Line spectrum confocal measuring head

Abstract

The line spectrum confocal measuring head comprises a slit and a lens barrel, the slit is arranged at one end of the lens barrel and is used for introducing a complex-color line light source with a fixed bandwidth into the lens barrel, a dispersion lens group is distributed in the lens barrel and along an emission light path of the slit, so that the complex-color light is separated and focused through the dispersion lens group; and the light with different wavelengths is focused at different positions in the optical axis direction and is sequentially distributed along with increasing of the wavelengths, so that a measured object is placed in a measuring head dispersion area, and the current position of the measured object relative to the dispersion lens group is obtained according to peak information of a reflected light spectrum on the surface of the measured object. The linear light source of the measuring head can realize linear field-of-view detection and obtain field-of-view position information on the axis and outside the axis of a measured object at the same time, the transverse measurement efficiency is improved while the longitudinal measurement range is ensured, the longitudinal measurement range can reach + / -3.6 mm, and the transverse measurement range can reach + / -8.5 mm.

Description

Technical Field

[0001] The invention relates to the technical field of spectrum measuring instruments, and in particular to a line spectrum confocal probe. Background Art

[0002] Spectral confocal displacement measurement is a non-contact precision distance measurement technology that uses a dispersion lens group to separate and focus the complex spectrum in the axial position. Based on the one-to-one correspondence between the strongest reflection spectrum of the object and the relative position of the measured object and the dispersion lens group, the conversion from spectrum measurement to distance measurement can be completed with the help of a spectrometer. Through axial point scanning, precise measurement of small distances can be achieved.

[0003] The mature scanning method of spectral displacement sensors is single-point scanning, and the relative distance information of one point is obtained in one measurement. If you need to measure the three-dimensional information of the surface of the object being measured, you need to use a two-dimensional scanning device to complete it, which will affect the efficiency of the measurement and is not suitable for fast measurement. At present, line spectrum confocal displacement measurement can improve the low efficiency of single-point scanning, specifically by replacing the point spot illumination in point spectrum confocal displacement measurement with linear light illumination. Such linear light illumination has higher requirements for the dispersion lens group. In addition to ensuring the longitudinal measurement range, it is also necessary to ensure that the imaging quality is the same on and off the axis to meet the consistency of off-axis and on-axis measurement accuracy. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide a line spectrum confocal probe. The line light source can realize line field detection and simultaneously obtain the on-axis and off-axis field position information of the object to be measured, thereby improving the lateral measurement efficiency while ensuring the longitudinal measurement range.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] A line spectrum confocal probe comprises a slit and a lens barrel, wherein the slit is arranged at one end of the lens barrel and is used to introduce a polychromatic line light source with a fixed bandwidth into the lens barrel, and a dispersion lens group is distributed in the lens barrel and along the slit emission light path, so that the polychromatic light is separated and focused by the dispersion lens group, and lights of different wavelengths are focused at different positions in the optical axis direction and are distributed in sequence as the wavelength increases, and is used to place an object to be measured into the dispersion area of ​​the probe, and obtain the current position of the object to be measured relative to the dispersion lens group according to the peak information of the spectrum of light reflected from the surface of the object to be measured.

[0007] Furthermore, the propagation direction of light along the slit emission light path of the dispersion lens group is sequentially a diffusion lens group, a first dispersion lens group, a first transfer lens group, a second dispersion lens group, a second transfer lens group and a third dispersion lens group. The diffusion lens group is used to expand the incident light beam, the first dispersion lens group is used to bear part of the dispersion of the dispersion lens group, the second dispersion lens group is used to bear the main dispersion of the dispersion lens group, the third dispersion lens group is used to bear part of the dispersion of the dispersion lens group, image the light on the image plane, and make the main light of each field of view perpendicular to the image plane, the first transfer lens group is used to transfer the first dispersion lens group and the second dispersion lens group, and the second transfer lens group is used to transfer the second dispersion lens group and the third dispersion lens group.

[0008] Furthermore, the focal length of the diffusion lens group is positive, with smaller positive spherical aberration and smaller negative chromatic aberration; the focal lengths of the first dispersion lens group, the second dispersion lens group and the third dispersion lens group are positive to cumulatively produce larger negative chromatic aberration, assume the dispersion function, and simultaneously produce larger positive spherical aberration; the focal lengths of the first transfer lens group and the second transfer lens group are negative to produce negative spherical aberration, which is used to correct the overall spherical aberration of the dispersion lens group, and simultaneously produce smaller positive chromatic aberration.

