Wide-angle spectrum confocal dispersion lens

Abstract

The utility model relates to the field of optical detection, in particular to a wide-angle spectrum confocal dispersion lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, and the net aperture of each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is smaller than 26mm. The utility model has the characteristics that the structure is compact, the total length of the lens is not more than 66mm, the maximum measurement angle can reach + / -30 degrees, the imaging quality is good, the measurement precision is high, and the resolution ratio is high. The dispersion lens provided by the utility model can effectively solve the defects of low resolution, small measurement angle, complex architecture, high cost and the like of the existing dispersion lens, thereby solving the problem of small measurement angle of the existing dispersion lens.

Description

Technical Field

[0001] The utility model relates to the field of optical detection, in particular to a large-angle spectral confocal dispersion lens. Background Art

[0002] Since it is insensitive to environmental changes, spectral confocal technology transmits and receives light through the same optical path, thus avoiding the possibility of the optical path being blocked. It not only has the advantages of high measurement accuracy and low environmental requirements, but also can adapt to a variety of measurement needs. This technology can not only measure surface profile and morphology, but also measure the thickness of transparent materials. Through the combination of multiple probes, it can also achieve more functional measurements. With the advantages of non-destructive, non-contact, and fast measurement, this technology is widely used in industrial manufacturing, aerospace, medical equipment, semiconductor chips and other 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. The image side numerical aperture NA determines its maximum measurement angle and also affects the spot size.

[0004] At present, with the continuous improvement of industrial inspection needs, the required measurement accuracy and comprehensiveness of information have also increased significantly. When inspecting objects with large curvature, spectral confocal lenses with large measurement angles and high precision are usually required. However, there are relatively few such lenses, and their structure is complex and the number of lenses is large, resulting in high costs. In addition, the assembly and debugging process of these lenses is time-consuming and labor-intensive, further increasing the difficulty and cost of use. Utility Model Content

[0005] The utility model aims to provide a large-angle spectral confocal dispersion lens, aiming to solve the problem of small measurement angle of the existing dispersion lens.

[0006] To achieve the above-mentioned object, the utility model provides a large-angle spectral confocal dispersion lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, from the end face of the optical fiber to the image plane are the light source emission end, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens in sequence, the first lens has a negative optical focal length and a plano-concave structure, the second lens has a positive optical focal length and a meniscus structure, the third lens has a positive optical focal length and a meniscus structure, the fourth lens has a positive optical focal length and a plano-convex structure, the fifth lens has a positive optical focal length, and the sixth lens has a positive optical focal length and a meniscus structure;

[0007] The effective focal length is f, and the focal length of the first lens f1 and the focal length of the sixth lens f6 must satisfy the relationship:

[0008] 0.68<|f1 / f|<1.58; 8.2<|f6 / f|<10.8.

[0009] The first lens is a plano-concave lens with a focal length of 6.6 mm, a surface on the object side that is bent toward the optical fiber end face, and a surface on the image side that is a plane.

[0010] The second lens is a meniscus lens with a focal length of 80.38 mm, and both the object side surface and the image side surface are bent toward the optical fiber end face.

[0011] Wherein, the third lens is a meniscus lens with a focal length of 65.30 mm, and both the object side and the image side are bent toward the optical fiber end face.

[0012] The fourth lens is a plano-convex lens with a focal length of 56.39 mm, a flat surface close to the optical fiber, and a side surface that is bent toward the end face of the optical fiber.

[0013] The fifth lens is a plano-convex lens with a focal length of 48.72 mm, which is bent toward the optical fiber end face close to the optical fiber surface, and the image side surface is a plane.

[0014] The sixth lens is a meniscus lens with a focal length of 57.16 mm, and both the object side surface and the image side surface are bent toward the image plane.

[0015] The utility model discloses a large-angle spectral confocal dispersion lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, wherein from the end face of the optical fiber to the image plane, there are in order a light source emission end, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens, the first lens has a negative focal power and a plano-concave structure, the second lens has a positive focal power and a meniscus structure, the third lens has a positive focal power and a meniscus structure, the fourth lens has a positive focal power and a plano-convex structure, the fifth lens has a positive focal power, and the sixth lens has a positive focal power and a meniscus structure; the effective focal length is f, and the first lens focal length f1 and the sixth lens focal length f6 must satisfy the following relationship: 0.68<|f1 / f|<1.58; 8.2<|f6 / f|<10.8. The net apertures of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all less than 26mm, and the mechanical apertures are all less than 27mm. The utility model has the characteristics of compact structure, the total length of the lens does not exceed 66mm, the maximum measurement angle can reach ±30°, the imaging quality is good, the measurement accuracy is high, and it has high resolution. The utility model dispersion lens can effectively solve the shortcomings of the existing dispersion lens such as low resolution, small measurement angle, complex structure and high cost, thereby solving the problem of small measurement angle of the existing dispersion lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The utility model is a structural schematic diagram of a large-angle spectral confocal dispersion lens.

