Telecentric lens based on double-reflector device

Abstract

The application provides a telecentric lens based on a double-reflector device, which comprises a first lens assembly, a first reflector device, a second reflector device and a second lens assembly arranged in sequence along an optical path; the first lens assembly comprises a first lens; the image side of the first lens is arranged with the first reflector device, the image side of the first reflector device is arranged with the second reflector device, and the image side of the second reflector device is arranged with the second lens assembly; the first lens assembly is used for receiving a telecentric light beam, converging the telecentric light beam, and making the telecentric light beam converge at the diaphragm position of the second lens assembly after being folded by the reflector device; the second lens assembly is used for receiving the telecentric light beam reflected by the first reflector device and the second reflector device in sequence and projecting an image. The application can shorten the optical path length of the whole telecentric lens, reduce the height of the telecentric lens, and thus can apply the telecentric lens to electronic devices such as mobile phones which have requirements on thickness.

Description

TECHNICAL FIELD

[0001] The present application relates to optical lens, in particular to a telecentric lens based on double-reflector device. BACKGROUND

[0002] Projection lens usually adopts object-side telecentric optical path to realize uniform field of view and CRA matching. Due to the principle limitation of telecentric projection lens, there is a large space between the first lens and the subsequent lens group. The conventional design scheme is a direct type structure, as shown in FIG. 1, the object plane is perpendicular to the optical axis, and the light rays pass through the object plane and the telecentric lens from bottom to top to project the object plane image. Or add a reflecting mirror at the end of the lens to realize 90° folding of the light beam to reduce the system height, but thus further increase the length of the lens, as shown in FIG. 2. Figure 2 Figure 3

[0003] With the development of mobile phones, tablet computers and other portable terminal devices, in specific applications, the device needs to have projection function. The conventional telecentric projection lens design needs to occupy a large space volume, which limits its application in portable devices. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide a telecentric lens based on double-reflector device, by setting a reflecting device inside the telecentric lens, the optical path length of the entire telecentric lens is shortened, so that the lens can be applied in compact devices such as mobile phones.

[0005] The telecentric lens based on double-reflector device provided by the present application comprises a first lens assembly, a first reflecting device, a second reflecting device and a second lens assembly arranged in sequence along the optical path.

[0006] The first lens assembly comprises a first lens.

[0007] The image side of the first lens is arranged with the first reflecting device, the image side of the first reflecting device is arranged with the second reflecting device, and the image side of the second reflecting device is arranged with the second lens assembly.

[0008] The first lens assembly is used for receiving a telecentric light beam, converging the telecentric light beam, so that the telecentric light beam converges at the stop position of the second lens assembly after being folded by the reflecting device.

[0009] The second lens assembly is used for receiving the telecentric light beam reflected by the first reflecting device and the second reflecting device in sequence, and projecting an image.

[0010] Preferably, the second lens assembly comprises a second lens, a third lens and a fourth lens arranged in sequence along the optical path. ​​

[0011] The second reflecting device is arranged with the second lens on the image side, the second lens is arranged with the third lens on the image side, and the third lens is arranged with the fourth lens on the image side.

[0012] Preferably, the first lens has positive focal power, and the object side and the image side are convex structures.

[0013] The second lens has positive focal power, the object side is convex, and the image side is concave.

[0014] The third lens has positive focal power, the object side is concave, and the image side is convex.

[0015] The fourth lens has negative focal power, the object side is concave, and the image side is convex.

[0016] Preferably, the reflecting surfaces of the first reflecting device and the second reflecting device are planes; the first reflecting device and the second reflecting device are sequentially arranged between the light paths of the first lens and the second lens.

[0017] The first reflecting device is inclined by 40° to 50° relative to the optical axis of the first lens; and the second reflecting device is inclined by 40° to 50° relative to the optical axes of the second lens, the third lens, and the fourth lens.

[0018] The first reflecting device is used to project the telecentric light beam emitted by the first lens to the second reflecting device after being folded.

[0019] The second reflecting device is used to project the telecentric light beam emitted by the first reflecting device to the second lens after being folded.

[0020] Preferably, the chief rays at different image heights of the object plane of the telecentric lens are parallel to the optical axis of the first lens.

[0021] Preferably, the reflecting surfaces of the first reflecting device and the second reflecting device are metal layers, dielectric film coatings, or internal total reflection surfaces of prisms.

