An ultra-large angle spectral confocal probe

Abstract

The present invention is an ultra-large angle spectral confocal probe, comprising a lens barrel, one end of which is externally connected to an optical fiber for introducing a fixed bandwidth polychromatic light source and forming an emission light path in the lens barrel, and in the lens barrel, along the emission light path direction, there are arranged in sequence: a diffusion lens group for expanding a fixed numerical aperture light beam emitted by the optical fiber; a first dispersion lens group for assuming the main dispersion; a transfer lens group for transferring light between the first dispersion lens group and the second dispersion lens group; and a second dispersion lens group for assuming partial dispersion and projecting light onto an image plane at an ultra-large angle. The present invention adopts a multi-segment grouped dispersion structure, which can make the focal length and dispersion of the total dispersion lens group reasonably weighted among each subdivided lens group, so as to adapt to different dispersion requirements, and at the same time, can more perfectly correct the influence of high-order aberrations brought by the large-angle light beam on the system, and can meet the ultra-large angle image incident angle of ±64.5°.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to an ultra-large angle spectral confocal probe. Background Art

[0002] At present, with the rapid growth of the demand for intelligent detection of traditional spherical lenses, non-contact rapid detection of asymmetric large arc surfaces and regular large-aperture optical devices has become a focus of increasing attention. Conventional laser displacement sensors can partially meet the above needs due to their long range, but they have inherent characteristics such as uneven on-axis light spots and slightly larger sizes, and tilted configurations between emission and detection optical paths, which make them unable to meet the needs of high-precision precision measurement and occupy too much space for integration, making them unable to be widely used in related detection equipment.

[0003] In contrast, the spectral confocal measurement method uses a dispersion lens group. After the complex light is separated and focused by the dispersion lens group, the focal points of light waves of different wavelengths will be distributed on the optical axis in sequence with increasing wavelengths. The object to be measured is placed in the dispersion area on the probe axis, and the real-time state of its spatial motion can be obtained based on the peak information in the surface return light spectrum. It has high detection accuracy and good integration. However, the high-order aberrations caused by large-angle beams will have an adverse effect on the accuracy of the system.

[0004] In order to obtain more accurate detection accuracy and more three-dimensional and comprehensive detection information, the present invention provides an ultra-large angle spectral confocal probe, which creatively adopts a multi-segment grouped dispersion structure, which can reasonably distribute the optical power and dispersion of the total dispersion lens group among each subdivided lens group. To meet different dispersion requirements, it can more perfectly correct the influence of high-order aberrations brought by large-angle light beams on the system. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems existing in the prior art and provide an ultra-large angle spectral confocal probe.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0007] An ultra-large angle spectral confocal probe comprises a lens barrel, one end of which is externally connected to an optical fiber for introducing a polychromatic light source with a fixed bandwidth and forming an emission light path in the lens barrel, characterized in that the lens barrel is provided with the following components in sequence along the emission light path:

[0008] The diffusion lens group is used to expand the fixed numerical aperture light beam emitted by the optical fiber, reduce the object side F number and shorten the length of the front section of the lens group;

[0009] The first dispersion lens group is used to bear the main dispersion;

[0010] A transfer lens group, used for transferring light between the first dispersion lens group and the second dispersion lens group;

[0011] The second dispersion lens group is used to bear part of the dispersion and project the light onto the image plane at a very large angle;

[0012] After light beams of different wavelengths are dispersed and focused by the first and second dispersion lens groups, the focal points of light waves of different wavelengths are distributed on the optical axis in sequence as the wavelength increases. When the object to be measured is placed in the dispersion area on the probe axis, the real-time state of its spatial movement is obtained based on the peak information in the return light spectrum on its surface.

[0013] Furthermore, the first dispersive lens group and the second dispersive lens group are positive lens groups with positive focal lengths, which are used to produce positive dispersion, bear the dispersion weight of the entire lens group, and produce corresponding positive spherical aberration. The diffusion lens group and the transfer lens group are negative lens groups with negative focal lengths, which are used to jointly produce an equal amount of negative spherical aberration to correct the overall spherical aberration of the lens group, while adding a smaller degree of negative dispersion.