[0018] Figure 2 This is the spot diagram of the utility model at a wavelength of 450nm in complex light.

[0019] Figure 3 This is the spot diagram of the utility model at a wavelength of 537nm in complex light.

[0020] Figure 4 This is a spot diagram of the utility model at a wavelength of 700nm in complex light.

[0021] Figure 5 This is the system MTF diagram of the utility model under the condition of wavelength 450nm.

[0022] Figure 6 This is the system MTF diagram of the utility model under the condition of wavelength 537nm.

[0023] Figure 7 This is the system MTF diagram of the utility model under the condition of wavelength 700nm.

[0024] 1-optical fiber end face, 2-first lens, 3-second lens, 4-third lens, 5-fourth lens, 6-fifth lens, 7-sixth lens. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] See also Figure 1-Figure 7The utility model provides a large-angle spectral confocal dispersion lens, comprising a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, a fifth lens 6 and a sixth lens 7, which are, from the optical fiber end face 1 to the image plane, a light source emission end, the first lens 2, the second lens 3, the third lens 4, the fourth lens 5, the fifth lens 6 and the sixth lens 7, the first lens 2 having a negative focal power and a plano-concave structure, the second lens 3 having a positive focal power and a meniscus structure, the third lens 4 having a positive focal power and a meniscus structure, the fourth lens 5 having a positive focal power and a plano-convex structure, the fifth lens 6 having a positive focal power, and the sixth lens 7 having a positive focal power and a meniscus structure;

[0027] The effective focal length is f, and the focal length f1 of the first lens 2 and the focal length f6 of the sixth lens 7 must satisfy the relationship:

[0028] 0.68<|f1 / f|<1.58; 8.2<|f6 / f|<10.8.

[0029] The first lens 2 is a plano-concave lens with a focal length of 6.6 mm. The surface on the object side is curved toward the optical fiber end face 1, and the surface on the image side is a plane.

[0030] The second lens 3 is a meniscus lens with a focal length of 80.38 mm, and both the object side surface and the image side surface are bent toward the optical fiber end face 1 .

[0031] The third lens 4 is a meniscus lens with a focal length of 65.30 mm. Both the object side and the image side are bent toward the optical fiber end face 1 .

[0032] The fourth lens 5 is a plano-convex lens with a focal length of 56.39 mm. It is flat near the optical fiber and its image side is curved toward the optical fiber end face 1 .

[0033] The fifth lens 6 is a plano-convex lens with a focal length of 48.72 mm, which is bent toward the optical fiber end face 1 close to the optical fiber surface, and the image side surface is a plane.

[0034] The sixth lens 7 is a meniscus lens with a focal length of 57.16 mm, and both the object side surface and the image side surface are curved toward the image plane.

[0035] In this embodiment, the first lens 2 is a plano-concave lens, the surface on the object side is curved towards the object side of the optical fiber, the image side is a plane, and the focal length is 6.6 mm. The second lens 3 is a meniscus lens, both the object side surface and the image side surface are curved towards the end of the optical fiber, and the focal length is 80.38 mm. The third lens 4 is a meniscus lens, both the object side surface and the image side surface are curved towards the end of the optical fiber, and the focal length is 65.30 mm. The fourth lens 5 is a plano-convex lens, the surface close to the optical fiber is a plane, and the image side surface is curved towards the end of the optical fiber, and the focal length is 56.39 mm. The fifth lens 6 is a plano-convex lens, the surface close to the optical fiber is curved towards the end of the optical fiber, and the surface close to the image plane is a plane, and the focal length is 48.72 mm. The sixth lens 7 is a meniscus lens, both the object side surface and the image side surface are curved towards the image plane, and the focal length is 57.16 mm. Linear dispersion is achieved through the combination of multiple lenses. By using a combination of positive and negative lenses, a negative lens is placed at the object-side optical fiber light source to generate positive dispersion, and a positive lens is placed on the image-side object to be measured to generate negative dispersion. The subtraction of the two results in a larger dispersion range.

[0036] Adopting a retrofocus structure with a negative optical power in the front group and a positive optical power in the rear group is beneficial for obtaining a larger dispersion. The more types of combined lenses, the easier it is to obtain a high-linearity dispersion. During the distribution of optical power, if the optical power borne by a single lens is too large, its curvature will be amplified, and at the same time, the spherical aberration will also increase. In this lens, the measurement angle on the image side is large, which makes the curvature of the sixth lens 7 close to the object to be measured on the image side too large. In order to eliminate the influence brought by spherical aberration, a split lens is used to balance this aberration.