[0022] Preferably, a diaphragm is arranged between the second lens and the third lens, so that the telecentric lens satisfies the following conditional expression:

[0023] 73° < FOV < 112°

[0024] Wherein, FOV is the field of view of the telecentric lens.

[0025] 0.95 < VP < 1

[0026] Wherein, VP is the depth of view of the telecentric lens.

[0027] | Distortion | < 8%

[0028] wherein Distortion is optical distortion of the optical system

[0029] Preferably, the first lens, the second lens, the third lens and the fourth lens are aspherical plastic lenses.

[0030] The refractive index nd of the first lens, the second lens, the third lens and the fourth lens satisfies the following formula:

[0031] 1.62 < nd < 1.69

[0032] wherein nd is the refractive index of the lens at a wavelength of 587.6 nm.

[0033] Preferably, the second lens assembly is movable along the optical axis direction, and changing the optical distance between the first lens assembly and the second lens assembly changes the object-side focal length of the telecentric lens, so as to realize focusing on different image planes.

[0034] When the distance between the object plane of the telecentric lens and the first lens assembly decreases, the second lens assembly is moved towards the reflecting device.

[0035] When the distance between the object plane and the first lens assembly increases, the second lens assembly is moved away from the reflecting device.

[0036] Preferably, when the object plane of the telecentric lens is a discrete light spot array, the focusing plane can be changed by adjusting the second lens assembly, so as to realize switching between a point light array and a surface light array.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] In the present application, the first reflecting device and the second reflecting device are arranged between the first lens assembly and the second lens assembly, which shortens the optical path length of the entire telecentric lens, and further reduces the height of the telecentric lens, so that the telecentric lens can be applied to electronic devices such as mobile phones which have requirements on thickness.

[0039] In the present application, when the relative position between the object plane and the first lens assembly changes, the second lens assembly can be moved correspondingly to realize group focusing, so as to facilitate focusing of the light projector using the telecentric lens, so as to be able to match different object plane positions without adjusting the positional relationship between the object plane and the first lens. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only aim to explain the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on the provided drawings. Other features, objects and advantages of the present application will become more apparent from the following detailed description of the non-limiting embodiments with reference to the accompanying drawings:

[0041] Fig. 1(a) is a schematic diagram of a structure of a telecentric lens based on double-reflector devices in an embodiment of the present application;

[0042] Fig. 1(b) is a schematic diagram of another structure of a telecentric lens based on double-reflector devices in an embodiment of the present application;

[0043] Figure 2 Fig. 2 is a schematic diagram of a structure of a telecentric lens without reflector devices in an embodiment of the present application;

[0044] Figure 3 Fig. 3 is a schematic diagram of a structure of a telecentric lens with reflector devices at the light exit end in an embodiment of the present application;

[0045] Figure 4 Fig. 4(a) is a schematic diagram of a side surface position of a telecentric lens based on double-reflector devices in a mobile phone in an embodiment of the present application;

[0046] Figure 4 Fig. 4(b) is a schematic diagram of a side surface position of a telecentric lens based on double-reflector devices in a mobile phone in an embodiment of the present application;

[0047] Fig. 5(a) is a schematic diagram of a size of a telecentric lens based on double-reflector devices in a mobile phone in an embodiment of the present application;

[0048] Fig. 5(b) is a schematic diagram of a size of a telecentric lens without reflector devices in a mobile phone in an embodiment of the present application;

[0049] Fig. 5(c) is a schematic diagram of a size of a telecentric lens with reflector devices at the light exit end in a mobile phone in an embodiment of the present application;

[0050] Figure 6 Fig. 6 is a curve diagram of a MTF transfer function of an optical system in an embodiment of the present application;

[0051] Figure 7 Fig. 7 is a curve diagram of a relative luminance of an optical system in an embodiment of the present application;

[0052] Figure 8 Fig. 8 is a curve diagram of distortion of an optical system in an embodiment of the present application.

[0053] In the drawings:

[0054] 1 is an object plane; 2 is a first lens; 3 is a first reflecting device; 4 is a second reflecting device; 5 is a second lens; 6 is a diaphragm; 7 is a third lens; 8 is a fourth lens; 9 is a lens opening; 10 is a telecentric lens. DETAILED DESCRIPTION

[0055] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but in no way limit the application. It should be noted that for those skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made. These are within the scope of the application.

[0056] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be for fixing or for electrical circuit communication.

