Switchable Polarization rotator

Liquid Crystal twisted nematic polarization rotator (TN cell) is very useful when one wants to rotate the orientation of a linear polarization by a fix amount of typically 45° or 90°. When light is traversing LC twisted nematic cell its polarization follows the rotation of the molecules (see figure below). The screens of any laptop computer is based on the same effect (polarization rotator tutorial). In optical systems the polarization is often rotated by quartz retardation plates (l/2 or l/4 plates). Quartz plates shows high quality and good transmission performances especially in the UV region. However such plates present also some disadvantages: They are expensive, functions only for a narrow spectral bandwidth and have a small incidence angle acceptance (field of view less then 2°). The liquid crystal nematic cells have therefore a large acceptance angle, function over a very large spectral range from VIS to NIR (if they are thick enough) and are less expensive. Optionally, by applying a voltage on the TN cell, the polarization rotation can be “switched off”. Also when placing a 90° twisted cell between crossed polarizers it can be used as a shutter.

   • l/2 plate for a very broadband range of wavelengths
     • Optionally rotation effect can be electrically switched off
     • In combination with two polarizers it can be used as optical shutter

For more information please download the product description PDF file or contact Arcoptix: info@arcoptix.com

DOWNLOAD detailed description of the polarization rotator

Polarization Rotators Type	Specificities	Applications	Price
Industrial grade	• Spacer (few microns) over the aperture • Large aperture (22mm) • Thin substrates • Phase distortions (spherical) • Low beam deviation	• Polarization manag. • Polarization vision	**
Scientific grade	• Low phase distortions • No beam deviation • No spacers over the aperture • Aperture 10mm or 20mm • Thick substrates • Broadband AR coating	• Interferometry • Metrology • Use in an imaging plane • colimated laser beam	***
Custom	• Larger apertures. • High switching speeds. • Large quantities/low price. • Zero phase shift	•Custom adapted cells for industrial applications • Specific scientific applications	* / ****

Specifications

The table below summarizes the principal characteristics of the device:

Rotation angle	90° or 45° (custom any angle possible for scientific and industrial grade)
wavelength range	350-1700 nm
Active area	scientific grade:10 mm or 20 mm (diam.) Industrial grade:22 mm (square)
Transmission	About 85% (VIS)
Retarder material	Nematic Liquid-Crystal Dn=0.28
Substrates	Glass
wavefront distortion	scientific grade: < lamda/4 (over 10 mm) Industrial grade: < 2lamda (over 23 mm)
temperature range	15°-35°
Rotation accuracy	+/-1° (wavelength dependent)
Maximum modulation frequency of the phase shift	< 10Hz
Save operating limit	500 W/cm2 CW 300 mJ/cm2 10 ns, visible 200 mJ/cm2 10 ns, 1064 nm
Anti-reflection coating (scientific grade only)	Broadband for VIS.
Total size (with housing)	Scientific grade: 25 mm diameter, 15mm long Industrial grade: 31mmx25mmx2.2mm (without housing).

Prices

Devices	Prices
Industrial grade 45° or 90° (23mm ap. without housing)	390 Euro
Industrial grade 90° (larger ap. without housing)	490 Euro
Scientific grade 45° or 90°(10mm ap.with housing)	890 Euro
Scientific grade any other angle (10mm ap.with housing)	990 Euro
Scientific grade (20mm ap.with housing)	1290 Euro
USB LC Driver (2 outputs)	590 Euro

For custom models please contact info@arcoptix.com for quotation.

DOWNLOAD detailed description of the polarization rotator

Driver (optional)

The Polarization rotator can be driven with a standard labor function generators but it can also be driven by the USB ARCoptix LC Driver.
The Arcoptix LC (Liquid Crystal) driver is a USB computer controlled electrical power supply optimized for driving one or two Polarization rotators.

The LC driver has two independent outputs (Lemo connectors). They are controlled via a simple windows compatible software. The output has a variable square amplitude with polarity inversion and a frequency of 1.6 KHz. This guarantees a homogenous variation of the LC layer inside the cell. An external trigger input can be provided on demand.