A detection method of a lens detection device

Abstract

The application provides a lens detection device and a detection method, which are used for detecting the imaging color restoration degree of a lens. The lens detection device comprises a detection light source, a light splitting device, a first detection light path and a second detection light path. The light splitting device splits the light beam of the detection light source into a first detection light beam and a second detection light beam. The first detection light path comprises a first light measuring device for detecting the first detection light beam, and the second detection light path comprises a second light measuring device for detecting the second detection light beam. When the imaging color restoration degree of the to-be-detected lens is detected, the second detection light beam passes through the to-be-detected lens and enters the second light measuring device. The lens detection device provided by the application can be used for directly detecting the imaging color restoration degree of the lens. The detection method of the application comprises steps such as dark calibration measurement, light calibration measurement, light splitting transmission ratio measurement, light beam transmittance calculation and color restoration degree calculation, and can conveniently and quickly detect the imaging color restoration degree of the lens.

Description

Technical Field

[0001] This application belongs to the field of lens inspection technology, and more specifically, relates to a detection method for a lens inspection device. Background Technology

[0002] With the widespread use of optical lenses, users have increasingly higher requirements for lens imaging. For a high-performance optical lens, image quality is no longer the only requirement; the lens's appearance, color reproduction of the subject, and other aspects are also becoming increasingly important.

[0003] To improve the performance of optical lenses, their complexity has increased significantly. Some lenses with wide zoom ranges require multiple lens elements. Furthermore, to minimize the overall size and weight of the lens during design, high-refractive-index light-transmitting materials are often used. While these materials have high refractive indices, they absorb light unevenly across different wavelengths, easily leading to color distortion in the image. The cumulative effect of color distortion from each lens element severely tests the overall color reproduction capability of the optical lens. Currently, there is a lack of commercially available testing devices and methods that can directly measure the color reproduction accuracy of optical lenses. Summary of the Invention

[0004] The purpose of this application is to provide a detection method for a lens detection device, so as to solve the technical problem of difficulty in detecting the color reproduction of optical lenses in the prior art.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] A lens inspection device is provided for detecting the color reproduction accuracy of a lens, comprising:

[0007] Detection light source;

[0008] The beam splitter divides the light beam of the detection light source into a first detection beam and a second detection beam.

[0009] The first detection optical path includes a first photometric device for detecting the first detection beam;

[0010] The second detection optical path includes a second photometric device for detecting the second detection beam;

[0011] When the lens under test is subjected to imaging color reproduction detection, the second detection beam passes through the lens under test and enters the second metering device.

[0012] As a further improvement to the above technical solution:

[0013] Optionally, the second detection optical path includes an illumination adjustment structure for adjusting the second detection beam, the illumination adjustment structure including a lens for the transmission of the second detection beam;

[0014] When the lens under test is a lens with an infinitely far object distance, the lens is a collimating lens; when the lens under test is a lens with a finite object distance, the lens is a focusing lens.

[0015] Optionally, the illumination adjustment structure further includes an aperture stop, which and the lens are arranged sequentially along the illumination direction of the second detection beam.

[0016] Optionally, the lens detection device further includes a focusing structure for focusing the light beam of the detection light source onto the light-transmitting aperture of the aperture.

[0017] Optionally, the second detection optical path further includes a diffuse reflection device, which includes a diffuse reflection cavity having a beam inlet and a beam outlet;

[0018] The light beam passing through the lens under test enters the diffuse reflection cavity through the beam inlet; the light beam in the diffuse reflection cavity enters the second photometric device through the beam outlet.

[0019] Optionally, the sum of the areas of the beam inlet and the beam outlet is less than 10% of the inner wall area of ​​the diffuse reflection cavity.

[0020] Optionally, the axial direction of the beam inlet is arranged at an angle to the axial direction of the beam outlet.

[0021] Optionally, the diffuse reflection device is an integrating sphere.

[0022] Optionally, the beam splitter is a semi-reflective mirror.

