What is the principle of color glasses? Summer color glasses good?

Life, we always see from time to time some people wearing a 'magic' glasses, indoors, glasses, just like ordinary glasses and glasses when outdoors will become gray or dark brown, such as different glasses. This magic glasses is color glasses, colorless indoors, can be used as ordinary glasses; In outdoor uv discoloration, it can be used as sunglasses, a mirror of dual-use. The mystery of the color glasses in the glass. This special glass called the photochromic glass. It in the process of manufacture, blending into the light sensitive material in advance, such as silver chloride, silver ( Generally referred to as the silver halide) , as well as small amounts of copper oxide catalyst. Glass lens from no color to light gray, tan, then back to the sound from the black glasses glasses, are silver halide magic '. In the glass of color glasses, and film exposure is similar to the imaging process of change. Silver halide see light decomposition, into a lot of black silver particles evenly distributed in the glass, glass lenses so look bleak, stop the traffic light, this is the color of glasses. But, unlike the situation on film, silver halide generated after decomposition of silver atoms and halogen atoms, still get together tightly. When the place is slightly a little bit dark, under the promoting of copper oxide catalyst, silver and halogen compound and generate the silver halide, glass lenses and became more transparent. Silver halide resident in glass, decomposition and combination of response to repeated AD infinitum. Photographic film and paper can only be used once, change color glasses can continue to be used. Color glasses can not only with the strength of the light dark bright, also can absorb harmful to the human eye of uv, indeed is the top grade in the glasses. If the window is changed into photochromic glass, sunny day, the sun shot wouldn't come to the room; Cloudy day or in the morning, at dusk, the light is not obscured, outdoor indoor still bright. It's as if hung up the automatic door window sunshade curtain. To see the summer is coming soon, the strong sunlight let person eyesight whiting, color glasses are very suitable for indoor and outdoor work alternately, is a necessary device to protect the eyes.
related: color glasses color glasses