Laser scattering probe system imaging objective lens

Abstract

A laser scattering detection system imaging objective lens comprises, from the object side to the image side, a first lens group with positive focal length, the lenses of the first lens group being made of glass material with refractive index n d <1.6, dispersion v d >50; a second lens group with negative focal length, the lenses of the second lens group being made of glass material with refractive index n d >1.6, dispersion v d >50; a third lens group with positive focal length, the lenses of the third lens group being made of glass material with refractive index n d <1.6, dispersion v d >50; and a fourth lens group with negative focal length, the lenses of the fourth lens group being made of glass material with refractive index n d >1.6, dispersion v d >50. The present application has good imaging quality, and the design result residual error is small, the optical modulation transfer function is close to the diffraction limit, and the energy concentration degree is close to the diffraction limit, so that a relatively ideal imaging quality is achieved.

Description

Technical Field

[0001] The present invention relates to the field of optical design of laser detection objective lenses, and in particular to an imaging objective lens of a laser scattering detection system. Background Art

[0002] Lasers are widely used in laser communications, material detection, and lidar. These applications require receiving laser light scattered back from objects. However, scattered light travels in all directions, and the energy reaching the optical system is very weak. To ensure sufficient light energy reaches the system, the laser detection system's light-collecting capability needs to be improved. However, most products currently on the market cannot meet the light-collecting requirements of long-distance laser detection users. Developing large-aperture imaging lenses for laser scattering detection optical systems specifically designed for long-distance laser detection has become an effective solution. Summary of the Invention

[0003] The present invention provides an imaging objective lens for a laser scattering detection system, so as to solve the problem of insufficient light-gathering capability of the laser scattering detection system.

[0004] The present invention provides an imaging objective lens for a laser scattering detection system, characterized in that it comprises, from the object side to the image side, the following components:

[0005] The first lens group has a positive focal length, and the lenses of the first lens group have a refractive index n d <1.6, dispersion ν d >50 glass material; the incident surface of the first lens group closest to the object side is convex, and the exit surface closest to the image side is flat;

[0006] The second lens group has a negative focal length, and the lenses of the second lens group are composed of refractive index n d >1.6, dispersion ν d <50 glass material; the incident surface of the second lens group closest to the object side is concave, and the exit surface closest to the image side is concave;

[0007] The third lens group has a positive focal length, and the lenses of the third lens group are composed of refractive index n d <1.6, dispersion ν d >50 glass material; the incident surface of the third lens group closest to the object side is concave, and the exit surface closest to the image side is convex;

[0008] The fourth lens group has a negative focal length, and the lenses of the fourth lens group are composed of refractive index n d >1.6, dispersion ν d <50 glass material; the incident surface of the fourth lens group closest to the object side is convex, and the exit surface closest to the image side is concave.

[0009] The present invention has the following technical effects: 1) all lenses adopt a standard spherical surface design, which has low manufacturing difficulty and can complete the development of the system in the shortest period at the lowest cost; 2) it has a relatively loose installation and adjustment tolerance, which is conducive to the integrated installation and adjustment of the system, shortens the development cycle, and reduces the development cost; 3) it has good imaging quality. The residual error of the design result of the present invention is small, the optical modulation transfer function is close to the diffraction limit, and the energy concentration is close to the diffraction limit, achieving relatively ideal imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 1 is an optical structure diagram of an embodiment of an imaging objective lens of a laser scattering detection system provided by the present invention;

[0011] Figure 2 yes Figure 1 The optical modulation transfer function (Mo) of the imaging objective lens of the laser scattering detection system of the embodiment shown is as follows: d ulation Transfer Function (MTF) design result diagram;

[0012] Figure 3 yes Figure 1 Graph showing the design results of the wavefront error and field of view (WFE) of the imaging objective lens of the laser scattering detection system of the embodiment shown;

[0013] Figure 4 yes Figure 1 The diffraction energy of the imaging objective lens of the laser scattering detection system of the embodiment shown ( D iffraction Encircle d Energy) design result diagram. DETAILED DESCRIPTION

[0014] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0015] Please refer to Figure 1 The present invention provides an imaging objective lens for a laser scattering detection system, which includes, from the object side to the image side IMAGE, the following components:

[0016] The first lens group has a positive focal length, and the lenses of the first lens group have a refractive index n d <1.6, dispersion νd Made of glass material >50;

[0017] The second lens group has a negative focal length, and the lenses of the second lens group are composed of refractive index n d >1.6, dispersion ν d Made of glass material <50;

[0018] The third lens group has a positive focal length, and the lenses of the third lens group are composed of refractive index n d <1.6, dispersion ν d Made of glass material >50;

[0019] The fourth lens group has a negative focal length, and the lenses of the fourth lens group are composed of refractive index n d >1.6, dispersion ν d <50 made of glass material.

