In various applications, it is necessary to obtain strip images having a 180-degree field of view. Such applications include terrain mapping, oceanographic studies, planetary exploration, cloud surveillance, and aerosol bidirectional reflectance distribution measuring.
For such applications, a fish eye lens is often employed. However, a fish eye lens having a 180-degree field of view suffers from unacceptable levels of distortion and chromatic aberration. Further, such optical systems are often susceptible to thermal distortion caused by uneven expansion or contraction of components of the optical system.
Alternatively, a single narrow field of view optical device is rotated through 180 degrees to sequentially scan a full 180-degree field of view. The provision of a rotating optical device yields unacceptable penalties in weight, cost, and reliability. Further, such a device does not simultaneously image the entire 180-degree field of view and, therefore, is not suitable in circumstances where the image environment is changing rapidly, or in circumstances where the device itself is moving through the environment, such as on an aircraft, satellite, or remote space vehicle.
As can be appreciated, there exists a need for an improved strip imaging system capable of simultaneously imaging an entire 180-degree strip of a target image.