CN215865737U - Lens refractive index measuring device - Google Patents

Abstract

The utility model relates to a device for measuring the refractive index of a lens, which comprises a diopter measuring module, an optical thickness measuring module, a confocal reflection measuring module and a measured lens, wherein the diopter measuring module comprises a first light source module, a first collimating lens, a Hartmann diaphragm and a photoelectric detector Cam, the optical thickness measuring module comprises a second light source module, a second collimating lens, a third light source module, a third collimating lens, a focusing lens, a first light splitter, a second light splitter, a third light splitter, a fourth light splitter, a reflector, a photoelectric detector D1 and a photoelectric detector D2, the optical thickness measuring module comprises a light source, a photoelectric detector D3, a Y-shaped optical fiber, a lens group and a mesoporous prism, the Y-shaped optical fiber comprises a first port, a second port and a third port, the device reduces the number of optical elements and simplifies the optical structure, convenient operation, low cost and reduced occupied space of the device.

Description

Lens refractive index measuring device

Technical Field

The utility model relates to the technical field of optical measurement, in particular to a device for measuring the refractive index of a lens.

Background

The refractive index parameter is an important parameter index of the optical lens, in order to ensure that an optical system has good imaging quality, the refractive index of an optical material needs to be accurately measured, and the high-precision measurement of the refractive index of the optical glass material is carried out by a minimum deviation angle method at present. The minimum deviation angle method has high precision and large wavelength range and is used for direct measurement, but the minimum deviation angle test method has the premise that a prism needs to be manufactured for light refraction, and the angle of the prism needs to be accurately tested, so that the prism is difficult to manufacture and has a long period; in addition, this method does not allow testing of planar optical elements, which is well suited for use in refractive index sample testing of glass manufacturers for the same batch of glass, and is not well suited for on-line high precision testing of actual lens materials. Especially, in some special application occasions, such as the refractive index detection of the spectacle lens, under the condition that the material of the optical element is unknown, the refractive index detection of the spectacle lens is required to be realized without damaging the element, and then the material property of the spectacle lens is determined.

At present, two detection methods for measuring the refractive index of a finished lens are mainly used, one method is reverse calculation according to a focal power formula, namely, the curvature of the upper surface and the lower surface, the central thickness and the focal power of the lens are measured by using a mechanical precision measurement method, and the refractive index of a test wavelength is calculated according to the focal power formula; another method is to change the "environment" refractive index, i.e. by changing the refractive index of the medium contacting the upper and lower surfaces of the lens, such as placing the lens in a solution with a known refractive index, or attaching flexible media with known refractive indexes to the upper and lower surfaces of the lens, the refractive powers of the lens in the air and in the solution are respectively tested, and the refractive index of the lens material can be calculated according to the change of the refractive power and the refractive index of the solution.

To overcome the drawbacks of the two methods for measuring refractive index, the utility model with patent No. CN 112556991a provides an improved device and method for measuring refractive index of lens, which can measure the refractive index of the lens without damaging the lens, and the operation is simpler and the detection is faster than the prior art. However, the device for measuring the refractive index of the lens proposed in the patent also has the following drawbacks: 1. the design principle of the whole optical system is complex, so that the optical structure of the optical system is complex; 2. the used optical measuring elements are more, the material consumption is large, and the cost is high; 3. the used optical measuring elements are more, so that the volume of the whole measuring device is larger, and the occupied space is large.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a lens refractive index measuring device which has the advantages of simplified structure, reduced number of optical measuring elements, less material consumption, low cost and reduced volume and can quickly detect the refractive index of a lens.

