OFR manufactures and stocks standard Beamsplitter
plates and prism cubes. As in all of our products, we will specially
manufacture on a custom basis to customer’s specifications.
BANDWIDTH OR TRANSMITTANCE, which is more important?
Metallic coatings are achromatic over an extremely wide spectral
range. For example, our beamsplitters are designed for equal reflection
and transmission when used with unpolarized light at 45°. However,
when used with S-polarized light, the R/T ratio is approximately
60/40, and with P-polarized, it is approximately 40/60. Absorption
in the metallic coating is 1/3, and it is seen that if reflection
equals transmission, then R=T=33%. Our standard metallic coating
is vacuum-deposited inconel which forms a tough and relatively scratch-resistant
film. It is recognized by its grey and neutral appearance, which
is a sure sign of its achromaticity.
In general, dielectric coated beamsplitters have a narrower bandwidth
than the metallic type, and are inherently of negligible absorption
loss. In general, dielectric coatings show much more effect upon
the R/T ratio of polarized light than do metallic types. Our standard
beamsplitters are designed for equal reflectance /transmittance
split when used with unpolarized light. However, when used with
S-polarized light, the R/T ratio is 70/30, and with P-polarized
the split is 30/70.