Eye Safe Laser Crystal Module

The damage threshold for human eye is high when a laser with a wavelength greater than 1.4 um, because when it is irradiated to the human eye, most of its light intensity is absorbed by the vitreous body, so it is not easy to damage the retina at a certain power.( Taking the 1.57um laser as an example, according to the US national security standards, its safe exposure to human eye is 400 thousand times that of the 1.06um Nd:YAG laser currently used.) So it is called the human eye safety wavelength. In this band, the safest band is located near 1.54um, so there are also people's eye safety limits to 1.5-1.7um, which has a large contrast to the background of many targets, such as vehicles, ships, cement buildings, etc., which is very attractive in laser radar, target recognition and so on.