The infrared sight consists of objective lens, shell, eyepiece, battery, connector, etc., as shown in the diagram 1.
Diagram 1 Infrared sight composition 1. Objective lens; 2. Shell; 3.Battery; 4. Eyepiece; 5. Connector
The basic working principles of infrared sight is as shown in the figure below.
Figure  Infrared sight’s working principle figure
The infrared sight is mounted to the firearm Picatinny rail via the connector; the infrared radiation from the target is focused by the objective lens assembly onto the sensitive element of the infrared uncooled focal plane detector. After thermal-electric conversion, a processable electrical signal is generated. The electronic circuit board performs pre-treatment of the electrical signal and converts it into a digital image signal. Then the digital image signal undergoes non-uniformity correction, blind pixel replacing, image enhancement, brightness and contrast adjustment and overlay of menu, interface and firing table information before being output to the eyepiece, so as to assist the shooter in achieving accurate shooting.