An apparatus and method for detecting defects in an optical lens of eyeglasses

Abstract

The application discloses a kind of physical defect detection devices and methods of spectacle optical lens. Including collimating light source, two-dimensional light point scanning system, power compensation optical system and integrating sphere arranged in sequence on light path, photovoltaic sensor on the reflecting surface of integrating sphere, data processing board connected with photovoltaic sensor, overflow port for light beam passing is opened on integrating sphere.The application solves the comprehensive detection technical problem of detecting the defects such as bubble, scratch and pitting of the lens with optical power, and establishes the industry standard accordingly.The application is simple in structure, low in cost and high in sensitivity, and the 100% detection rate makes the operator only need to recheck the lenses that are misdetected as defects due to removable dirt on the surface.Usually, these lenses that need to be rechecked are about 3%.Thus, the application greatly reduces the intensity of workers and improves the efficiency, and also avoids unnecessary waste.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of physical defects detection device and method of spectacle optical lens, in particular to a kind of physical defects detection device and method of spectacle optical lens. BACKGROUND

[0002] Now more and more people wear glasses, there are myopia population with eye fatigue, there are middle-aged and old people with eye function degradation, these groups need to wear glasses to correct refractive power, which makes the demand for glasses for correcting optical vision or for protecting vision increases. In a lifetime, it is impossible to leave glasses, or myopia, or aging. It is because everyone cannot leave glasses, so the base of glasses is very large.

[0003] The physical defects of spectacle optical lens can be divided into three types of defects: surface scratches, pitting and internal bubbles. Among them, surface scratches and pitting are collectively referred to as surface defects. Lens manufacturers generally need to detect defects in the φ55mm area of the lens, and according to the size of the defects and the area where the defects are located, three levels of A, B and C are divided, and A is the best. However, since these defects are in micrometer scale, it is very eye-damaging to observe them under strong light with the naked eye.

[0004] Using instruments to check the physical defects of the lens has always been the dream of industry practitioners. There have been related attempts on the market. Common inspection methods include: one is the photographing method, which is also the most commonly used method at present. Its principle is to use a high-definition camera to directly photograph the surface defects of the object under the irradiation of directional light or structured light, and then combine image analysis technology to sort out the surface defects. The biggest defect of this technology is that multiple angles are needed for photography, and it is unpredictable to determine which angle can capture the defects due to the random changes in the shape and optical power of the lens. Therefore, although many people have studied it, no product has been put into commercial application. Two is the interference measurement method, which uses the obvious changes of interference fringes pattern at the defects to check the surface defects. The characteristics of this method are high precision and no directionality in detection. However, this method is only suitable for lenses with small optical path difference, such as plain lenses, otherwise the fringes will be too dense due to the large optical path difference, and it is impossible to distinguish the fringes for interference measurement. Because of the refractive power, the optical path difference of spectacle optical lens is huge, so the interference measurement method cannot be directly applied to the physical defect detection of spectacle optical lens. SUMMARY

[0005] The purpose of the present application is to solve the above problems, and to design a kind of physical defects detection device and method of spectacle optical lens by using the scattering phenomenon of the physical defects of the lens under the irradiation of light.

[0006] The present application is realized by the following technical solutions:

[0007] The application discloses an optical lens defect detection device for glasses, comprising a collimated light source, a two-dimensional light point scanning system, a power compensation optical system and an integrating sphere arranged in sequence on a light path, a photoelectric sensor located on a reflecting surface of the integrating sphere, and a data processing board connected with the photoelectric sensor.

[0008] As a further improvement, the collimated light source of the application is a visible or near-infrared band LED or SLD or ASE spontaneous emission light source or laser or other high-brightness collimated light source.

[0009] As a further improvement, the two-dimensional light point scanning system of the application is a galvanometer or a rotating mirror or a mixed deflection scanning system of the two.

[0010] As a further improvement, the power compensation optical system of the application is an optical system composed of an empty or single lens or multiple lens groups.

