Pellicle Beamsplitters
In
certain situations pellicle beamsplitters have distinct advantages over either
plate or cube beamsplitters.
The
splitting surface is a 2μm thick nitrocellulose film, which has been
stretched flat over a lapped aluminium
frame. As the material is so thin, the first and second surface
reflections are superimposed resulting in a lack of ghost imaging.
Also, there is no change in the optical path length for the two beams and
no chromatic aberration is introduced into converging or diverging beams.
The
natural reflectivity of this film at 45° provides 10% reflectance and 90%
transmittance. Pellicles can be
supplied uncoated and work well as 10% beamsplitters.
However,
pellicles transmit from 400—2500 nm and may be coated for 33%, 40% or 50%
reflectance at 633 nm.
Pellicle
clear apertures offered are: 25.4, 50.8, 76.2, 101.6 mm.
They are mounted in metal rings of larger diameter - see datasheet for details.