[0057] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0058] In addition, the terms "first", "second", are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0059] In the embodiments of the application, the application provides a telecentric lens based on double reflecting devices, comprising a first lens assembly, a first reflecting device, a second reflecting device and a second lens assembly arranged in sequence along an optical path;

[0060] The first lens assembly comprises a first lens;

[0061] The image side of the first lens is arranged with the first reflecting device, the image side of the first reflecting device is arranged with the second reflecting device, and the image side of the second reflecting device is arranged with the second lens assembly.

[0062] The first lens assembly is configured to receive a telecentric light beam, and converge the telecentric light beam to be focused on a stop position of the second lens assembly after being reflected by the reflecting device.

[0063] The second lens assembly is configured to receive the telecentric light beam reflected by the first reflecting device and the second reflecting device in sequence, and project an image.

[0064] In the present application, the first reflecting device and the second reflecting device are arranged between the first lens assembly and the second lens assembly, thereby shortening the optical path length of the entire telecentric lens, and reducing the height of the telecentric lens, so that the telecentric lens can be applied to electronic devices such as mobile phones which have requirements for thickness.

[0065] The above is the core idea of the present application. In order to make the above-mentioned purposes, characteristics and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0066] Fig. 1(a) is a structural schematic diagram of a telecentric lens based on double reflecting devices according to an embodiment of the present application, and Fig. 1(b) is another structural schematic diagram of a telecentric lens based on double reflecting devices according to an embodiment of the present application. As shown in Figs. 1(a) and 1(b), the telecentric lens based on double reflecting devices provided by the present application comprises a first lens assembly, a first reflecting device, a second reflecting device and a second lens assembly arranged in sequence along an optical path.

[0067] The first lens assembly comprises a first lens.

[0068] The first lens is arranged with the first reflecting device on an image side of the first lens, the first reflecting device is arranged with the second reflecting device on an image side of the first reflecting device, and the second reflecting device is arranged with the second lens assembly on an image side of the second reflecting device.

[0069] The first lens assembly is configured to receive a telecentric light beam, and converge the telecentric light beam to be focused on a stop position of the second lens assembly after being reflected by the reflecting device.

[0070] The second lens assembly is configured to receive the telecentric light beam reflected by the first reflecting device and the second reflecting device in sequence, and project an image.

[0071] The light path composition of the telecentric lens based on the double-reflector device comprises an object plane 1, a first lens 2, a first reflector device 3, a second reflector device 4, a second lens 5, a diaphragm 6, a third lens 7 and a fourth lens 8.

[0072] The object plane 1 is used for providing a projection pattern, and the object plane 1 can be any light projector, such as a structured light projector or a laser for projecting a pattern.

[0073] In the embodiment of the present application, the first lens 2 is used for converging the telecentric light beam from the object plane 1, and the focal plane is at the diaphragm 6.

[0074] The first reflector device 3 is used for reflecting the telecentric light beam and projecting it to the second reflector device 4 after a 90° turn.

[0075] The second reflector device 4 is used for reflecting the telecentric light beam emitted by the first reflector device 3 and projecting it to the second lens 5.

[0076] The first reflector device 3 and the second reflector device 4 can adopt a planar coated mirror, and the reflectivity of the light on the surface of the mirror can be improved by a metal layer or a multi-layer dielectric film coating. Alternatively, a right-angle total reflection prism can be adopted. Since the telecentric light beam is totally reflected on the inclined surface of the right-angle reflection prism, the reflectivity on the inclined surface is 100% without coating, but the right-angle surface needs to be coated with an antireflection film to improve the transmittance.

[0077] The second lens 5 adopts a meniscus convex lens, which is used for converging the telecentric light beam to the diaphragm 6.

[0078] The diaphragm 6 is a virtual plane, and the telecentric light beam is collected to the narrowest at the diaphragm 6.

[0079] The third lens 7 adopts a meniscus convex lens, which is used for diverging the telecentric light beam incident through the diaphragm 6.

[0080] The fourth lens 8 adopts a meniscus concave lens, which is used for further diverging the telecentric light beam incident through the third lens 7.

[0081] In the embodiment of the present application, the first lens 2 has a positive focal power, and the object side and the image side are convex structures. The chief rays at different image heights of the object plane 1 of the telecentric lens are parallel to the optical axis of the first lens 2.

[0082] The reflecting surface of the first reflecting device 3 is a plane, which is inclined by 40-50 degrees relative to the optical axis of the first lens 2 or the second lens 5, the third lens 7 and the fourth lens 8, preferably by 45 degrees; the first reflecting device 3 is used to project the telecentric light beam emitted by the first lens 2 to the second lens 5 after being turned by 90 degrees.

