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 present application relates to the field of spectral measurement instrument, in particular to a line spectrum confocal probe head. BACKGROUND

[0002] Spectral confocal displacement measurement is a non-contact precision ranging technology, which realizes the axial position separation and focusing of complex light spectrum by using a dispersion lens group, and converts the spectral measurement to distance measurement by means of a spectrometer according to the one-to-one correspondence between the strongest reflected spectrum of an object and the relative position of the measured object and the dispersion lens group. Through axial point scanning, precise measurement of a small distance can be achieved.

[0003] The mature spectral displacement sensor scanning method is single-point scanning, and one point of relative distance information is obtained by one measurement. If three-dimensional information of the measured object surface is required to be measured, a two-dimensional scanning device is required to complete the measurement, which will affect the measurement efficiency and is not suitable for rapid measurement. At present, line spectral confocal displacement measurement can improve the low efficiency of single-point scanning, which is specifically through line light illumination instead of point light spot illumination in point spectral confocal displacement measurement. Such line light illumination has higher requirements for the dispersion lens group, and in addition to ensuring the longitudinal measurement range, it also needs to ensure the same imaging quality on and off the axis to meet the consistency of the measurement accuracy on and off the axis. SUMMARY

[0004] The present application aims to overcome the problems existing in the prior art, and provides a line spectral confocal probe head, which can realize line field detection and simultaneously obtain the position information of the measured object on and off the axis, thereby ensuring the longitudinal measurement range and improving the transverse measurement efficiency.

[0005] In order to achieve the above technical purposes and achieve the above technical effects, the present application realizes the following technical solutions:

[0006] A line spectral confocal probe head, comprising a slit and a lens barrel, the slit is arranged at one end of the lens barrel and used to introduce a fixed-bandwidth complex line light source into the lens barrel, a dispersion lens group is distributed along the light emission path in the lens barrel and emits light, so that the complex light is separated and focused by the dispersion lens group, the light of different wavelengths is focused at different positions in the optical axis direction and is distributed in sequence with the increase of wavelength, the measured object is placed in the dispersion area of the probe head, and the current position of the measured object relative to the dispersion lens group is obtained according to the peak value information of the reflected light spectrum of the measured object surface.

[0007] Further, the dispersion lens group is arranged along the light propagation direction on the light path of the slit in sequence as a diffusion lens group, a first dispersion lens group, a first adapter lens group, a second dispersion lens group, a second adapter lens group and a third dispersion lens group, the diffusion lens group is used for expanding the incident light beam, the first dispersion lens group is used for bearing part of the dispersion of the dispersion lens group, the second dispersion lens group is used for bearing the main dispersion of the dispersion lens group, the third dispersion lens group is used for bearing part of the dispersion of the dispersion lens group, and the light is imaged on the image plane, and the chief ray of each field of view is perpendicular to the image plane, the first adapter lens group is used for bearing the first dispersion lens group and the second dispersion lens group, and the second adapter lens group is used for bearing the second dispersion lens group and the third dispersion lens group.

[0008] Further, the focal length of the diffusion lens group is positive, has a small positive spherical aberration and a small negative chromatic aberration, the focal length of the first dispersion lens group, the second dispersion lens group and the third dispersion lens group is positive, so as to accumulate a large negative chromatic aberration, bear the dispersion function, and at the same time generate a large positive spherical aberration, the focal length of the first adapter lens group and the second adapter lens group is negative, so as to generate a negative spherical aberration, correct the overall spherical aberration of the dispersion lens group, and at the same time generate a small positive spherical aberration.

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

[0010] Further, the fifth single lens and the sixth single lens with positive focal length are arranged in sequence from the object side to the image side in the first dispersion lens group.

[0011] Further, the seventh single lens and the eighth single lens with negative focal length are arranged in sequence from the object side to the image side in the first adapter lens group.

[0012] Further, the ninth single lens, the tenth single lens, the eleventh single lens and the twelfth single lens with positive focal length are arranged in sequence from the object side to the image side in the second dispersion lens group.

[0013] Further, the thirteenth single lens and the fourteenth single lens with negative focal length are arranged in sequence from the object side to the image side in the second adapter lens group.

[0014] Further, the fifteenth single lens, the sixteenth single lens and the seventeenth single lens with positive focal length are arranged in sequence from the object side to the image side in the third dispersion lens group.

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

[0016] The linear light source of the probe of this invention can realize linear field of view detection and simultaneously acquire the position information of the object on and off the axis. While ensuring the longitudinal measurement range, it improves the lateral measurement efficiency. Its longitudinal measurement range can reach ±3.6mm and its lateral measurement range can reach ±8.5mm. Attached Figure Description

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

[0018] Figure 2 This is a schematic diagram of the image parameters of the line spectrum confocal measurement head of the present invention.