The technical scheme adopted by the utility model is that the device for measuring the refractive index of the lens comprises a diopter measuring module, an optical thickness measuring module, a confocal reflection measuring module and a measured lens;

the diopter measurement module comprises a first light source module, a first collimating lens, a Hartmann diaphragm and a photoelectric detector Cam;

the optical thickness measuring module comprises a second light source module, a second collimating lens, a third light source module, a third collimating lens, a focusing lens, a first light splitter, a second light splitter, a third light splitter, a fourth light splitter, a reflector, a photoelectric detector D1 and a photoelectric detector D2;

the confocal reflection measurement module comprises a light emitting source, a photoelectric detector D3, a Y-shaped optical fiber, a lens group and a mesoporous prism, wherein the Y-shaped optical fiber comprises a first port, a second port and a third port;

the light emitted by the first light source module passes through the first collimating lens to become parallel light beams, and the parallel light beams pass through the measured lens and the Hartmann diaphragm and then enter the photoelectric detector Cam;

the third light source module emits a light beam, the light beam is transmitted by the first light splitter and reflected by the second light splitter in sequence, the light beam is divided into two light beams by the third light splitter, one light beam is reflected to the reflector and then reflected back by the original path of the reflector, and a part of light reflected back by the original path is transmitted by the third light splitter and then transmitted by the fourth light splitter to enter the photoelectric detector D2; the other beam of light is transmitted by the third light splitter, and is reflected by the upper surface of the Hartmann diaphragm in the original path, and the light reflected by the original path enters the photoelectric detector D2 after being reflected by the third light splitter and transmitted by the fourth light splitter; when the reflecting mirror moves, when the optical paths of one beam reflected by the moving reflecting mirror and the other beam reflected by the Hartmann diaphragm are equal, an interference phenomenon is detected in a photoelectric detector D2;

the light emitted by the second light source module is converted into parallel light beams after passing through the second collimating lens, the parallel light beams are reflected by the first light splitting sheet and the second light splitting sheet and then are divided into two beams of light by the third light splitting sheet, one beam of light is reflected to the reflecting mirror and then is reflected back by the original path of the reflecting mirror, and a part of light reflected back by the original path is transmitted by the third light splitting sheet and then is reflected by the fourth light splitting sheet to enter the photoelectric detector D1; the other beam of light is transmitted by the third light splitter, and is reflected by the upper surface of the Hartmann diaphragm in the original path, and the light reflected by the original path enters the photoelectric detector D1 after being reflected by the third light splitter and the fourth light splitter; when the reflector is moved, in the moving process, when the optical paths of one beam reflected by the movable reflector and the other beam reflected by the Hartmann diaphragm are equal, an interference phenomenon is detected in the photoelectric detector D1;

the first port of the Y-shaped optical fiber is a test light outlet, light emitted by the light emitting source is coupled into the Y-shaped optical fiber through the third port and is emitted from the first port, the first port is positioned on the back focal point of the lens group, and light beams are converged through the lens group, reflected by the mesoporous prism and finally focused at the measured lens; when the first port and the lens group are moved, in the moving process, the light beam focused on the measured lens can be focused on the upper surface or the lower surface of the measured lens, when the light beam is focused on the upper surface or the lower surface of the measured lens, the surface reflected light returns to the first port from the original path, and is transmitted through the Y-shaped optical fiber and then is emitted to the photodetector D3 from the second port.

The utility model has the beneficial effects that: the device for measuring the refractive index of the lens has the advantages that the device is simple in structure and convenient to operate, the cost of the device is reduced, and the occupied space area of the device is reduced.

Preferably, the Hartmann diaphragm consists of a plurality of light transmission holes arranged in an array manner and a light-tight area, a reflection film is plated on the light transmission hole in the middle position of the plurality of light transmission holes arranged in the array manner, the spectral range of the reflection film is 400-650nm, and the reflectivity of the reflection film is more than 80%.

Preferably, the diameter range of the light transmission hole plated with the reflecting film is as follows: 0.3-1.0 mm; the central distance range between the light holes is 0.5-0.6mm, and the number of the light holes is not less than 10 x 10.

Preferably, the first light source module comprises a first light source and a first light hole, the first light source is a monochromatic LED light source, the spectral width of the first light source is larger than 10nm and smaller than 50nm, the first light hole is arranged at a position close to the light emitting surface of the first light source, the diameter of the first light hole is smaller than 0.5mm, and the distance between the first light hole and the first light source is smaller than 0.5 mm.

Preferably, the focal length of the first collimating lens is greater than 50 mm.

