A large-angle spectral confocal measurement lens

Abstract

The present invention belongs to the field of optical measurement technology, and specifically relates to a large-angle spectral confocal measurement lens, comprising a first lens group, an aperture, and a second lens group; the first lens group, the aperture, and the second lens group are arranged in sequence from the image side to the object side; the focal length of the first lens group is positive, and the focal length of the second lens group is also positive. The present invention has a novel structure and ingenious design. The first lens group expands and collimates the input light source aperture so that the lens can obtain a longer working distance and measurement angle; the second lens group separates and focuses light of different wavelengths to different positions on the optical axis. When the light hitting the object surface is reflected back to the lens, it is finally coupled into an optical fiber and transmitted to an external processor. The external processor determines the thickness, height difference, and other data of the surface of the measured object based on the wavelength of the reflected light. The present invention has high measurement accuracy, a large measurement angle, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of optical measurement, and in particular relates to a large-angle spectral confocal measurement lens. Background Art

[0002] Currently, spectral confocal measurement is increasingly being used in the field of precision testing. There are a variety of lenses with different specifications depending on the measurement accuracy, measurement spot size, range, and maximum measurement angle.

[0003] Currently, with the increasing application of curved screens, detecting the curved surface profile of such curved glass requires the use of spectral confocal measurement lenses with characteristics such as high precision and large detection angle. However, such lenses are relatively rare and costly, resulting in bottlenecks in research and development applications. Summary of the Invention

[0004] In view of the problems in the prior art, the present invention provides a large-angle spectral confocal measurement lens with high measurement accuracy, large measurement angle and low cost.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A wide-angle spectral confocal measurement lens, comprising a first lens group, an aperture, and a second lens group; the first lens group, the aperture, and the second lens group are arranged in sequence from the image side to the object side;

[0007] The focal length of the first lens group is positive, and the focal length of the second lens group is positive.

[0008] Wherein, the focal length of the first lens group is set to f1, and the focal length of the second lens group is set to f2, then 2.55 <F1 / F2<3.83。

[0009] Wherein, the first lens group includes a third lens group and a fourth lens group arranged in sequence from the image side to the object side;

[0010] The focal length of the third lens group is negative, and the focal length of the fourth lens group is positive.

[0011] Wherein, the focal length of the first lens group is set to f1, and the focal length of the third lens group is set to f11, then -0.41 <F11 / F1<-0.62。

[0012] Wherein, the focal length of the first lens group is set to f1, and the focal length of the fourth lens group is set to f12, then 0.62 <F12 / F1<0.94。

[0013] Among them, the third lens group includes a first lens and a second lens arranged in sequence from the image side to the object side, and the fourth lens group includes a third lens and a fourth lens arranged in sequence from the image side to the object side. The focal length of the first lens is negative, and the focal lengths of the second lens, the third lens, and the fourth lens are all positive.

[0014] Among them, the focal length range of the first lens is -25.7mm to -21mm; the focal length range of the second lens is 39mm to 48mm, the focal length range of the third lens is 310mm to 370mm, and the focal length range of the fourth lens is 185.5mm to 228mm.

[0015] The second lens group includes a fifth lens, a sixth lens, and a seventh lens arranged in sequence from the image side to the object side, and the focal lengths of the fifth lens, the sixth lens, and the seventh lens are all positive.

[0016] The focal length of the fifth lens is in the range of 194.2 mm to 237.9 mm; the focal length of the sixth lens is in the range of 117.1 mm to 145.2 mm; and the focal length of the seventh lens is in the range of 133.4 mm to 164 mm.

[0017] Wherein, the refractive index of the seventh lens is greater than 1.9.

[0018] The present invention has a novel structure and ingenious design. An optical fiber for transmission and reception is provided on the image side. A light source is used to illuminate the object being measured. The light source passes through a first lens group and a second lens group for dispersion processing. The first lens group expands and collimates the input light source, allowing the lens to achieve a longer working distance and measurement angle. The second lens group separates and focuses light of different wavelengths onto different positions on the optical axis. When the light strikes the object surface, it is reflected back to the lens, finally coupled into the optical fiber and transmitted to an external processor. The external processor determines the thickness, height difference, and other data of the surface of the object being measured based on the wavelength of the reflected light. The present invention has high measurement accuracy, a large measurement angle, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Figure 2 This is the optical path diagram of the present invention.

