A dual band optical system for a framing aerial reconnaissance camera is described. The camera including at least two two-dimensional image recording media for generating frames of imagery of a scene external of an aerial reconnaissance vehicle carrying the camera. The camera includes a Cassegrain optical system forming an objective lens for the optical system, including a a primary mirror having a central aperture and a secondary mirror. The primary and secondary mirrors are aligned along an objective optical axis. The optical system also includes an azimuth mirror receiving radiation from the secondary mirror. The azimuth mirror is placed between the primary and secondary mirrors. A spectrum-dividing element in the form of a prism receives radiation from the azimuth mirror. The spectrum-dividing element directs radiation in a first band of the electromagnetic spectrum into a first optical path and radiation in a second band of the electromagnetic spectrum into a second optical path different from the first optical path. A first two-dimensional image recording medium is placed in the first optical path and a second two-dimensional image recording medium is placed in the second optical path. The first and second image recording media generating first and second images in two different portions of the electromagnetic spectrum simultaneously.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to the following patent applications filed on the same date as this application, the contents of each of which is incorporated by reference herein:
Andrew J. Pattynski et al., METHOD FOR FRAMING RECONNAISSANCE WITH ROLL MOTION COMPENSATION, Ser. No. 09/654,031;
Andrew J. Partynski et al., DUAL BAND FRAMING RECONNAISSANCE CAMERA, Ser. No. 09/652,524;
Stephen R. Beran et al., METHOD FOR FORWARD MOTION COMPENSATION IN AN AERIAL RECONNAISSANCE CAMERA, Ser. No. 09/652,965.
A reconnaissance camera is described which has a Cassegrain optical system forming an objective lens that directs radiation to a spectrum-dividing prism. The prism directs radiation in a portion of the electromagnetic spectrum (e.g., visible) into a first optical path having a two-dimensional image-recording medium. Radiation in a second band of the spectrum (e.g., IR or UV) is directed to a second optical path, which has a two-dimensional image-recording medium. A motor system is coupled to a camera housing that encloses the optical elements of the camera and the image recording media. The motor steps the entire camera housing about the roll axis while the image recording media are exposed to generate frames of imagery.
