An off-axis light field imaging system

Abstract

An off-axis light field imaging system, which includes an off-axis reflection subsystem, a micro-mirror array and a photosensitive device in sequence along an imaging light path; the off-axis reflection subsystem includes at least one optical device including a reflective curved surface and at least one adjustment mechanism cooperating with the optical device including the reflective curved surface, the imaging light path passes through the optical device including the reflective curved surface, and the at least one adjustment mechanism is configured to adjust the optical device including the reflective curved surface.

Description

Technical Field

[0001] The present application relates to the field of optics, and in particular to an off-axis light field imaging system. Background Art

[0002] The definition of light field can be traced back to Faraday in 1846. It refers to the amount of light passing through each point in each direction, represented by a seven-dimensional function, P(Vx, Vy, Vz, θ, Based on this definition, later scientists simplified it into the 5D plenoptic function, using the function P(Vx,Vy,Vz,θ, ), but the five-dimensional function is still difficult to reconstruct, and it is finally simplified to the four-dimensional light field theory, represented by the function P(u,v,x,y). The full light field camera we see today is based on the research results of this theory. This technology is used in cameras and has brought about a revolution in camera technology.

[0003] Light field imaging systems have been described in the prior art, such as US patent application document US 7,949,252B1, which discloses a light field imaging system, in which an optical fiber passes through one or more lenses (main lens 104) and then enters a microlens matrix (microlens 106) to form an image on a photosensitive element (photosensor 108). The existing light field imaging system represented by the above patent has the following technical defects:

[0004] 1. The optical distortion is large. Optical lenses will have different degrees of distortion due to the influence of their structure.

[0005] 2. Dispersion. Since light of different wavelengths has different refractive indices in the same medium, it will cause dispersion problems.

[0006] 3. Secondary spectrum. For a telephoto lens, the focal length is longer and the chromatic aberration of the secondary spectrum is large, which will reduce the clarity and resolution of the photo.

[0007] 4. Energy loss. As light passes through different media, its energy will be lost and the final image quality will be reduced.

[0008] 5. Complex preparation. In order to avoid some problems, optical lenses are generally composed of multiple lenses, so the preparation process is complex.

[0009] 6. High cost. Since slight errors in optical lenses will lead to a decrease in image quality, the current costs of optical lenses are generally high.

[0010] Therefore, the prior art requires a technology that effectively overcomes the above-mentioned defects in the light field imaging system. Summary of the invention

[0011] In order to solve the above problems, the present application proposes an off-axis light field imaging system, which includes an off-axis reflection subsystem, a micro-mirror array and a photosensitive device in sequence along the imaging light path;

[0012] The off-axis reflection subsystem includes at least one optical device including a reflective curved surface and at least one adjustment mechanism cooperating with the optical device including the reflective curved surface. The imaging light path passes through the optical device including the reflective curved surface, and the at least one adjustment mechanism is configured to adjust the optical device including the reflective curved surface.

[0013] Preferably, the at least one adjustment mechanism is configured to adjust the optical device including the reflective curved surface, specifically:

[0014] The adjustment mechanism is suitable for adjusting at least one of the position, angle and curvature of the optical device.

[0015] Preferably, the off-axis light field imaging system further comprises:

[0016] A supporting structure, on which the off-axis reflection subsystem, the micro-mirror array and the photosensitive device are arranged.

[0017] Preferably, the support structure comprises a first support surface and a second support surface which are substantially parallel, and the off-axis reflection subsystem comprises a plurality of optical devices including reflective curved surfaces, and the plurality of optical devices including reflective curved surfaces are sequentially arranged on the first support surface and the second support surface along the imaging light path.

[0018] Preferably, the first supporting surface and the second supporting surface have circular cross-sections, and the reflective curved surface of the optical device is symmetrical about the center of the circular cross-sections.

[0019] Preferably, the off-axis light field imaging system further comprises:

[0020] A signal processing subsystem is provided, wherein the signal processing subsystem is adapted to convert the collected optical signal into a digital signal.

[0021] The imaging system of the present application has the following advantages:

[0022] 1. Small optical distortion, reflective imaging system, no spherical aberration, distortion and other problems caused by transmissive optical lenses.

[0023] 2. No dispersion, reflective imaging, no lens, will not cause dispersion problems.