[0014] Furthermore, the diffusion lens group includes a first single lens and a second single lens with negative focal lengths, which are arranged in sequence from the object side to the image side; the first dispersion lens group includes a third single lens, a fourth single lens and a fifth single lens with positive focal lengths, which are arranged in sequence from the object side to the image side; the transfer lens group includes a sixth single lens and a seventh single lens with negative focal lengths, which are arranged in sequence from the object side to the image side; and the second dispersion lens group includes an eighth single lens, a ninth single lens, a tenth single lens and an eleventh single lens with positive focal lengths, which are arranged in sequence from the object side to the image side.

[0015] Furthermore, the focal length range of the first single lens is -11.3 mm to -9 mm, and the focal length range of the second single lens is -44 mm to -39 mm.

[0016] Furthermore, the focal length range of the third single lens is 120 mm to 180 mm, the focal length range of the fourth single lens is 100 mm to 160 mm, and the focal length range of the fifth single lens is 140 mm to 180 mm.

[0017] Furthermore, the sixth single lens is a field lens with close centers of curvature of the front and rear surfaces, which is used to correct the system field curvature, and its focal length range is -900mm to -1000mm. The focal length range of the seventh single lens is -50mm to -90mm, which is used to produce a larger negative spherical aberration.

[0018] Furthermore, the focal length range of the eighth single lens is 120 mm to 180 mm, the focal length range of the ninth single lens is 170 mm to 210 mm, the focal length range of the tenth single lens is 80 mm to 120 mm, and the focal length range of the eleventh single lens is 70 mm to 110 mm.

[0019] The beneficial effects of the present invention are:

[0020] The present invention adopts a multi-segment grouped dispersion structure, which can reasonably distribute the optical power and dispersion of the total dispersion lens group among each subdivided lens group to meet different dispersion requirements. At the same time, it can more perfectly correct the influence of high-order aberrations caused by large-angle light beams on the system and meet the ultra-large-angle image incident angle of ±64.5°. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the ultra-large angle spectral confocal probe of the present invention;

[0022] Figure 2 for Figure 1 Schematic diagram of the image-side parameters of the ultra-wide-angle spectral confocal probe.

[0023] Explanation of the numbers in the figure: 1. diffusion lens group, 11. first single lens, 12. second single lens, 2. first dispersion lens group, 21. third single lens, 22. fourth single lens, 23. fifth single lens, 3. transfer lens group, 31. sixth single lens, 32. seventh single lens, 4. second dispersion lens group, 41. eighth single lens, 42. ninth single lens, 43. tenth single lens, 44. eleventh single lens. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0025] like Figure 1 As shown, an ultra-large angle spectral confocal probe comprises a lens barrel, one end of which is externally connected to an optical fiber for introducing a polychromatic light source with a fixed bandwidth and forming an emission light path in the lens barrel, characterized in that the lens barrel is provided in sequence along the emission light path direction:

[0026] The diffusion lens group 1 is used to expand the fixed numerical aperture light beam emitted by the optical fiber, reduce the object side F number and shorten the length of the front section of the lens group;

[0027] The first dispersion lens group 2 is used to bear the main dispersion;

[0028] The transfer lens group 3 is used for light transfer between the first dispersion lens group 2 and the second dispersion lens group 4:

[0029] The second dispersion lens group 4 is used to undertake partial dispersion and project light onto the image plane at an ultra-large angle:

[0030] After the light beams of different wavelengths are dispersion-separated and refractive-focused by the first dispersion lens group 2 and the second dispersion lens group 4, the focal points of the light waves of different wavelengths are sequentially distributed on the optical axis as the wavelength increases. When the object to be measured is placed in the dispersion region on the probe axis, the real-time state of its spatial movement is obtained according to the peak information in the surface echo spectrum.