Preferably, the second light source module is composed of a second light source and a second light hole, the second light source is a monochromatic LED light source, and the central wavelength range of the second light source is: 470nm-485nm, its spectral width is greater than 10nm and is less than 50nm, the second light trap sets up in the light emitting area department that is close to the second light source, and the diameter of second light trap is less than 0.3mm, the distance between second light trap and the second light source is less than 0.5 mm.

Preferably, the focal length of the second collimating lens is greater than 50 mm.

Drawings

FIG. 1 is a schematic diagram of an optical structure of a device for measuring refractive index of a lens according to the present invention;

FIG. 2 is a schematic structural diagram of a Hartmann diaphragm of the present invention;

as shown in the figure: 1. a first light source module; 2. a first collimating lens; 3. a Hartmann diaphragm; 4. a photodetector Cam; 5. A second light source module; 6. a second collimating lens; 7. a third light source module; 8. a third collimating lens; 9. a focusing lens; 10. A first light splitting sheet; 11. a second dichroic sheet; 12. a third light splitter; 13. a fourth light-splitting sheet; 14. a mirror; 15. a photodetector D1; 16. a photodetector D2; 17. a light emitting source; 18. a photodetector D3; 19. a Y-shaped optical fiber; 20. a lens group; 21. a mesoporous prism; 22. a first port; 23. a second port; 24. a third port; 25. a measured lens; 26. a first optical axis; 27. a second optical axis; 28. a third optical axis; 29. a light-transmitting hole; 30. a light-tight region; 31. a light-reflecting film.

Detailed Description

The utility model is further described with reference to the accompanying drawings in connection with specific embodiments for enabling a person skilled in the art to practice the utility model with reference to the description, without the scope of protection of the utility model being limited to the specific embodiments.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above terms should not be construed as limiting the present invention.

The utility model relates to a device for measuring the refractive index of a lens, which comprises a diopter measuring module, an optical thickness measuring module, a confocal reflection measuring module and a measured lens 25;

as shown in fig. 1, the diopter measurement module includes a first light source module 1, a first collimating lens 2, a hartmann diaphragm 3, and a photodetector Cam 4;

as shown in fig. 1, the optical thickness measuring module includes a second light source module 5, a second collimating lens 6, a third light source module 7, a third collimating lens 8, a focusing lens 9, a first light splitter 10, a second light splitter 11, a third light splitter 12, a fourth light splitter 13, a mirror 14, a photodetector D115, and a photodetector D216;

as shown in fig. 1, the confocal reflection measurement module includes a light emitting source 17, a photodetector D318, a Y-shaped optical fiber 19, a lens group 20, and a mesoporous prism 21, where the Y-shaped optical fiber 19 includes a first port 22, a second port 23, and a third port 24;

as shown in fig. 1, the first light source module 1, the first collimating lens 2, the second dichroic filter 11, the third dichroic filter 12, the mesoporous prism 21, the measured lens 25, the hartmann diaphragm 3, and the photodetector Cam4 are sequentially distributed in the direction of the first optical axis 26;

as shown in fig. 1, the third light source module 7, the third collimating lens 8, the first light splitter 10, the focusing lens 9, and the second light splitter 11 are sequentially distributed along a second optical axis 27;

as shown in fig. 1, the reflector 14, the third light splitter 12, the fourth light splitter 13 and the photodetector D216 are sequentially distributed in the direction of the third optical axis 28;

as shown in fig. 1, light emitted by the first light source module 1 passes through the first collimating lens 2 and then becomes parallel light beams, and the parallel light beams pass through the measured lens 25 and the hartmann diaphragm 3 and then enter the photodetector Cam 4;

as shown in fig. 1, a light beam emitted by the third light source module 7 is transmitted through the first light splitter 10 and reflected by the second light splitter 11 in sequence, and then is split into two beams of light by the third light splitter 12, wherein one beam of light is reflected to the reflector 14 and then is reflected back by the original path of the reflector 14, and a part of light reflected back by the original path is transmitted through the third light splitter 12 and then is transmitted through the fourth light splitter 13 to enter the photodetector D216; the other beam of light is transmitted through the third light splitter 12, and is reflected by the upper surface of the Hartmann diaphragm 3 in the original path, and the light reflected by the original path enters the photoelectric detector D216 after being reflected by the third light splitter 12 and transmitted by the fourth light splitter 13; the reflecting mirror 14 is positioned on the moving component, when the reflecting mirror 14 is moved by the moving component, in the moving process of the reflecting mirror 14, when the optical paths of one beam of light reflected by the moving reflecting mirror 14 and the other beam of light reflected by the Hartmann diaphragm 3 are equal, an interference phenomenon is detected in the photoelectric detector D216;