[0083] The first reflecting device 3 and the second reflecting device 4 are arranged by taking the characteristics of the telecentric optical path of the first lens 2 and the second lens 5, i.e. large optical distance and small inclination, so as to embed the first reflecting device 3 and the second reflecting device 4 in the optical path to realize the folding of the optical path without increasing the total length of the telecentric lens, which is beneficial to the miniaturization of the lens.

[0084] The second lens 5 has positive focal power, and the object side is convex and the image side is concave;

[0085] The third lens 7 has positive focal power, and the object side is concave and the image side is convex;

[0086] The fourth lens 8 has negative focal power, and the object side is concave and the image side is convex.

[0087] In the embodiment of the present application, the second lens 5 and the third lens 7 are provided with a diaphragm 6, so that the telecentric lens satisfies the following condition formula:

[0088] 73°<FOV<112°

[0089] Wherein, FOV is the field of view of the telecentric lens; FOV is used to limit the range of the field of view of the lens to realize large-angle projection.

[0090] 0.95<VP<1

[0091] Wherein, VP is the depth of view of the telecentric lens; VP is used to constrain the depth of view of the lens to reduce the size of the aperture and the vignetting, which is beneficial to improving the uniformity of the illumination of the image surface.

[0092] |Distortion|<8%

[0093] Wherein, Distortion is the optical distortion of the optical system; Distortion is used to constrain the distortion of the wide-angle lens, and the smaller the distortion is, the more real the image contour is.

[0094] In the embodiment of the present application, the chief rays at different image heights of the object surface 1 of the telecentric lens are parallel to the optical axis of the first lens 2.

[0095] In an embodiment of the present application, the first lens 2, the second lens 5, the third lens 7 and the fourth lens 8 are aspherical plastic lenses. The refractive index nd of the first lens 2, the second lens 5, the third lens 7 and the fourth lens 8 satisfies the following formula:

[0096] 1.62 < nd < 1.69

[0097] wherein nd is the refractive index of the lens at a wavelength of 587.6 nm.

[0098] The center of the object plane 1 is in line with the optical axis of the first lens 2;

[0099] The optical axes of the second lens 5, the third lens 7 and the fourth lens 8 are in line;

[0100] The optical axis of the first lens 2 is perpendicular to the optical axes of the second lens 5, the third lens 7 and the fourth lens 8.

[0101] Figure 2 Figure 1 is a schematic diagram of a telecentric lens structure in which the reflector is omitted in an embodiment of the present application, as shown in Figure 1, the optical axes of the object plane 1, the first lens 2, the second lens 5, the third lens 7 and the fourth lens 8 are in line, and the same projection effect can be achieved, but the height of the telecentric lens is significantly increased after the first reflector 3 is omitted. Figure 2

[0102] Figure 2 is a schematic diagram of a telecentric lens structure in which the first reflector 3 is located at the light exit end in an embodiment of the present application, as shown in Figure 2, the optical axes of the object plane 1, the first lens 2, the second lens 5, the third lens 7 and the fourth lens 8 are in line, the first reflector 3 is arranged on the image side of the fourth lens 8, and the same projection effect can be achieved, but the length and height of the telecentric lens are both significantly increased. Figure 3 Figure 3 Figure 3 is a schematic diagram of a telecentric lens structure in which the first reflector 3 is located at the light exit end in an embodiment of the present application, as shown in Figure 3, the optical axes of the object plane 1, the first lens 2, the second lens 5, the third lens 7 and the fourth lens 8 are in line, the first reflector 3 is arranged on the image side of the fourth lens 8, and the same projection effect can be achieved, but the length and height of the telecentric lens are both significantly increased.

[0103] Figure 4 (a) is a schematic diagram of a side surface position of a telecentric lens based on double reflectors in a mobile phone in an embodiment of the present application, Figure 4 (b) is a schematic diagram of a side surface position of a telecentric lens based on double reflectors in a mobile phone in an embodiment of the present application, as shown in (a) and (b), in compact devices such as mobile phones, there are restrictions on the height and aperture size of the telecentric lens, therefore, the aperture size of the telecentric lens should be as small as possible, and the height of the telecentric lens needs to be less than the thickness of the mobile phone. Figure 4 Figure 4

