is shown above; this distance is used as the second reference distance.

[0050] S34: Calculate the difference between the second reference distance and the first reference distance. The difference between these two distances is the spot position offset.

[0051] S35: Calculate the refractive power of the tested lens 3 using the spot position offset. The formula for calculating the obtained refractive power is as follows; In the formula, This represents the diopter of the lens being tested (3), measured in m⁻¹, and is usually denoted by "D". Represents the offset of the light spot position (unit: millimeters). Represents a light spot array Figure 1 The distance (in millimeters) from the center of the specified spot to the reference optical axis is shown above. Represents a light spot array Figure 2 The distance (in millimeters) from the center of the specified spot to the reference optical axis is shown above. This represents the distance from Hartmann stop 4.1 to camera 4.2 (unit: millimeters, horizontal distance in this embodiment). This represents the distance from the tested lens 3 to the Hartmann stop 4.1 (unit: mm; in this embodiment, the horizontal distance is taken).

[0052] S4: The reflected beam of the lens 3 under test is imaged by the camera 25.2 in the second imaging module 5 to obtain a reflection information map.

[0053] S5: Extract the center of the lens design reference mark and the geometric center of the microstructure in the defocus area based on the reflection information map. Calculate the equivalent prism power of the tested lens 3 using the deviation distance between them and the refractive power obtained in step S3. This is used to measure the processing quality of the tested lens 3 and assess the rationality of its center deviation.

[0054] In this embodiment, step S5 includes the following steps: S51: Image binarization. This involves setting a threshold based on the distribution of microstructures in the out-of-focus areas of the image, and then binarizing the reflection information map according to the set threshold to convert it into a black-and-white image, such as... Figure 4 As shown.

[0055] S52: Determine the microstructure of the defocus area. Extract the bright-dark boundary circle on the black-and-white image using least-squares circle fitting or curve approximation. The interior of this circle represents the microstructure of the defocus area of ​​the tested lens 3. Figure 4 As shown S53: Two-center localization. Extract the center of the fitted circle, such as... Figure 5 and Figure 6 As shown, the center of the "+" mark represents a circle, and the center of this circle is the geometric center of the microstructure of the defocus area of ​​the tested lens 3. The black dot next to it is the imaging position of the lens design reference mark, that is, the center of the lens design reference mark position.

[0056] S54: Calculate the equivalent prism power of the tested lens 3 using the deviation distance and refractive power of the two. The formula for calculating the equivalent prism power is: In the formula, Represents the equivalent prism power of the tested lens 3. It represents the deviation distance between the center of the lens design benchmark mark and the geometric center of the microstructure in the defocus area.

[0057] The defocus lens center detection system disclosed in this embodiment employs a geometric optics imaging method. It consists of a light source module 1, a beam splitter 6, a lens support 2, a first imaging module 4, and a second imaging module 5, forming an optical system. Light emitted from the light source module 1 is transmitted through the beam splitter 6 and incident on the lens under test 3. After being transmitted through the lens under test 3, it is received by the first imaging module 4, which performs Hartmann detection imaging on the lens under test 3. Simultaneously, the light beam reflected by the lens under test 3 is captured by the second imaging module 5 and imaged to obtain a reflection information map. This optical system creatively integrates a dual-mode detection mechanism of Hartmann detection and reflection imaging. Specifically, on the one hand, the system has a focimeter function. The first imaging module 4 performs Hartmann detection through its included Hartmann aperture 4.1 to obtain a light spot array map, enabling it to accurately capture wavefront aberrations within the lens, just like a focimeter, thereby precisely determining the optical center of the lens. On the other hand, the system also has the function of measuring the geometric center of the microstructure in the defocus area. The second imaging module 5 captures the reflected light beam from the lens surface, enabling clear identification of the physical contours and markings of the lens under test. This allows for the detection of microstructures in the defocused area of ​​the lens, thus accurately locating the geometric center of the lens. By comparing and analyzing two sets of data, the offset between the optical center and the geometric center (i.e., "optical center offset") can be precisely quantified, yielding the equivalent prism power parameter. This meets the requirements for multi-center positioning and microstructure detection of defocused lenses, solving the problem that a single detection method cannot simultaneously consider both internal optical performance and external physical characteristics.

