Pellin-Broca Prisms
These prisms are solid dispersing prisms with 90°
deviation. They can be envisaged as a combination of two 30° dispersing
prisms with one right angle reflection prism. The combination of the two
30° prisms works like a 60° dispersing prism and the 90° prism
only does a pure reflection without dispersion.
The two 30° prisms (i.e. the 60° dispersing
prism) are transmitted in the so-called „minimum of deviation" by light
of one wavelength. The entire prism deflects light of this wavelength by
exactly 90°; for this wavelength the spectroscopic angular dispersion
is maximum.
If the prism is rotated about axis A (see sketch),
then a different wavelength is deviated by 90°. This way the prism
can be tuned without the necessity to alter anything else in the geometry
of the experimental setup.
The three polished surfaces of the prism produced
from one block have a surface accuracy of λ/10.
The angular errors are about 2'.
The following table lists a selection of Pellin-Broca
prisms including individual beam cross-sections, material and reflection
value Rs and Rp (per surface) of light polarized
parallel or perpendicular to the plane of incidence (at some wavelengths
λ).
| Height of Entrance Surface* |
Length of Entrance Surface |
λ | Incident Angle for 90° -deviation |
Rs | Rp |
| 10 mm 15 mm 20 mm 10 mm 15 mm 20 mm 10 mm 15 mm 20 mm |
24 mm 32 mm 42 mm 18 mm 27 mm 36 mm 16 mm 23 mm 32 mm |
405 nm 633 nm 1060 nm 405 nm 546 nm 633 nm 200 nm 250 nm 500 nm |
62.61 ° 59.49 ° 58.34 ° 55.62 ° 54.30 ° 53.93 ° 50.83 ° 48.06 ° 46.98 ° |
29.1 % 24.2 % 22.5 % 18.8 % 17.1 % 16.6 % 13.0 % 10.0 % 9.0 % |
0.09 % < 0.01 % 0.02 % 0.13 % 0.20 % 0.22 % 0.38 % 0.48 % 0.50 % |
| For each prism material values of
Rs and Rp are given for some exemplary wavelengths. |
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| Height of Entrance Surface* |
Length of Entrance Surface |
Material | Ordernr. | Price 1 pc. | Price 2-5 pc. | Price 6-10 pc. |
| 10 mm 15 mm 20 mm 10 mm 15 mm 20 mm 10 mm 15 mm 20 mm |
24 mm 32 mm 42 mm 18 mm 27 mm 36 mm 16 mm 23 mm 32 mm |
SF 10 SF 10 SF 10 F 2 F 2 F 2 Suprasil Suprasil Suprasil |
DPB 10.73** DPB 15.73** DPB 20.73** DPB 10.62 DPB 15.62 DPB 20.62 DPB 10.46 DPB 15.46 DPB 20.46 |
€ 315 € 468 € 636 € 279 € 389 € 546 € 342 € 594 € 846 |
€ 270 € 401 € 545 € 239 € 333 € 468 € 293 € 509 € 725 |
€ 210 € 312 € 424 € 186 € 259 € 364 € 228 € 396 € 564 |
| *: The usable height of the ligth beam is about 0.5mm less.
**: These prisms are almost the same as a Brewster prism for 633 nm. |
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Other sizes and materials → on request
Literature
W. M. McClain, Appl. Opt. 12,(1973), S.153ff, "How to Mount a Pellin-Broca Prism for Laser Work"
J.Raeder, Appl. Opt. 12,(1973), S.1405, "Comment on: How to Mount a Pellin-Broca Prism for Laser Work"
Data sheet