[0011] As a further improvement, the power compensation optical system of the application can be used for power compensation of the optical lens of glasses with a power range of -48D to +30D. According to the power data of the measured lens, the structure of the power compensation optical system can be automatically adjusted, so that the laser beam can avoid hitting the reflecting surface of the integrating sphere after passing through the power compensation system and the lens with power, and can be emitted from the overflow window in the integrating sphere.

[0012] As a further improvement, the reflecting surface of the integrating sphere of the application is a curved surface. It is a device for collecting scattered light in different directions, and can also be other devices that can collect scattered light in different directions.

[0013] As a further improvement, the ratio of the overflow port of the integrating sphere to the diameter is between 0.01 and 0.8.

[0014] As a further improvement, the photoelectric sensor of the application is a phototube, a photocell, a CCD, a CMOS, a PSD or a photomultiplier. The data processing board is used to amplify the weak signal of the photoelectric sensor into a voltage or current signal for AD acquisition.

[0015] As a further improvement, the photoelectric sensor of the application is preferably a visible light band phototube, and the detection device analyzes the physical defects of the lens and the lens grading through the distribution diagram of the scattered light intensity.

[0016] The application also discloses an optical lens defect detection method for glasses, comprising the following steps:

[0017] 1) According to the optical power value of the measured lens, the structure of the optical power compensation system is adjusted so that the light beam emitted by the collimated light source can be emitted from the overflow port of the integrating sphere after passing through the optical power compensation system and the measured area of the lens;

[0018] 2) The light beam emitted by the collimated light source passes through the two-dimensional light point scanning system and the optical power compensation system and hits the measured area point (x, y) of the lens, as shown in Figure 6

[0019] 3) The scattered light in different directions generated by the lens at (x, y) under the irradiation of the light beam is reflected multiple times on the integrating sphere or directly incident on the photoelectric sensor on the wall of the integrating sphere;

[0020] 4) The intensity signal B of the scattered light at the lens (x, y) is obtained by processing the signal of the photoelectric sensor through the data processing board.

[0021] 5) Through the action of the two-dimensional scanning system, the scattered light intensity signal B distribution map of the entire measured area on the lens can be obtained. Through certain criteria, the grading of the lens can be quantified according to the intensity and distribution of the scattered light intensity signal B, thereby achieving the purpose of inspection.

[0022] The innovation points of the present application are as follows:

[0023] 1) The innovation point of the present application is to solve the technical problem of comprehensive detection of defects such as bubbles, scratches and spots on lenses with optical power, and to establish an industry standard accordingly.

[0024] 2) The present application detects three different forms of physical defects by detecting scattered light, establishing a simple and unified quantitative standard.

[0025] 3) The present application makes it possible to automatically detect physical defects of spectacle lenses, and can realize full-automatic monitoring of surface and internal defects of lenses, improving production efficiency.

[0026] 4) The present application is simple in structure, low in cost and high in sensitivity, and has a 100% detection rate, so that the operator only needs to recheck the lenses that are misdetected as defects due to surface removable dirt. Usually, these lenses that need to be rechecked are about 3%. Therefore, the present application greatly reduces the intensity of labor and improves the efficiency, and also avoids unnecessary waste. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural schematic diagram of the detection device of the present application;

[0028] Figure 2 is a detection light path diagram of two +12D to +1.5D lenses; ​

[0029] Figure 3 is the detection light path diagram of 3 pieces +1.25D to -10D lenses;

[0030] Figure 4 is the detection light path diagram of 2 pieces -10D to -12D lenses;

[0031] Figure 5 is the examination result diagram of 6 pieces of 58mm diameter, optical power SPH=-4D lenses;

[0032] Figure 6 is the coordinate diagram when the lens light spot is scanned.

