Detection system of optical athermal design effect based on image processing

Athermalization is an important part of IR optical system design. In order to measure the effect of the IR athermalization, a method was presented, which was based on image processing. The system under test was focused automatically with this method, and then the defocusing amount of the system under different temperatures was deduced while the focal points of different temperatures were recorded and analyzed. A system used to measure the effect of athermal design was invented, whose composition, working principle for measuring the defocusing amount, auto-focusing algorithm and selection of the focusing region were introduced. A multi-focusing strategy based on image gray gradient was also presented and validated. The result of the experiment indicates that the system has many advantages such as high speed, satisfactory repetition, high precision, and high noise tolerance.