High-resolution spectral confocal measurement device

Abstract

The utility model provides a high-resolution spectral confocal measurement device, which includes a light source, a fiber coupler, a spectral confocal lens, a spectral analysis unit and a data processing unit. The spectral confocal lens is arranged between the fiber coupler and the sample to be measured. The spectral confocal lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence. The first lens is a double concave lens, the second lens is a meniscus lens, the third lens is a plano-convex lens, the fourth lens is a double-cemented lens, the fifth lens is a meniscus lens, and the sixth lens is a meniscus lens. With such an arrangement, the spectral confocal lens is improved from multiple aspects such as expanding the incident light beam, correcting aberrations, reducing spherical aberrations, and correcting coma and chromatic aberration, thereby greatly improving the resolution of the lens. The light source is further connected to the spectral confocal lens through a fiber coupler, so that the entire device has a compact structure and is easy to integrate and install.

Description

Technical Field

[0001] The utility model relates to the field of photoelectric measurement, in particular to a high-resolution spectral confocal measurement device. Background Art

[0002] Spectral confocal measurement technology, with its non-contact characteristics, can be applied to a variety of opaque materials, such as metals, ceramics and plastics. This technology is less sensitive to factors such as surface texture, tilt angle and stray light, and has rapid measurement capabilities. Therefore, it is widely used in many fields such as 3D profile scanning, roughness detection, and micro-displacement measurement.

[0003] Spectral confocal technology measures distance by analyzing wavelength information. The specific principle is as follows: the wide-spectrum composite light emitted by the light source (usually white light) is dispersed by the dispersion lens group to form monochromatic light of different wavelengths. The light focus of each wavelength corresponds to a specific distance value. When the measuring light is directed to the surface of the object and reflected back, only the monochromatic light that meets the confocal condition can be captured by the spectrometer through the small hole or slit. By calculating the detected focal wavelength, it can be converted into the corresponding distance data.

[0004] However, the challenges currently faced by spectral confocal thickness measurement equipment include but are not limited to the following: high resolution requirements place extremely high demands on the accuracy and stability of the equipment, so existing equipment faces difficulties in measuring samples with a thickness of less than 0.01 mm; the optical path of the spectral box is difficult to adjust, which makes the calibration process of the device complicated, increasing the difficulty and cost of use; there are large differences in performance between each device, affecting the consistency and repeatability of the measurement results.

[0005] Therefore, it is necessary to design a high-resolution spectral confocal measurement device to solve the above problems. Utility Model Content

[0006] The utility model aims to provide a high-resolution spectral confocal measuring device with high precision, high efficiency, simple light path adjustment and the ability to measure samples with smaller sample thickness.

[0007] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a high-resolution spectral confocal measurement device, which includes a light source, a fiber coupler, a spectral confocal lens, a spectral analysis unit and a data processing unit. The spectral confocal lens is arranged between the fiber coupler and the sample to be measured. The spectral confocal lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object side to the image side. The first lens is a biconcave lens, the second lens is a meniscus lens, the third lens is a plano-convex lens, the fourth lens is a double cemented lens, the fifth lens is a meniscus lens, and the sixth lens is a meniscus lens.

[0008] As a further improved technical solution of the utility model, the focal length of the first lens is -46 to -45 mm, the focal length of the second lens is 40 to 45 mm, the focal length of the third lens is 125 to 130 mm, the focal length of the fourth lens is 145 to 150 mm, the focal length of the fifth lens is 60 to 65 mm, and the focal length of the sixth lens is 40 to 45 mm.

[0009] As a further improved technical solution of the utility model, the refractive indexes of the first lens and the third lens are 1.61-1.68, the refractive indexes of the second lens and the fifth lens are 1.72-1.78, the refractive index of the first sub-lens glued together in the fourth lens is 1.75-1.78, the refractive index of the second sub-lens is 1.68-1.72, and the refractive index of the sixth lens is 1.78-1.80.

