Low magnification mode of operation for common mechanical axis field of view switching and image de-roll
AssigneeThe United States of America as represented by the Scretary of the Army
InventorJohn M. Hall
Life of this patent
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Abstract
A low magnification mode of operation of a multiple field of view optical system is based on off-axis reflective afocal assemblies with a common optical exit pupil and having a common mechanical axis of rotation which provides both field of view switching and image de-roll functions. A reflective afocal switching assembly permits variable fields of view while at the same time providing a common axis and mechanism to achieve an optical de-roll of the image. This complex arrangement provides a relatively large change in magnification for an all-reflective optical system than can image over 0.4-12.0 micron spectrum.
Claims5
A low magnification mode of operation of a multiple field of view optical system based on off-axis reflective afocal assemblies with a common optical exit pupil and having a common mechanical axis of rotation which provides both field of view switching and image de-roll functions, the steps of the low magnification mode of operation comprising:
- Rotating a low magnification mode reflective afocal subassembly about a common mechanical axis of rotation, which provides both field of view switching and image de-roll functions, relative to a high magnification mode off-axis reflective afocal assembly in order to intercept a different set of light rays from a scene such that:
- a concave primary mirror is oriented such that the different set of light rays from a scene reflects from a concave reflective surface of the concave primary mirror as first reflected light rays,
- the first reflected light rays then propagate to reflect from a negative powered secondary mirror as second reflected light rays,
- the second reflected light rays then are reflected from a flat surface mirror as third reflected light rays, and
- the third reflected light rays then are reflected from a low power afocal tertiary mirror as a low magnification light, which are directed along the common mechanical axis to the common optical exit pupil.
Dependencies are inferred from the claim text.