[0021] Figure 3 Schematic diagram of the structure of the second lens group of the present invention.

[0022] Reference numerals are: 1, first lens group; 2, aperture; 3, second lens group;

[0023] 11. Third lens group, 12. Fourth lens group;

[0024] 111, first lens, 112, second lens, 121, third lens, 122, fourth lens;

[0025] 301, fifth lens, 302, sixth lens, 303, seventh lens DETAILED DESCRIPTION

[0026] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the embodiments and the accompanying drawings. The contents mentioned in the embodiments are not intended to limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0027] A wide-angle spectral confocal measurement lens, such as Figure 1-Figure 3 As shown, it comprises a first lens group 1, an aperture 2 and a second lens group 3; the first lens group 1, the aperture 2 and the second lens group 3 are arranged in sequence from the image side to the object side;

[0028] The focal length of the first lens group 1 is positive, and the focal length of the second lens group 3 is positive.

[0029] Specifically, an optical fiber for transmission and reception is positioned on the image side. A light source is used to illuminate the object being measured. The light source sequentially passes through the first lens group 1 and the second lens group 3 for dispersion processing. After the light strikes the object surface, it is reflected back through the lens, coupled into the optical fiber, and transmitted to an external processor. The external processor uses the wavelength of the reflected light to determine the thickness, height difference, and other data of the surface being measured. In the present invention, the first lens group 1 expands and collimates the input light source, allowing the lens to achieve a longer working distance and measurement angle. The second lens group 3 separates and focuses light of different wavelengths onto different positions on the optical axis.

[0030] In the wide-angle spectral confocal measurement lens described in this example, the first lens group 1 includes a third lens group 11 and a fourth lens group 12 arranged in sequence from the image side to the object side;

[0031] The focal length of the third lens group 11 is negative, and the focal length of the fourth lens group 12 is positive.

[0032] In this example, a wide-angle spectral confocal measurement lens is described. The third lens group 11 includes a first lens 111 and a second lens 112 arranged in sequence from the image side to the object side. The fourth lens group 12 includes a third lens 121 and a fourth lens 122 arranged in sequence from the image side to the object side. The focal length of the first lens 111 is negative, and the focal lengths of the second lens 112, the third lens 121, and the fourth lens 122 are all positive.

[0033] Specifically, the focal length of the first lens 111 is negative, which can diverge the light, making the overall structure of the first lens 111 / third lens 121 compact, and then collimated by the second lens 112, the third lens 121 and the fourth lens 122 in sequence; the third lens group 11 adopts a reverse telephoto structure, which can shorten the lens length.

[0034] In this example, the wide-angle spectral confocal measurement lens described herein comprises a second lens group 3 comprising a fifth lens 301, a sixth lens 302, and a seventh lens 303, arranged sequentially from the image side to the object side. The focal lengths of the fifth lens 301, the sixth lens 302, and the seventh lens 303 are all positive. Specifically, the second lens group 3 employs a zigzag lens structure, which eliminates spherical aberration, coma, and astigmatism, while increasing the object-side numerical aperture and broadening the lens's measurement angle.

[0035] In this example, a large-angle spectral confocal measurement lens is described. The focal length of the first lens group 1 is set to f1, and the focal length of the second lens group 3 is set to f2. Then 2.55 <F1 / F2<3.83。

[0036] Specifically, the above-mentioned setting has high measurement accuracy, which can meet the requirements of a maximum inclination angle of 44.8 degrees for the measured surface, a maximum working measurement distance of 20.4 mm, and a spectral focusing range of 1.8 mm.

[0037] In the wide-angle spectral confocal measurement lens described in this example, the focal length of the first lens group 1 is set to f1, and the focal length of the third lens group 11 is set to f11, then -0.41 <F11 / F1<-0.62。

[0038] In the wide-angle spectral confocal measurement lens described in this example, the focal length of the first lens group 1 is set to f1, and the focal length of the fourth lens group 12 is set to f12, then 0.62 <F12 / F1<0.94。

[0039] Specifically, the above arrangement makes the structure of the first lens group 1 compact and achieves a good collimation effect after light dispersion.

