Wide-range spectrum confocal dispersion lens

Abstract

The utility model provides a wide-range spectrum confocal dispersion lens. A first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power and a fifth lens with positive focal power are sequentially arranged between an optical fiber end of a light source and an image plane. The first lens has a positive focal power, the second lens has a negative focal power, the sixth lens has a negative focal power, the seventh lens has a negative focal power, the eighth lens has a positive focal power, and the ninth lens has a positive focal power. The fifth lens and the sixth lens are glued, and the seventh lens and the eighth lens are glued. The lens is good in imaging quality and high in resolution, and can solve the problems that an existing dispersion lens is small in measurement range, sensitive in tolerance, high in cost and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical detection, and particularly relates to a large-range spectral confocal dispersion lens. Background Art

[0002] The spectral confocal technology is insensitive to environmental changes. It completes the emission and reception of light through the same optical path, avoiding the risk of the optical path being blocked. It not only has the advantages of high precision and low environmental dependence, but also can adapt to various measurement tasks. In addition to measuring surface profiles and topographies, it can also be used to detect the thickness of transparent materials. Through the cooperation of multiple probes, this technology can also achieve more functional measurements. Its non-destructive, non-contact and efficient characteristics make it widely used in industrial manufacturing, aerospace, medical devices and semiconductor fields.

[0003] The spectral confocal dispersion lens is the core component of the spectral confocal displacement sensor. Its axial dispersion range determines the dispersion range of the spectral confocal displacement sensor, and the image-side numerical aperture NA determines its maximum measurement angle and also affects the spot size.

[0004] Currently, with the continuous improvement of industrial inspection requirements, the required measurement range and comprehensiveness of information have also increased significantly. Especially in fields with high requirements for the measurement range. Taking measured objects such as flat glass and tempered glass with relatively large thicknesses as examples, the difficulty of detection increases significantly with the increase in the thickness of the material. To meet such complex detection requirements, it is usually necessary to use a spectral confocal lens with large measurement range, high resolution and high precision for measurement. However, the supply of such high-performance lenses is relatively small, and they are relatively long, with a large number of lenses of various types. The use of multiple optical materials makes their production process complex and the process requirements high, directly leading to a substantial increase in manufacturing costs. In addition, the assembly and debugging processes of these lenses are time-consuming and laborious, further increasing the difficulty and cost of use. Summary of the Utility Model

[0005] The utility model provides a large-range spectral confocal dispersion lens to solve problems such as the small measurement range existing in the prior art.

[0006] According to the first aspect of the utility model, one or more embodiments of the present application provide a large-range spectral confocal dispersion lens, which includes:

[0007] A first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power are sequentially arranged between the fiber end of the light source and the image plane.

[0008] The fifth lens and the sixth lens are cemented, and the seventh lens and the eighth lens are cemented.

[0009] Among them, the effective focal length of the large-range spectral confocal dispersion lens is f, the focal length of the first lens is f1, and the focal length of the ninth lens is f9. Then 0.88 < |f1 / f| < 1.3, 3.92 < |f9 / f| < 7.98.

[0010] Among them, the first lens is a plano-concave lens, the incident surface is concave, and the exit surface is flat;

[0011] The second lens is a meniscus lens, the incident surface is concave, and the exit surface is convex;

[0012] The third lens is a meniscus lens, the incident surface is concave, and the exit surface is convex;

[0013] The fourth lens is a meniscus lens, the incident surface is concave, and the exit surface is convex;

[0014] The fifth lens is a plano-convex lens, the incident surface is convex, and the exit surface is flat;

[0015] The sixth lens is a plano-concave lens, the incident surface is flat, and the exit surface is concave;

[0016] The seventh lens is a biconcave lens, the incident surface is concave, and the exit surface is concave;

[0017] The eighth lens is a biconvex lens, the incident surface is convex, and the exit surface is convex;

[0018] The ninth lens is a biconvex lens, the incident surface is convex, and the exit surface is convex;

[0019] Among them, the aperture stop is located at the concave surface of the first lens.

