Infra-red optical systems
First Claim
1. An infra-red optical system including optical means for imaging a field of view onto a thermal sensor, the perimeter of the field of view being defined by an aperture stop located within the system and at least part of which is within said field of view;
- and means for controlling the temperature of the aperture stop in dependence on the temperature of the field of view.
2 Assignments
0 Petitions
Accused Products
Abstract
The system relates to a telescope having optics and a scanning head which images a two-dimensional field of view point by point onto a localized thermal sensor. An aperture stop is mounted within the telescope housing and at least part of it is within the field of view of the sensor. The temperature of the stop is controlled by means of Peltier thermo-electric modules so that it corresponds to the average temperature of the external field of view. This prevents halation or blooming which would result from extreme temperature contrasts. The vignetting which occurs when the aperture stop is within the field of view gives an increased magnification for a given size of objective optics, and the benefits outweigh the corresponding reduction in thermal sensitivity.
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Citations
7 Claims
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1. An infra-red optical system including optical means for imaging a field of view onto a thermal sensor, the perimeter of the field of view being defined by an aperture stop located within the system and at least part of which is within said field of view;
- and means for controlling the temperature of the aperture stop in dependence on the temperature of the field of view.
- View Dependent Claims (2, 3, 4, 5, 6, 7)
Specification