A low-distortion small industrial lens with a large imaging target surface and an imaging device

Abstract

The application belongs to the technical field of industrial lenses, and particularly discloses a low-distortion small industrial lens with a large imaging target surface, which comprises, in sequence from the object side to the image side along the optical axis, a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9 and a photosensitive chip. The low-distortion small industrial lens with a large imaging target surface has the advantages of small size, high resolving power, high temperature resistance, high relative luminance at the edge, and low distortion.

Description

Technical Field

[0001] This invention belongs to the field of industrial lens technology, specifically a small industrial lens with low distortion and a large imaging target surface, and an imaging device. Background Technology

[0002] Industrial lenses are optical imaging components specifically designed for industrial vision systems (such as machine vision, industrial inspection, and automated measurement). They need to simultaneously meet requirements such as high resolution, low distortion, resistance to temperature and humidity changes, vibration resistance, and standardized interfaces (C / CS interface, F interface). With the widespread adoption of high-pixel cameras, lenses also need to match higher resolutions. Currently, industrial lenses generally suffer from drawbacks such as large structural size, high optical distortion, and unclear field of view edges, making them unable to meet the miniaturization needs of industrial inspection.

[0003] Therefore, there is an urgent need in the market for a small industrial lens with high resolution, resistance to high and low temperatures, high edge relative illumination, and low distortion. Summary of the Invention

[0004] To address the aforementioned technical problems in the prior art, this invention provides a small, low-distortion industrial lens with a large imaging target surface, comprising, along the optical axis from the object side to the image side: a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, and a photosensitive chip; the first lens G1 is a meniscus lens with positive optical power, its object side being convex and its image side being concave; the second lens G2 is a meniscus lens with negative optical power, its object side being convex and its image side being concave; the third lens G4... Lens G3 is a meniscus lens with negative optical power, its object side is concave, and its image side is convex; the fourth lens G4 is a meniscus lens with positive optical power, its object side is concave, and its image side is convex; the fifth lens G5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave; the sixth lens G6 is a meniscus lens with positive optical power, its object side is concave, and its image side is convex; the seventh lens G7 is a biconcave lens with negative optical power; the eighth lens G8 is a biconvex lens with positive optical power; and the ninth lens G9 is a biconvex lens with positive optical power.

[0005] Based on a thorough understanding of optical glass materials, this application selects appropriate materials for some positive and negative focal spherical lenses to control the temperature drift of the optical system within a reasonable range, while also employing a stable mechanical structure to complement it.

[0006] Furthermore, an aperture stop ST is provided between the fifth lens G5 and the sixth lens G6.

[0007] Furthermore, the third lens G3 and the fourth lens G4 are a cemented lens group.

[0008] Furthermore, the total lens length (TTL) is less than 24mm.

[0009] Furthermore, the relative illuminance at the edges is greater than 91%.

[0010] Furthermore, optical distortion is <6%.

[0011] Furthermore, the Abbe number Vd1 of the first lens G1, the Abbe number Vd2 of the second lens G2, and the Abbe number Vd6 of the sixth lens G7 of the low-distortion miniature industrial lens satisfy the following formula:

[0012] Vd1≥50

[0013] Vd2≥55

[0014] Vd6≥50.

[0015] This application uses low-dispersion lens material and a set of cemented lenses to reduce lens dispersion, achieving a resolution of over 8 megapixels and meeting the requirements for infrared confocal focus and violet halo.

[0016] Furthermore, the refractive indices Nd3 of the third lens G3, Nd4 of the fourth lens G4, and Nd5 of the fifth lens G5 satisfy the following relationship:

[0017] Nd3≤1.80

[0018] Nd4≤1.90

[0019] Nd5≤1.90.

[0020] This application appropriately selects low refractive index materials to make the light change more gradual, and places the aperture as close to the front as possible to improve the relative illumination at the edges.

[0021] An imaging device comprising a low-distortion, compact industrial lens with a large imaging target area as described in any one of the claims.

[0022] Beneficial effects

[0023] The small industrial lens with low distortion and large imaging target surface of the present invention is not only small in size, but also has high resolution, resistance to high and low temperatures, high relative illumination at the edges, and low distortion. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the low-distortion industrial lens of this application;

[0025] Figure 2 This is the MTF curve of Embodiment 1 of the present invention;

[0026] Figure 3This is the MTF vs. Field curve of Embodiment 1 of the present invention;

[0027] Figure 4a and Figure 4b These are the scene and optical distortion curve diagram of Embodiment 1 of the present invention, respectively;

[0028] Figure 5 This is a relative illumination curve diagram of Embodiment 1 of the present invention;

[0029] Figure 6 This is the CRA curve diagram of Embodiment 1 of the present invention;

[0030] Figure 7 This is a defocus curve diagram of the infrared band in Embodiment 1 of the present invention;

[0031] Figure 8 This is a schematic diagram of a specific embodiment of the imaging device provided in this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] Example 1

[0035] like Figure 1 As shown, the low-distortion miniature industrial lens with a large imaging target surface of the present invention includes, along the optical axis from the object side to the image side, a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, and a photosensitive chip.