as shown in fig. 1, light emitted by the second light source module 5 is converted into parallel light beams by the second collimating lens 6, the parallel light beams are reflected by the first light splitter 10 and the second light splitter 11, and are then split into two light beams by the third light splitter 12, wherein one light beam is reflected onto the reflector 14 and is then reflected back by the reflector 14 in the original path, and a part of light reflected by the original path is transmitted by the third light splitter 12 and is reflected by the fourth light splitter 13 to enter the photodetector D115; the other beam of light is transmitted through the third light splitter 12, and is reflected by the upper surface of the Hartmann diaphragm 3 in the original path, and the light reflected by the original path enters the photoelectric detector D115 after being reflected by the third light splitter 12 and the fourth light splitter 13; when the mirror 14 is moved, in the moving process, when the optical paths of one beam of light reflected by the moving mirror 14 and the other beam of light reflected by the Hartmann diaphragm 3 are equal, an interference phenomenon is detected in the photoelectric detector D115;

as shown in fig. 1, a first port 22 of the Y-shaped optical fiber 19 is a test light outlet, light emitted by the light source 17 is coupled into the Y-shaped optical fiber 19 through a third port 24 and is emitted through the first port 22, the first port 22 is located at a back focus of the lens group 20, and light beams are converged through the lens group 20, reflected by the mesoporous prism 21, and finally focused at a measured lens 25; the first port 22 and the lens mirror group 20 are located on the moving component, when the first port 22 and the lens mirror group 20 are moved by the moving component, in the moving process, the light beam focused on the measured lens 25 is focused on the upper surface or the lower surface of the measured lens 25, that is, the light beam focused on the measured lens 25 is alternately focused on the upper surface and the lower surface of the measured lens 25, when the light beam is focused on the upper surface or the lower surface of the measured lens 25, the surface reflection light returns to the first port 22, and then is transmitted through the Y-shaped optical fiber 19 and then is emitted to the photodetector D318 through the second port 23. The light source 17 is an LED light source or a laser light source, and the center wavelength thereof is equal to the center wavelength of the first light source in the first light source module 1.

As shown in fig. 2, the hartmann diaphragm 3 is composed of a plurality of light transmission holes 29 arranged in an array and a light-tight region 30, a reflective film 31 is plated on the light transmission hole 29 at the middle position of the plurality of light transmission holes 29 arranged in an array, the spectral range of the reflective film 31 is 400-650nm, and the reflectivity thereof is greater than 80%.

As shown in fig. 2, the diameter range of the light transmission hole 29 plated with the reflective film 31 is: 0.3-1.0 mm; the central distance range between the light holes 29 is 0.5-0.6mm, and the number of the light holes 29 is not less than 10 x 10.

First light source module 1 comprises first light source and first light trap, first light source is monochromatic LED light source, and its spectral width is greater than 10nm and is less than 50nm, first light trap sets up in the light emitting area department that is close to first light source, and the diameter of first light trap is less than 0.5mm, preferably is less than 0.2mm, the distance between first light trap and the first light source is less than 0.5 mm.

The focal length of the first collimating lens 2 is greater than 50mm, preferably greater than 100 mm.

The second light source module 5 is composed of a second light source and a second light hole, the second light source is a monochromatic LED light source, and the central wavelength range is as follows: 470nm-485nm, its spectral width is greater than 10nm and is less than 50nm, the second light trap sets up in the light emitting area department that is close to the second light source, and the diameter of second light trap is less than 0.3mm, preferably is less than 0.2mm, the distance between second light trap and the second light source is less than 0.5 mm.

