BK7 WindowsFeatures: High Precision Dimension Control, Minimal Transmitted Beam Deviation, Excellent Environmental Durability.Applications: Projection Optics System, Imaging Optics System, Optical Measurement Systems.Description:Windows are optical glass with ground and polished faces that are relatively parallel. They are used to isolate two physical environments while allowing light to pass.BK7 window is the most common type of window. It has good performance over visible and near infrared wavelength region. At the same time,BK7 window is ideal for applications require minimal transmitted beam deviation. It is suitable for coating AR film.Optical Windows are flat, plane-parallel plates that are often used as protective barriers for electronic sensors or detectors from outside environments. Optical Windows should be selected based on the material transmission or mechanical properties of the substrate. Optical Windows do not cause change in the magnification of a system.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.Some commonly used materials in windows are BK7, UV Fused silica, Borofloat 33, Pyrex, CaF2,BaF2 ,Other optical glasses from Schott,CDGM.Made from BK7 material, which has transparent range from 330-2100nm. The refractive index is 1.5168 at 587.6nm. The BK7 window has good performance over visible and near IR spectrum for most application.Specifications: Dimension Tolerance: +0.0/-0.2mmThickness Tolerance: ±0.2mm（General),±0.05(High Precision)Surface Quality:  60/40（General),10/5(High Precision)Clear Aperture: ＞90%Flatness:λ/2@633nm（General),λ/10@633nm (High Precision)Parallelism:  <3 arc min.(General). <3 arc sec.(High Precision)AR Coated:  Uncoated, AR, HR, PR, etc.