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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 |
: 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 |
: made of S grade calcite but
polarizer has beam deviation of one instead of three arc minutes |
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surface flatness |
: at least quarter wave @ 633 nm
over the clear aperture |
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surface quality |
: 40-20 scratch dig |
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transmission
( uncoated ) |
: 25-30% at 250 nm, 40-45% at 300 nm, 65-70% at 400 nm and 85-87% 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 scattered 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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