[0020] Among them, the first lens is made of lanthanum crown glass material, the second lens is made of lanthanum flint glass material, the third lens is made of heavy flint glass material, the fourth lens is made of heavy flint glass material, the fifth lens is made of heavy flint glass material, the sixth lens is made of light crown glass material, the seventh lens is made of light crown glass material, and the eighth lens and the ninth lens are made of heavy flint glass material.

[0021] Among them, the total length of the large-range spectral confocal dispersion lens is less than 100 mm, the measurement angle is at least 30°, and the dispersion range is 18 mm.

[0022] Among them, the apertures of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all less than 32 mm.

[0023] Among them, the light emitted by the light source is polychromatic light.

[0024] The beneficial effects of the present utility model are as follows: The present utility model provides a large-range spectral confocal dispersion lens, which consists of a total of 9 lenses; the structure of the dispersion lens of the spectral confocal displacement sensor includes, along the optical axis from the light source optical fiber end to the object to be measured: a light source, a first lens with negative optical power, a second lens with positive optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power; among them, the fifth and sixth lenses are cemented, and the seventh and eighth lenses are cemented. After the light emitted from the object surface passes through the above lenses in sequence from left to right, it finally converges at the image plane in sequence according to different wavelengths. The reverse telephoto structure is adopted, which is beneficial to shortening the lens length, and the first negative lens helps to expand the divergence angle for light collection. The 9 lenses are combined with each other to correct aberrations; in this system, there is mainly spherical aberration related to the aperture. Among them, the third, fourth, and fifth lenses are split by a single lens to share the optical power. The middle group forms a double-cemented lens through the combination of positive and negative lenses to assist in the correction of monochromatic aberrations, and the optical power distribution of this system is reasonable. The total length of this lens does not exceed 100 mm, which is convenient for assembly and debugging. The working distance is 42 mm, the dispersion range within the wavelength range of 450 nm - 700 nm is 18 mm, the maximum measurement angle is greater than 30°, the imaging quality of the lens is good, and the resolution is high, which can solve the problems of small measurement range, tolerance sensitivity, high cost, etc. of the existing dispersion lenses. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of a large-range spectral confocal dispersion lens according to an embodiment of the present utility model.

[0026] Figure 2 It is a schematic optical path diagram of a large-range spectral confocal dispersion lens according to an embodiment of the present utility model.

[0027] Figure 3 It is a spot diagram of the 450 nm wavelength in polychromatic light according to an embodiment of the present utility model.

[0028] Figure 4 It is a spot diagram of the 537.5 nm wavelength in polychromatic light according to an embodiment of the present utility model.

[0029] Figure 5 It is a spot diagram of the 700 nm wavelength in polychromatic light according to an embodiment of the present utility model.

[0030] Figure 6 It is an MTF diagram under the condition of a wavelength of 450 nm according to an embodiment of the present utility model.

[0031] Figure 7This is the MTF graph of the embodiment of the present utility model under the condition of a wavelength of 537.5 nm.

[0032] Figure 8 This is the MTF graph of the embodiment of the present utility model under the condition of a wavelength of 700 nm.

[0033] Among them, the end face 0 of the optical fiber, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7, the eighth lens G8, and the ninth lens G9. Specific Embodiment

[0034] To make the purpose, technical solution, and advantages of the present disclosure clearer, the following further elaborates on the present disclosure in detail in combination with specific embodiments and with reference to the accompanying drawings.

[0035] It should be noted that unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of the present application should have the ordinary meaning understood by those of ordinary skill in the field to which the present disclosure pertains. The "first", "second", and similar terms used in one or more embodiments of the present application do not denote any order, quantity, or importance, but are only used to distinguish different components. The terms such as "include" or "comprise" mean that the elements or items appearing before this term cover the elements or items listed after this term and their equivalents, without excluding other elements or items. The terms such as "connect" or "couple" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0036] As Figures 1 - 8 shown, a large-range spectral confocal dispersion lens in one or more embodiments of the present application includes:

[0037] A first lens G1 with a negative optical power, a second lens G2 with a negative optical power, a third lens G3 with a positive optical power, a fourth lens G4 with a positive optical power, a fifth lens G5 with a positive optical power, a sixth lens G6 with a negative optical power, a seventh lens G7 with a negative optical power, an eighth lens G8 with a positive optical power, and a ninth lens G9 with a positive optical power are sequentially arranged between the fiber end of the light source and the image plane;

[0038] The fifth lens G5 and the sixth lens G6 are cemented, and the seventh lens G7 and the eighth lens G8 are cemented.