[0033] 1 is a collimated light source; 2 is a two-dimensional light spot scanning system; 3 is an optical power compensation optical system; 4 is a lens; 5 is an integrating sphere; 6 is an overflow port, 7 is a photoelectric sensor, 8 is a data processing board. DETAILED DESCRIPTION

[0034] The present application is a kind of eyeglasses optical lens defect detection device, the device includes collimated light source 1, two-dimensional light spot scanning system 2, optical power compensation optical system 3, integrating sphere 5, photoelectric sensor 7 and data processing board 8.

[0035] In principle, as long as the photoelectric acceptor can respond to the wavelength of laser can be used in the present application. However, some lenses 4 because of UV400 or UV420 film layer, so visible and near infrared LED light source or SLD light source or ASE spontaneous emission light source or laser light source is the first choice, because the semiconductor laser has long service life, high brightness, good collimation, low cost, so the collimated light source is preferably red semiconductor laser.

[0036] Two-dimensional light spot scanning system is a system that can deflect and scan the light beam in two directions, which can be a galvanometer, a rotating mirror, or a hybrid deflection scanning system. The collimated light source can scan the measured area of the measured lens 4 point by point under the action of the two-dimensional light spot scanning system.

[0037] Optical power compensation optical system 3 is an optical system composed of empty or single lens or multiple lens groups. It is a system that can automatically adjust its optical system structure according to the optical power data of the measured lens 4. The optical power compensation optical system 3 can be used for optical power compensation of the optical power range of -48D to +30D of the eyeglasses optical lens 4. According to the optical power data of the measured lens 4, the structure of the optical power compensation optical system 3 can be automatically adjusted, so that the laser beam can avoid hitting the reflecting surface of the integrating sphere 5 after passing through the optical power compensation optical system 3 and the lens 4 with optical power, and can be emitted from the overflow port 6 in the integrating sphere 5.

[0038] The purpose of introducing the power compensation optical system 3 is to make the light beam emitted by the collimated light source exit from the overflow port 6 in the integrating sphere 5 after passing through the power compensation optical system 3 and the measured area of the lens 4, as shown in Figure 1 The power compensation optical system 3 can be a simple single lens, a complex optical system or no lens system. As optimization, the power compensation optical system 3 can be a set of fixed lenses, corresponding to three types of lenses 4 with power of +12D to +1.5D, +1.5D to -10D and -10D to -12D respectively by having no lens in the optical path, lenses in position 1 and position 2, as shown in Figure 2 , Figure 3 and Figure 4 . The three types of lenses 4 can cover 98% of the lenses on the market. If 100% of the lens range is to be covered, the system will be very complex and expensive, which is unnecessary.

[0039] The design of the power compensation optical system 3 is related to the size of the measured area of the lens 4, the size of the refractive range of the measured lens 4, the diameter of the integrating sphere 5 and the size of the overflow port 6 of the integrating sphere 5. If the measured area of the lens 4 is larger, the refractive range of the measured lens 4 is larger, the diameter of the integrating sphere 5 is smaller and the size of the overflow port 6 of the integrating sphere 5 is smaller, the structure of the power compensation optical system 3 is more complex, and vice versa, which can even be without the power compensation optical system 3.

[0040] The integrating sphere 5 is used to collect the scattered light in all directions caused by the defects of the lens 4 after the light beam passes through the lens 4. The ratio of the size of the overflow port 6 of the integrating sphere 5 D1 to the diameter of the integrating sphere 5 D2 is a value between 0 and 1. If D1:D2 is too small, the power compensation optical system 3 is more complex, and if it is close to 1, the collection ability of the scattered light of the integrating sphere 5 is greatly reduced. As a balance, D1:D2 is generally between 0.01 and 0.8, and in the case of D2=200mm, it is preferably 0.3.

[0041] The photoelectric sensor 7 is a device for converting light into an electrical signal, which is installed on the reflecting surface of the integrating sphere 5 for collecting scattered light, and can be a phototube, a photocell, a CCD, a CMOS, a PSD and other photoelectric devices. As optimization, the visible light band phototube of Hamamatsu Company is selected as the photoelectric sensor 7.

