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N-BK7 λ/2 D25.4x0.2mm Uncoated Windows

Code: 135-003


Qty 2-5
Qty 6
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Material N-BK7 Diameter 25.4(+0.0/-0.1)mm
Thickness 0.2(+/-0.02)mm Wavefront Distortion λ/2
Surface Quality 10 /5 S/D Parallelism <10 arc Sec
chamfer 0.2mmx45° Coating uncoated

Thin windows made from BK7 and UV fused silica are provided, windows has high specifications as: surface quality of 10-5 S/D, parallelism of 10 arc second, which are suitable for ultra-fast laser applications. And the customized windows are available upon your request.

Interference Photo (Measured by Zygo)

Femto-line lasers and applications are developing fast in recent years, some demanding components are needed to make Femto-line laser systems, one of them is the small thickness (such as 0.1mm, 0.2mm) windows or substrates with high flatness (Lambda/10 or Lambda/4 @633nm).

Classical single surface polishing method are often used to make the high precision laser grade optics products, but it is difficult to make the high flatness optics with small thickness using classical method. For the polished optics is often put on pitch plate in polishing processing , even though you get a high quality surface (high surface quality and high flatness) in polishing, when it is taken off pitch plate, the flatness would be lowered, because there is stress in the optics when it is bonded to pitch, when it is taken off pitch plate, the stress would be released, the flatness would be lowered in the stress releasing, for the small thickness one, the flatness would become very lower. To get high flatness and ultra thin windows is always challenging for manufacturers.

Hangzhou Shalom EO develop a double surface polishing method to make the high precision optical windows or substrates, the double surface are polished in single polishing processing,  the optics don’t need to be put on pitch plate in the polishing, and there is no stress releasing problem, there would be no flatness change when it is taken from tools. Double surface polishing method is not used in precise optics fabrication previously because the finished optics is low surface quality, Hangzhou Shalom EO has done improvements on polishing machine, and the 10/5 S/D is get. And furthermore, the parallelism is excellent (10 arc sec) for this polishing windows. 

10/5 S/D
10 arcsec
2 weeks