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BK7 Windows
BK7 is borosilicate crown optical glass. It has
an excellent physical and chemical properties for
applications in visible and near IR. Large BK7 glass with high homogeneity, low bubble and inclusion content can
be produced at a large quantity and at low cost, making it the
standard material for optical components in visible and IR. Various high
quality HR, AR, and partial reflective coatings are available on BK7
faces.
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Shapes and Geometries
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Round Parallel Windows
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Round Wedge Windows
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Square Parallel Windows
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Rectangular Parallel Windows
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* Other shapes and
geometries are routinely fabricated by Newlight Photonics Inc.. Please contact us for your
specific needs.
Basic Properties of BK7 Glass
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Transparency Range: 360 - 2300 nm |
Transmission Curve |
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Density: 2.51 g/cm3 |
Therm-Optic Coefficients:
dn/dT= x 10-6 /oC
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Optical Homogeneity: Δn
< 10-6/cm
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Knoop Hardness: 610 |
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Thermal Expansion Coefficients: |
α = 8 x 10-6/K
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Sellmeier equations
(λ in µm):
n2=1+1.03961λ2/(λ2-
0.0060007 )+0.23179λ2/(λ2-0.020018)+1.01047 λ2/(λ2-103.5600) |
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Wavelength(nm) |
Index of refraction |
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532 |
1.5194 |
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588 |
1.5167 |
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632.8 |
1.5150 |
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1064 |
1.5066 |
Specifications of BK7 Windows
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Dimension tolerance |
±0.1mm |
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Clear Aperture |
> 85% |
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Surface Quality |
20/10 Scratch and Dig
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Perpendicularity |
<10 arc min |
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Parallelism (For parallel windows) |
<10" |
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Wedge Angle tolerance (For wedges) |
1' |
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Flatness
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λ/8 @ 632.8 nm
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Transmission
Wavefront Distortion |
<λ/8 @632.8 nm
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Bevel |
<0.25mm X 45° |
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coatings: |
AR Coatings: R<0.3%
HR Coatings: R>99.6%
PR Coatings: R=3-95%
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