Kösters Interference Double Prisms
The prisms are made of fused silica (Homosil) and consist of two identical cemented prisms The angles of these prisms are 30° - 60° - 90°. The long cathetus of one of the prisms is coated with a partially reflecting protected silver layer for the visible spectral range.
A Kösters prisms generates two parallel output beams. It allows a simple realization of a white light interferometer having exactly equal optical length in both arms.
Optical specifications
| material | fused silica |
| spectral range | 400-700 nm |
| splitting ratio (unpolarized) | 45:45 (±5) % |
| Polarisationsempfindlichkeit | |Rs-Rp|<5% |
| absorption loss | ca. 10% |
| flatness the surfaces | <λ/10 |
| angular tolerance | ±1' |
| angular equality of the prisms | ±1'' |
| connection of the prisms | cemented |
Standard dimensions
| side length |
|
20 mm | 30 mm | 40 mm | 60 mm | 100mm |
| height | [mm] | 10 | 15 | 20 | 30 | 50 |
| useable diameter | [mm²] | 9,0 x 9,0 | 14,0 x 14,0 | 19,0 x 19,0 | 28,0 x 28,0 | 48,0 x 18,0 |
| long cathetus | [mm] | 17 | 26 | 34 | 52 | 86 |
| Art. No. |
|
IKP 020 | IKP 030 | IKP 040 | IKP 060 | IKP 100 |
Prices
| order no. | 1 piece in € | 2 piece in € | 3-5 piece in € |
|---|---|---|---|
| IKP 020 | 1548.- | 1276.- | 1058.- |
| IKP 030 | 2003.- | 1608.- | 1293.- |
| IKP 040 | 2633.- | 2163.- | 1787.- |
| IKP 060 | 3977.- | 3586.- | 3274.- |
| IKP 100 | 7382.- | 6617.- | 6004.- |
Price custom version
| antireflection coating on entrance and exit surfaces | on request |
| dielectric coatings (absorptionfree) | on request |
| combination of prisms for other interferometers | on request |
