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Kösters Interference Double Prisms

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