[0042] The data processing board 8 is used to amplify the weak signal of the photoelectric sensor 7 into a voltage or current signal for AD acquisition to obtain the scattered light intensity signal B.

[0043] The application also discloses a lens optical lens defect detection method, comprising the following steps:

[0044] 1) According to the optical power value of the measured lens 4, the structure of the optical power compensation optical system 3 is adjusted so that the light beam emitted by the collimated light source 1 can be emitted from the overflow port 6 of the integrating sphere 5 after passing through the optical power compensation optical system 3 and the measured area of the measured lens 4;

[0045] 2) The light beam emitted by the collimated light source 1 hits the measured area point (x, y) of the lens 4 after passing through the two-dimensional light point scanning system 2 and the optical power compensation optical system 3;

[0046] 3) The scattered light of different directions generated by the lens 4 at (x, y) under the irradiation of the light beam is reflected multiple times on the integrating sphere 5 or directly incident on the photoelectric sensor 7 on the wall of the integrating sphere 5;

[0047] 4) The signal of the scattered light intensity at (x, y) of the lens 4 is obtained by processing the signal of the photoelectric sensor 7 through the data processing board 8;

[0048] 5) Through the action of the two-dimensional light point scanning system 2, the scattered light intensity signal B distribution diagram of the entire measured area on the lens 4 can be obtained. Through certain criteria, the grading of the lens 4 can be quantified according to the strength and distribution of the scattered light intensity signal, so as to achieve the purpose of inspection.

[0049] Principle of the application:

[0050] Light scattering refers to the phenomenon that a part of light deviates from the original direction of propagation when passing through particles or inhomogeneous media. The light deviating from the original direction is called scattered light. According to the comparison of the size of incident light and the size of scattering particles, when the size of scattering particles is smaller than or close to the wavelength of incident light, the scattering is Rayleigh scattering, but when the size of particles is larger than about 10% of the wavelength of incident radiation, the Rayleigh scattering model will fail. For particles with a size larger than this, the Mie scattering model can be used to calculate the intensity of scattered radiation. The intensity of Mie scattering radiation is given by the sum of an infinite series of terms, rather than by a simple mathematical expression. The characteristics of Mie scattering radiation are that it is roughly independent of wavelength and is larger in the forward direction than in the backward direction. The larger the particle size, the more light is scattered forward. Since the defects to be detected are generally above 5λ, the principle of Mie scattering is used to inspect the lens 4.

[0051] Since the optical lens 4 has optical power, if there is no optical power compensation system or the optical power compensation system cannot be adjusted according to the optical power of the lens 4, the incident light beam can directly irradiate on the reflecting surface of the integrating sphere 5 after passing through some lenses 4, which can be regarded as scattered light and cause system measurement error. Therefore, it is necessary to ensure that the incident light beam directly exits from the overflow port 6 of the integrating sphere 5 after passing through the optical power compensation system and the lens 4 to be measured, so that only scattered light is incident on the reflecting surface of the integrating sphere 5. In order to achieve this purpose, the optical power compensation system must be introduced. The function of the optical power compensation optical system 3 is to adjust the structure change of the optical system itself according to the optical power value of the lens 4 to be measured, so as to ensure that the incident light beam will not directly irradiate on the reflecting surface of the integrating sphere 5 after passing through the optical power compensation optical system 3 and the lens 4, thereby ensuring the realization of the detection purpose.

[0052] The present application uses a 650nm semiconductor laser with good collimation and low price, and the beam diameter is 0.5mm. The light beam is irradiated on the lens 4 after passing through the two-dimensional light point scanning system 2 and the optical power compensation optical system 3, and then exits from the integrating sphere 5. The integrating sphere 5 is used to collect scattered light, and the collected scattered light is collected by the photoelectric device on the integrating sphere 5, uploaded to the data acquisition system through the data processing board 8, and then analyzed by the computer system to obtain the scattered light intensity signal B distribution diagram of the lens 4, as shown in Figure 5

[0053] The embodiments of the present application will be further described in detail in combination with the drawings of the specification:

[0054] Embodiment one:

[0055] The present embodiment is a kind of glasses optical lens defect detection device, as shown in Figure 1

[0056] The present embodiment is an optical lens 4 defect detector, which comprises a collimated light source 1, a two-dimensional light point scanning system 2, an optical power compensation optical system 3, an integrating sphere 5, a photoelectric sensor 7 and a data processing board 8.