The focal length of the second collimator lens 6 is larger than 50mm, preferably larger than 100 mm.

The third collimating lens 8 is placed between the second dichroic sheet 11 and the first dichroic sheet 10 and has a focal length of more than 50mm, preferably more than 100 mm. The second light splitter 11 is a semi-transparent and semi-reflective mirror 14, and the ratio of the transmittance to the reflectance is 5: 5.

a method for measuring the refractive index of a lens, comprising the steps of:

(1) before the test lens is placed, firstly, the distribution of the light beam emitted by the first light source module 1 on the photoelectric detector Cam4 is recorded, and the position x10 of the reflector 14 when the interference phenomenon occurs in the photoelectric detector D115 by the second light source module 5 of the light source, and the position x20 of the reflector 14 when the interference phenomenon occurs in the photoelectric detector D216 by the third light source module 7 are recorded;

(2) then the measured lens 25 is placed, the measured lens 25 can cause the change of the distribution of the light beam of the first light source module 1 in the photoelectric detector Cam4 after being placed, whether the center of the measured lens 25 is coincided with the center of the light path of the first light source module 1 or not is monitored by using the change condition of the position of the light point in the photoelectric detector Cam4, so that an operator is prompted to move the position of the measured lens 25 until the center of the measured lens 25 is coincided with the center of the light path of the first light source module 1, and the diopter of the measured lens 25 is calculated step by step according to the light intensity in the photoelectric detector Cam 4;

(3) turning off the first light source module 1, turning on the second light source module 5, the third light source module 7 and the light emitting source 17, moving the components at a constant speed to make the reflector 14, the lens set 20 and the first port 22 of the Y-shaped optical fiber 19 move synchronously at a constant speed, monitoring the change of optical signals by the photoelectric detector D115 and the photoelectric detector D216 in real time, and recording the interference peak position x11 of the second light source module 5 and the interference peak position x21 of the third light source module 7 after the measured lens 25 is placed, recording the confocal reflection position z2 of the upper surface of the measured lens 25 and the confocal reflection position z3 of the lower surface of the measured lens 25 by the photoelectric detector D318;

(4) the refractive index n of the lens can be calculated according to x11, x21, z2 and z 3.

The formula for calculating the refractive index n of the lens is as follows:

wherein

Beta is a fixed constant coefficient, and then through fitting calculation, the dispersion coefficient is further calculated as follows:

Claims (7)

1. the utility model provides a lens refractive index measuring device, includes diopter measuring module, optics thickness measuring module, confocal reflection measuring module and measured lens (25), its characterized in that: the diopter measuring module comprises a first light source module (1), a first collimating lens (2), a Hartmann diaphragm (3) and a photoelectric detector Cam (4); the optical thickness measuring module comprises a second light source module (5), a second collimating lens (6), a third light source module (7), a third collimating lens (8), a focusing lens (9), a first light splitter (10), a second light splitter (11), a third light splitter (12), a fourth light splitter (13), a reflector (14), a photoelectric detector D1(15) and a photoelectric detector D2 (16); the confocal reflection measurement module comprises a light emitting source (17), a photoelectric detector D3(18), a Y-shaped optical fiber (19), a lens group (20) and a mesoporous prism (21), wherein the Y-shaped optical fiber (19) comprises a first port (22), a second port (23) and a third port (24);

light emitted by the first light source module (1) becomes parallel light beams after passing through the first collimating lens (2), and the parallel light beams are emitted into the photoelectric detector Cam (4) after passing through the measured lens (25) and the Hartmann diaphragm (3);

the third light source module (7) emits a light beam, the light beam is transmitted through the first light splitter (10) and reflected through the second light splitter (11) in sequence, the light beam is divided into two light beams through the third light splitter (12), one light beam is reflected to the reflector (14), the light beam is reflected back through the original path of the reflector (14), and a part of the light beam reflected back through the original path is transmitted through the third light splitter (12) and then is transmitted through the fourth light splitter (13) to enter the photoelectric detector D2 (16); the other beam of light is transmitted through the third light splitter (12), and is reflected by the upper surface of the Hartmann diaphragm (3) in the original path, and the light reflected by the original path enters the photoelectric detector D2(16) after being reflected by the third light splitter (12) and transmitted by the fourth light splitter (13); when the reflecting mirror (14) is moved, when the optical paths of one beam of light reflected by the moving reflecting mirror (14) and the other beam of light reflected by the Hartmann diaphragm (3) are equal in the moving process of the reflecting mirror (14), an interference phenomenon is detected in a photoelectric detector D2 (16);