[0031] The first dispersion lens group 2 and the second dispersion lens group 4 are positive lens groups with positive focal lengths, which are used to generate positive dispersion, undertake the dispersion weight of the entire lens group, and generate corresponding positive spherical aberration. The diffusing lens group 1 and the relay lens group 3 are negative lens groups with negative focal lengths, which are used to jointly generate equal negative spherical aberration to correct the overall spherical aberration of the lens group, and at the same time add a small degree of negative dispersion.

[0032] The spherical aberrations of the diffusing lens group 1, the first dispersion lens group 2, the relay lens group 3, and the second dispersion lens group 4 are respectively expressed as: ∑S I一 、∑S I二 、∑S I三 、∑S I四 ; The chromatic aberrations are respectively expressed as: ∑C I一 、∑C I二 、∑C I三 、∑C I四 ; Each lens group can flexibly adjust the single lenses therein to meet various different dispersion and optical power requirements, that is, ∑S 1一 +∑S I三 =-(∑S I二 +∑S I四 ), ∑C I一 +∑C I二 +∑C I三 +∑C I四 =MR, where MR is the spectral confocal measurable range. In this embodiment, MR = 2.4 mm, the numerical aperture of the fiber-optic emission beam on the emission optical path is na, the focal length of the diffusing lens group 1 is f1, the exit pupil is #1, then the image-side F number is f1 / #1, and The focal length of the first dispersion lens group 2 is f2, the focal length of the relay lens group 3 is f3, and the focal length of the second dispersion lens group 4 is f4, then: -0.8 < f2 / f3 < -0.5, 1.4 < f2 / f4 < 1.6.

[0033] In the diffusion lens group 1, a first single lens 11 and a second single lens 12, both with negative focal lengths, are arranged in sequence from the object side to the image side; in the first dispersion lens group 2, a third single lens 21, a fourth single lens 22 and a fifth single lens 23, both with positive focal lengths, are arranged in sequence from the object side to the image side; in the transfer lens group 3, a sixth single lens 31 and a seventh single lens 32, both with negative focal lengths, are arranged in sequence from the object side to the image side; in the second dispersion lens group 4, an eighth single lens 41, a ninth single lens 42, a tenth single lens 43 and an eleventh single lens 44, all with positive focal lengths, are arranged in sequence from the object side to the image side.

[0034] The focal length range of the first single lens 11 is from -11.3 mm to -9 mm, and the focal length range of the second single lens 12 is from -44 mm to -39 mm.

[0035] The focal length range of the third single lens 21 is 120 mm to 180 mm, the focal length range of the fourth single lens 22 is 100 mm to 160 mm, and the focal length range of the fifth single lens 23 is 140 mm to 180 mm.

[0036] The sixth single lens 31 is a field lens with close centers of curvature of the front and rear surfaces, which is used to correct the system field curvature, and its focal length range is -900mm to -1000mm. The focal length range of the seventh single lens 32 is -50mm to -90mm, which is used to produce a large negative spherical aberration.

[0037] The focal length range of the eighth single lens 41 is 120 mm to 180 mm, the focal length range of the ninth single lens 42 is 170 mm to 210 mm, the focal length range of the tenth single lens 43 is 80 mm to 120 mm, and the focal length range of the eleventh single lens 44 is 70 mm to 110 mm.

