COTS Windows are used in defense or security applications to separate multiple environments. COTS Windows are designed to protect sensitive optical components or people from harmful laser beams. COTS Windows use a variety of substrates, coatings, or a combination of the two to reflect only specific wavelengths. COTS Windows are a low cost alternative to developing custom optical windows. COTS Windows designed for use in the ultraviolet, visible, or infrared are available.