A unique phenomenon exists in the natural world: on nights with moonlight or starlight, the eyes of felines appear exceptionally bright when observed, standing in sharp contrast to the surrounding dark environment. This phenomenon is defined as the “cat’ eye effect”.
The cat’ eye effect stems from the unique optical structure of feline eyes, which functions as a typical focused optical system. The cornea and crystalline lens act as a focusing lens, while the retina and tapetum lucidum serve as reflective elements. When light enters this optical system, it is first converged onto the focal plane by the lens, then reflected backward by the reflective elements located on the focal plane. The reflected light travels back along its original path, with an intensity approximately 2 to 3 orders of magnitude higher than that of ordinary diffuse reflected light. This is why the eyes appear so bright. 
Many electro-optical observation & aiming devices (EOADs) feature the cat’ eye effect, including telescopes, optical sights, low-light night vision devices, cameras and other similar devices. The complex optical lens assemblies composed of multiple optical elements inside such device can be equivalent to a single lens, and focal plane components (such as CCD, CMOS imaging detectors, reticles, etc.) act as reflective elements. When such EOAD is illuminated by a laser beam, the echo intensity of the reflected laser is far stronger than the disordered diffuse reflection echoes from the surrounding background due to the cat’ eye effect. This enables effective identification of enemy OOTDs from complex backgrounds.
The anti-reconnaissance and anti-sniper system utilize the cat's eye effect for detection. It emits detection laser beams to scan and search suspicious areas, receives and processes reflected echo signals to locate the positions of enemy OOTDs. While issuing early warnings, the system emits suppression lasers to implement optical jamming.
