The camera system consists of a folded optical system that focuses object in the visible waveband on a plurality of CCD detector arrays ( 6 ). The camera system is a push-broom imager with a plurality of long, substantially linear CCD arrays ( 6 ) arranged orthogonal to the scan direction S. The camera system is capable of image resolutions down to 1 m from a space orbit.
1. A camera system for scanning a remote object from space, comprising:
a plurality of object detectors each comprising a pixellated array of charge coupled devices (CCDs) acting as a single detector channel; and
a telescope arrangement of mirrors defining a folded optical path for focusing an object on the plurality of object detectors;
wherein the number of CCD pixels of each object detector in a direction orthogonal to a scan direction of the camera system is greater than the number of CCD pixels in the scan direction; and
wherein the plurality of object detectors are substantially in a line orthogonal to the scan direction.
2. A camera system as claimed in claim 1 , wherein each object detector is positioned substantially in the focal plane of the camera system.
3. A camera system as claimed in claim 2 , wherein at least one end of each object detector partially overlaps with an end of an adjacent object detector.
4. A camera system as claimed in claim 1 , wherein at least one end of each object detector partially overlaps with an end of an adjacent object detector.
5. A camera system as claimed in claim 1 , further comprising addressing circuitry for addressing the CCD pixels in each of the pixellated arrays and wherein the addressing circuitry is adapted to perform time delay integration of the outputs from the CCD pixels.
6. A camera system as claimed in claim 1 , wherein each pixellated array of CCDs is divided into a plurality of separately addressable sectors and the addressing circuitry is separately connected to each addressable sector thereby enabling parallel readout of the outputs from each sector.
7. A camera system as claimed in claim 1 , wherein the camera system is a push-broom imager.
8. A camera system as claimed in claim 1 , wherein the telescope arrangement of mirrors is an off-axis telescope arrangement.
9. A camera system as claimed in claim 8 , wherein the off-axis telescope arrangement of mirrors has a decentered pupil.
10. A camera system as claimed in claim 1 , wherein the ratio of the number of CCD pixels in a plane orthogonal to the scan direction of the camera system to the number of CCD pixels in a plane parallel to the scan direction is at least 2:1.
11. A camera system as claimed in claim 10 , wherein the ratio is at least 10:1.
12. A camera system as claimed in claim 11 , wherein the ratio is around 64:1.
13. A camera system as claimed in claim 1 , suitable for spaceborne observation providing a spatial ground resolution of at least 4 m.
14. A camera system as claimed in claim 13 , suitable for spaceborne observation providing a spatial ground resolution of around 1 m.