[0020] Furthermore, the incident surface of the first lens group closest to the object side is convex, and the exit surface closest to the image side IMAGE is flat; the incident surface of the second lens group closest to the object side is concave, and the exit surface closest to the image side IMAGE is concave; the incident surface of the third lens group closest to the object side is concave, and the exit surface closest to the image side IMAGE is convex; the incident surface of the fourth lens group closest to the object side is convex, and the exit surface closest to the image side IMAGE is concave.

[0021] Furthermore, the first lens group includes one or more lenses, and the one or more lenses include lenses made of the same or different glass materials.

[0022] Furthermore, the second lens group includes one or more lenses, and the one or more lenses include lenses made of the same or different glass materials.

[0023] Furthermore, the third lens group includes one or more lenses, and the one or more lenses include lenses made of the same or different glass materials.

[0024] Furthermore, the fourth lens group includes one or more lenses, and the one or more lenses include lenses made of the same or different glass materials.

[0025] Example

[0026] Please refer again Figure 1 ,exist Figure 1In the illustrated embodiment, the first lens group L1 consists of a first lens L101 and a second lens L102, spaced apart from the object side to the image side IMAGE. The object-side surface L101F of the first lens L101 is convex, and the image-side surface L101B is flat. The object-side surface L102F of the second lens L102 is convex, and the image-side surface L102B is flat. The incident surface of the first lens group L1 closest to the object side is the object-side surface L101F of the first lens L101, and the exit surface of the first lens group L1 closest to the image side IMAGE is the image-side surface L102B of the second lens L102. In one embodiment, the first lens L101 and the second lens L102 can be made of H-K9L glass.

[0027] The second lens group L2 consists of a third lens L201, a fourth lens L202-1, and a fifth lens L202-2, from the object side to the image side IMAGE. The object-side surface L201F of the third lens L201 is concave, and the image-side surface L201B is concave. The object-side surface L202-2F of the fourth lens L202-1 is convex, and the image-side surface L202M is convex. The object-side surface of the fifth lens L202-2 is concave and is cemented with the image-side surface L202M of the fourth lens L202-1. The image-side surface L202-2B is also concave. The incident surface of the second lens group L2 closest to the object side is the object-side surface L201F of the third lens L201. The exit surface of the second lens group L2 closest to the image side IMAGE is the image-side surface L202-2B of the fifth lens L202-2. In one embodiment, the third lens L201 is made of H-ZF6 glass material, the fourth lens L202-1 is made of H-K9L glass material, and the fifth lens L202-2 is made of H-ZF2 glass material.

[0028] The third lens group L3 consists of a sixth lens L301 and a seventh lens L302, spaced apart from each other from the object side to the image side (IMAGE). The object-side surface L301F of the sixth lens L301 is concave, and the image-side surface L301B is convex. The object-side surface L302F of the seventh lens L302 is convex, and the image-side surface L302B is convex. The incident surface of the third lens group L3 closest to the object side is the object-side surface L301F of the sixth lens L301, and the exit surface of the third lens group L3 closest to the image side (IMAGE) is the image-side surface L302B of the seventh lens L302. In one embodiment, the sixth lens L301 and the seventh lens L302 can be made of H-K9L glass.

[0029] The fourth lens group L4 consists of, from the object side to the image side IMAGE, an eighth lens element L401-1, a ninth lens element L401-2, and a tenth lens element L402. The object-side surface L401F of the eighth lens element L401-1 is convex, and the image-side surface L401M is concave. The object-side surface L401B of the ninth lens element L401-2 is concave and cemented with the image-side surface L401M of the eighth lens element L401-1. The object-side surface L401B of the ninth lens element L401-2 is concave. The tenth lens element L402 is spaced apart from the ninth lens element L401-2, and has a concave object-side surface L402F and a concave image-side surface L402B. The incident surface of the fourth lens group L4 closest to the object side is the object-side surface L401F of the eighth lens element L401-1. The exit surface of the fourth lens group L4 closest to the image side IMAGE is the image-side surface L402B of the tenth lens element L402. In one embodiment, the eighth lens L401-1 is made of H-LAF4 glass material, the ninth lens L401-2 is made of H-ZF6 glass material, and the tenth lens L402L402 is made of H-QK3L glass material.

[0030] A stop STOP is further provided between the first lens group L1 and the second lens group L2 to limit the diameter range of light.

[0031] Table 1 shows the actual design parameters of the above embodiment.

