Imaging device without cat eye effect

Abstract

The invention discloses an imaging device without a cat eye effect. The imaging device comprises a front optical system, a main lens and a detector array which are arranged in sequence, the detector array is inclined to the optical axis of the main lens, and an angle is formed between the detector array and the focal plane of the main lens; an optical wedge is arranged on the surface, close to the main lens, of the detector array; the optical wedge is used for gathering the light rays gathered by the main lens to the surface of the detector array; the vertex angle of the optical wedge and the top edge of the detector array are located on the focal plane of the main lens. Through simple structural change, the cat eye effect can be effectively eliminated, and the imaging quality can be guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of optical imaging systems, and in particular to an imaging device without a cat's eye effect. Background Art

[0002] In the traditional focused optical imaging and sensing system structure, the sensor array is usually located on the focal plane and perpendicular to the optical axis. This can ensure the imaging quality, but it makes the system have a strong back echo reflection, which is usually called the "cat's eye effect", that is, all the light that reaches the sensor but is not absorbed will be reflected back along the original path of the incident light. The "cat's eye effect" makes the focused optical imaging and sensing system invisible under laser active illumination reconnaissance.

[0003] In order to reduce or eliminate the "cat's eye effect", many methods have been proposed at home and abroad, such as placing the sensor array out of focus, partially blocking the optical aperture, and placing the sensor array tilted to the optical axis. These methods are conducive to reducing the "cat's eye effect", but at the same time they also reduce the imaging quality of the system. The U.S. patent "Methods and apparatus for imaging without retro-reflection using a tilted image plane and structured relay optic (US9400414)" proposes to use a tilted sensor array combined with a structural delay optical element to eliminate the "cat's eye effect" while ensuring the imaging quality. However, this method uses a structural delay optical element to replace the existing main lens, making the structure of the system very complicated.

[0004] Therefore, an imaging device without cat's eye effect is proposed. Summary of the invention

[0005] The object of the present invention is to provide an imaging device without cat's eye effect, aiming to solve or improve at least one of the above-mentioned technical problems.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides an imaging device without cat's eye effect, comprising a front optical system, a main lens and a detector array arranged in sequence;

[0007] The detector array is arranged obliquely to the optical axis of the main lens, and the detector array is arranged at an angle to the focal plane of the main lens;

[0008] The surface of the detector array close to the main lens is provided with an optical wedge; the optical wedge is used to focus the light converged by the main lens onto the surface of the detector array;

[0009] The top angle of the optical wedge and the top edge of the detector array are both located on the focal plane of the main lens.

[0010] According to an imaging device without cat's eye effect provided by the present invention, the optical wedge adopts a light-transmitting medium, and the refractive index of the optical wedge is greater than the refractive index of air.

[0011] According to an imaging device without a cat's eye effect provided by the present invention, the material of the optical wedge includes silicon, silicon dioxide, glass, germanium, germanium oxide, sulfide, and zinc sulfide.

[0012] According to an imaging device without cat's eye effect provided by the present invention, the optical wedge is fixedly mounted on a surface of the detector array close to the main lens.

[0013] According to an imaging device without a cat's eye effect provided by the present invention, the optical wedge is integrally formed with a surface of the detector array close to the main lens.

[0014] The present invention discloses the following technical effects:

[0015] The present invention eliminates the cat's eye effect of the imaging system by adopting an inclined detector array placed behind the focal plane of the main lens; by introducing an optical wedge, the converged light passing through the main lens can be focused on the surface of the detector array, thereby ensuring the imaging quality of the system; the present invention eliminates the cat's eye effect and ensures the imaging quality at the same time through simple structural changes. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0017] Figure 1 A schematic diagram of the structure of a traditional optical imaging system with a cat's eye effect;

[0018] Figure 2 It is a structural schematic diagram of a molding system in which a detector array is placed obliquely in the prior art;

[0019] Figure 3 is a diagram showing the positional relationship between the main lens and its focal plane and the detector array in the present invention;