[0019] The following are the labeling instructions in the diagram: 1. Diffusion lens group; 11. First single lens; 12. Second single lens; 13. Third single lens; 14. Fourth single lens; 2. First dispersive lens group; 21. Fifth single lens; 22. Sixth single lens; 3. First adapter lens group; 31. Seventh single lens; 32. Eighth single lens; 4. Second dispersive lens group; 41. Ninth single lens; 42. Tenth single lens; 43. Eleventh single lens; 44. Twelfth single lens; 5. Second adapter lens group; 51. Thirteenth single lens; 52. Fourteenth single lens; 6. Third dispersive lens group; 61. Fifteenth single lens; 62. Sixteenth single lens; 63. Seventeenth single lens. Detailed Implementation

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

[0021] A line spectrum confocal probe includes a slit and a lens barrel. The slit is located 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. A dispersive lens group is distributed inside the lens barrel and along the light path emitted by the slit, so that the polychromatic light is separated and focused by the dispersive lens group. Light of different wavelengths is focused at different positions in the optical axis direction and is distributed sequentially with increasing wavelength. It is used to place the object to be measured in the dispersive region of the probe and obtain the current position of the object relative to the dispersive lens group based on the peak information of the spectrum of the reflected light from the surface of the object.

[0022] like Figure 1As shown, the dispersive lens group consists of a diffusion lens group 1, a first dispersive lens group 2, a first transition lens group 3, a second dispersive lens group 4, a second transition lens group 5, and a third dispersive lens group 6, arranged sequentially along the light propagation direction of the emitted light path through the slit. 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 dispersive dispersion of the dispersive lens group. The second dispersive lens group 4 is used to bear the main dispersive dispersion of the dispersive lens group. The third dispersive lens group 6 is used to bear part of the dispersive dispersion of the dispersive lens group, image the light on the image plane, and make the principal rays of each field of view perpendicular to the image plane. The first transition lens group 3 is used to transfer the first dispersive lens group 2 and the second dispersive lens group 4. The second transition lens group 5 is used to transfer the second dispersive lens group 4 and the third dispersive lens group 6.

[0023] The diffuser lens group 1 has a positive focal length, exhibiting small positive spherical aberration and small negative chromatic aberration. The first dispersive lens group 2, the second dispersive lens group 4, and the third dispersive lens group 6 have positive focal lengths to accumulate and generate a large negative chromatic aberration, thus fulfilling the dispersive function, while also generating a large positive spherical aberration. The first adapter lens group 3 and the second adapter lens group 5 have negative focal lengths to generate negative spherical aberration, used to correct the overall spherical aberration of the dispersive lens group, while also generating a small positive chromatic aberration. The spherical aberrations of the diffuser lens group 1, the first dispersive lens group 2, the first adapter lens group 3, the second dispersive lens group 4, the second adapter lens group 5, and the third dispersive lens group 6 are respectively denoted as ΣS. I1 , ΣS I2 , ΣS I3 , ΣS I4 , ΣS I5 , ΣS I6 The axial color differences are ΣC I1 , ΣC I2 , ΣC I3 , ΣC I4 , ΣC I5 , ΣC I6 This structure can be flexibly adjusted to meet various chromatic aberration and optical power requirements, and the selected dimensions of the dispersive lens group are constrained. The maximum diameter of the lens in the lens group is D = 90 mm. Within its working wavelength range [λ1, λ2], λ1 and λ2 are the short-wavelength and long-wavelength limits of the working wavelength range, respectively, so that the dispersive lens group satisfies:

[0024] ΣS I1 +ΣS I2 +ΣS I4 +ΣS I6 =-(ΣS I3 +ΣS I5 )

[0025] ΣC I1 +ΣC I2 +ΣCI3 +ΣC I4 +ΣC I5 +ΣC I6 =MR=7.2mm, where MR is the measurable range of the spectral confocal focal plane.

[0026] In this embodiment, the numerical aperture of the slit-emitted beam is na, the focal length of the dispersive probe of this invention is f, and the exit pupil is #out. Therefore, the image-side F-number is f / #out, and... The first dispersive lens group 2 is a positive lens group with a focal length of f2; the first transition 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 transition 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. Therefore, -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 diffuser 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 sequentially from the object side to the image side. The first single lens 11 and the fourth single lens 14 have negative focal lengths, while the second single lens 12 and the third single lens 13 have positive focal lengths. 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 dispersive lens group 2 includes a fifth single lens 21 and a sixth single lens 22, both with positive focal lengths, arranged sequentially from the object side to the image side. In this embodiment, the focal length of the fifth single lens 21 ranges from 150mm to 190mm, and the focal length of the sixth single lens 22 ranges from 160mm to 200mm.