[0023] This application also provides a detection method based on the above-described lens detection device, comprising the following steps:

[0024] Dark calibration measurement: With the lens under test not loaded and the detection light source off, read the brightness readings from the first and second metering devices respectively, and record them as V. a1 and V b1 ;

[0025] Optical calibration measurement: With the lens under test not loaded and the detection light source in the on state, the detection light source emits a light beam with a preset wavelength. The brightness readings of the first and second photometric devices under the light beam in the preset wavelength are read respectively and recorded as V. a2 and V b2 ;

[0026] Spectrophotometer transmittance measurement: With the lens under test mounted and the detection light source turned on, the detection light source emits a light beam with the preset wavelength. The brightness readings of the first and second photometers under the light beam in the preset wavelength are recorded as V. a3 and V b3 ;

[0027] Beam transmittance calculation: The beam transmittance of the lens under test in the preset wavelength band is denoted as Tλ. The formula for calculating the transmittance of the lens under test is as follows:

[0028] V 测 = (V b3 - V b1 ) / (V a3 - V a1 );

[0029] V 校 = (V b2 - V b1 ) / (V a2 - V a1 );

[0030] T λ = V 测 / V 校 ;

[0031] Color reproduction calculation: Obtain the chromaticity data and spectral reflectance of the standard 24-color color chart, and then use the spectrum of the standard light source D55 to perform a weighted multiplication of the spectral reflectance of the 24-color color chart and the spectral transmittance of the lens to obtain the color reproduction index of the lens itself.

[0032] The beneficial effects of the detection method of the lens detection device provided in this application are as follows:

[0033] This application provides a lens testing device for detecting the color reproduction accuracy of a lens, comprising a detection light source, a beam splitter, a first detection optical path, and a second detection optical path. The beam splitter divides the light beam from the detection light source into a first detection beam and a second detection beam. The first detection optical path includes a first metering device for detecting the first detection beam, and the second detection optical path includes a second metering device for detecting the second detection beam. When the lens under test is subjected to color reproduction accuracy detection, the second detection beam passes through the lens under test and enters the second metering device.

[0034] The detection light source provides a beam of light in a preset wavelength band, specifically a white LED, halogen lamp, xenon lamp, or infrared LED. The lens testing device of this application can select an appropriate detection light source based on the imaging wavelength band of the lens under test. The beam splitter divides the beam of light in the preset wavelength band into a first detection beam and a second detection beam with equal intensity. The intensity of the first detection beam is directly measured by the first photometer. After the second detection beam passes through the lens under test, the lens absorbs light unevenly across different wavelength bands, resulting in a weakening of the transmitted beam intensity, which is measured by the second photometer. Specifically, the first and second photometers can be spectrometers. The spectral transmittance of the lens under test in the preset wavelength band can be calculated based on the measurements from the first and second photometers. By weighted multiplying the spectral reflectance of the 24-color card under the spectrum of the standard light source D55 and the spectral transmittance of the lens under test, the imaging color reproduction value of the lens under test can be obtained.

[0035] The lens inspection device provided in this application can be used for direct detection of the color reproduction of a lens, and is suitable for measuring and evaluating the color reproduction of each optical lens on a lens assembly line.

[0036] The detection method of this application includes steps such as dark calibration measurement, light calibration measurement, spectral transmittance measurement, beam transmittance calculation, and color reproduction calculation, which can conveniently and quickly detect the imaging color reproduction of the lens. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of the lens inspection device provided in this application;

[0039] Figure 2 A schematic diagram of the structural partitions of the lens testing device provided in this application;

[0040] Figure 3 for Figure 2 Schematic diagram of the local magnified structure Figure 1 ;

[0041] Figure 4 for Figure 2 Schematic diagram of the local magnified structure Figure 2 ;

[0042] Figure 5 for Figure 2 Schematic diagram of the local magnified structure Figure 3 .

