OPTICAL ARRANGEMENTS FOR USE WITH AN ARRAY CAMERA
A variety of optical arrangements and methods of modifying or enhancing the optical characteristics and functionality of these optical arrangements are provided. The optical arrangements being specifically designed to operate with camera arrays that incorporate an imaging device that is formed of a plurality of imagers that each include a plurality of pixels. The plurality of imagers include a first imager having a first imaging characteristics and a second imager having a second imaging characteristics. The images generated by the plurality of imagers are processed to obtain an enhanced image compared to images captured by the imagers. In many optical arrangements the MTF characteristics of the optics allow for contrast at spatial frequencies that are at least as great as the desired resolution of the high resolution images synthesized by the array camera, and significantly greater than the Nyquist frequency of the pixel pitch of the pixels on the focal plane, which in some cases may be 1.5, 2 or 3 times the Nyquist frequency.
1 . A camera array, comprising:
A plurality of cameras, where each camera includes a separate optics, and a plurality of light sensing elements, and each camera is configured to independently capture an image of a scene;
wherein the optics of each camera are configured so that each camera has a field of view that is shifted with respect to the field-of-views of the other cameras so that each shift includes a sub-pixel shifted view of the scene;
wherein the light sensing elements have a pixel pitch defining the Nyquist frequency, and where the optics of each camera have a modular transfer function (MTF) such that the optics optically resolve, with sufficient contrast, spatial frequencies larger than the Nyquist frequency (Ny);
wherein the camera array is a monolithic integrated module comprising a single semiconductor substrate on which all of the sensor elements are formed, and optics including a plurality of lens elements, where each lens element forms part of the separate optics for one of the cameras;
wherein each of the cameras includes one of a plurality of different types of filer; and
wherein cameras having the same type of filter are uniformly distributed about the geometric center of the camera array.
2 . The camera array of claim 1 , wherein the cut-off MTF of the optics is at least 1.5 times the Ny.
3 . The camera array of claim 1 , wherein the cut-off MTF of the optics is at least 2 times the Ny.
4 . The camera array of claim 1 , wherein the cut-off MTF of the optics is at least 3 times the Ny.
5 . The camera array of claim 1 , wherein the optics of each camera comprise a three-surface optical arrangement comprising:
a first lens element having a first convex proximal surface and a first concave distal surface, wherein the diameter of the first convex surface is larger than the diameter of the first concave surface;
a second lens element having a substantially flat second proximal surface and a second convex distal surface, wherein the diameter of the flat second proximal surface is smaller than the diameter of the second convex surface, and wherein the diameter of the second convex surface is intermediate between the diameters of the first convex surface and the first concave surface; and
wherein the first and second lens elements are arranged sequentially in optical alignment with an imager positioned at the distal end thereof.
6 . The camera array of claim 1 , wherein the optics of each camera comprise a five-surface optical arrangement comprising:
a first lens element having a first convex proximal surface and a first concave distal surface, wherein the diameter of the first convex surface is larger than the diameter of the first concave surface;
a second lens element having a second concave proximal surface and a second convex distal surface, wherein the diameter of the second concave proximal surface is smaller than the diameter of the second convex surface;
a third lens element having a third concave proximal surface and a third planar distal surface, wherein the diameter of the third concave proximal surface is larger than the diameters of any of the surfaces of the first and second lens elements; and
wherein the first, second and thirds lens elements are arranged sequentially in optical alignment with an imager positioned at the distal end thereof.
7 . The camera array of claim 1 , wherein the optics of each camera comprise a substrate embedded hybrid lens optical arrangement comprising:
a substrate having proximal and distal sides;
a first monolithic lens element having first proximal and distal surfaces disposed on the proximal side of said substrate;
a second monolithic lens element having second proximal and distal surfaces disposed on the distal side of said substrate;
at least one aperture disposed on said substrate in optical alignment with said first and second lens elements; and
wherein the first and second lens elements are arranged sequentially in optical alignment with an imager positioned at the distal end thereof.
8 . The camera array of claim 1 , wherein the optics of each camera comprise a monolithic lens optical arrangement comprising:
at least one lens element comprising:
a first monolithic lens having first proximal and distal surfaces, wherein the first proximal surface of the first monolithic lens has one of either a concave or convex profile, and wherein the first distal surface of the first monolithic lens has a plano profile;
at least one aperture disposed on the first distal surface of the first monolithic lens and in optical alignment therewith;
a second monolithic lens having second proximal and distal surfaces, wherein the second proximal surface of the second monolithic lens has a plano profile, and wherein the second distal surface of the second monolithic lens has one of either a concave or convex profile, and wherein the second monolithic lens is arranged in optical alignment with said aperture; and
wherein the first monolithic lens element is in direct contact with the aperture and the second monolithic lens.