[0009] Furthermore, in the diffusion lens group, a first single lens, a second single lens, a third single lens and a fourth single lens are arranged in sequence from the object side to the image side, wherein the focal lengths of the first single lens and the fourth single lens are negative, the focal lengths of the second single lens and the third single lens are positive, and the first single lens and the second single lens form a cemented lens with a negative focal length.

[0010] Furthermore, the first dispersion lens group includes a fifth single lens and a sixth single lens, both of which have positive focal lengths, which are arranged in sequence from the object side to the image side.

[0011] Furthermore, the first transfer lens group includes a seventh single lens and an eighth single lens, both of which have negative focal lengths, arranged in sequence from the object side to the image side.

[0012] Furthermore, the second dispersion lens group includes a ninth single lens, a tenth single lens, an eleventh single lens and a twelfth single lens, all of which have positive focal lengths, arranged in sequence from the object side to the image side.

[0013] Furthermore, the second transfer lens group includes a thirteenth single lens and a fourteenth single lens having the same focal length, which are arranged in sequence from the object side to the image side.

[0014] Furthermore, the third dispersion lens group includes a fifteenth single lens, a sixteenth single lens and a seventeenth single lens, all of which have positive focal lengths, which are arranged in sequence from the object side to the image side.

[0015] The beneficial effects of the present invention are:

[0016] The linear light source of the probe of the present invention can realize linear field detection and simultaneously obtain the on-axis and off-axis field position information of the object being measured, thereby improving the lateral measurement efficiency while ensuring the longitudinal measurement range. The longitudinal measurement range can reach ±3.6mm and the lateral measurement range can reach ±8.5mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the line spectrum confocal probe of the present invention;

[0018] Figure 2 It is a schematic diagram of image parameters of the line spectrum confocal probe of the present invention.

[0019] Explanation of numbers in the figure: 1. diffusion lens group, 11. first single lens, 12. second single lens, 13. third single lens, 14. fourth single lens, 2. first dispersion lens group, 21. fifth single lens, 22. sixth single lens, 3. first transfer lens group, 31. seventh single lens, 32. eighth single lens, 4. second dispersion lens group, 41. ninth single lens, 42. tenth single lens, 43. eleventh single lens, 44. twelfth single lens, 5. second transfer lens group, 51. thirteenth, 52. fourteenth single lens, 6. third dispersion lens group, 61. fifteenth single lens, 62. sixteenth single lens, 63. seventeenth single lens. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0021] A line spectrum confocal probe comprises a slit and a lens barrel, wherein the slit is arranged at one end of the lens barrel and is used to introduce a polychromatic line light source with a fixed bandwidth into the lens barrel, and a dispersion lens group is distributed in the lens barrel and along the slit emission light path, so that the polychromatic light is separated and focused by the dispersion lens group, and lights of different wavelengths are focused at different positions in the optical axis direction and are distributed in sequence as the wavelength increases, and is used to place an object to be measured into the dispersion area of ​​the probe, and obtain the current position of the object to be measured relative to the dispersion lens group according to the peak information of the spectrum of light reflected from the surface of the object to be measured.

[0022] like Figure 1As shown, the light propagation directions of the dispersive lens groups along the slit emission light path are, in sequence, a diffusion lens group 1, a first dispersive lens group 2, a first transfer lens group 3, a second dispersive lens group 4, a second transfer lens group 5 and a third dispersive lens group 6. The diffusion lens group 1 is used to expand the incident light beam, the first dispersive lens group 2 is used to bear part of the dispersion of the dispersive lens group, the second dispersive lens group 4 is used to bear the main dispersion of the dispersive lens group, the third dispersive lens group 6 is used to bear part of the dispersion of the dispersive lens group, image the light on the image plane, and make the main light of each field of view perpendicular to the image plane, the first transfer lens group 3 is used to transfer the first dispersive lens group 2 and the second dispersive lens group 4, and the second transfer lens group 5 is used to transfer the second dispersive lens group 4 and the third dispersive lens group 6.