[0020] Figure 4 It is a schematic structural diagram of an imaging device without cat's eye effect of the present invention;

[0021] Figure 5Schematic diagram of the relative position of the optical wedge and the detector array and the light propagation in the present invention;

[0022] Among them, 1, incident light; 2, refracted light; 3, first reflected light; 4, second reflected light; 201, main lens; 202, focal plane; 203, detector array; 204, optical axis; 205, optical wedge. DETAILED DESCRIPTION

[0023] The following will be combined with the 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0024] Reference Figure 1 The conventional optical imaging system is composed of a front optical system (not shown in the figure), a main lens 201 and a detector array 203, wherein the detector array 203 is located on the focal plane 202 of the main lens 201 and is perpendicular to the optical axis 204 of the main lens 201. Therefore, the incident light is focused on the surface of the detector array 203 after being converged by the main lens 201; when the incident light cannot be completely absorbed by the detector array 203, the reflected light will be emitted in the opposite direction of the incident light, thereby forming a cat's eye effect. At this time, if laser is used for active irradiation, the reflected laser beam will expose the characteristics and position of the imaging system.

[0025] Reference Figure 2 In order to reduce or even eliminate the cat's eye effect of the imaging system, a molding system with an inclined detector array is proposed in the prior art. The dotted line is the focal plane 202 of the main lens 201, and the center of the detector array 203 is located at the intersection of the focal plane 202 of the main lens 201 and the optical axis 204 of the main lens 201; during the imaging detection process, the imaging quality of the central part of the detector array 203 is better; while the detectors on the upper and lower sides of the center of the detector array 203 will be defocused due to the deviation from the focal plane 202, resulting in a decrease in imaging quality.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Reference Figure 3-5 The present invention provides an imaging device without a cat's eye effect, comprising a front optical system (not shown in the figure), a main lens 201 and a detector array 203 arranged in sequence; the front optical system (not shown in the figure) is a common front optical system in an optical imaging system;

[0028] The detector array 203 is arranged to be inclined with respect to the optical axis 204 of the main lens 201, and the detector array 203 is arranged at an angle to the focal plane 202 of the main lens 201; the detector array 203 is not perpendicular to the focal plane 202 of the main lens 201, and forms a certain angle; with this structure, the detector array 203 is not only in a defocused position, but also inclined and not perpendicular to the optical axis 204 of the main lens 201, which will significantly reduce or even eliminate the amount of reflected light on the surface of the detector array 203 that passes through the main lens 201 and returns along the incident light path, that is, reduce or even eliminate the cat's eye effect of the imaging system.

[0029] An optical wedge 205 is provided on the surface of the detector array 203 close to the main lens 201; the optical wedge 205 is closely attached to the surface of the detector array 203 close to the main lens 201;

[0030] The optical wedge 205 is used to focus the light rays converged by the main lens 201 onto the surface of the detector array 203; and all points on the detector array 203 except for one edge at the top are located outside the focal plane 202 of the main lens 201;

[0031] The top corner of the optical wedge 205 and the top edge of the detector array 203 are both located on the focal plane 202 of the main lens 201;

[0032] With such arrangement, the present invention eliminates the cat's eye effect of the imaging system by adopting an inclined detector array 203 disposed behind the focal plane 202 of the main lens 201; by introducing the optical wedge 205, the converged light passing through the main lens 201 can be focused on the surface of the detector array 203, thereby ensuring the imaging quality of the system and solving the problem that the detector array 203 is defocused as a whole and different defocus amounts at different parts lead to a decrease in imaging quality; the present invention eliminates the cat's eye effect and ensures the imaging quality at the same time through simple structural changes.

[0033] In a further optimized solution, the optical wedge 205 adopts a light-transmitting medium, and the refractive index of the optical wedge 205 is greater than the refractive index of air.