[0043] The following are the labeling elements in the figure:

[0044] 1. Detection light source; 2. Spectrophotometer;

[0045] 3. First photometric device; 4. Second photometric device;

[0046] 5. Lens under test; 6. Illumination adjustment structure;

[0047] 61. Lens; 62. Aperture;

[0048] 7. Focusing structure; 8. Diffuse reflection device;

[0049] 81. Beam entrance; 82. Beam exit;

[0050] 83. Diffuse reflection cavity. Detailed Implementation

[0051] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0052] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0053] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0055] like Figure 1 and Figure 2 As shown, this application provides a lens inspection device for detecting the color reproduction accuracy of a lens, including a detection light source 1, a beam splitter 2, a first detection optical path, and a second detection optical path. The beam splitter 2 splits the light beam from the detection light source 1 into a first detection beam and a second detection beam. The first detection optical path includes a first metering device 3 for detecting the first detection beam, and the second detection optical path includes a second metering device 4 for detecting the second detection beam. When the lens under test 5 is subjected to color reproduction accuracy detection, the second detection beam passes through the lens under test 5 and enters the second metering device 4.

[0056] The detection light source 1 provides a beam of light in a preset wavelength band, specifically a white LED, halogen lamp, xenon lamp, or infrared LED. The lens testing device of this application can select an appropriate detection light source 1 according to the imaging wavelength band of the lens 5 under test. The beam splitter 2 divides the beam of light in the preset wavelength band into a first detection beam and a second detection beam with equal light intensity. The light intensity of the first detection beam is directly measured by the first photometer 3. After the second detection beam passes through the lens 5 under test, the lens 5 absorbs light unevenly in different wavelength bands, resulting in a weakening of the transmitted beam intensity, which is measured by the second photometer 4. Specifically, the first photometer 3 and the second photometer 4 can be spectrometers. The spectral transmittance of the lens 5 under the preset wavelength band can be calculated based on the measurements from the first photometer 3 and the second photometer 4. The color reproduction value of the lens 5 under test is obtained by weighted multiplication of the spectral reflectance of the 24-color card under the spectrum of the standard light source D55 and the spectral transmittance of the lens 5 under test.

[0057] The lens inspection device provided in this application can be used for direct detection of the color reproduction of a lens, and is suitable for measuring and evaluating the color reproduction of each optical lens on a lens assembly line.

[0058] like Figure 2 and Figure 4 As shown, in one embodiment of this application, the second detection optical path includes an illumination adjustment structure 6 for adjusting the second detection beam, and the illumination adjustment structure 6 includes a lens 61 for the transmission of the second detection beam;

[0059] When the lens under test 5 is a lens with an infinite object distance, lens 61 is a collimating lens; when the lens under test 5 is a lens with a finite object distance, lens 61 is a focusing lens (not shown in the figure).

[0060] Among them, lens 61 is used to adjust the divergence angle of the second detection beam. For example, the collimating lens can convert the second detection beam into a parallel beam so as to facilitate lens detection at infinite object distance; the focusing lens (not shown) can convert the second detection beam into a focused beam so as to facilitate lens detection at finite object distance.

[0061] It should be noted that infinity object distance means that when the object distance exceeds a certain threshold, the object can be considered to be captured by the lens as a parallel beam of light from an infinitely distant point. Generally, any object distance exceeding 25 meters can be treated as infinity. At infinity object distance, the distance from the front boundary of the depth of field to the lens is the hyperfocal distance.

[0062] like Figure 2 and Figure 4 As shown, in one embodiment of this application, the illumination adjustment structure 6 further includes an aperture 62, and the aperture 62 and the lens 61 are arranged sequentially along the illumination direction of the second detection beam.

[0063] Among them, the aperture 62 refers to the element in the optical system that plays a role in limiting the beam. The aperture 62 can limit the size of the beam so that the second detection beam is fully irradiated on the lens 61.