[0057] As shown in Figure 1 , the collimated light source 1 selects a 650nm semiconductor laser light source. In order to prevent the influence of ambient light, modulation or narrow-band filter in front of the detector can be used. In the present application, a double anti-interference mechanism is adopted. In practice, a 20kHz TTL signal is used to modulate the 650nm semiconductor laser.

[0058] ​​According to the requirement of automatic detection, the whole lens 4 should be checked within 2 seconds. The 650nm semiconductor laser is collimated and the beam is limited to less than 0.5mm by the optical lens. According to the detection range of φ55mm, about 10000 points should be scanned within 2 seconds, about 5kHz. For such a fast scanning speed, the two-dimensional light spot scanning system 2 uses a two-dimensional galvanometer to achieve it, with a scanning frequency of 20kHz.

[0059] Considering that the lenses 4 with optical power in the range of -12D to +12D account for more than 98% of the whole spectacle lens market. Therefore, if there is a simple optical power compensation system that can achieve the purpose of detecting the above lenses, it is a very good solution. After detailed optical design, a very simple optical power compensation system is found. A lens group consisting of two identical single convex lenses is used, as shown in Figure 2 、 Figure 3 and Figure 4 The diameter of the lens group is 120mm. The lens has a radius of curvature R233 and is made of BK7, which is divided into three grades to cover the detection range of the lens 4, L1=20, L2=32.

[0060] Because the dust and dirt attached to the surface of the lens 4 will also be incorrectly checked as defects, in order to avoid detection errors, a high-pressure ion nozzle can also be arranged near the area of the lens 4 to be detected, which is used to blow off the dust and dirt attached to the surface of the lens 4, reducing the false detection rate.

[0061] The integrating sphere 5 uses a Lambertian body with a diameter of φ200mm, with a reflectivity of more than 98%, and the diameter of the light beam overflow port 6 is φ60mm.

[0062] The phototube uses S1227-66BR of Hamamatsu. The data processing board 8 also uses the data processing board of Hamamatsu, Japan, which is used to amplify the weak signal of the photoelectric sensor 7 and convert it into a voltage or current signal for AD acquisition.

[0063] Method of use:

[0064] The operator first measures the optical power of the lens 4 to be measured with a transmission power meter, and then places the lens 4 on the upper port of the integrating sphere 5, Figure 1 as shown.

[0065] If the measured optical power of the lens 4 is in the range of +12D to +1.5D, the optical power compensation system does not need to be inserted into the optical path to detect the lens 4 from +12D to +1.5D, as shown in Figure 2 .

[0066] If the optical power of the lens 4 is in the range of +1.25D to -10D, the lens group is placed at a distance L1=20mm from the measured lens 4; the lenses 4 of +1.25D to -10D can be detected, as shown in Figure 3 .

[0067] If the optical power of the lens 4 is in the range of -10D to -12D, the lens group is placed at a distance L2=32mm from the measured lens 4; the lenses 4 of -10D to -12D can be detected, as shown in Figure 4 .

[0068] After the optical power compensation optical system 3 is selected and adjusted, the light beam emitted by the collimated light source 1 is projected in the area of φ55mm of the lens 4 under the control of the two-dimensional light point scanning system 2, and the light beam is refracted at the (x, y) point of the optical power compensation optical system 3 and the lens 4, and then is emitted from the overflow port 6 of the integrating sphere 5. At the same time, the data processing board 8 of the phototube continuously records the current data I or voltage V value during the scanning of the light beam, and finally normalizes the scattering light intensity signal B between (0, 255) to form a series of (x, y, B) data files, and obtain the distribution diagram of the scattering light intensity signal B in the entire measured lens area, as shown in Figure 5 .