[0104] ​​​Figure 5(a) is a schematic diagram of the dimensions of the telecentric lens based on the dual reflector in a mobile phone according to an embodiment of the present invention. Figure 5(b) is a schematic diagram of the dimensions of the telecentric lens without the reflector in a mobile phone according to an embodiment of the present invention. Figure 5(c) is a schematic diagram of the dimensions of the telecentric lens with the reflector located at the light-emitting end according to an embodiment of the present invention. As shown in Figures 5(a), 5(b), and 5(c), the telecentric lens based on the dual reflector in this embodiment of the present invention has a lower optical height than the telecentric lens without the first reflector 3. The telecentric lens based on the dual reflector has a lower optical height, shorter length, and smaller aperture than the telecentric lens with the first reflector 3 located at the light-emitting end, and can have better compatibility in compact devices.

[0105] In this embodiment of the invention, the second lens assembly can move along the optical axis direction, changing the optical distance between the first lens assembly and the second lens assembly to change the object-side focal length of the telecentric lens, thereby achieving focusing at different image plane positions.

[0106] When object plane 1 is located at the dotted line, a relative displacement occurs between the first lens assembly and object plane 1, resulting in loss of focus, which produces the following effect: Figure 6 The horizontal displacement shown in the figure can be obtained through... Figure 6 The vertical movement shown in the diagram adjusts the position of the second lens assembly to compensate for the refocusing.

[0107] The specific focusing direction is as follows: when the distance between the object surface 1 and the first lens assembly decreases, the second lens assembly is moved closer to the first reflecting device 3; when the distance between the object surface 1 and the first lens assembly increases, the second lens assembly is moved further away from the first reflecting device 3.

[0108] In this embodiment of the invention, the surface type, radius of curvature, thickness, refractive index nd, and dispersion coefficient vd of the object surface 1, the first lens 2, the first reflecting device 3, the second lens 5, the aperture 6, the third lens 7, and the fourth lens 8 are shown in Table 1.

[0109] Table 1

[0110] Surface No. Surface Type Radius of Curvature Thickness Material (nd, vd) 1 Asphere 3.260 0.289 1.65，25.48 2 Asphere 0.661 0.537 3 Asphere 0.866 0.377 1.64，27.56 4 Asphere 0.780 0.135 Stop Plane Infinite 0.119 6 Asphere -9.956 0.604 1.65，25.48 7 Asphere -0.800 2.100 Reflector 1 Plane Infinite -2.700 Reflector 2 Plane Infinite 1.000 10 Asphere 2.954 0.447 1.62，33.24 11 Asphere -3.102 0.260

[0111] In Table 1, surface number 1 is the light-emitting surface of the fourth lens 8, surface number 2 is the light-receiving surface of the fourth lens 8; surface number 3 is the light-emitting surface of the third lens 7, surface number 4 is the light-receiving surface of the third lens 7; surface number 6 is the light-emitting surface of the second lens 5, surface number 7 is the light-receiving surface of the second lens 5; surface number 10 is the light-emitting surface of the first lens 2, and surface number 11 is the light-receiving surface of the first lens 2.

[0112] Figure 6 For the MTF transfer function curve of the optical system in the embodiment of the present application, the MTF transfer function can comprehensively reflect the imaging quality of the optical system, and the higher and smoother the curve is on the Y axis, the better the imaging quality of the optical system is; as shown in Figure 6 The horizontal coordinate: SPATIAL FREQUENCY IN CYCLES PER MILLIMETER represents the spatial frequency of 1p / mm. The vertical coordinate represents the MTF value. The higher the curve is, the better the imaging quality is. The vertical coordinate: MODULUS OF THE OTF, where OTF stands for optical transfer function, that is, the vertical coordinate is the optical modulation transfer function. The resolving power of the telecentric lens based on the double-reflector device in the embodiment of the present application is >110lp / mm.

[0113] Figure 7 For the relative illumination curve of the optical system in the embodiment of the present application, as shown in Figure 7 The vertical coordinate RelativeIllumination is the relative illumination, and the horizontal coordinate Y Field Millimeters is the Y direction to high, with the unit of millimeter.

[0114] When the curve is higher and smoother on the Y axis, the relative illumination of the optical system is more uniform, and the maximum field of view relative illumination of the telecentric lens based on the double-reflector device in the embodiment of the present application is >70%;

[0115] Figure 8 For the distortion curve of the optical system in the embodiment of the present application, as shown in Figure 8 The horizontal coordinate Percent is the percentage, and the vertical coordinate Distortion is the distortion. The distortion of the telecentric lens based on the double-reflector device in the embodiment of the present application is <7% in the full field of view range.

