f35mm mechanical passive-type athermalization lens and assembly method therefor

The invention relates to an f35mm mechanical passive-type athermalization lens and an assembly method therefor. The lens comprises an optical system and a mechanical structure. The optical system of the lens is sequentially provided with a positive lens A, a negative lens B and a positive lens C in an incident direction of light. The mechanical structure of the lens comprises a front lens cone and a main lens cone, wherein the front and main lens cones are sequentially arranged in the incident direction of light. The front lens cone is fixedly connected with the main lens cone, and the interior of the front lens cone is provided with the positive lens A. The interior of the main lens cone is provided with the negative lens B and the positive lens C. The lens reasonably distributes the focal power in a design process of an optical-mechanical structure, and the positive lens A is pushed to move through the combination of lens cone materials with different expansion factors, so as to compensate image plane drift, achieving temperature self-adaption mechanical passive-type athermalization, and enabling an infrared optical system to be capable of maintaining good imaging quality in a larger temperature range. The lens can be matched with a long-wave infrared non-refrigeration type 640*480 17 micron detector, and carries out recording and monitoring of actual conditions.