9 . The camera array of claim 1 , wherein the optics of each camera comprise a three-element monolithic lens optical arrangement comprising:
a first lens element having a first convex proximal surface and a first plano distal surface;
a second lens element having a second concave proximal surface and a second convex distal surface;
a third menisci lens element having a third concave proximal surface and a third convex distal surface;
at least one aperture disposed on the first plano distal surface; and
wherein the first, second and third lens elements are arranged sequentially in optical alignment with the aperture stop and an imager.
10 . A camera array, comprising:
a plurality of cameras, where each camera includes a separate optics, and a plurality of light sensing elements each having a pixel pitch defining the Nyquist frequency, and each camera is configured to independently capture a low resolution image of a scene;
a processor configured to synthesize a higher resolution image from the plurality of lower resolution images, the high resolution image has a characteristic MTF;
wherein the optics of each camera are configured so that each camera has a field of view that is shifted with respect to the field-of-views of the other cameras so that each shift includes a sub-pixel shifted view of the scene;
wherein the optics of each camera have a modular transfer function (MTF) at least as large of the MTF of the high resolution image;
wherein the camera array is a monolithic integrated module comprising a single semiconductor substrate on which all of the sensor elements are formed, and optics including a plurality of lens elements, where each lens element forms part of the separate optics for one of the cameras;
wherein each of the cameras includes one of a plurality of different types of filer; and
wherein cameras having the same type of filter are uniformly distributed about the geometric center of the camera array.
11 . The camera array of claim 10 , wherein the MTF of the optics is at least 1.5 times the Ny.
12 . The camera array of claim 10 , wherein the MTF of the optics is at least 2 times the Ny.
13 . The camera array of claim 10 , wherein the MTF of the optics is at least 3 times the Ny.
14 . The camera array of claim 10 , wherein the optics of each camera comprise a three-surface optical arrangement comprising:
a first lens element having a first convex proximal surface and a first concave distal surface, wherein the diameter of the first convex surface is larger than the diameter of the first concave surface;
a second lens element having a substantially flat second proximal surface and a second convex distal surface, wherein the diameter of the flat second proximal surface is smaller than the diameter of the second convex surface, and wherein the diameter of the second convex surface is intermediate between the diameters of the first convex surface and the first concave surface; and
wherein the first and second lens elements are arranged sequentially in optical alignment with an imager positioned at the distal end thereof.
15 . The camera array of claim 10 , wherein the optics of each camera comprise a five-surface optical arrangement comprising:
a first lens element having a first convex proximal surface and a first concave distal surface, wherein the diameter of the first convex surface is larger than the diameter of the first concave surface;
a second lens element having a second concave proximal surface and a second convex distal surface, wherein the diameter of the second concave proximal surface is smaller than the diameter of the second convex surface;
a third lens element having a third concave proximal surface and a third planar distal surface, wherein the diameter of the third concave proximal surface is larger than the diameters of any of the surfaces of the first and second lens elements; and
wherein the first, second and thirds lens elements are arranged sequentially in optical alignment with an imager positioned at the distal end thereof.
16 . The camera array of claim 10 , wherein the optics of each camera comprise a substrate embedded hybrid lens optical arrangement comprising:
a substrate having proximal and distal sides;
a first monolithic lens element having first proximal and distal surfaces disposed on the proximal side of said substrate;
a second monolithic lens element having second proximal and distal surfaces disposed on the distal side of said substrate;
at least one aperture disposed on said substrate in optical alignment with said first and second lens elements; and
wherein the first and second lens elements are arranged sequentially in optical alignment with an imager positioned at the distal end thereof.
17 . The camera array of claim 10 , wherein the optics of each camera comprise a monolithic lens optical arrangement comprising:
at least one lens element comprising:
a first monolithic lens having first proximal and distal surfaces, wherein the first proximal surface of the first monolithic lens has one of either a concave or convex profile, and wherein the first distal surface of the first monolithic lens has a plano profile;
at least one aperture disposed on the first distal surface of the first monolithic lens and in optical alignment therewith;
a second monolithic lens having second proximal and distal surfaces, wherein the second proximal surface of the second monolithic lens has a plano profile, and wherein the second distal surface of the second monolithic lens has one of either a concave or convex profile, and wherein the second monolithic lens is arranged in optical alignment with said aperture; and
wherein the first monolithic lens element is in direct contact with the aperture and the second monolithic lens.
18 . The camera array of claim 10 , wherein the optics of each camera comprise a three-element monolithic lens optical arrangement comprising:
a first lens element having a first convex proximal surface and a first plano distal surface;
a second lens element having a second concave proximal surface and a second convex distal surface;
a third menisci lens element having a third concave proximal surface and a third convex distal surface;
at least one aperture disposed on the first plano distal surface; and
wherein the first, second and third lens elements are arranged sequentially in optical alignment with the aperture stop and an imager.