[0024] 3. There is no secondary spectrum. Light of different wavelengths has the same incident and reflection angles. There is no secondary spectrum. The wavelength range available for multispectral imaging is very wide.

[0025] 4. Low energy loss, light is reflected from the surface and is not filtered by different mirrors, so the energy loss is very low.

[0026] 5. The preparation is simple. Only the imaging range needs to be considered. The number of parts required is very small and the preparation is simple.

[0027] 6. Low cost, simple process, and easy access to materials, so the preparation cost is very low.

[0028] 7. Size compression: through reflective folded optical path, a larger range and more complex optical path can be achieved in a smaller size.

[0029] 8. The movable and rotatable independent components can flexibly formulate collection plans according to needs, meet the different granularity requirements of different dimensions of information in different application scenarios, and balance the scene switching problem well. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 This is a schematic diagram of the off-axis light field imaging system of the present application.

[0032] The figure includes: off-axis optical device groups 1001, 1002, a micro-mirror array 1003, adjustable mechanisms 2001, 2002, 2003, 2004, a photosensitive device 3001, and a supporting structure 4001. DETAILED DESCRIPTION

[0033] In order to more clearly explain the overall concept of the present application, the following is described in detail in conjunction with the accompanying drawings of the specification by way of example. It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is such an actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other similar description is intended to cover non-exclusive inclusion, so that a series of processes, methods, articles or equipment are included, not only including these elements, but also including other elements that are not clearly listed, or also including elements inherent to such processes, methods, articles or equipment. In the absence of more restrictions, the elements limited by the statement "including one" and the like are not excluded from including the elements, and also include other identical elements.

[0034] like Figure 1 As shown, the present application proposes an off-axis light field imaging system, which includes an off-axis reflection subsystem, a micro-mirror array 1003 and a photosensitive device 3001 in sequence along the imaging light path.

[0035] Specifically, the off-axis reflection subsystem includes optical devices 1001, 1002 having reflective surfaces, and adjustment mechanisms 2001, 2003 that cooperate with the optical devices 1001, 1002 including reflective surfaces. The imaging light path passes through the optical devices 1001, 1002 including reflective surfaces, and the adjustment mechanisms 2001, 2003 are configured to adjust the optical devices including reflective surfaces.

[0036] A set of reflective free-form surface optical device combination is formed by the cooperation of off-axis optical devices 1001, 1002 and the adjustment mechanisms 2001, 2003. The imaging light is reflected from the curved surface of the optical device 1001 to the curved surface of the optical device 1002, and the light is further reflected to the micro-mirror array 1003, and reaches the photosensitive device 3001 through the micro-mirror array 1003 to form image information. The off-axis optical device group in this system refers to a plurality of optical components distributed in space. These optical components are not distributed on the optical axis, but distributed outside the optical axis. The incident light is reflected by multiple surfaces to achieve the final imaging. An adjustable support structure is used in this system to support independent optical components so that the position and angle can be adjusted, thereby adjusting the collection range and viewing angle to achieve the purpose of special data collection.

[0037] The adjustment mechanism 2001, 2003 is configured to adjust at least one of the position, angle or curvature of the optical device including the reflective curved surface. For example, in an embodiment not shown, the adjustment mechanism 2001, 2003 includes a lead screw adjustment mechanism so that the optical device 1001, 1002 can move along the reflective curved surface relative to the adjustment mechanism 2001, 2003. In another embodiment not shown, the adjustment mechanism 2001, 2003 includes a structure capable of driving the optical device 1001, 1002 to move up and down, for example, a telescopic mechanism. The off-axis optical device group 1001, 1002, and the micro-mirror array 1003 are all reflective free-form surface optical devices. By adjusting the position, angle and curvature of 1001, 1002 and the micro-mirror array 1003, the depth of field and range of optical data acquisition can be adjusted to adapt to different application scenarios. 1003 is a micro-curved surface structure, and the collected light field matrix can be obtained through the coordinated calculation of the micro-curved surface structure and the optical collection and processing system 3001.

[0038] The off-axis light field imaging system further includes: a supporting structure 4001, on which the off-axis reflection subsystem, the micro-mirror array 1003 and the photosensitive device 3001 are arranged.

