In the process of athermal design of the infrared optical system, the following issues should be paid attention to.

(1) With the change of temperature, the original aberration compensation relationship is destroyed, and the best focus position of the system may change nonlinearly with the change of temperature.

(2) For the reflection system, if the material of the mirror is the same as the material of the lens barrel (or the material has the same thermal expansion coefficient), when the temperature changes, the system will only zoom in or out to a certain extent, and the temperature will affect the performance of the system Not big, in principle, no heat dissipation design is required.

(3) Since the mechanical lens barrel for installing the lens is complex in most cases, the way of expansion (or contraction) of the lens barrel with different structures is not necessarily the same when the temperature changes. Based on the heating equation, specific analysis is made according to the specific problems of different lens barrel structures to ensure a good heat dissipation effect.