Electro-optical devices can easily be captured by active laser detection weapons according to the Cat-eye effect of optical windows. The focal shift method was proposed to decrease retroreflected wave power for Cat-eye target stealth when the image quality of these devices was under controlled. The principle of focal shift was analyzed and experimental validation was carried out respectively. Furthermore, digital image of focal shift device was evaluated based on gray gradient function, and the blurred images were restored. The results show that the divergent angle of reflected wave is enlarged and retroreflected wave power decreased when the focal shift distance increases. Meanwhile, high-frequency information of images captured by focal shift electro-optical devices decrease accordingly. However, the deteriorative range of image quality is acceptable. After restoration, the visual effects of the images are improved efficiently．