Optical 101

Laser mirror is used for various laser light sources. A metal or dielectric film is coated on the glass substrate, and it exhibits various characteristics depending on the type of coating. It can also act like a filter, reflecting only light of a specific wavelength. In addition, even among laser light sources, it can be designed according to the wavelength, output, and application of the laser. In laser processing, it is incorporated into various products by using it properly according to the application.

Usage of laser mirror

Laser mirrors are mainly used for laser machining. For example, welding and cutting. High-power lasers are widely used when processing objects, but it is necessary to reflect light in various directions. Laser mirrors are used to make the laser easier to use. It is also used to improve the output of the laser. The output of a laser excited by a diode may be weak if it is left as it is. In such a case, the light is amplified by reflecting it with a laser mirror.

Laser mirror principle

The laser mirror has a structure in which a thin film is coated on a glass substrate. Specifically, it is a metal or dielectric film. Since the characteristics and applications vary depending on the coating, we will introduce three typical coatings.

• Metal coating
  A mirror coated with gold, silver or aluminum. It is inexpensive and can be used in a wide wavelength band. In addition, gold has the property of transmitting 600 nm or less, and silver has the property of transmitting 400 nm or less. The disadvantage is that the surface is easily scratched.
• Wideband articulated film A
  wideband, highly reflective coated mirror. Light is not absorbed by the film and is used for laser light sources that use multiple wavelengths.
• Laser attractant film
  A mirror coated with high reflectance at a specific wavelength. It is the most common laser mirror used for short wavelength lasers and high power lasers. Another advantage is that the film does not absorb light and the film is hard and not easily damaged.

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