[0023] The focal length of the diffusion lens group 1 is positive, and has a small positive spherical aberration and a small negative chromatic aberration. The focal lengths of the first dispersion lens group 2, the second dispersion lens group 4 and the third dispersion lens group 6 are positive, so as to cumulatively generate a large negative chromatic aberration, undertake the dispersion function, and generate a large positive spherical aberration at the same time. The focal lengths of the first transfer lens group 3 and the second transfer lens group 5 are negative, so as to generate a negative spherical aberration, which is used to correct the overall spherical aberration of the dispersion lens group, and generate a small positive chromatic aberration at the same time. The spherical aberrations of the diffusion lens group 1, the first dispersion lens group 2, the first transfer lens group 3, the second dispersion lens group 4, the second transfer lens group 5, and the third dispersion lens group 6 are respectively expressed as Axial chromatic aberration is The structure can be flexibly adjusted to meet various chromatic aberration and optical power requirements, and the size of the dispersion lens group is constrained. The maximum diameter of the lens in the lens group is D = 90mm. 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 dispersion lens group satisfies:

[0024]

[0025] , where MR is the spectral confocal measurable range.

[0026] In this embodiment, the numerical aperture of the slit-emitted light beam is na, the focal length of the dispersion probe of the present invention is f, the exit pupil is #out, and the image-side F number is f / #out. The first dispersive lens group 2 is a positive lens group with a focal length of f2, the first transfer lens group 3 is a negative lens group with a focal length of f3, the second dispersive lens group 4 is a positive lens group with a focal length of f4, the second transfer lens group 5 is a negative lens group with a focal length of f5, and the third dispersive lens group 6 is a positive lens group with a focal length of f6, then -2.7 <f2 / f3<-2.3,1.7<f2 / f4<2,-1.8<f2 / f5<-1.6,1.4<f2 / f6<1.7。

[0027] The diffusion lens group 1 is provided with a first single lens 11, a second single lens 12, a third single lens 13 and a fourth single lens 14 arranged in sequence from the object side to the image side, wherein the focal lengths of the first single lens 11 and the fourth single lens 14 are negative, the focal lengths of the second single lens 12 and the third single lens 13 are positive, and the first single lens 11 and the second single lens 12 form a cemented lens with a negative focal length. In this embodiment, the focal length range of the first single lens 11 is -48mm to -43mm, the focal length range of the second single lens 12 is 60mm to 70mm, the focal length range of the third single lens 13 is 80mm to 100mm, and the focal length range of the fourth single lens 14 is -170mm to -150mm.

[0028] The first dispersion lens group 2 is provided with a fifth single lens 21 and a sixth single lens 22, both of which have positive focal lengths, arranged in sequence from the object side to the image side. In this embodiment, the focal length range of the fifth single lens 21 is 150 mm to 190 mm, and the focal length range of the sixth single lens 22 is 160 mm to 200 mm.

[0029] The first transfer lens group 3 is provided with a seventh single lens 31 and an eighth single lens 32, both of which have negative focal lengths, arranged in sequence from the object side to the image side. In this embodiment, the focal length range of the seventh single lens 31 is -90mm to -60mm, and the focal length range of the eighth single lens 32 is -90mm to -50mm.

[0030] The second dispersion lens group 4 is provided with a ninth single lens 41, a tenth single lens 42, an eleventh single lens 43 and a twelfth single lens 44, all of which have positive focal lengths, arranged in sequence from the object side to the image side. In this embodiment, the focal length range of the ninth single lens 41 is 160 mm to 240 mm, the focal length range of the tenth single lens 42 is 160 mm to 230 mm, the focal length range of the eleventh single lens 43 is 160 mm to 230 mm, and the focal length range of the twelfth single lens 44 is 160 mm to 240 mm.

[0031] The second transfer lens group 5 has a thirteenth single lens 51 and a fourteenth single lens 52 arranged in sequence from the object side to the image side. In this embodiment, the focal length of the thirteenth single lens 51 ranges from -120mm to -70mm, and the focal length of the fourteenth single lens 52 ranges from -150mm to -100mm.

[0032] The third dispersion lens group 6 is provided with a fifteenth single lens 61, a sixteenth single lens 62 and a seventeenth single lens 63, all of which have positive focal lengths, arranged in sequence from the object side to the image side. In this embodiment, the focal length range of the fifteenth single lens 61 is 140 mm to 200 mm, the focal length range of the sixteenth single lens 62 is 120 mm to 180 mm, and the focal length range of the seventeenth single lens 63 is 150 mm to 250 mm.

