Optical Glass Protective Window

Windows are used to admit light into an optical system and to exclude dirt and moisture. When selecting windows you should consider materials, transmission, scattering, wavefront distortion, parallelism and resistance to certain environment. Windows may also be used as coating substrates for use in a wide range of applications.
Optical windows are used to allow optical radiation to pass from one environment to another without allowing other elements of these environments to mix. And it does not change the wavelength distribution of the beam, the transmitted wavefront, nor does it scatter any of the light out of the beam.