[0038] In this embodiment, the maximum diameter of the single lens in the lens group is D=90 mm. In its working band [λ1, λ2], λ1 and λ2 are the short-wave and long-wave limits of the working band, respectively, so that the lens group satisfies:

[0039] ∑C I一 +∑C I二 +∑C I三 +∑C I四 =MR=2.4mm;

[0040] The spectral confocal probe corresponds to the back intercept at a specific wavelength λ0 within its working band [λ1, ..., λ0, ..., λ2]. The absolute value of the difference between the short-wave limit λ1 and the long-wave limit λ2 and the back intercept is 1.2 mm, that is:

[0041]

[0042]

[0043]

[0044] -Δ1 = Δ2 = 1.2 mm. At the focus of the light ray emitted by the present spectral confocal probe at the wavelength λ0, see Figure 2 in which the included angle between the maximum aperture ray and the optical axis

[0045] In addition, it should be noted that unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, rather than to represent the logical relationship or sequential relationship, etc. between the various components, elements, steps.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An ultra-large angle spectral confocal probe, comprising a lens barrel, one end of the lens barrel is externally connected to an optical fiber for introducing a polychromatic light source with a fixed bandwidth and forming an emission optical path in the lens barrel, and is characterized in that, Inside the lens barrel, the following components are arranged in sequence along the emission optical path direction: A diffusing lens group (1) for expanding the beam with a fixed numerical aperture emitted by the optical fiber, reducing the object space F number and shortening the front section length of the lens group; A first dispersion lens group (2) for undertaking the main dispersion; A relay lens group (3) for relaying the light between the first dispersion lens group (2) and the second dispersion lens group (4); A second dispersion lens group (4) for undertaking partial dispersion and projecting the light onto the image plane at an ultra-large angle; After the light beams of different wavelengths are dispersion-separated and refractive-focused by the first dispersion lens group (2) and the second dispersion lens group (4), the foci of the light waves of different wavelengths are sequentially distributed on the optical axis with the increase of the wavelength. When the object to be measured is placed in the dispersion region on the axis of the probe head, the real-time state of its spatial movement is obtained according to the peak information in the surface echo spectrum; The first dispersion lens group (2) and the second dispersion lens group (4) are positive lens groups with positive focal lengths, used to generate positive dispersion, undertake the dispersion weight of the entire lens group, and generate corresponding positive spherical aberration. The diffusing lens group (1) and the relay lens group (3) are negative lens groups with negative focal lengths, used to jointly generate an equal amount of negative spherical aberration to correct the overall spherical aberration of the lens group and additionally generate negative dispersion; In the diffusing lens group (1), a first single lens (11) and a second single lens (12) with negative focal lengths are arranged in sequence from the object side to the image side; in the first dispersion lens group (2), a third single lens (21), a fourth single lens (22), and a fifth single lens (23) with positive focal lengths are arranged in sequence from the object side to the image side; in the relay lens group (3), a sixth single lens (31) and a seventh single lens (32) with negative focal lengths are arranged in sequence from the object side to the image side; in the second dispersion lens group (4), an eighth single lens (41), a ninth single lens (42), a tenth single lens (43), and an eleventh single lens (44) with positive focal lengths are arranged in sequence from the object side to the image side.

2. The super-large angle spectral confocal probe according to claim 1, wherein The focal length range of the first single lens (11) is from -11.3 mm to -9 mm, and the focal length range of the second single lens (12) is from -44 mm to -39 mm.

3. The super-large-angle spectral confocal probe according to claim 2, characterized in that, The focal length range of the third single lens (21) is from 120 mm to 180 mm, the focal length range of the fourth single lens (22) is from 100 mm to 160 mm, and the focal length range of the fifth single lens (23) is from 140 mm to 180 mm.

4. The ultra-large angle spectral confocal probe according to claim 3, wherein, The sixth single lens (31) is a field lens with the curvature centers of the front and rear surfaces close to each other, used to correct the field curvature of the system. Its focal length range is from -900 mm to -1000 mm, and the focal length range of the seventh single lens (32) is from -50 mm to -90 mm, used to generate negative spherical aberration.

5. The super-large angle spectral confocal probe according to claim 4, characterized in that, The focal length range of the eighth single lens (41) is from 120 mm to 180 mm, the focal length range of the ninth single lens (42) is from 170 mm to 210 mm, the focal length range of the tenth single lens (43) is from 80 mm to 120 mm, and the focal length range of the eleventh single lens (44) is from 70 mm to 110 mm.

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