An analysis of the optimal size of image sensors in free space optic systems

There are several advantages offered by free space optic systems compared with conventional radio frequency systems. As a consequence of shorter wavelengths, the high directivity of the transmitted beam makes acquisition and pointing difficult, thus an imaging system is set up for acquisition and pointing. Optical wave front distortions induced by atmospheric turbulence result in a spreading of the beam leads to image jitter take place in the focal plane, where the image sensor is. The behavior of the image jitter can be described in a statistical manner. Consequently, the size, which is a very important parameter to an image sensor, can be determined by the statistical quantity of image jitter, which customarily is the root mean square (RMS) image displacement. The quantity of the RMS image displacement is as a function of several measurable parameters. In this paper, variations of the estimated RMS image displacement were calculate and discussed in detail. The calculation showed good agreement with the experimental results conducted with a propagation path length of 96 km. The optimal sizes of image sensors that are used for some specific circumstances were analyzed and proposed based on the RMS image displacement.