China Optical Coatings laboratory provide
three basic forms of Beamsplitters:
Forms of Beamsplitters
Descriptions
Parallel plates
Consists of a carefully generated
transparent substrate with a partially
reflective coating on one side and an
Anti-Reflection coating on the second
surface. These are usually designed to be
used at an angle of 45 degrees. By making
the second surface at a wedged angle to the
first surface any residual ghost image can
be made to fall outside of field of view of
the following system
Cubes
Two
right angle prisms cemented together with a
partially reflecting surface on the internal
(protected) face. The beamsplitting film is
deposited on the hypotenuse face of a
precision BK7 prism whose faces are
λ/4
and the prism is cemented to an identical
prism to form a cube which is parallel sided
within 5arcmin. The four outer faces are all
Anti-Reflection (AR) coated.
Pellicles
Single surfaced beamsplitters. In this case
one face carries the partially reflecting
film and the second, uncoated, surface will
produce a roughly 4% ghost image. But the
ghost image will be displaced only ~2
microns laterally from the primary image and
may be usually ignored.
Specifications for
Mirror-type Beamsplitters
Material: BK7
Surface Accuracy: 4-6 lambda
Surface Quality: 80-50
Edges: Cut
Coatings (45 degree both sides)
1st side: Dielectric (R/T as defined)＼5%
R/T at 550nm
2nd side AR 1/4 lambda MgF2 at 550nm:
