Pellin-Broca Prisms

Pellin-Broca-Prisms/Drawing(2k)

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.

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
€ 332
€ 493
€ 670
€ 294
€ 410
€ 575
€ 361
€ 625
€ 890
€ 285
€ 423
€ 574
€ 252
€ 350
€ 493
€ 309
€ 536
€ 762
€ 250
€ 371
€ 503
€ 221
€ 308
€ 432
€ 271
€ 470
€ 669
*: 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.

Other sizes and materials → on request

Literatureto top

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"

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