[0036] The first lens G1 is a meniscus lens with positive optical power, its object-side surface is convex, and its image-side surface is concave; the second lens G2 is a meniscus lens with negative optical power, its object-side surface is convex, and its image-side surface is concave; the third lens G3 is a meniscus lens with negative optical power, its object-side surface is concave, and its image-side surface is convex; the fourth lens G4 is a meniscus lens with positive optical power, its object-side surface is concave, and its image-side surface is convex; the fifth lens G5 is a meniscus lens with positive optical power, its object-side surface is convex, and its image-side surface is concave; the sixth lens G6 is a meniscus lens with positive optical power, its object-side surface is concave, and its image-side surface is convex; the seventh lens G7 is a biconcave lens with negative optical power; the eighth lens G8 is a biconvex lens with positive optical power; and the ninth lens G9 is a biconvex lens with positive optical power.

[0037] An aperture stop ST is provided between the fifth lens G5 and the sixth lens G6 to control the amount of light entering the lens. The third lens G3 and the fourth lens G4 are a cemented lens group, which can be used to better correct chromatic aberration, etc.

[0038] The specific parameters of the optical elements used in this embodiment 1, including the radius of curvature, thickness, and spacing of each surface, are shown in the table below:

[0039]

[0040] Table 1 Optical Component Parameter Table

[0041] It should be noted that the face number in Table 1 is Figure 1 The diagram of the industrial lens structure shown has the lens face numbers from left to right.

[0042] The industrial lens provided in this embodiment 1 has the following optical technical specifications:

[0043] like Figure 2-7 As shown, the focal length is 8mm, the image space F-number is 5.5, the field of view can reach 65°, the optical distortion is less than 6%, the total optical length is less than 24mm, the CRA is less than 10°, the edge relative illumination reaches 91%, the operating temperature range is -30℃ to +60℃, and the lens can be adapted to 1 / 1.6-inch compatible 2 / 3-inch target surface image sensors.

[0044] In this embodiment 1, the industrial lens also has the following properties:

[0045] 1. The MTF image quality is uniform and consistent, with high edge sharpness. At Ф10mm, the resolution can reach 0.3 at 160lp / mm.

[0046] 2. Adjustable working distance, 0.08m~2m;

[0047] 3. The number of lenses is small, with only a nine-lens structure.

[0048] like Figure 8 As shown, the imaging device 10 of this application embodiment includes at least one industrial lens 11. Specifically, the industrial lens 11 can be the industrial lens of Embodiment 1 above, and its specific structure will not be described in detail here.

[0049] The imaging device 10 in this embodiment can be applied to industrial fields such as defect detection, dimensional measurement, and security monitoring. For example, it can be installed on a product defect detection device to acquire images of the product for defect detection. In other embodiments, the imaging device 10 can also be applied to other devices, such as security inspection equipment, dimensional measuring instruments, etc.

Claims

1. A small, low-distortion industrial lens with a large imaging target surface, comprising, from the object side to the image side along the optical axis: The system comprises a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, and a photosensitive chip. The first lens G1 is a meniscus lens with positive optical power, its object-side surface being convex and its image-side surface being concave. The second lens G2 is a meniscus lens with negative optical power, its object-side surface being convex and its image-side surface being concave. The third lens G3 is a meniscus lens with negative optical power, its object-side surface being concave and its image-side surface being concave. The fourth lens G4 is a meniscus lens with positive optical power, its object side is concave, and its image side is convex; the fifth lens G5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave; the sixth lens G6 is a meniscus lens with positive optical power, its object side is concave, and its image side is convex; the seventh lens G7 is a biconcave lens with negative optical power; the eighth lens G8 is a biconvex lens with positive optical power; and the ninth lens G9 is a biconvex lens with positive optical power.

2. The low-distortion compact industrial lens with a large imaging target surface as described in claim 1, characterized in that: An aperture stop ST is provided between the fifth lens G5 and the sixth lens G6.

3. The low-distortion compact industrial lens with a large imaging target area as described in claim 1, characterized in that: The third lens G3 and the fourth lens G4 are a cemented lens group.

4. The low-distortion compact industrial lens with a large imaging target surface as described in claim 1, characterized in that: The total length of the lens (TTL) is less than 24mm.

5. The low-distortion compact industrial lens with a large imaging target surface as described in claim 1, characterized in that: The relative illuminance at the edge is greater than 91%.

6. The low-distortion compact industrial lens with a large imaging target surface as described in claim 1, characterized in that: Optical distortion <6%.

7. The low-distortion compact industrial lens with a large imaging target surface as described in claim 1, characterized in that: The Abbe numbers Vd1 of the first lens G1, Vd2 of the second lens G2, and Vd6 of the sixth lens G7 of the low-distortion miniature industrial lens satisfy the following formula: Vd1≥50 Vd2≥55 Vd6≥50.

8. The low-distortion compact industrial lens with a large imaging target surface as described in claim 1, characterized in that: The refractive indices Nd3 of the third lens G3, Nd4 of the fourth lens G4, and Nd5 of the fifth lens G5 satisfy the following relationship: Nd3≤1.80 Nd4≤1.90 Nd5≤1.

90.

9. An imaging device, characterized in that, The imaging device includes a low-distortion miniature industrial lens with a large imaging target surface as described in any one of claims 1 to 7.

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