[0039] The support structure includes a first support surface and a second support surface that are substantially parallel, and the off-axis reflection subsystem includes a plurality of optical devices including reflective curved surfaces, and the plurality of optical devices including reflective curved surfaces are sequentially arranged on the first support surface and the second support surface along the imaging optical path. Figure 1 As shown, the optical device 1001 and the micro-mirror array 1003 are mounted on a first supporting surface, and the optical device 1002 and the photosensitive device 3001 are mounted on a second supporting surface.

[0040] In an embodiment not specifically shown, the first support surface and the second support surface have a circular cross section, and the reflective curved surface of the optical device is symmetrical about the center of the circular cross section. The first support surface and the second support surface together form a 360-degree annular structure, so that the system can collect light field information in a larger range.

[0041] In an embodiment not specifically shown, the off-axis light field imaging system also includes: a signal processing subsystem, wherein the signal processing subsystem is suitable for converting the collected optical signal into a digital signal. The signal processing subsystem includes an optical sensor and a post-processing unit, wherein the optical sensor is a CCD, CMOS or other similar optical sensor, which can convert the image formed by the microlens into a point digital signal, and perform post-processing such as calculation, conversion, and compression on the image. The optical system can collect multi-spectral data including but not limited to visible light, infrared, ultraviolet, X-ray, terahertz, millimeter wave, etc. for different application scenarios, without affecting the overall structure.

[0042] The off-axis optical device and micro-mirror structure in the system can be convex, concave, or a free-form surface of other specific structures according to the use requirements.

[0043] The imaging system proposed by the present embodiment can overcome a large number of defects existing in the prior art. The advantages of the present embodiment include, for example, small optical distortion, a reflective imaging system, and no spherical aberration, distortion and other problems caused by transmissive optical lenses; no dispersion, reflective imaging, no lenses, and no dispersion problems; no secondary spectrum, light of different wavelengths has the same incident and reflection angles, there is no secondary spectrum, and the available wavelength range for multi-spectral imaging is very wide; low energy loss, light is reflected from the surface and will not be filtered by different mirrors, so the energy loss is very low; simple preparation, only the imaging range problem needs to be considered, very few parts can be made, and the preparation is simple; low cost, simple process, easy to obtain materials, so the preparation cost is very low; size compression, through the reflective folded optical path, a larger range and more complex optical path can be achieved in a smaller size; movable and rotatable independent components, can flexibly formulate acquisition plans according to needs, meet the different granularity requirements for different dimensional information for different application scenarios, and balance the scene switching problem well.

[0044] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0045] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. An off-axis light field imaging system, characterized in that: The off-axis light field imaging system includes an off-axis reflection subsystem, a micro-mirror array and a photosensitive device in sequence along the imaging light path; The off-axis reflection subsystem includes at least one optical device including a reflective curved surface and at least one adjustment mechanism cooperating with the optical device including the reflective curved surface, the imaging light path passes through the optical device including the reflective curved surface, and the at least one adjustment mechanism is configured to adjust the optical device including the reflective curved surface; The system further comprises: a supporting structure, on which the off-axis reflection subsystem, the micro-mirror array and the photosensitive device are arranged; The support structure comprises a first support surface and a second support surface which are substantially parallel, the off-axis reflection subsystem comprises a plurality of optical devices comprising a reflective curved surface, and the plurality of optical devices comprising a reflective curved surface are sequentially arranged on the first support surface and the second support surface along an imaging optical path; Among them, the micro-mirror array is arranged on the first supporting surface along the imaging light path, and the photosensitive device is arranged on the second supporting surface; the multiple optical devices including reflective surfaces are distributed in the part outside the optical axis, and the multiple optical devices including reflective surfaces and the micro-mirror array are non-axisymmetric about the optical axis.

2. The off-axis light field imaging system according to claim 1, characterized in that: The at least one adjustment mechanism is configured to adjust the optical device including a reflective curved surface, specifically: the adjustment mechanism is suitable for adjusting at least one of the position, angle and curvature of the optical device.

3. The off-axis light field imaging system according to claim 2, characterized in that: The first supporting surface and the second supporting surface have substantially circular cross-sections, and the reflective curved surface of the optical device is symmetrical about the center of the circular cross-section.

4. The off-axis light field imaging system according to claim 1, characterized in that: Also includes: A signal processing subsystem is provided, wherein the signal processing subsystem is adapted to convert the collected optical signal into a digital signal.

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