[0064] like Figure 2 and Figure 3 As shown, in one embodiment of this application, the lens detection device further includes a focusing structure 7, which is used to focus the light beam of the detection light source 1 onto the light-transmitting aperture of the aperture 62.

[0065] Specifically, the focusing structure 7 can be a focusing structure composed of two or more lenses. By adjusting the position of the lens on the optical axis between the detection light source 1 and the aperture 62, it is not only ensured that the light beam emitted from the detection light source 1 can be focused into the light-transmitting aperture of the aperture 62, but also the divergence angle of the emitted light beam from the light-transmitting aperture can be changed. By changing the divergence angle of the emitted light beam from the light-transmitting aperture, the height of the light beam after collimation by the collimating lens can be changed, allowing the lens detection device to match optical lenses with different entrance pupil diameters, and the measured data will be more objective and accurate.

[0066] In other embodiments, the focusing structure 7 may specifically be a concave mirror, with the light-transmitting hole of the aperture 62 located at the focal point of the concave mirror.

[0067] like Figure 2 and Figure 5 As shown, in one embodiment of this application, the second detection optical path further includes a diffuse reflection device 8, which includes a diffuse reflection cavity 83 having a beam inlet 81 and a beam outlet 82.

[0068] The light beam passing through the lens 5 under test enters the diffuse reflection cavity 83 through the beam inlet 81; the light beam in the diffuse reflection cavity 83 enters the second photometric device 4 through the beam outlet 82.

[0069] The diffuse reflection device 8 can reflect and diffuse the light beam passing through the lens 5 under test multiple times, thereby forming a uniform emitted light beam at the beam exit 82 for measurement by the second photometric device 4.

[0070] In one embodiment of this application, the sum of the areas of the beam inlet 81 and the beam outlet 82 is less than 10% of the inner wall area of ​​the diffuse reflection cavity 83.

[0071] Specifically, the opening size of the beam inlet 81 must ensure that the entire second detection beam can be incident into the diffuse reflection cavity 83. Furthermore, to obtain high measurement accuracy, the ratio of the sum of the areas of the beam inlet 81 and the beam outlet 82 to the inner wall area of ​​the diffuse reflection cavity 83 should be as small as possible. Experimental analysis shows that the sum of the areas of the beam inlet 81 and the beam outlet 82 should occupy at most 10% of the inner wall area of ​​the diffuse reflection cavity 83 to obtain accurate measurement values.

[0072] In one embodiment of this application, the axial direction of the beam inlet 81 is arranged at an angle to the axial direction of the beam outlet 82.

[0073] Specifically, the axial direction of the beam inlet 81 is offset from the axial direction of the beam outlet 82 to prevent the incident beam from exiting directly from the beam outlet 82. This ensures that the incident beam undergoes sufficient multiple reflections and diffusion within the diffuse reflection cavity 83, thereby forming a uniform emitted beam at the beam outlet 82. Preferably, the angle between the axial direction of the beam inlet 81 and the axial direction of the beam outlet 82 is 90°±5°.

[0074] In one embodiment of this application, the diffuse reflection device 8 is an integrating sphere.

[0075] The integrating sphere is a hollow sphere with its inner wall coated with a white diffuse reflective material. After the light beam enters through beam inlet 81, it is uniformly reflected and diffused within the sphere, forming a uniform intensity distribution on the sphere's surface. Therefore, the light obtained from the output aperture is a highly uniform scattered beam. Furthermore, the incident angle, spatial distribution, and polarity of the incident light do not affect the intensity and uniformity of the output light. The inner wall of the sphere is coated with an ideal diffuse reflective material, that is, a material with a diffuse reflectance coefficient close to 1. Commonly used materials include polytetrafluoroethylene, magnesium oxide, or barium sulfate. These diffuse reflective material coatings have a spectral reflectance ratio of over 99% in the visible spectrum. After multiple reflections and diffusions by the coating on the inner wall of the sphere, the incident light beam entering the integrating sphere provides a uniform beam for measurement to the second photometric device 4.