[0058] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the system or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0059] In the description of this application, the references to terms such as "an embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0060] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A center detection system for a defocused lens, characterized in that, The central detection system includes: Light source module (1), used to provide signal beam; Lens holder (2) is used to place the lens under test (3) so that the lens under test (3) is on the propagation path of the signal beam; The first imaging module (4) is used to perform Hartmann detection imaging on the lens under test (3) to obtain a spot array pattern; The second imaging module (5) is used to image the reflected beam of the lens under test (3) to obtain a reflection information map. The beam splitter (6) is used to transmit the signal beam onto the lens under test (3) and reflect the reflected beam from the lens under test (3) toward the second imaging module (5). The light source module (1), the lens holder (2), the beam splitter (6) and the first imaging module (4) are arranged sequentially along the direction of the signal beam propagation, and the lens holder (2), the beam splitter (6) and the second imaging module (5) are arranged sequentially along the direction of the reflected beam propagation of the lens under test (3).

2. The center detection system for defocused lenses according to claim 1, characterized in that, The light source module (1) includes components arranged sequentially along the propagation direction of the signal beam: A light source (1.1) is used to provide a signal beam; A collimating lens (1.2) is used to collimate the signal beam into a parallel beam and direct it toward the beam splitter (6).

3. The center detection system for defocused lenses according to claim 2, characterized in that, The light source (1.1) is a monochromatic laser light source.

4. The center detection system for defocused lenses according to claim 1, characterized in that, The first imaging module (4) includes the following components arranged sequentially along the propagation direction of the signal beam: Hartmann stop (4.1), consisting of a two-dimensional array of microlenses, is used to perform wavefront spatial sampling of the signal beam transmitted from the lens under test (3); Camera 1 (4.2) is used to acquire the wavefront spatial sampling results of the Hartmann aperture (4.1) to obtain a spot array map.

5. The center detection system for defocused lenses according to any one of claims 1-4, characterized in that, The second imaging module (5) includes components arranged sequentially along the propagation direction of the reflected beam from the lens under test (3): An imaging lens (5.1) is used to focus and image the reflected beam of the lens under test (3); Camera 2 (5.2) is used to receive and record the light spot image formed by the focusing imaging of the imaging lens (5.1) to obtain the reflection information map.

6. The center detection system for defocused lenses according to claim 5, characterized in that, The tilt angle of the beam splitter (6) is 45°.

7. The center detection system for defocused lenses according to claim 6, characterized in that, The central detection system also includes a data processing unit, which is used to obtain the position offset of the light spot caused by the tested lens (3) based on the light spot array diagram obtained by the first camera (4.2); and to extract the center of the lens design reference mark position and the geometric center of the microstructure part of the defocus area based on the reflection information diagram obtained by the second camera (5.2).

8. A method for detecting the center of a defocused lens, characterized in that, The center detection system for defocused lenses according to any one of claims 1-7 includes the following steps: S1: Place the central detection system in a bright environment, and make the light source module (1) emit a signal beam to obtain a light spot array diagram through the first imaging module (4); S2: Place the lens to be tested (3) on the lens holder (2) and obtain the second spot array diagram through the first imaging module (4); S3: By comparing the spot array diagram 2 with the spot array diagram 1, the position offset of the spot caused by the lens under test (3) is obtained, and the refractive power of the lens under test (3) is calculated using the position offset of the spot. S4: The reflected beam of the lens under test (3) is imaged by the second imaging module (5) to obtain a reflection information map; S5: Extract the center of the lens design reference mark and the geometric center of the microstructure of the defocus area based on the reflection information map, and calculate the equivalent prism power of the tested lens (3) using the deviation distance between the two and the refractive power obtained in step S3.

9. The method for detecting the center of a defocused lens according to claim 8, characterized in that, The formula for calculating the refractive power obtained in step S3 is as follows; In the formula, This represents the refractive power of the tested lens (3). This represents the offset of the light spot position. This represents the distance from the center of the specified spot shown in the image of the light spot array to the reference optical axis. The distance from the center of the specified spot shown in Figure 2 to the reference optical axis represents the distance of the spot array. This represents the distance from the Hartmann aperture (4.1) to camera one (4.2). This represents the distance from the tested lens (3) to the Hartmann stop (4.1).

10. The method for detecting the center of a defocused lens according to claim 8 or 9, characterized in that, The formula for calculating the equivalent prism power in step S5 is: In the formula, Represents the equivalent prism power of the tested lens (3), It represents the deviation distance between the center of the lens design benchmark mark and the geometric center of the microstructure in the defocus area.

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