DUAL-Q IMAGING SYSTEM
A optical system carried by a flying object such as a satellite or aircraft having a pair of optical paths having different Q values for obtaining a pair of images of the same spot on the Earth's (or other celestial body's) surface. The optical paths may have a portion in common with each other and a portion not in common with each other. Light is directed into the optical paths via a field sharing arrangement. One of the optical paths together with an imaging device creates relatively narrower field of view images with a higher ground resolution than the other optical path together with an imaging device.
A 1 . An optical system for use in an object above a celestial body in combination with an imaging device also in the object, the system and the device being used to obtain images of portions of the surface of the celestial body, the system comprising:
a first optical path having a plurality of optical elements therein, the first optical path have a first focal length; and
a second optical path having a plurality of optical elements therein, the second optical path have a second focal length that is different from the first focal length;
wherein light entering the optical system is directed into one of the first and second optical paths based on a shared field arrangement.
2 . An optical system as defined in claim 1 , wherein the shared field arrangement includes a pair of mirrors, one in the first optical path and one in the second optical path, that direct the light in the optical system into one of the first and second optical paths.
3 . An optical system as defined in claim 1 , wherein the pair of mirrors each reflect light of the entire visible spectrum.
4 . An optical system as defined in claim 1 , wherein the imaging devices associated with the two optical paths are operated at different times with only the imaging device associated with the first optical path operating during certain times and only the second imaging device associated with the second optical path operating during certain other times.
5 . An optical system as defined in claim 1 , wherein the imaging device captures images from the light directed thereto by the first and second optical paths, the images from the two optical paths being captured simultaneously.
6 . An optical system as defined in claim 5 , wherein the pair of simultaneous images are taken with a central point in each image being offset from each other on the Earth's surface, with one image having a relatively narrow field of view and relatively higher ground resolution and the other image having a relatively wider field of view and relatively lower ground resolution.
7 . An optical system as defined in claim 1 , wherein the two different focal lengths are different by a factor of approximately two.
8 . An optical system as defined in claim 1 , wherein the two different focal lengths are different by a factor in the range from 1.4 to 2.
9 . An optical system as defined in claim 1 , wherein a portion of the optical elements of the first optical path are in the second optical path and the remainder of the optical elements of the first optical path are not in the second optical path.
10 . An optical system for use in an object above a celestial body in combination with a pair of imaging devices also in the object, the system and the device being used to obtain images of portions of the surface of the celestial body, the system comprising:
a first imaging system including a first optical path and a first imaging device, the first imaging system having a Q value of Q 1 ; and
a second imaging system including a second optical path and a second imaging device, the second imaging system having a Q value of Q 2 , wherein Q 2 is different than Q 1 ;
where Q=(A*focal length)/ aperture diameter/pixel size, where A is a specified wavelength of light obtained by the optical system, and pixel size is the size of the pixels in the imaging device.
11 . An optical system as defined in claim 10 , wherein the light coming into the system is directed into one of the first and second optical paths via a field sharing arrangement.
12 . An optical system as defined in claim 10 , wherein the first and second imaging device are substantially identical.
13 . An optical system as defined in claim 10 , wherein the first and second imaging device are operated at different times with only the first imaging device operating during certain times and only the second imaging device operating during certain other times.
14 . An optical system as defined in claim 10 , wherein the first and second imaging device are operated simultaneously to each obtain a series of images.
15 . An optical system as defined in claim 14 , wherein the images from the first and second imaging device are taken at substantially the same instant in time and are taken with a central point in each image being offset from each other on the celestial body's surface, with one image having a relatively narrow field of view and relatively higher ground resolution and the other image having a relatively wider field of view and relatively lower ground resolution.
16 . An optical system as defined in claim 10 , wherein the values of Q 1 and Q 2 are different by a factor of approximately two.
17 . An optical system as defined in claim 10 , wherein the values of Q 1 and Q 2 are different by a factor in the range from 1.4 to 2.
18 . An optical system for use in an object above a celestial body in combination with an imaging device also in the object, the system and the device being used to obtain images of portions of the surface of the celestial body, the system comprising:
an optical telescope that receives light from the outer surface of the celestial body and forms a focused image at an image plane;
a first optical path that includes at least a relay mirror and an image sensor, the relay mirror being located on an opposite side of the image plane from the optical telescope to receive light diverging from the focused image at the image plane; and
a second optical path that includes at least a relay mirror and an image sensor, the relay mirror being located on an opposite side of the image plane from the optical telescope to receive light diverging from the focused image at the image plane, the second optical path being different from the first optical path, and the second optical path producing an image of the outer surface of the celestial body that has a relatively narrower field of view than the first optical path and a relatively higher ground resolution than the first optical path;
wherein the relay mirror of the first optical path and the relay mirror of the second optical path are positioned so as to receive light from two different portions of the focused image.
19 . An optical system as defined in claim 18 , wherein the optical telescope is a reflecting telescope.
20 . An optical system as defined in claim 19 , wherein the reflecting telescope is a Cassegrain telescope having a primary mirror and a secondary mirror, the primary mirror having an opening defined at a center thereof.
21 . An optical system as defined in claim 20 , wherein the image plane is located on an opposite side of the opening from the secondary mirror.
22 . An optical system as defined in claim 18 , wherein the optical paths have Q values that are different by a factor of approximately two.
23 . An optical system as defined in claim 18 , wherein the optical paths have Q values that are different by a factor in the range from 1.4 to 2.