cube beamsplitters divide unpolarized light into two orthogonal
polarized beams at 90กใ to each other. The transmitted beam
is mostly polarized parallel to the plane of incidence (p-polarized),
and the reflected beam is mostly polarized perpendicular to
the plane of incidence. Each beamsplitter consists of a pair
of precision high tolerance right angle prisms, which must
be fixed in relation to one another by either mounting or
cement. A multi-layer antireflective coating is then applied
to each face of the beamsplitter in order to produce maximum
are three main types of polarizing cube beamsplitters: prism,
broadband, and laser-line. Prism cube beamsplitters are constructed
by cementing together two precision right angle prisms with
the appropriate interference coating on the hypotenuse surface.
This is the most common style of polarizing cube beamsplitters.
Broadband cube beamsplitters operate in the visible and very
near infrared (to 850 nm) with constant performance over a
200 nm range. Laser-line cube beamsplitters are tuned for
optimum performance at specific laser wavelengths. They exhibit
lower loss, but have a narrower operating range, typically
25 nm or less.
polarizing cube beamsplitters use reflection to polarize the
light, the materials from which the cubes are made are less
bifringent than those used in other types of polarizers. The
materials tend to be oriented more towards bandpass. Some
of the more common materials used in the creation of polarizing
beamsplitter cubes are BK7 glass, SF2 Glass, and UV grade
fused silica; although custom and proprietary material styles
can also be found. BK7 Glass is boro-crown glass (borosilicate
glass). It has a wavelength range of 330-2100 nm. SF2 Glass
is dense flint (alkaline silicate glasses with 47% wt. PbO).
UV grade fused silica offers improved transmission in the
ultraviolet region when compared to crown glass. Its wavelength
range is 200-2500 nm.
collimated beams of light can be used with polarizing cube
beamsplitters. A shear plate may be used to make sure that
an expanded beam is properly collimated before striking the