[0010] As a further improved technical solution of the utility model, the distance between the first lens and the second lens is 2 to 3 mm, the distance between the second lens and the third lens is 77 to 80 mm, the distance between the third lens and the fourth lens is 2 to 3 mm, the distance between the fourth lens and the fifth lens is 5 to 10 mm, and the distance between the fifth lens and the sixth lens is 4 to 8 mm.

[0011] As a further improved technical solution of the utility model, the center thickness of the first lens is 3.8-4.5 mm, the center thickness of the second lens is 4-6 mm, the center thickness of the third lens is 6-8 mm, the center thickness of the fourth lens is 10-13 mm, the center thickness of the fifth lens is 5-6 mm, and the center thickness of the sixth lens is 5-6 mm.

[0012] As a further improved technical solution of the utility model, the spectral confocal lens is connected to the fiber coupler through an optical fiber, and the spectral confocal lens has an entrance slit on the side facing the fiber coupler, and the size of the entrance slit is equal to the effective light diameter of the port of the optical fiber.

[0013] As a further improved technical solution of the utility model, the axial dispersion range of the image-side focal plane of the spectral confocal lens is 0-0.4 mm.

[0014] As a further improved technical solution of the utility model, the light source is a complex color light source.

[0015] As a further improved technical solution of the utility model, the optical fiber coupler is a Y-type optical fiber coupler.

[0016] It can be seen from the above technical solutions that the high-resolution spectral confocal measurement device of the utility model improves the spectral confocal lens from multiple aspects such as expanding the incident light beam, correcting aberrations, reducing spherical aberrations, and correcting coma and chromatic aberration, thereby greatly improving the resolution of the lens. The light source is further connected to the spectral confocal lens through a fiber optic coupler, making the entire device compact and easy to integrate and install. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a high-resolution spectral confocal measurement device according to an embodiment of the present invention.

[0018] Figure 2 for Figure 1 Schematic diagram of a mid-spectral confocal lens.

[0019] Figure 3 for Figure 1 Spot diagram of the medium- and high-resolution spectral confocal measurement setup. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Please refer to Figure 1 As shown, the utility model provides a high-resolution spectral confocal measurement device, which includes a light source 10, a fiber coupler 20, a spectral confocal lens 30, a spectral analysis unit 50 and a data processing unit 60 arranged in sequence along the optical path. The spectral confocal lens 30 is arranged between the fiber coupler 20 and the sample 40 to be measured.

[0022] Among them, the light source 10 is a polychromatic light source, and the fiber coupler 20 is a Y-type fiber coupler. An optical fiber 201 is connected between the light source 10 and the fiber coupler 20, and an optical fiber 203 is connected between the fiber coupler 20 and the spectral confocal lens 30. The spectral confocal lens 30 has an incident slit on the side facing the fiber coupler 20, and the size of the incident slit is equal to the effective light diameter of the port of the optical fiber 203. An optical fiber 202 is connected between the fiber coupler 20 and the spectral analysis unit 50. The fiber coupler 20 adopts a Y-type fiber coupler to replace the traditional pinhole and the beam splitter prism, which not only makes the structure of the entire optical path system more compact, but also reduces the difficulty of adjusting the conjugate relationship of the pinhole; in addition, the fiber coupler 20 has the advantages of small size, light weight, low loss, fast transmission speed, and anti-electromagnetic interference. It can also separate larger light sources, spectrometers and other equipment from the probe, and can be used for measurements at longer distances and in more scenes.

[0023] Please refer to Figure 2As shown, the spectral confocal lens 30 includes a first lens 302, a second lens 303, a third lens 304, a fourth lens 305, a fifth lens 306 and a sixth lens 307 which are sequentially arranged from the object side 301 (the side of the sample to be measured) to the image side 308. Among them, the first lens 302 is a biconcave lens, the second lens 303 is a meniscus lens, the third lens 304 is a plano-convex lens, the fourth lens 305 is a double cemented lens, the fifth lens 306 is a meniscus lens, and the sixth lens 307 is a meniscus lens.