[0039] In a possible embodiment, the effective focal length of the large-range spectral confocal dispersion lens is f, the focal length of the first lens G1 is f1, and the focal length of the ninth lens G9 is f9. Then 0.88 < |f1 / f| < 1.3 and 3.92 < |f9 / f| < 7.98.

[0040] In a possible embodiment, the first lens G1 is a plano-concave lens, with the incident surface being concave and the exit surface being flat, and the optical power being -0.106 mm -1 ;

[0041] The second lens G2 is a meniscus lens, with the incident surface being concave and the exit surface being convex, and the optical power being -0.06 mm -1 ;

[0042] The third lens G3 is a meniscus lens, with the incident surface being concave and the exit surface being convex, and the optical power being 0.0323 mm -1 ;

[0043] The fourth lens G4 is a meniscus lens, with the incident surface being concave and the exit surface being convex, and the optical power being 0.0209 mm -1 ;

[0044] The fifth lens G5 is a plano-convex lens, with the incident surface being convex and the exit surface being flat, and the optical power being 0.026 mm -1 ;

[0045] The sixth lens G6 is a plano-concave lens, with the incident surface being flat and the exit surface being concave, and the optical power being -0.025 mm -1 ;

[0046] The seventh lens G7 is a bi-concave lens, with the incident surface being concave and the exit surface being concave, and the optical power being -0.0255 mm -1 ;

[0047] The eighth lens G8 is a bi-convex lens, with the incident surface being convex and the exit surface being convex, and the optical power being 0.0315 mm -1 ;

[0048] The ninth lens G9 is a bi-convex lens, with the incident surface being convex and the exit surface being convex, and the optical power being 0.0166 mm -1 ;

[0049] Among them, the aperture stop is located at the concave surface of the first lens G1.

[0050] In a possible embodiment, the first lens G1 is made of lanthanum crown glass material, the second lens G2 is made of lanthanum flint glass material, the third lens G3 is made of heavy flint glass material, the fourth lens G4 is made of heavy flint glass material, the fifth lens G5 is made of heavy flint glass material, the sixth lens G6 is made of light crown glass material, the seventh lens G7 is made of light crown glass material, and the eighth lens G8 and the ninth lens G9 are made of heavy flint glass material.

[0051] In a possible embodiment, the total length of the large-range spectral confocal dispersion lens is less than 100 mm, the measurement angle is at least 30°, and the dispersion range is 18 mm.

[0052] In a possible embodiment, the apertures of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7, the eighth lens G8, and the ninth lens G9 are all less than 32 mm.

[0053] In a possible embodiment, the light emitted by the light source is polychromatic light. The polychromatic light is dispersed by the spectral confocal lens to form light of different wavelengths and irradiates the object to be measured. If the object is exactly at the convergence point of a certain wavelength, the light of that wavelength will be reflected on the surface of the object to be measured. The optical fiber is used to receive the light reflected from the object to be measured and converged back to the optical fiber port through the spectral confocal lens.

[0054] Specifically, in this embodiment, linear dispersion is achieved through the combination of multiple lenses. A positive lens and a negative lens are combined. The negative lens is placed at the object-side optical fiber light source to generate positive dispersion, and the positive lens is placed on the image-side object to be measured to generate negative dispersion. The two are subtracted to obtain a larger dispersion range.