[0037] The refractive index n1 of the first lens 2 satisfies 1.64 < n1 < 1.84; the refractive index n2 of the second lens 3 satisfies 1.6 < n2 < 1.8; the refractive index n3 of the third lens 4 satisfies 1.34 < n3 < 1.74; the refractive index n4 of the fourth lens 5 satisfies 1.51 < n4 < 1.81; the refractive index n5 of the fifth lens 6 satisfies 1.64 < n5 < 1.84; the refractive index n6 of the sixth lens 7 satisfies 1.80 < n6 < 2.05.

[0038] The Abbe number v1 of the first lens 2 satisfies 39 < v1 < 59; the Abbe number v2 of the second lens 3 satisfies 34 < v2 < 54; the Abbe number v3 of the third lens 4 satisfies 40 < v3 < 70; the Abbe number v4 of the fourth lens 5 satisfies 40 < v4 < 70; the Abbe number v5 of the fifth lens 6 satisfies 42 < v5 < 70; the Abbe number v6 of the sixth lens 7 satisfies 22 < v6 < 42.

[0039] In this embodiment, the parameters of each optical element of the spectral confocal displacement sensor dispersion lens are as follows:

[0040]

[0041] The lenses in the above table are all glass spherical lenses. The faces represent the two surfaces of each lens, the radius is the radius of curvature corresponding to each face, the thickness is the distance between the faces of each optical element, and N is the refractive index corresponding to each optical element.

[0042] The outer diameters of the first lens 2, the second lens 3, the third lens 4, the fourth lens 5, the fifth lens 6 and the sixth lens 7 are all less than 26 mm.

[0043] In the working wavelength range of 450-700nm, the axial dispersion range is 1.5mm, the measuring angle is ±30°, the total optical length of the lens is within 66mm, the maximum aperture of the single lens in the lens group is 25mm, and the mechanical aperture is less than 27mm.

[0044] See attached Figure 2 , Figure 3 , Figure 4 , which is the standard spot diagram of the dispersion lens provided in this embodiment at 450nm, 537nm, and 700nm. It studies the imaging quality of the system by the concentration of light reaching the image plane. It can be seen from the figure that the root mean square of the light spot of each wavelength at its corresponding focusing position is within the range of the Airy disk, indicating that the image quality has reached the diffraction limit.

[0045] See attached Figure 5 , Figure 6 , Figure 7 , which is the transfer function of the dispersion lens provided in this embodiment at 450nm, 537nm, and 700nm. It can be seen that the three wavelength curves in the dispersion lens system value are close to the diffraction limit.

[0046] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope covered by the utility model.

Claims

1. A wide-angle spectral confocal dispersion lens, characterized in that: It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, which are the light source emission end, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens in order from the end face of the optical fiber to the image plane, wherein the first lens has a negative optical focal power and a plano-concave structure, the second lens has a positive optical focal power and a meniscus structure, the third lens has a positive optical focal power and a meniscus structure, the fourth lens has a positive optical focal power and a plano-convex structure, the fifth lens has a positive optical focal power, and the sixth lens has a positive optical focal power and a meniscus structure; The effective focal length is f, and the focal length of the first lens f1 and the focal length of the sixth lens f6 must satisfy the relationship: 0.68<|f1 / f|<1.58; 8.2<|f6 / f|<10.

8.

2. The wide-angle spectral confocal dispersion lens according to claim 1, wherein: The first lens is a plano-concave lens with a focal length of 6.6 mm. The surface on the object side is bent toward the optical fiber end face, and the surface on the image side is a plane.

3. The wide-angle spectral confocal dispersion lens according to claim 1, wherein: The second lens is a meniscus lens with a focal length of 80.38 mm, and both the object side surface and the image side surface are bent toward the optical fiber end face.

4. The wide-angle spectral confocal dispersion lens according to claim 1, wherein: The third lens is a meniscus lens with a focal length of 65.30 mm. Both the object side and the image side are bent toward the optical fiber end face.

5. The wide-angle spectral confocal dispersion lens according to claim 1, wherein: The fourth lens is a plano-convex lens with a focal length of 56.39 mm. It is flat near the optical fiber and its image side is curved toward the end face of the optical fiber.

6. The wide-angle spectral confocal dispersion lens according to claim 1, wherein: The fifth lens is a plano-convex lens with a focal length of 48.72 mm, which is bent toward the optical fiber end face close to the optical fiber surface, and the image side surface is a plane.

7. The wide-angle spectral confocal dispersion lens according to claim 1, wherein: The sixth lens is a meniscus lens with a focal length of 57.16 mm, and both the object side surface and the image side surface are bent toward the image plane.

Images