[0076] In one embodiment of this application, the beam splitter 2 is a semi-reflective semi-transparent lens.

[0077] A semi-reflective mirror is an optical element that alters the transmission and reflection ratio of an incident light beam by coating a semi-reflective film on optical glass. When a light beam passes through the semi-reflective mirror, the intensity of the transmitted light and the intensity of the reflected light each account for 50%. The light beam reflected by the semi-reflective mirror is the first detection beam, and the light beam transmitted by the semi-reflective mirror is the second detection beam; or, the light beam reflected by the semi-reflective mirror is the second detection beam, and the light beam transmitted by the semi-reflective mirror is the first detection beam.

[0078] In other embodiments, the beam splitter 2 may also be an optical circuit or the like.

[0079] This application also provides a method for detecting the color reproduction accuracy of an image from a lens, comprising the following steps:

[0080] Dark calibration measurement: With the lens under test 5 not loaded and the detection light source 1 in the off state, read the brightness readings on the first metering device 3 and the second metering device 4 respectively, and record them as V. a1 and V b1 ;

[0081] Optical calibration measurement: With the lens under test 5 not loaded and the detection light source 1 in the on state, the detection light source 1 emits a light beam with a preset wavelength. The brightness readings of the first photometer 3 and the second photometer 4 under the light beam in the preset wavelength are read respectively and recorded as V. a2 and V b2 ;

[0082] Spectrophotometer transmittance measurement: With the lens 5 under test mounted and the detection light source 1 in the on state, the detection light source 1 emits a light beam with a preset wavelength. The brightness readings of the first photometer 3 and the second photometer 4 under the light beam in the preset wavelength are read respectively and recorded as V. a3 and V b3 ;

[0083] Beam transmittance calculation: The beam transmittance of the lens 5 under test in the preset wavelength band is denoted as T. λ The formula for calculating the transmittance of lens 5 under test is:

[0084] V 测 = (V b3 - V b1 ) / (V a3 - V a1 );

[0085] V 校 = (V b2 - V b1 ) / (V a2 - V a1 );

[0086] T λ = V 测 / V 校 ;

[0087] The following is a practical example to illustrate this:

[0088] With the lens off and the light source off, the dark calibration values ​​for metering devices 3 and 4 are both 2000, i.e., V. a1 and V b1 The values ​​are all 2000. Without the lens installed, the light source 1 is turned on, and the brightness readings of the first metering device 3 and the second metering device 4 under the preset wavelength beam are read respectively. They are 4000 and 12000, i.e., V. a2 and V b2 The value of V, so we can determine it based on V. 校 = (V b2 - V b1 ) / (V a2 - V a1 This formula can be used to calculate V. 校 The value is 5; this value is also the data value under the condition of 100% light transmittance.

[0089] After mounting the lens 5 to be tested, the brightness readings of the first metering device 3 and the second metering device 4 under the preset wavelength beam are read again. If, due to the difference in the stability of the light source, V... a3 The value changed to 4500, and V b3 The value is 10000, so according to the formula V 测 = (V b3 - V b1 ) / (V a3 - V a1 ), to obtain V 测 The value is approximately 3.2. According to formula T... λ = V 测 / V 校 The calculation yields T under this band condition. λ It is 64%.

[0090] The first photometric device 3 and the second photometric device 4 scan 400nm-700nm according to the wavelength interval Δλ, so as to obtain the spectral transmittance of the lens 5 under test in this spectral band.

[0091] Color reproduction calculation: Obtain the chromaticity data and spectral reflectance of the standard 24-color color chart, and then use the spectrum of the standard light source D55 to perform a weighted multiplication of the spectral reflectance of the 24-color color chart and the spectral transmittance of the lens to obtain the color reproduction index of the lens itself.