[0055] Specifically, in this embodiment, a reverse telephoto structure with a front group of negative optical power in front and a rear group of positive optical power behind is adopted, which is beneficial to obtaining a larger dispersion. During the distribution of optical power, if the optical power borne by a single lens is too large, its curvature will be magnified, and at the same time, spherical aberration will increase. In this lens, the main aberration is related to the aperture size. On the one hand, positive and negative optical powers are combined to reduce spherical aberration. On the other hand, optical power splitting is adopted to disperse the strong optical power to two other lenses to reduce the angle of light rays.

[0056] For ease of implementation, by way of example, in this embodiment, the refractive index n1 of the first lens G1 satisfies 1.63 < n1 < 1.75; the refractive index n2 of the second lens G2 satisfies 1.69 < n2 < 1.83; the refractive index n3 of the third lens G3 satisfies 1.92 < n3 < 1.96; the refractive index n4 of the fourth lens G4 satisfies 1.92 < n4 < 1.96; the refractive index n5 of the fifth lens G5 satisfies 1.92 < n5 < 1.96; the refractive index n6 of the sixth lens G6 satisfies 1.45 < n6 < 1.5; the refractive index n7 of the seventh lens G7 satisfies 1.45 < n7 < 1.5; the refractive index n8 of the eighth lens G8 satisfies 1.92 < n8 < 1.96; the refractive index n9 of the ninth lens G9 satisfies 1.7 < n9 < 1.84;

[0057] The Abbe number v1 of the first lens G1 satisfies 44 < v1 < 57; the Abbe number v2 of the second lens G2 satisfies 45 < v2 < 57; the Abbe number v3 of the third lens G3 satisfies 17 < v3 < 29; the Abbe number v4 of the fourth lens G4 satisfies 17 < v4 < 29; the Abbe number v5 of the fifth lens G5 satisfies 17 < v5 < 29; the Abbe number v6 of the sixth lens G6 satisfies 66 < v6 < 79; the Abbe number v7 of the seventh lens G7 satisfies 66 < v7 < 79; the Abbe number v8 of the eighth lens G8 satisfies 17 < v8 < 29; the Abbe number v9 of the ninth lens G9 satisfies 28 < v9 < 33;

[0058] In addition, in this embodiment, the range of the curvature radius R of the lens is as follows:

[0059] For the object side of the first lens G1: -10 mm < R < -5 mm, for the image side of the first lens G1: R = ∞;

[0060] For the object side of the second lens G2: -15 mm < R < -8 mm, for the image side of the second lens G2: -68 mm < R < -50 mm;

[0061] For the object side of the third lens G3: -28 mm < R < -19 mm, for the image side of the second lens G2: -20 mm < R < -12 mm;

[0062] For the object side of the fourth lens G4: -230 mm < R < -200 mm, for the image side of the second lens G2: -48 mm < R < -35 mm;

[0063] For the object side of the fifth lens G5: 32 mm < R < 45 mm, for the image side of the second lens G2: R = ∞;

[0064] For the object side of the sixth lens G6: R = ∞, for the image side of the second lens G2: 10 mm < R < 25 mm;

[0065] Object side of the seventh lens G7: -57 mm < R < -40 mm, image side of the second lens G2: 20 mm < R < 39 mm;

[0066] Object side of the eighth lens G8: 20 mm < R < 35 mm, image side of the second lens G2: -400 mm < R < -300 mm;

[0067] Object side of the ninth lens G9: 78 mm < R < 110 mm, image side of the second lens G2: -100 mm < R < -57 mm;

[0068] The following is illustrated by specific embodiments. The specific parameters of each lens are shown in Table 1, where the surface numbers S1 - S18 are the arrangement numbers of each optical surface from the object side to the image side.

[0069] Table 1

[0070]

[0071]

[0072] All the lenses in the above table are glass spherical lenses. The surface represents the two surfaces of each lens, the radius is the curvature radius corresponding to each surface, and the thickness is the central thickness of each optical element and the distance between surfaces.

[0073] A large-range spectral confocal dispersion lens described in this example has an axial dispersion range of 18 mm within the working wavelength range of 450 - 700 nm, a maximum measurement angle greater than 30°, and the total optical length of the lens is within 100 mm.

