Hanle Depolarizer (Scrambler)

The depolarizer consists of two optically contacted wedges. At least one wedge is birefringent and affects the polarization state differently at different locations. The depolarization arises from the spatial superposition of rotated polarizations. The second wedge compensates for the prismatic deviation (as good as possible). The divergence of the two emerging beams polarized at right angles to each other is about 4 arc minutes. Flatness of the outer surfaces is λ/10. The total thickness is about 6 to 10 mm.
The depolarizer influences the polarization of light sources or of a device's own polarization so that the average degree of polarization is close to zero. Thus for each respective polarization the depolarizer must be adjusted to the most favourable orientation achievable by experimentation. (Usually it is a good starting value to orient the divergence under 45° to the prevailing polarization direction of the incident light) The effectiveness of the depolarizer increases with the size of the beam cross-section.

Type I

Crystal wedge of synthetic quartz, compensator wedge of fused silica Suprasil. Spectral range about 180 nm - 2.5 µm. unmounted.

Type II

Crystal and compensator wedge of MgF2, crystal axes crossed, spectral range about 125 nm - 7 µm, umounted
Cross section 15x15 → PDH 15.00

The depolarizers can be supplied in a mount with a mounting post. Mounted in such a holder the depolarizer can be rotated 360° and locked into any position. The clear diameters of the holders are 9 mm, 14 mm, 19 mm und 24 mm; the outer diameters are 30 mm, 30 mm, 36 mm and 38 mm. → PDH 0

Literature

W. Hanle, Zeitschrift für Instrumentenkunde 51 (1931), 488 "Messung des Polarisationsgrades von Spektrallinien."
translated title: „Measurement of the degree of polarization of spectral lines."