 Windows are commonly used to isolate two atmospheric regions of an optical system while permitting light to pass. The quality of the window can be critical. It should be of high purity and polish in order not to affect the optical system. When large pressure differences are anticipated across the window extra thickness will be required to hold the flatness and parallelism specifications.
Windows may also be used as coating substrates for use in a wide range of applications.
Optical windows are supplied in a wide range of materials and shapes and to various levels of flatness and parallelism:
Material: BK7, UV Fused Silica
Shape: Circular, Square, Elliptical
Flatness: λ/10, λ/4, λ/2, 2λ per 25mm.
Parallelism: 10 arcsec, 3 arcmin
Wedge: 0, 30 arcmin, 1°, 2°, 3°
We can supply circular optical windows in diameters of 10.0, 12.7, 19.1, 20.0, 25.4, 30.0, 38.1, 40.0, 50.8, 76.2 or 101.6 mm or any custom size.
We can supply square optical windows in sides of 10.0, 12.7, 19.1, 20.0, 25.4, 30.0, 38.1, 40.0, 50.8 mm or any custom size.
We can supply elliptical optical windows with a minor axis of 12.7, 15.0, 19.1, 25.4 mm or any custom size.
Glass and fused silica windows may be anti-reflection coated on both sides to provide high transmittance or on one side only to provide a weak (~ 4%) reflected beam for sampling.
The coating types which may be applied to 1 or 2 sides are:
Single wavelength A/R coat R = 0.25% @ 0° R = 0.5% @ 45°
Broadband A/R coat Rave = 0.5% @ 0° Rave = 0.5% @ 45°
Dual wavelength A/R coat λ1 R = 0.25% @ 0° R = 0.5% @ 45° λ2 R = 0.5% @ 0° R = 1.0% @ 45° . | 