[0040] In this example, a wide-angle spectral confocal measurement lens is described. The focal length range of the first lens 111 is -25.7 mm to -21 mm; the focal length range of the second lens 112 is 39 mm to 48 mm; the focal length range of the third lens 121 is 310 mm to 370 mm; and the focal length range of the fourth lens 122 is 185.5 mm to 228 mm.

[0041] In the wide-angle spectral confocal measurement lens described in this example, the focal length of the fifth lens 301 ranges from 194.2 mm to 237.9 mm; the focal length of the sixth lens 302 ranges from 117.1 mm to 145.2 mm; and the focal length of the seventh lens 303 ranges from 133.4 mm to 164 mm.

[0042] In the wide-angle spectral confocal measurement lens described in this example, the refractive index of the second lens 112 and the seventh lens 303 is greater than 1.9.

[0043] Specifically, the greater the refractive index of the lens, the more conducive it is to correcting the spherical aberration of the system, thereby making the focused spot of the light on the object plane smaller and the measurement result more accurate.

[0044] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are all within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A wide-angle spectral confocal measurement lens, characterized by: The lens comprises a first lens group, an aperture and a second lens group; the first lens group, the aperture and the second lens group are arranged in sequence from the image side to the object side; The focal length of the first lens group is positive, and the focal length of the second lens group is positive; An optical fiber for transmission and reception is set on the image side. A light source is used to illuminate the object to be measured. The light source passes through the first lens group and the second lens group in sequence for dispersion processing. When the light hits the object surface, it is reflected back to the lens, finally coupled into the optical fiber, and transmitted to the external processor. The external processor determines the thickness and height difference of the surface of the measured object by the wavelength of the reflected light. The first lens group expands and collimates the input light source to achieve a longer working distance and measurement angle. The second lens group separates and focuses light of different wavelengths to different positions on the optical axis. The first lens group includes a third lens group and a fourth lens group arranged in sequence from the image side to the object side; the focal length of the third lens group is negative, and the focal length of the fourth lens group is positive; The third lens group includes a first lens and a second lens arranged in sequence from the image side to the object side, and the fourth lens group includes a third lens and a fourth lens arranged in sequence from the image side to the object side, the focal length of the first lens is negative, and the focal lengths of the second lens, the third lens, and the fourth lens are all positive; The first lens has a negative focal length and is used to diverge the light, which is then collimated by the second lens, the third lens, and the fourth lens in sequence; The third lens group adopts a retro-telephoto structure to shorten the lens length; The focal length range of the first lens is -25.7 mm to -21 mm; the focal length range of the second lens is 39 mm to 48 mm; the focal length range of the third lens is 310 mm to 370 mm; and the focal length range of the fourth lens is 185.5 mm to 228 mm. The second lens group includes a fifth lens, a sixth lens, and a seventh lens arranged in sequence from the image side to the object side, and the focal lengths of the fifth lens, the sixth lens, and the seventh lens are all positive; The second lens group adopts a Qiming lens structure to eliminate spherical aberration, coma and astigmatism, while increasing the object side numerical aperture and the lens measurement angle; The focal length of the fifth lens is in the range of 194.2 mm to 237.9 mm; the focal length of the sixth lens is in the range of 117.1 mm to 145.2 mm; and the focal length of the seventh lens is in the range of 133.4 mm to 164 mm.

2. The wide-angle spectral confocal measurement lens according to claim 1, characterized in that: The focal length of the first lens group is set to F1, and the focal length of the second lens group is set to F2, then 2.55 <F1 / F2<3.83。 3. The wide-angle spectral confocal measurement lens according to claim 1, characterized in that: The focal length of the first lens group is set to F1, and the focal length of the third lens group is set to F11, then -0.41 <F11 / F1<-0.62。 4. The wide-angle spectral confocal measurement lens according to claim 3, characterized in that: The focal length of the first lens group is set to F1, and the focal length of the fourth lens group is set to F12, then 0.62 <F12 / F1<0.94。 5. The wide-angle spectral confocal measurement lens according to claim 1, characterized in that: The refractive index of the seventh lens element is greater than 1.9.

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