[0033] The spectral confocal probe of the present invention is at a specific wavelength λ0 within its working wavelength band [λ1, ..., λ0, ..., λ2], such as Figure 2 As shown, it corresponds to the back intercept The absolute value of the difference between the short-wave limit λ1 and the long-wave limit λ2 and the corresponding back intercept is 3.6 mm, that is:

[0034]

[0035]

[0036]

[0037] -Δ1=Δ2=3.6mm; at this time, the lateral measurement range of the line spectrum confocal probe is h=17mm.

[0038] 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, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A line spectrum confocal probe, comprising a slit and a lens barrel, wherein the slit is arranged at one end of the lens barrel and is used to introduce a polychromatic line light source with a fixed bandwidth into the lens barrel, characterized in that: A dispersion lens group is distributed in the lens barrel and along the slit emission light path, so that the complex light is separated and focused by the dispersion lens group, and light of different wavelengths is focused at different positions in the optical axis direction and distributed in sequence as the wavelength increases. It is used to place the object to be measured into the dispersion area of ​​the probe, and obtain the current position of the object to be measured relative to the dispersion lens group according to the peak information of the spectrum of the light reflected from the surface of the object to be measured.

2. The line spectrum confocal probe according to claim 1, characterized in that: The light propagation directions of the dispersion lens group along the slit emission light path are, in order, a diffusion lens group (1), a first dispersion lens group (2), a first transfer lens group (3), a second dispersion lens group (4), a second transfer lens group (5) and a third dispersion lens group (6); the diffusion lens group (1) is used to expand the incident light beam; the first dispersion lens group (2) is used to bear part of the dispersion of the dispersion lens group; the second dispersion lens group (4) is used to bear the main dispersion of the dispersion lens group; the third dispersion lens group (6) is used to bear part of the dispersion of the dispersion lens group, image the light on the image plane, and make the main light of each field of view perpendicular to the image plane; the first transfer lens group (3) is used to transfer the first dispersion lens group (2) and the second dispersion lens group (4); the second transfer lens group (5) is used to transfer the second dispersion lens group (4) and the third dispersion lens group (6).

3. The line spectrum confocal probe according to claim 2, characterized in that: The focal length of the diffusion lens group (1) is positive, and has a small positive spherical aberration and a small negative chromatic aberration; the focal lengths of the first dispersion lens group (2), the second dispersion lens group (4) and the third dispersion lens group (6) are positive, so as to cumulatively generate a large negative chromatic aberration, assume the dispersion function, and generate a large positive spherical aberration; the focal lengths of the first transfer lens group (3) and the second transfer lens group (5) are negative, so as to generate a negative spherical aberration, which is used to correct the overall spherical aberration of the dispersion lens group, and generate a small positive chromatic aberration.

4. The line spectrum confocal probe according to claim 3, characterized in that: The diffusion lens group (1) comprises a first single lens (11), a second single lens (12), a third single lens (13) and a fourth single lens (14) arranged in sequence from the object side to the image side, wherein the focal lengths of the first single lens (11) and the fourth single lens (14) are negative, the focal lengths of the second single lens (12) and the third single lens (13) are positive, and the first single lens (11) and the second single lens (12) form a cemented lens with a negative focal length.

5. The line spectrum confocal probe according to claim 3, characterized in that: The first dispersion lens group (2) comprises a fifth single lens (21) and a sixth single lens (22) which are arranged in sequence from the object side to the image side and both have positive focal lengths.

6. The line spectrum confocal probe according to claim 3, characterized in that: The first transfer lens group (3) comprises a seventh single lens (31) and an eighth single lens (32) which are both of negative focal lengths and are arranged in sequence from the object side to the image side.

7. The line spectrum confocal probe according to claim 3, characterized in that: The second dispersion lens group (4) comprises a ninth single lens (41), a tenth single lens (42), an eleventh single lens (43) and a twelfth single lens (44) which all have positive focal lengths and are arranged in sequence from the object side to the image side.

8. The line spectrum confocal probe according to claim 3, characterized in that: The second transfer lens group (5) is provided with a thirteenth single lens (51) and a fourteenth single lens (52) having the same focal length, which are arranged in sequence from the object side to the image side.

9. The line spectrum confocal probe according to claim 3, characterized in that: The third dispersion lens group (6) comprises a fifteenth single lens (61), a sixteenth single lens (62) and a seventeenth single lens (63) which are all arranged in sequence from the object side to the image side, and all of which have positive focal lengths.

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