[0029] The first adapter lens group 3 includes a seventh single lens 31 and an eighth single lens 32, both with negative focal lengths, arranged sequentially 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 dispersive lens group 4 includes a ninth single lens 41, a tenth single lens 42, an eleventh single lens 43, and a twelfth single lens 44, all with positive focal lengths, arranged sequentially from the object side to the image side. In this embodiment, the focal length range of the ninth single lens 41 is 160mm to 240mm, the focal length range of the tenth single lens 42 is 160mm to 230mm, the focal length range of the eleventh single lens 43 is 160mm to 230mm, and the focal length range of the twelfth single lens 44 is 160mm to 240mm.

[0031] The second adapter lens group 5 includes a thirteenth single lens 51 and a fourteenth single lens 52, both with the same focal length, arranged sequentially from the object side to the image side. In this embodiment, the focal length range of the thirteenth single lens 51 is -120mm to -70mm, and the focal length range of the fourteenth single lens 52 is -150mm to -100mm.

[0032] The third dispersive lens group 6 includes, from object to image, a fifteenth single lens 61, a sixteenth single lens 62, and a seventeenth single lens 63, all with positive focal lengths. In this embodiment, the focal length range of the fifteenth single lens 61 is 140mm to 200mm, the focal length range of the sixteenth single lens 62 is 120mm to 180mm, and the focal length range of the seventeenth single lens 63 is 150mm to 250mm. The spectral confocal probe of this invention operates at a specific wavelength λ0 within its working band [λ1,…,λ0,…,λ2], such as… Figure 2 As shown, its corresponding back intercept The absolute value of the difference between the back intercept and the shortwave limit λ1 and the longwave limit λ2 is 3.6 mm, that is: At this point, the lateral measurement range of the line spectrum confocal probe is h = 17 mm.

[0033] Furthermore, it should be noted that, unless otherwise specified or indicated, the terms "first," "second," "third," etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, and steps.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A line spectrum confocal probe, comprising a slit and a lens barrel, wherein the slit is disposed at one end of the lens barrel for introducing a polychromatic line light source of fixed bandwidth into the lens barrel, characterized in that, A dispersive lens group is distributed inside the lens barrel and along the light path emitted by the slit, so that polychromatic light is separated and focused by the dispersive lens group. Light of different wavelengths is focused at different positions in the optical axis direction and is distributed sequentially as the wavelength increases. This is used to place the object under test into the dispersive area of ​​the probe and obtain the current position of the object under test relative to the dispersive lens group based on the peak information of the spectrum of the reflected light from the surface of the object under test.

2. The line spectral confocal probe according to claim 1, characterized in that, The dispersive lens group consists of a diffusion lens group (1), a first dispersive lens group (2), a first transition lens group (3), a second dispersive lens group (4), a second transition lens group (5), and a third dispersive lens group (6) along the light propagation direction of the light emitted from the slit. 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 dispersive dispersion of the dispersive lens group. The second dispersive lens group (4) is used to bear the main dispersive dispersion of the dispersive lens group. The third dispersive lens group (6) is used to bear part of the dispersive dispersion of the dispersive lens group, image the light on the image plane, and make the principal rays of each field of view perpendicular to the image plane. The first transition lens group (3) is used to transfer the first dispersive lens group (2) and the second dispersive lens group (4). The second transition lens group (5) is used to transfer the second dispersive lens group (4) and the third dispersive 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 it has positive spherical aberration and negative chromatic aberration. The focal lengths of the first dispersive lens group (2), the second dispersive lens group (4) and the third dispersive lens group (6) are positive, so as to accumulate and generate negative chromatic aberration, undertake the dispersive function, and generate positive spherical aberration at the same time. The focal lengths of the first adapter lens group (3) and the second adapter lens group (5) are negative, so as to generate negative spherical aberration, which is used to correct the overall spherical aberration of the dispersive lens group, and generate positive chromatic aberration at the same time.

4. The line spectrum confocal probe according to claim 3, characterized in that, The diffuser lens group (1) consists of a first single lens (11), a second single lens (12), a third single lens (13), and a fourth single lens (14) arranged sequentially from the object side to the image side. The first single lens (11) and the fourth single lens (14) have negative focal lengths, while the second single lens (12) and the third single lens (13) have positive focal lengths. 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 dispersive lens group (2) has a fifth single lens (21) and a sixth single lens (22) with positive focal lengths arranged sequentially from the object side to the image side.

6. The line spectrum confocal probe according to claim 3, characterized in that, The first adapter lens group (3) has a seventh single lens (31) and an eighth single lens (32) with negative focal lengths arranged sequentially from the object side to the image side.

7. The line spectral confocal probe according to claim 3, characterized in that, The second dispersive lens group (4) is arranged in sequence from the object side to the image side with a ninth single lens (41), a tenth single lens (42), an eleventh single lens (43) and a twelfth single lens (44), all with positive focal lengths.

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

9. The line spectral confocal probe according to claim 3, characterized in that, The third dispersive lens group (6) includes a fifteenth single lens (61), a sixteenth single lens (62), and a seventeenth single lens (63), all with positive focal lengths, arranged sequentially from the object side to the image side.

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