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DOWNLOAD detailed description of the variable phase retarder

The liquid crystal variable phase shifter is a transmitive element with an electrically tunable optical phase retardance.Optical retardation is often obtained with piezoelectric mirrors. However this option is not ideal if robust and compact design is necessary. This product offer an interesting alternative especially when working with polarized light (which is often the case when working with lasers). The polaroptic phase shifter is a thin transmissive element causing minimal losses and can be simply placed within the optical path of our system. The more, its optical retardation is electrically tunable with the LC driver of ARCoptix (but it can also be driven with simple labor alternative power supply). It can also be used as optical valve (for a narrow wavelength range) or as polarization State controller. To summarize :

Arcoptix scientific grade LC phase retarder with its 1” housing

• Compact and robust device
• Transmissive element
• No moving parts
• Electrically Tunable
• Needs polarized light
• weak absorption in VIS
• Optical valve (with extra polarizer)
• Polarization state controller

The liquid crystal variable phase shifter (or phase retarder) can be compared to a variable waveplate. By addressing it with the right voltage, it is able to provide any phase shift from zero to several times the light wavelength. They can be used throughout the visible and the near infrared region (400nm to 1800nm) without losses higher than 15%. Thanks to the use of thick substrate (scientific grade) and a special liquid crystal bend were are capable to offer robust equipment with minimal wavefront distortion and power absorbtion.

Contact ARCoptix for more information:info@arcoptix.com sh

Retarder type selection

In functions of your needs you can select essentially between three categories of products:i

Retarder Type Specificities  Applications Price  Industrial grade Spacer (few microns) over the aperture Large aperture 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 10 mm Thick substrates Interferometry Metrology Use  in an imaging plane *** Custom Larger apertures. High switching speeds. Large quantities/low price. Zero phase shift Custom adapted cells for industrial applications Specific scientific applications * / ****

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Specifications

The table below summarizes the principal characteristics of the device:

Phase shift range  50-2300 nm  wavelength range  400-1800 nm  Active area Scientific grade: 10 mm (diam.) Industrial grade: 22 mm (square)  Transmission  About  85% (VIS)  Retarder material Nematic Liquid-Crystal Dn=0.28  Substrates Glass  (2x3mm)  Wavefront distortion  scientific grade: < lamda/4 (over 10 mm) Industrial grade: < 2lamda (over 23 mm)  Temperature range  10C°-35C°  Retardance temperature   dependency  About 0.5%/°K (wavelength dependent)  Phase shift adjustment precision   10nm  Maximum modulation frequency of  the phase shift   < 0Hz  Phase shift stability (with arcoptix  LC driver and at thermal   equilibrium)   Better than 10 nm.  Save operating limit 500 W/cm2 CW 300 mJ/cm2 10 ns, visible 200 mJ/cm2 10 ns, 1064 nm  Total size (with housing) Scientific grade: 25.4mm diameter, 16mm long Industrial grade: 31mmx25mmx2.2mm (without housing).

For More information,please download the pdf description file below:

DOWNLOAD detailed description of the phase shifter

Principle

The polaroptic variable phase retarders are manufactured with standard liquid crystal technology. As depicted in figure 1, they are principally made of a liquid crystal layer sandwiched between two flat glass plates coated with a transparent electrode (ITO) and an alignment layer. The two glass plates are precisely spaced apart with a matrix of glass fibers. The cavity formed by these plates is filled with a special blend of liquid crystals optimized for high birefringence, small temperature dependence and high stability. The cell is hermetically sealed with a polymer frame. The alignment layer is a gently rubbed polyimide layer necessary for the alignment of the LC molecules. The electric field that can be induced by applying a voltage on the transparent ITO electrodes (0-7V) modifies the alignment of the LC molecules and by the same way the apparent retardance of the cell. Figure (a) shows the alignment of the LC molecules when no voltage is applied. In this case the molecules are aligned along the glass plates and the retardance (along the optical axis) is maximum. Figure (c) shows the other extreme case where a “high” voltage (7V) is applied and the electric field forces the LC molecules to align perpendicularly to the glass plates (parallel to the electric field). Figure (b) shows an intermediate state where we apply a small voltage of about 3V. In this case  the molecules have an oblique orientation and the apparent retardation is somewhere in between the maximum retardation (several times the wavelength) and the minimum retardation (almost zero).