[0024] Preferably, the focal length of the first lens 302 is -46 to -45 mm, the focal length of the second lens 303 is 40 to 45 mm, the focal length of the third lens 304 is 125 to 130 mm, the focal length of the fourth lens 305 is 145 to 150 mm, the focal length of the fifth lens 306 is 60 to 65 mm, and the focal length of the sixth lens 307 is 40 to 45 mm.

[0025] Preferably, the refractive indexes of the first lens 302 and the third lens 304 are 1.61-1.68, the refractive indexes of the second lens 303 and the fifth lens 306 are 1.72-1.78, the refractive index of the first sub-lens 3051 glued together in the fourth lens 305 is 1.75-1.78, the refractive index of the second sub-lens 3052 is 1.68-1.72, and the refractive index of the sixth lens 307 is 1.78-1.80.

[0026] Preferably, the distance between the first lens 302 and the second lens 303 is 2 to 3 mm, the distance between the second lens 303 and the third lens 304 is 77 to 80 mm, the distance between the third lens 304 and the fourth lens 305 is 2 to 3 mm, the distance between the fourth lens 305 and the fifth lens 306 is 5 to 10 mm, and the distance between the fifth lens 306 and the sixth lens 307 is 4 to 8 mm.

[0027] Preferably, the center thickness of the first lens 302 is 3.8-4.5 mm, the center thickness of the second lens 303 is 4-6 mm, the center thickness of the third lens 304 is 6-8 mm, the center thickness of the fourth lens 305 is 10-13 mm, the center thickness of the fifth lens 306 is 5-6 mm, and the center thickness of the sixth lens is 5-6 mm.

[0028] This embodiment provides a better spectral confocal lens 30, and the following Table 1 shows the relevant parameters of the spectral confocal lens 30. Among them, the focal length of the first lens 302 is -45.01 mm, the focal length of the second lens 303 is 40.06 mm, the focal length of the third lens 304 is 122.8 mm, the focal length of the fourth lens 305 is 143.05 mm, the focal length of the fifth lens 306 is 60.3 mm, and the focal length of the sixth lens 307 is 40.4 mm. The axial dispersion range of the image side 308 focal plane of the spectral confocal lens 30 of this embodiment is 0-0.4 mm.

[0029] Table 1 Optical parameters of spectral confocal lens

[0030]

[0031] By designing the curvature, material, spacing and sequence of the first lens 302 to the sixth lens 307, aberrations, especially chromatic aberration and spherical aberration, are reduced, thereby improving the resolution and greatly improving the optical performance of the lens.

[0032] The spectral analysis unit 50 includes an incident slit, a collimating lens, a beam splitter, an imaging lens, and a camera arranged in sequence. The incident slit is connected to the optical fiber 202 to image the light passing through the spectral confocal lens 30 on the camera after collimation and dispersion, and further perform data processing and analysis through the data processing unit. The resolution of the spectral analysis unit 50 is better than 4nm, and the axial dispersion range of the image focal plane of the spectral confocal lens 30 is 0-0.4mm. Therefore, the high-resolution spectral confocal measurement device in this embodiment can distinguish the minimum thickness of the sample as low as 8μm. Please refer to Figure 3 As shown, it is a point diagram measured by the high-resolution spectral confocal measurement device of this embodiment, wherein the spot diameter ranges from 0.546 μm to 0.554 μm, indicating that the optical system has good focusing ability and meets the high-resolution requirement of the utility model.