[0092] The specific measurement and calculation process is as follows:

[0093] Prepare the 24-color chart data to be measured. Generally, the supplier will provide standard data for the 24-color chart, such as LAB values ​​and spectral reflectance. The spectral reflectance curve is denoted as R0λ. If spectral reflectance data is not provided, the measurement can be completed using a spectrophotometer.

[0094] By multiplying the spectral reflectance curve of the 24-color chart by the spectral transmittance of the lens itself using a weighted average, we obtain the spectral transmittance curve of the 24-color chart after passing through the lens, which we denote as R1. λ R1 λ = R0 λ T λ ;

[0095] According to R1 λ From the data, we can calculate the LAB value of the 24-color chart after passing through the lens. The specific calculation method is as follows:

[0096] First, calculate the tristimulus values. The specific calculation formula is as follows:

[0097]

[0098] Where K is a constant, and ψ(λ) is the weighted product of the light source spectrum and the lens transmission spectrum. These are the spectral tristimulus values ​​for standard colorimetric observation as specified by the CIE. Δλ is the spectral interval, which can be selected as 10 nm or 20 nm.

[0099] Based on the XYZ values ​​in the above formula, calculate L in the uniform color space. a b The value of is calculated using the following formula:

[0100]

[0101]

[0102] If Z / Z n ≤ ,but f(Z / Z) n ) = (841 / 108)(Z / Z n )+16 / 116.

[0103] Where XYZ are the tristimulus values ​​of the sample, X n Y n Z n These are the tristimulus values ​​for the specified white point, defined by the CIE international standard.

[0104] After calculating each color patch, we obtain color reproduction data according to the calculation process below.

[0105]

[0106] Where K L K C C H S is a coefficient, usually defaulted to 1. L S C S H The calculation process for ΔL', ΔC', and ΔH' is as follows:

[0107]

[0108]

[0109]

[0110]

[0111] Where, ΔE 00 ΔC 00 The three parameters, Mean saturation ...

[0112] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A detection method for a lens detection device, the lens detection device comprising a detection light source (1), a beam splitter (2), a first detection optical path and a second detection optical path, wherein the beam splitter (2) splits the light beam of the detection light source (1) into a first detection beam and a second detection beam; the first detection optical path includes a first photometer (3) for detecting the first detection beam; the second detection optical path includes a second photometer (4) for detecting the second detection beam; when the lens under test (5) is subjected to imaging color reproduction detection, the second detection beam passes through the lens under test (5) and enters the second photometer (4). Its features are, Includes the following steps: Dark calibration measurement: When the lens under test (5) is not loaded and the detection light source (1) is in the off state, the brightness readings on the first metering device (3) and the second metering device (4) are read respectively and recorded as V. a1 and V b1 ; Optical calibration measurement: When the lens under test (5) is not loaded and the detection light source (1) is in the on state, the detection light source (1) emits a light beam with a preset wavelength. The brightness readings of the first photometer (3) and the second photometer (4) under the light beam in the preset wavelength are read respectively and recorded as V. a2 and V b2 ; Spectrophotometer transmittance measurement: When the lens to be tested (5) is mounted and the detection light source (1) is in the on state, the detection light source (1) emits a light beam with the preset wavelength band. The brightness readings of the first photometer (3) and the second photometer (4) under the light beam in the preset wavelength band are read respectively and recorded as V. a3 and V b3 ; Beam transmittance calculation: The beam transmittance of the lens under test (5) in the preset band is denoted as T. λ The formula for calculating the transmittance of the lens (5) under test is: V 测 = (V b3 - V b1 ) / (V a3 - V a1 ); V 校 = (V b2 - V b1 ) / (V a2 - V a1 ); T λ = V 测 / V 校 ; Color reproduction calculation: Obtain the chromaticity data and spectral reflectance of the standard 24-color color chart, and then use the spectrum of the standard light source D55 to perform a weighted multiplication of the spectral reflectance of the 24-color color chart and the spectral transmittance of the lens to obtain the color reproduction index of the lens itself.

Images