Why do color-changing lenses change color

Color-changing lenses are also called "photosensitive lenses". Because silver halide chemicals are added to the lenses, the originally transparent and colorless lenses will turn into colored lenses for protection when exposed to strong light. Suitable for indoor and outdoor use at the same time.

The color-changing lens is made of optical glass containing silver halide microcrystals. According to the principle of the reversible reaction between light and color, it can be quickly darkened under sunlight and ultraviolet rays, completely absorb ultraviolet rays, and neutrally absorb visible light, returning to the dark. It can quickly restore colorless and transparent. The color-changing lens is mainly used in open-air, snowy, and indoor workplaces with strong light sources to prevent sunlight, ultraviolet light, and glare from harming the eyes.

Strictly speaking, most photochromic lenses do not belong to sunglasses because they hardly reduce visible light. However, in foggy and twilight hours, the yellow lenses in photochromic lenses can increase the contrast and provide more accurate vision, so it is also called Night vision goggles, some young people wear yellow lenses "sunglasses" as a decoration, which is an option for those with glaucoma and patients who need to improve their visual brightness.

The response of the color-changing lens to light will be affected by temperature. A decrease in temperature will change the "vitality" of the photochromic reaction, so that the compound reaction-the reaction of the lens to restore light-slows down and delays the color change time. In a lower environment, the discoloration of the color-changing glasses will be larger and appear darker when exposed to light. Since the added silver halide has been integrated with the optical materials, the color-changing glasses can be repeatedly discolored and used for a long time, which can not only protect the eyes from strong light stimulation, but also correct vision.