[0033] When the high-resolution spectral confocal measurement device in this embodiment is working, the light emitted by the light source 10 is incident on the spectral confocal lens 30 through the optical fibers 201 and 203. After passing through the spectral confocal lens 30, the light of different wavelengths is focused at different positions of the optical axis, thereby forming a series of focused light spots, and then generating axial dispersion. When the sample 40 to be measured is located in the axial dispersion range, the light of a specific wavelength is reflected back to the spectral confocal lens 30, and then enters the spectral analysis unit 50 through the optical fibers 203 and 202 in sequence, and the spectra of different wavelengths are identified. The peak wavelength can be obtained after a series of data processing is performed on the spectral signal collected by the spectral analysis unit by the data quantity unit 60. When the object to be measured moves within the measurement range, the peak wavelength will change. The extracted peak wavelength has a one-to-one correspondence with the position of the object to be measured. The mapping relationship between the peak wavelength and the position of the object to be measured can be obtained by calibration. During measurement, the displacement value of the object to be measured can be obtained by the change of the peak wavelength.

[0034] Terms such as "upper", "lower", "front", "back" and the like used herein to indicate spatial relative positions are used for the purpose of convenience to describe the relationship of one feature relative to another feature as shown in the drawings. It is understood that, depending on the placement of the product, the terms of spatial relative positions may be intended to include different orientations in addition to the orientation shown in the drawings, and should not be construed as limitations on the claims.

[0035] In addition, the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. The understanding of this specification should be based on the technical personnel in the relevant technical field. Although this specification has described the present invention in detail with reference to the above embodiments, ordinary technical personnel in the field should understand that the technical personnel in the relevant technical field can still modify or make equivalent substitutions to the present invention, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A high-resolution spectral confocal measurement device, characterized in that: The invention comprises a light source, an optical fiber coupler, a spectral confocal lens, a spectral analysis unit and a data processing unit. The spectral confocal lens is arranged between the optical fiber coupler and the sample to be measured. The spectral confocal lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object side to the image side. The first lens is a double concave lens, the second lens is a meniscus lens, the third lens is a plano-convex lens, the fourth lens is a double cemented lens, the fifth lens is a meniscus lens, and the sixth lens is a meniscus lens.

2. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The focal length of the first lens is -46 to -45 mm, the focal length of the second lens is 40 to 45 mm, the focal length of the third lens is 125 to 130 mm, the focal length of the fourth lens is 145 to 150 mm, the focal length of the fifth lens is 60 to 65 mm, and the focal length of the sixth lens is 40 to 45 mm.

3. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The refractive indexes of the first lens and the third lens are 1.61 to 1.68, the refractive indexes of the second lens and the fifth lens are 1.72 to 1.78, the refractive index of the first sub-lens glued together in the fourth lens is 1.75 to 1.78, the refractive index of the second sub-lens is 1.68 to 1.72, and the refractive index of the sixth lens is 1.78 to 1.

80.

4. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The distance between the first lens and the second lens is 2 to 3 mm, the distance between the second lens and the third lens is 77 to 80 mm, the distance between the third lens and the fourth lens is 2 to 3 mm, the distance between the fourth lens and the fifth lens is 5 to 10 mm, and the distance between the fifth lens and the sixth lens is 4 to 8 mm.

5. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The center thickness of the first lens is 3.8-4.5 mm, the center thickness of the second lens is 4-6 mm, the center thickness of the third lens is 6-8 mm, the center thickness of the fourth lens is 10-13 mm, the center thickness of the fifth lens is 5-6 mm, and the center thickness of the sixth lens is 5-6 mm.

6. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The spectral confocal lens is connected to the fiber coupler via an optical fiber. The spectral confocal lens has an incident slit on the side facing the fiber coupler. The size of the incident slit is equal to the effective light diameter of the port of the optical fiber.

7. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The axial dispersion range of the image side focal plane of the spectral confocal lens is 0-0.4 mm.

8. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The light source is a polychromatic light source.

9. The high-resolution spectral confocal measurement device according to claim 1, characterized in that: The optical fiber coupler is a Y-type optical fiber coupler.

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