Steve Griffin (Boeing), Brandoch Calef (Boeing)
Keywords: Image stabilization
Abstract:
Raw images from telescopes, where the dome moves with the aperture, have been observed to be much less resolved than telescopes without a dome. This degradation is much larger than can be explained by diffraction related to aperture size. One likely cause is the higher vibration environment associated with dome motion. Dome seeing is another possible cause. An optical inertial reference is an inertially stabilized platform with an integral collimated light source that traverses the same path in an imaging system as the image. The use of an inertial reference with an integrated optical source is not new and has been at the heart of almost every directed energy (DE) system on a moving platform. When attempting to put a beam of energy on a target, it is necessary to use the information from the inertial reference in real time over a very broad frequency band to stabilize the optical line of sight using fast steering mirrors and an inertially stabilized gimbal. Assuming the vibration environment is a major contributor to degradation in a staring, imaging system, the problem is much less difficult, as the camera filters out low frequency motion and the lowest frequency which a useful reference must appear stable above is inversely proportional to the exposure time. Images and information from the reference can also be stored and corrected in a post processing mode, which is not possible in a DE system. Assuming LOS jitter is controlled enough to keep the target on the image plane, the inertial reference only has to appear inertially stable above roughly half the sampling frequency to reduce jitter over the integration time of the image. The cost and complexity are inextricably linked to very low frequency performance in a traditional optical inertial reference, so the inertial reference for a staring, imaging system does not have to be complex or expensive and may be as simple as a passively isolated pointing laser. This work will establish feasibility of post processing and real time, solid-state image stabilization techniques using the collimated light source projected from a simplified inertial reference in place of a star.
Date of Conference: September 9-12, 2014
Track: Daylight Imaging