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Specifications
:
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B
grade calcite
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:
greater than one wave wavefront deformation @ 633 nm due to striae only |
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A
grade calcite
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:
quarter to one wave wavefront deformation @ 633 nm due to striae only |
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S grade calcite |
:
quarter wave wavefront deformation @ 633 nm due to striae only |
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E
type
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:
made of S grade calcite but polarizer has beam deviation of one arc minute
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surface
flatness
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:
at least quarter wave @ 633 nm over the clear aperture |
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surface
quality
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:
40-20 scratch dig |
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transmission
( uncoated ) |
: 25-30% at 250 nm, 40-45% at 300
nm, 70-75% at 400 nm, 83-87% at > 500 nm |
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please visit
Anti Reflection Coating page for
reflectivity plots of available coatings |
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Calcite is a natural mined
crystal . Defects in bulk calcite are characterized by bubbles ( presence
of randomly bubbles vary from relatively large to small sizes and fine
bubble lines), striae ( streaks of sudden variation of refractive index
which can be detected interferometrically ), optical inhomogeneity (
gradual variation of refractive index in bulk material ) and stress
birefringence ( variation of birefringence in bulk material due to
defective growth of the crystal ). These defects cause degradation of
polarization and transmission loss due to scattering and absorption.
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