US 6,555,803 B1 · Method and apparatus for imaging a field of regard by scanning the field of view of an imaging electro-optical system in a series of conical arcs to compensate for image rotation

Abstract

A two-dimensional field of regard is scanned with a single plane mirror in the object space of a telescope, maintaining a fixed relationship between the rotational direction of scan and the projection of the telescope's focal plane. The two dimensional field of regard is covered by a series of conical arcs, each arc being scanned by rotation at constant angular velocity about the inner axis of the two-axis system. This scanning system accommodates applications such as TDI that require an opto-mechanical scan with a constant linear velocity (magnitude and direction) in the focal plane. Shading of IR images is mitigated by calibration at the ends of each scan line and by a scan geometry that minimizes changes in reflection angle.

Claims16

Dependent claims

A method of scanning a field of view of an imager across a field of regard using a scan mirror mounted on a gimbal having an inner axis and an outer axis, the method comprising:

sweeping the field of view across the field of regard in a selected direction by rotating the gimbal about the inner axis while maintaining the gimbal at a fixed angle with respect to the outer axis;
progressing to a subsequent scan position by rotating the gimbal about the outer axis by a predetermined increment angle while maintaining the gimbal at a fixed angle with respect the inner axis;
repeating the act of sweeping such that the selected direction is chosen alternately from a first direction and a second direction that is opposed to the first direction;
and
repeating the act of progressing prior to each repeated act of sweeping;
wherein a line of sight of the imager is perpendicular to the outer axis, so that there is substantially no rotation, with respect to the instantaneous direction of scan, of an image formed on the imager.

3 more elements

Dependencies are inferred from the claim text.

Method and apparatus for imaging a field of regard by scanning the field of view of an imaging electro-optical system in a series of conical arcs to compensate for image rotation

Life of this patent

Method and apparatus for imaging a field of regard by scanning the field of view of an imaging electro-optical system in a series of conical arcs to compensate for image rotation

Life of this patent

Abstract

Claims16