[0034] According to a further optimization scheme, the material of the optical wedge 205 includes silicon, silicon dioxide, glass, germanium, germanium oxide, sulfide, and zinc sulfide. When used in an imaging device working in the visible light band, the optical wedge 205 is mainly selected from silicon, silicon dioxide or glass. When used in an imaging device working in the near-infrared, mid-infrared and far-infrared bands, the optical wedge 205 is selected from corresponding materials that can transmit radiation in the near-infrared, mid-infrared and far-infrared bands, such as germanium and its oxide, sulfide or zinc sulfide.

[0035] In a further optimized solution, the optical wedge 205 is fixedly mounted on the surface of the detector array 203 close to the main lens 201 .

[0036] A further optimization scheme is that the optical wedge 205 is integrally formed with the surface of the detector array 203 close to the main lens 201. Considering that the front surface of the detector array 203 is usually composed of a light-transmitting medium, the front surface of the detector array 203 can also be directly processed into the optical wedge 205 structure, that is, the optical wedge 205 is used as the front surface of the detector array 203 to form an integrated molding structure.

[0037] In a further optimization scheme, the cross section of the optical wedge 205 is a triangle, and the angle of the top angle of the optical wedge 205 is determined by the refractive index of the material of the optical wedge 205 and the angle between the detector array 203 and the focal plane 202 of the main lens 201 during actual application, which is not specifically limited in this embodiment.

[0038] Reference Figure 5 , showing the relative position of the optical wedge 205 and the detector array 203 and the light propagation diagram in the present invention, the cross section of the optical wedge 205 is a triangle, and the vertex of the vertex angle of the optical wedge 205 and one side of the detector array 203 are both located on the focal plane 202 of the main lens 201;

[0039] When the incident light 1 converged from the main lens 201 reaches the left surface of the optical wedge 205, since the optical wedge 205 adopts a light-transmitting medium and the refractive index of the optical wedge 205 is greater than the refractive index of the air, the refraction angle corresponding to the refracted light 2 of the incident light 1 in the optical wedge 205 is smaller than the incident angle on the left side of the interface of the optical wedge 205, so that the incident light 1 converged can propagate a longer distance in the optical wedge 205 and be focused on the surface of the detector array 203, thereby compensating for the defocus amount caused by the tilted placement of the detector array 203 and ensuring the imaging quality of the imaging system.

[0040] At the same time, part of the refracted light 2 is reflected by the surface of the detector array 203, and the first reflected light 3 penetrates the surface of the optical wedge 205 to form a second reflected light 4 in the free space. At this time, the direction corresponding to the second reflected light 4 deviates far from the direction corresponding to the incident light 1, thereby greatly reducing or even eliminating the cat's eye effect.

[0041] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0042] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An imaging device without cat's eye effect, characterized in that: It comprises a front optical system, a main lens (201) and a detector array (203) which are arranged in sequence; The detector array (203) is arranged obliquely to the optical axis (204) of the main lens, and the detector array (203) is arranged at an angle to the focal plane (202) of the main lens (201); An optical wedge (205) is provided on the surface of the detector array (203) close to the main lens (201); the optical wedge (205) is used to focus the light rays converged by the main lens (201) onto the surface of the detector array (203); The top angle of the optical wedge (205) and the top edge of the detector array (203) are both located on the focal plane (202) of the main lens (201).

2. The imaging device without cat's eye effect according to claim 1, characterized in that: The optical wedge (205) is made of a light-transmitting medium, and the refractive index of the optical wedge (205) is greater than the refractive index of air.

3. The imaging device without cat's eye effect according to claim 1, characterized in that: The material of the optical wedge (205) includes silicon, silicon dioxide, glass, germanium, germanium oxide, sulfide, and zinc sulfide.

4. The imaging device without cat's eye effect according to claim 1, characterized in that: The optical wedge (205) is fixedly mounted on a surface of the detector array (203) close to the main lens (201).

5. The imaging device without cat's eye effect according to claim 1, characterized in that: The optical wedge (205) and the surface of the detector array (203) close to the main lens (201) are integrally formed.

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