[0116] In the embodiment of the present application, the first reflector device and the second reflector device are arranged between the first lens assembly and the second lens assembly, the optical path length of the entire telecentric lens is shortened, and the height of the telecentric lens is reduced, so that the telecentric lens can be applied to electronic devices such as mobile phones which have requirements on thickness; in the embodiment of the present application, when the relative position of the object plane and the first lens assembly changes, the second lens assembly can be moved correspondingly to realize grouped focusing, so that the focusing of the light projector using the telecentric lens is facilitated, and different object plane positions can be matched without adjusting the positional relationship between the object plane and the first lens.

[0117] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0118] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A dual-reflector device based telecentric lens characterized in that, The first lens assembly, the first reflecting device, the second reflecting device and the second lens assembly are sequentially arranged along an optical path; The first lens assembly comprises a first lens; The image side of the first lens is arranged with the first reflecting device, the image side of the first reflecting device is arranged with the second reflecting device, and the image side of the second reflecting device is arranged with the second lens assembly; The first lens assembly is used for receiving a telecentric light beam, converging the telecentric light beam, and converging the telecentric light beam on the stop position of the second lens assembly after being folded by the reflecting device; The second lens assembly is used for receiving the telecentric light beam reflected by the first reflecting device and the second reflecting device in sequence and projecting an image. The second lens assembly comprises a second lens, a third lens and a fourth lens sequentially arranged along an optical path; The image side of the second reflecting device is arranged with the second lens, the image side of the second lens is arranged with the third lens, and the image side of the third lens is arranged with the fourth lens; A stop is arranged between the second lens and the third lens, and the telecentric lens satisfies the following conditional expression: 73° < FOV < 112° Wherein, FOV is the field of view of the telecentric lens; 0.95 < VP < 1 Wherein, VP is the depth of view of the telecentric lens; | Distortion | < 8% Wherein, Distortion is the optical distortion of the optical system; The first lens has positive focal power.

2. The dual-reflecting device based telecentric lens according to claim 1, wherein, The object side and the image side of the first lens are convex structures; The second lens has positive focal power, the object side is convex, and the image side is concave; The third lens has positive focal power, the object side is concave, and the image side is convex; The fourth lens has negative focal power, the object side is concave, and the image side is convex.

3. The dual-reflector device based telecentric lens of claim 1, wherein, The reflecting surfaces of the first reflecting device and the second reflecting device are planes; the first reflecting device and the second reflecting device are sequentially arranged between the optical paths of the first lens and the second lens; The first reflecting device is inclined by 40° to 50° relative to the optical axis of the first lens; the second reflecting device is inclined by 40° to 50° relative to the optical axes of the second lens, the third lens and the fourth lens; The first reflecting device is used for folding and projecting the telecentric light beam emitted by the first lens to the second reflecting device; The second reflecting device is used for folding and projecting the telecentric light beam emitted by the first reflecting device to the second lens.

4. The dual-reflecting device based telecentric lens according to claim 1, wherein, The chief rays at different image heights of the object plane of the telecentric lens are parallel to the optical axis of the first lens.

5. The dual-reflector device based telecentric lens of claim 1, wherein, The reflecting surfaces of the first reflecting device and the second reflecting device are metal layers, dielectric film coatings or internal total reflection surfaces of prisms.

6. The dual-reflector device based telecentric lens of claim 1, wherein, The first lens, the second lens, the third lens and the fourth lens adopt aspherical plastic lenses; The refractive index nd of the first lens, the second lens, the third lens and the fourth lens satisfies the following formula: 1.62 < nd < 1.69 Wherein, nd is the refractive index of the lens at a wavelength of 587.6 nm.

7. The dual-reflector device based telecentric lens of claim 1, wherein, The second lens assembly is capable of moving along the optical axis direction to change the optical distance between the first lens assembly and the second lens assembly, thereby changing the object-side focal length of the telecentric lens and realizing focusing on different image planes; When the distance between the object plane of the telecentric lens and the first lens assembly decreases, the second lens assembly is moved towards the reflecting device; When the distance between the object plane and the first lens assembly increases, the second lens assembly is moved away from the reflecting device.

8. The dual-reflector device based telecentric lens of claim 1, wherein, When the object plane of the telecentric lens is a discrete light spot array, the focusing plane can be changed by adjusting the second lens assembly, thereby realizing switching between a point light array and a surface light array.

Images