Pellin-Broca Prism

Product description:

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.

Pellin Broca Prism

Schematic drawing

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.

Photonchina Specifications


Material BK7 or Fused Silica
Design Wavelength 546.1nm
Dimension Tolerance 0.0, -0.2mm
α 79.5º
β 60º
Angular Tolerance (α, β) < 20 arc minutes
Flatness λ/4 @ 632.8nm
Clear Aperture > 85%
Surface Quality 20~10
Coating Specified by customer