Pellin Broca prisms are constant deviation (90°) dispersing prisms. The input angle is arranged so that total internal reflection occurs at the internal face. This will provide a constant 90° deflection for the beam with dispersion. If the input beam enters the long side of the prism the longer wavelengths will be deviated less.
See the following illustration, a light beam enters the prisms via surface S1, undergoes total internal reflection from S2 surface and exits via surface S3. The prism is designed in a way that one particular wavelength is deviated by 90°. As the prism is rotated, the selected wavelength which is deviated by 90° is changed without changing the geometry or relative positions of the input and output beams.
These Pellin Broca prisms provide a convenient way to compensate for group velocity dispersion in ultra-fast lasers or to separate harmonic wavelengths in an incoming laser beam. For this reason, they are commonly used in optical atomic spectroscopy.
|Material||BK7 or Fused Silica|
|Dimension Tolerance||0.0, -0.2mm|
|Angular Tolerance (α, β)||< 20 arc minutes|
|Flatness||λ/4 @ 632.8nm|
|Clear Aperture||> 85%|
|Coating||Specified by customer|