CN214474187U

CN214474187U - Structured light receiving lens based on oral cavity scanning

Info

Publication number: CN214474187U
Application number: CN202023310938.3U
Authority: CN
Inventors: 贺艳芳; 林清华; 黄淮; 林峰
Original assignee: Fujian Normal University
Current assignee: Fujian Normal University
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-10-22
Anticipated expiration: 2030-12-31

Abstract

The utility model relates to a structured light receiving lens based on oral cavity scanning, including the first lens, second lens, third lens, fourth lens, fifth lens and the sixth lens that set up on same optical axis from the thing side to the image side, and satisfy following relational expression: -3.2< f1/f < -2.6,0.5< f2/f <0.8, -1.2< f3/f < -0.9, -0.8< f4/f < -0.5,0.6< f5/f <0.9,1.0< f6/f <1.3, TTL <35mm, FOV <24 °; wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f is the focal length of the whole lens, and TTL is the distance from the object side surface of the first lens to the image surface; the FOV is the maximum field angle range of the receiving lens; and a diaphragm is arranged between the third lens and the fourth lens, and various aberrations of the lens are balanced and eliminated by using a symmetrical structure. The whole system has simple structure, easy processing and excellent imaging quality.

Description

Structured light receiving lens based on oral cavity scanning

Technical Field

The utility model relates to a structured light receiving lens based on oral cavity scanning.

Background

The 3D structured light projection technique uses the principle of triangulation to project a structured (temporal or spatial) feature pattern through a projector, and detects corresponding features in an image captured by a camera and establishes a corresponding relationship with the features in the projected image, and then calculates distance information of the object surface using a triangulation model.

The 3D structured light projection technology is gradually used for three-dimensional reconstruction of objects, the existing three-dimensional reconstruction lenses are large-sized objects for reconstruction, and the instrument is large in size and is not suitable for reconstruction of small-sized objects. And the research on the reconstruction of small objects such as oral cavity needs to be solved. The problems of large volume, low detection precision, high price and the like exist at present. The lens is a structured light receiving lens for oral cavity scanning, has small volume and is very suitable for oral cavity reconstruction.

SUMMERY OF THE UTILITY MODEL

In view of the not enough of prior art, the utility model aims to solve the technical problem that a structured light receiving lens based on oral cavity scanning is provided, simple structure not only, optical property is good, and is small, and imaging quality is good moreover.

In order to solve the technical problem, the technical scheme of the utility model is that: a structured light receiving lens based on oral scanning comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are arranged on the same optical axis from an object side to an image side, and the following relational expressions are satisfied: -3.2< f1/f < -2.6,0.5< f2/f <0.8, -1.2< f3/f < -0.9, -0.8< f4/f < -0.5,0.6< f5/f <0.9,1.0< f6/f <1.3, TTL <35mm, FOV <24 °; wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f is the focal length of the whole lens, and TTL is the distance from the object side surface of the first lens to the image surface; the FOV is the maximum field angle range of the receiving lens; and a diaphragm is arranged between the third lens and the fourth lens.

The first lens is a meniscus lens, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens; the fourth lens and the fifth lens are glued to form a composite lens; the sixth lens element is a meniscus lens element, the object-side surface of the sixth lens element is convex, and the image-side surface of the sixth lens element is concave.

Further, the refractive index of each lens should satisfy the following requirements: 1.5< n1<1.6, 1.7< n2<1.8, 1.5< n3<1.6, 1.7< n4<1.8, 1.7< n5<1.8, 1.75< n6<1.85, wherein n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, and n6 is the refractive index of the sixth lens.

Further, the abbe number of each lens material satisfies the following relation: the following relation is satisfied: 55< v1<65, 45< v2<55, 45< v3<55, 25< v4<35, 45< v5<55, 40< v6<50, wherein v1 is the abbe number of the first lens, v2 is the abbe number of the second lens, v3 is the abbe number of the third lens, v4 is the abbe number of the fourth lens, v5 is the abbe number of the fifth lens, and v6 is the abbe number of the sixth lens.

Furthermore, the wavelength band satisfying the optical system is 480-. In particular, the technical indexes of the optical system are as follows:

center wavelength: 270nm, spectral range: 480nm-660 nm;

effective relative pore size: 1: 2.8;

pixel size: 3.75 μm

Focal length: 17.143mm

CCD size: 4.8mm by 3.6 mm;

133lp/mm (line pair/mm), full field MTF (modulation transfer function) > 0.6;

distortion (Distortion) < 2%.

Compared with the prior art, the utility model discloses following beneficial effect has: by using a symmetrical structure in an optical system, the surface type is reasonably optimized, the focal power is reasonably distributed, fewer lenses and fewer glass materials are used, various aberrations are corrected, and clear imaging is realized.

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Drawings

Fig. 1 is a schematic diagram of a system structure in an embodiment of the present invention;

fig. 2 is a diffuse speckle pattern in an embodiment of the present invention;

FIG. 3 is a graph of field curvature according to an embodiment of the present invention

Fig. 4 is a distortion curve diagram in an embodiment of the present invention;

fig. 5 is a transfer function evaluation diagram of an image plane position in an embodiment of the present invention;

in the figure: l1-first lens, L2-second lens, L3-third lens, L4-fourth lens, L5-fifth lens, L6-sixth lens, C-diaphragm.