the light emitted by the second light source module (5) is converted into parallel light beams after passing through the second collimating lens (6), the parallel light beams are reflected by the first light splitter (10) and the second light splitter (11), and then are divided into two beams of light by the third light splitter (12), wherein one beam of light is reflected to the reflector (14) and then is reflected back by the reflector (14) in the original path, and a part of light reflected back by the original path is transmitted by the third light splitter (12) and then is reflected by the fourth light splitter (13) to enter the photoelectric detector D1 (15); the other beam of light is transmitted by the third light splitter (12), and is reflected by the upper surface of the Hartmann diaphragm (3) in the original path, and the light reflected by the original path enters the photoelectric detector D1(15) after being reflected by the third light splitter (12) and the fourth light splitter (13); when the reflecting mirror (14) is moved, when the optical paths of one beam reflected by the moving reflecting mirror (14) and the other beam reflected by the Hartmann diaphragm (3) are equal in the moving process, an interference phenomenon is detected in the photoelectric detector D1 (15);

a first port (22) of the Y-shaped optical fiber (19) is a test light outlet, light emitted by the light emitting source (17) is coupled into the Y-shaped optical fiber (19) through a third port (24) and is emitted out from the first port (22), the first port (22) is positioned on a back focus of the lens group (20), and light beams are converged through the lens group (20), reflected by the mesoporous prism (21) and finally focused at a measured lens (25); when the first port (22) and the lens group (20) are moved, the light beam focused on the measured lens (25) can be focused on the upper surface or the lower surface of the measured lens (25) in the moving process, when the light beam is focused on the upper surface or the lower surface of the measured lens (25), the surface reflected light returns to the first port (22) in the original path, then is transmitted through the Y-shaped optical fiber (19), and then is emitted to the photoelectric detector D3(18) through the second port (23).

2. A device for measuring the refractive index of a lens according to claim 1, wherein: the Hartmann diaphragm (3) consists of a plurality of light holes (29) which are arranged in an array type and a light-tight area (30), wherein a reflecting film (31) is plated on the light holes (29) at the middle position of the plurality of light holes (29) which are arranged in the array type, the spectral range of the reflecting film (31) is 400-650nm, and the reflectivity of the reflecting film is more than 80%.

3. A device for measuring the refractive index of an ophthalmic lens according to claim 2, wherein: the diameter range of the light transmission hole (29) plated with the reflecting film (31) is as follows: 0.3-1.0 mm; the central distance range between the light holes (29) is 0.5-0.6mm, and the number of the light holes (29) is not less than 10 x 10.

4. A device for measuring the refractive index of a lens according to claim 1, wherein: first light source module (1) comprises first light source and first light trap, first light source is monochromatic LED light source, and its spectral width is greater than 10nm and is less than 50nm, first light trap sets up in the light emitting area department that is close to first light source, and the diameter of first light trap is less than 0.5mm, distance between first light trap and the first light source is less than 0.5 mm.

5. A device for measuring the refractive index of a lens according to claim 1, wherein: the focal length of the first collimating lens (2) is greater than 50 mm.

6. A device for measuring the refractive index of a lens according to claim 1, wherein: the second light source module (5) is composed of a second light source and a second light hole, the second light source is a monochromatic LED light source, and the central wavelength range of the second light source is as follows: 470nm-485nm, its spectral width is greater than 10nm and is less than 50nm, the second light trap sets up in the light emitting area department that is close to the second light source, and the diameter of second light trap is less than 0.3mm, the distance between second light trap and the second light source is less than 0.5 mm.

7. A device for measuring the refractive index of a lens according to claim 1, wherein: the focal length of the second collimating lens (6) is greater than 50 mm.

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