[0032] Table 1

[0033] Surface number Surface type Curvature radius / mm Thickness of air gap / mm Dielectric materials L101F Standard surface 1045.15 50 H-K9L L101B Standard surface Infinity 10 L102F Standard surface 526 50 H-K9L L102B Standard surface Infinity 190 STOP Standard surface Infinity 190 L201F Standard surface -220.82 28 H-ZF6 L201B Standard surface 249.32 20 L202F Standard surface 327.57 35 H-K9L L202M Standard surface -200.03 25 H-ZF2 L202B Standard surface -1144 20 L301F Standard surface -378.73 35 H-K9L L301B Standard surface -176.04 130.65 L302F Standard surface 291.121 35 H-K9L L302B Standard surface -509.96 98.98 L401F Standard surface 222.17 30 H-LAF4 L401M Standard surface 119.01 25 H-ZF6 L401B Standard surface 3572.27 12.36 L402F Standard surface -275.11 20 H-QK3L L402B Standard surface 209.65 70.094

[0034] As shown in Table 2, these are the actual design indicators achieved in this implementation case.

[0035] Table 2

[0036] Serial number Indicator Design indicators 1 Clear aperture 300mm 2 focal length 600mm 3 Working wavelength 532nm±3nm 4 Field of view 1.25°

[0037] See also Figures 2 to 4 , respectively Figure 1 The optical modulation transfer function (Mo) of the imaging objective lens of the laser scattering detection system of the embodiment shown is as follows: d ulation Transfer Function, MTF) design result diagram, Wave Front Error and Field of View Distribution (WFE) design result diagram, Diffraction Energy ( D iffraction Encircle d Energy) design result diagram.

[0038] from Figures 2 to 4It can be seen that the present invention has the following technical effects: 1) All lenses adopt a standard spherical surface design, which is easy to manufacture and can complete the system development in the shortest period and at the lowest cost; 2) It has a relatively loose installation and adjustment tolerance, which is conducive to the integrated installation and adjustment of the system, shortens the development cycle, and reduces the development cost; 3) It has good imaging quality. In the above embodiment, the design results of the present invention have a small residual error, the optical modulation transfer function is close to the diffraction limit, and the energy concentration is close to the diffraction limit. Therefore, relatively ideal imaging quality is achieved.

[0039] The above-described embodiments merely represent one or several embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A laser scattering detection system imaging objective lens, characterized in that: From the object side to the image side, it includes: The first lens group has a positive focal length, and the lenses of the first lens group have a refractive index n d <1.6, dispersion ν d >50 glass material; the incident surface of the first lens group closest to the object side is convex, and the exit surface closest to the image side is flat, wherein the first lens group is composed of a first lens and a second lens spaced apart from the object side to the image side, the object-side surface of the first lens is convex, and the image-side surface is flat; the object-side surface of the second lens is convex, and the image-side surface is flat; the incident surface of the first lens group closest to the object side is the object-side surface of the first lens; the exit surface of the first lens group closest to the image side is the image-side surface of the second lens; The second lens group has a negative focal length, and the lenses of the second lens group are composed of refractive index n d >1.6, dispersion ν d <50 glass material; the incident surface of the second lens group closest to the object side is concave, and the exit surface closest to the image side is concave, wherein the second lens group consists of a third lens, a fourth lens, and a fifth lens from the object side to the image side; the object-side surface of the third lens is concave, and the image-side surface is concave; the object-side surface of the fourth lens is convex, and the image-side surface is convex; the object-side surface of the fifth lens is concave and is cemented with the image-side surface of the fourth lens, and the image-side surface is concave; the incident surface of the second lens group closest to the object side is the object-side surface of the third lens; the exit surface of the second lens group closest to the image side is the image-side surface of the fifth lens; The third lens group has a positive focal length, and the lenses of the third lens group are composed of refractive index n d <1.6, dispersion ν d >50 glass material; the incident surface of the third lens group closest to the object side is concave, and the exit surface closest to the image side is convex; the third lens group is composed of a sixth lens and a seventh lens spaced apart from the object side to the image side, the object-side surface of the sixth lens is concave, and the image-side surface is convex; the object-side surface of the seventh lens is convex, and the image-side surface is convex; the incident surface of the third lens group closest to the object side is the object-side surface of the sixth lens; the exit surface of the third lens group closest to the image side is the image-side surface of the seventh lens; The fourth lens group has a negative focal length, and the lenses of the fourth lens group are composed of refractive index n d >1.6, dispersion ν d <50 glass material; the incident surface of the fourth lens group closest to the object side is convex, and the exit surface closest to the image side is concave, wherein the fourth lens group consists of an eighth lens, a ninth lens, and a tenth lens from the object side to the image side; the object-side surface of the eighth lens is convex, and the image-side surface is concave; the object-side surface of the ninth lens is convex and is cemented with the image-side surface of the eighth lens, and the image-side surface is concave; the tenth lens is spaced apart from the ninth lens and has a concave object-side surface and a concave image-side surface; the incident surface of the fourth lens group closest to the object side is the object-side surface of the eighth lens; the exit surface of the fourth lens group closest to the image side is the image-side surface of the tenth lens.

2. The imaging objective lens of the laser scattering detection system according to claim 1, characterized in that: The imaging objective lens of the laser scattering detection system has an aperture of 300 mm, a focal length of 600 mm, and an operating wavelength of 532 nm.

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