Rosette scanning surveillance sensor

DETAILED DESCRIPTION The present invention avoids or overcomes these and other deficiencies, drawbacks or problems of conventional mechanisms by utilizing a pair of rotating gimbals which independently nutate and precess the line-of-sight of the sensor to generate a stable rosette pattern.
Specifically, a first gimbal, mounted on a supporting vehicle, rotates about a precession or roll axis.
A second gimbal is mounted on the first gimbal and rotates about an axis, called a nutation axis, which is angled with respect to the precession or roll axis, this offset angle termed an angle of precession.
The sensor is fixed to the second gimbal and has a line-of-sight which is angled with respect to the nutation angle.
The angle of nutation must be equal to the angle of precession to generate a rosette pattern.
With proper selection of precession and nutation rates, a stable, contiguous scan occurs.
In addition, other electro-optic mechanisms may be included in or combined with the above optical system.
Several advantages are derived from this mechanization.
Its construction is simple and, therefore, it is relatively less costly and complex than conventional designs.
The translation of the entrance aperture at the optical window is reduced as the detector field-of-view is scanned across the field-of-regard, to minimize optical abberations due to defects either in conformal window curvature or from diffraction/obscuration at segmented window partitions.
Thus, these advantages as to cost are derived from the opto-mechanical simplicity of the scanning mechanism and the avoidance of complex optical and/or electronic mechanisms which are required in prior constructions to correct optical abberations resulting a large conformal window.
In addition, gimbal torque requirements are minimized because both gimbals rotate at constant rates, consequently, to minimize weight and power of the torquer mechanisms.
Other aims and advantages, as well as a more complete understanding of the present invention, will appear from the following explanation of an exemplary embodiment and the accompanying drawings thereof