Detailed Description

In order to make the aforementioned and other features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

As shown in fig. 1 to 5, a structured light receiving lens based on oral cavity scanning includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens disposed on the same optical axis from an object side to an image side, and satisfies the following relations: -3.2< f1/f < -2.6,0.5< f2/f <0.8, -1.2< f3/f < -0.9, -0.8< f4/f < -0.5,0.6< f5/f <0.9,1.0< f6/f <1.3, TTL <35mm, FOV <24 °; wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f is the focal length of the whole lens, and TTL is the distance from the object side surface of the first lens to the image surface; the FOV is the maximum field angle range of the receiving lens; and a diaphragm is arranged between the third lens and the fourth lens.

In the embodiment of the present invention, the first lens element is a meniscus lens element, the object side surface of the first lens element is a convex surface, and the image side surface of the first lens element is a concave surface; the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens; the fourth lens and the fifth lens are glued to form a composite lens; the sixth lens element is a meniscus lens element, the object-side surface of the sixth lens element is convex, and the image-side surface of the sixth lens element is concave.

In the embodiment of the present invention, the refractive index of each lens needs to satisfy the following requirements: 1.5< n1<1.6, 1.7< n2<1.8, 1.5< n3<1.6, 1.7< n4<1.8, 1.7< n5<1.8, 1.75< n6<1.85, wherein n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, and n6 is the refractive index of the sixth lens.

In an embodiment of the present invention, the abbe number of each lens material satisfies the following relation: the following relation is satisfied: 55< v1<65, 45< v2<55, 45< v3<55, 25< v4<35, 45< v5<55, 40< v6<50, wherein v1 is the abbe number of the first lens, v2 is the abbe number of the second lens, v3 is the abbe number of the third lens, v4 is the abbe number of the fourth lens, v5 is the abbe number of the fifth lens, and v6 is the abbe number of the sixth lens.

As an embodiment of the present invention, each lens of the lens all adopts a spherical mirror, the focal length of the whole lens is 17.143mm, and the data of the focal length, the refractive index and the abbe number of each lens are respectively shown in the following table:

further, the thickness parameters and the pitch parameters of each optical device in this embodiment are shown in the following table:

compared with the prior art, the utility model provides an optical property is good, provides the imaging method of the structure light receiving lens of oral cavity scanning, entire system simple structure, and the imaging quality is good.

As shown in fig. 2, the lens shown in fig. 1 has a speckle pattern close to airy disc and excellent imaging quality; FIG. 3 is a field curvature diagram of the lens shown in FIG. 1, within 0.05; FIG. 4 is a distortion diagram of the lens shown in FIG. 1, wherein the distortion is within 2%; FIG. 5 is an MTF graph of the lens shown in FIG. 1, which is greater than 0.6 at a full field of view 133lp/mm, and the imaging resolution is good.

The present invention is not limited to the above preferred embodiments, and any person can obtain other various forms of structured light receiving lenses based on oral cavity scanning according to the teaching of the present invention. All the equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims

1. A structured light receiving lens based on oral cavity scanning is characterized in that: the zoom lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens which are disposed on the same optical axis from an object side to an image side, and satisfies the following relation: -3.2< f1/f < -2.6,0.5< f2/f <0.8, -1.2< f3/f < -0.9, -0.8< f4/f < -0.5,0.6< f5/f <0.9,1.0< f6/f <1.3, TTL <35mm, FOV <24 °; wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f is the focal length of the whole lens, and TTL is the distance from the object side surface of the first lens to the image surface; the FOV is the maximum field angle range of the receiving lens; and a diaphragm is arranged between the third lens and the fourth lens.

2. The structured light receiving lens based on oral cavity scanning as claimed in claim 1, wherein: the first lens is a meniscus lens, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens; the fourth lens and the fifth lens are glued to form a composite lens; the sixth lens element is a meniscus lens element, the object-side surface of the sixth lens element is convex, and the image-side surface of the sixth lens element is concave.

3. The structured light receiving lens based on oral cavity scanning as claimed in claim 1, wherein: the following relation is satisfied: 1.5< n1<1.6, 1.7< n2<1.8, 1.5< n3<1.6, 1.7< n4<1.8, 1.7< n5<1.8, 1.75< n6<1.85, wherein n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, and n6 is the refractive index of the sixth lens.

4. A structured light receiving lens according to any one of claims 1 to 3, wherein: the following relation is satisfied: 55< v1<65, 45< v2<55, 45< v3<55, 25< v4<35, 45< v5<55, 40< v6<50, wherein v1 is the abbe number of the first lens, v2 is the abbe number of the second lens, v3 is the abbe number of the third lens, v4 is the abbe number of the fourth lens, v5 is the abbe number of the fifth lens, and v6 is the abbe number of the sixth lens.