Abstract: The System is a test instrument used to measure the quality of the optical path through the atmosphere. The device measures the atmospheric transverse coherence length, also known as Fried's parameter or the diffraction limited aperture of the atmosphere, and the angle-of-arrival of incident optical radiation. The system consists of a high resolution Charge Coupled Device (CCD) camera mounted at the focal plane of a telescope and interfaced with a high resolution frame grabber and computer. Incident optical radiation is focused by the telescope onto the CCD array in the camera. The picture frame is then transferred to the frame grabber where the computer determines the size of the focussed spot and position of the spot in pixel coordinates, the Atmospheric Transverse Coherence Length and the Angle-of-Arrival. The software required to control the camera and determine the parameters is an integral part of the system.