Mirror is an optical element that works according to the law of reflection. Reflector mirror can be divided into three types according to shape: plane reflector, spherical reflector and aspheric reflector; According to the degree of reflection, it can be divided into total reflection mirror and semi-transparent semi-reflection mirror (also known as beam splitting mirror). Mirrors manufactured in the past are often silver-plated on glass. Its standard manufacturing process is to evaporate aluminum on a highly polished substrate in vacuum and then coat it with silicon oxide or magnesium fluoride. In special applications, the loss caused by metal can be replaced by multilayer dielectric film.
Because the reflection law has nothing to do with the frequency of light, this kind of element works in a wide frequency band, which can reach the ultraviolet and infrared regions of the visible light spectrum, so its application range is becoming wider and wider. On the back of the optical glass, a layer of metallic silver (or aluminum) film is coated through vacuum coating to make the incident light reflect the optical element. The output power of the laser can be doubled by using a mirror with high reflectivity; And it is reflected by the reflecting surface. The reflected image is not distorted and has no ghost. It is reflected by the front surface. If a common mirror is used as the second reflecting surface, it will not only have low reflectivity and no selectivity to wavelength, but also easily produce ghost. With the coated surface reflector, the image obtained is not only bright, but also accurate and unbiased, with clearer picture quality and more vivid color. The front surface mirror is usually used for optical high-fidelity scanning reflection imaging.