[0069] Figure 5 The measured results of the lens with an optical power of SPH=-4D and a diameter of 58mm. The distance L1=20mm between the optical power compensation system and the measured lens 4. From the results, the distribution of the lens defects and the strength and distribution of the scattering light intensity signal value B have a certain correlation. It is proved that the results of the present application are reliable. If a suitable criterion is set, the A-level, B-level or C-level of the lens 4 can be automatically classified, and the physical defect detection of the lens 4 is completed.

[0070] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the technical field, several improvements and refinements can be made without departing from the core technical features of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. An apparatus for detecting defects in an optical lens (4) of eyeglasses, characterized in that, The utility model relates to a kind of lens detection device, including collimating light source (1), two-dimensional light point scanning system (2), the optical power compensation optical system (3) and integrating sphere (5) sequentially arranged on light path, photodetector (7) on the reflecting surface of integrating sphere (5), data processing board (8) connected with photodetector (7), the overflow port (6) for light beam to pass through is opened on the integrating sphere (5), the optical power compensation optical system (3) is for the structure of optical power compensation optical system (3) is automatically adjusted according to the optical power data of measured lens (4), so that laser beam can avoid hitting the reflecting surface of integrating sphere (5) after passing through the optical power compensation optical system (3) and lens (4) with optical power, and can emit from overflow port (6) in integrating sphere (5), the ratio of overflow port (6) of the integrating sphere (5) and the diameter of integrating sphere (5) is between 0.01 and 0.8;The optical power compensation optical system (3) is empty or single lens or optical system consisting of multiple lens groups;The detection device is analyzed by the intensity of scattered light intensity and distribution to detect the physical defect of lens (4) and lens grading.

2. The eyeglasses optical lens (4) defect detection apparatus according to claim 1, characterized in that, The collimating light source (1) is visible or near-infrared band LED or SLD or ASE spontaneous emission light source or laser light source or other high-brightness light source.

3. The device for detecting defects of an optical lens (4) of eyeglasses according to claim 1, characterized in that, The two-dimensional light point scanning system (2) is a galvanometer or a rotating mirror or a hybrid deflection scanning system of the two.

4. The device for detecting defects of an optical lens (4) of eyeglasses according to claim 1, characterized in that, The reflecting surface of the integrating sphere (5) is a curved surface.

5. The device for detecting defects of an optical lens (4) of eyeglasses according to claim 1, characterized in that, The photodetector (7) is a phototube, a photocell, a CCD, a CMOS, a PSD or a photomultiplier tube.

6. The device for detecting defects of an optical lens (4) of eyeglasses according to claim 5, characterized in that, The photodetector (7) is a visible light phototube.

7. A defect detection method based on the defect detection apparatus of any one of claims 1 to 6, characterized in that, The method comprises the following steps: 1) Adjust the structure of the optical power compensation system according to the optical power value of the measured lens (4), so that the light beam can emit from the overflow port (6) of the integrating sphere (5) after passing through the optical power compensation system (3) and different regions of the measured lens (4); 2) The light beam hits the measured region point (x, y) of the lens (4) after passing through the two-dimensional light point scanning system (2) and the optical power compensation optical system (3); 3) The scattered light in different directions generated by the measured region point (x, y) of the lens (4) under the irradiation of the light beam is reflected multiple times on the integrating sphere (5) or directly incident on the photodetector (7) on the wall of the integrating sphere (5); 4) The intensity signal B of the scattered light at the measured region point (x, y) of the lens (4) is obtained by processing the signal of the photodetector through the data processing board (8); 5) The scattered light intensity signal B distribution diagram of the entire measured region on the lens is obtained through the action of the two-dimensional light point scanning system (2); the lens is quantified according to the intensity and distribution of the scattered light intensity signal through certain criteria, so as to achieve the purpose of inspection.

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