[0074] A large-range spectral confocal dispersion lens described in this example, through the combination of optical elements and material selection, optimizes the design of the radii and thicknesses of different lenses, enabling it to have a large dispersion range, low tolerance sensitivity, greatly improving the production quality of the lens, and facilitating the wide production of spectral confocal dispersion lenses. By using lenses of the same material, the cost of the lenses in the dispersion lens is reduced, thereby reducing the lens cost. On the basis of ensuring the indicators of the dispersion lens, the problem of a large variety of lens materials in spectral confocal dispersion lenses is solved, facilitating the wide production and application of the lens and improving its applicability. See Appendix Figure 3 、 Figure 4 、 Figure 5 , which are the standard spot diagrams of the dispersion lens provided in this embodiment at 450 nm, 537.5 nm, and 700 nm. It studies the imaging quality of the system by the light concentration reaching the image plane. It can be seen from the figure that the RMS root mean square radius of each field of view is less than the Airy disk radius, and the imaging quality of the system is relatively good, indicating that the image quality has reached the diffraction limit and meets the requirements of the spectral confocal dispersion lens indicators.

[0075] See the appendix Figure 6 、 Figure 7 、 Figure 8 , which are the transfer functions of the dispersion lens provided in this embodiment at 450 nm, 537.5 nm, and 700 nm. It can be seen that the three wavelength curves in the system value of this dispersion lens all approach the diffraction limit.

[0076] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0077] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A large-range spectral confocal dispersion lens, characterized in that A first lens with a negative focal power, a second lens with a negative focal power, a third lens with a positive focal power, a fourth lens with a positive focal power, a fifth lens with a positive focal power, a sixth lens with a negative focal power, a seventh lens with a negative focal power, an eighth lens with a positive focal power, and a ninth lens with a positive focal power are sequentially arranged between the fiber end of the light source and the image plane. The fifth lens and the sixth lens are cemented, and the seventh lens and the eighth lens are cemented.

2. The large-range spectral confocal dispersion lens according to claim 1, characterized in that For the large-range spectral confocal dispersion lens, the effective focal length is f, the focal length of the first lens is f1, and the focal length of the ninth lens is f9. Then 0.88 < |f1 / f| < 1.3 and 3.92 < |f9 / f| < 7.

98.

3. A large-range spectral confocal dispersion lens according to claim 1, characterized in that The first lens is a plano-concave lens, with the incident surface being concave and the exit surface being flat. The second lens is a meniscus lens, with the incident surface being concave and the exit surface being convex. The third lens is a meniscus lens, with the incident surface being concave and the exit surface being convex. The fourth lens is a meniscus lens, with the incident surface being concave and the exit surface being convex. The fifth lens is a plano-convex lens, with the incident surface being convex and the exit surface being flat. The sixth lens is a plano-concave lens, with the incident surface being flat and the exit surface being concave. The seventh lens is a bi-concave lens, with the incident surface being concave and the exit surface being concave. The eighth lens is a bi-convex lens, with the incident surface being convex and the exit surface being convex. The ninth lens is a bi-convex lens, with the incident surface being convex and the exit surface being convex.

4. The large-range spectral confocal dispersion lens according to claim 3, characterized in that, The aperture stop is located at the concave surface of the first lens.

5. The large-range spectral confocal dispersion lens according to claim 1, wherein, The first lens is made of lanthanum crown glass material, the second lens is made of lanthanum flint glass material, the third lens is made of heavy flint glass material, the fourth lens is made of heavy flint glass material, the fifth lens is made of heavy flint glass material, the sixth lens is made of light crown glass material, the seventh lens is made of light crown glass material, and the eighth lens and the ninth lens are made of heavy flint glass material.

6. The large-range spectral confocal dispersion lens according to claim 1, characterized in that, The total length of the large-range spectral confocal dispersion lens is less than 100 mm, the measurement angle is at least 30°, and the dispersion range is 18 mm.

7. The large-range spectral confocal dispersion lens according to claim 1, wherein The apertures of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all less than 32 mm.

8. The large-range spectral confocal dispersion lens according to claim 1, characterized in that, The light emitted by the light source is polychromatic light.

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