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Features

• 2 Orthogonally Polarized Outputs
• 2.7 mm, 4.0 mm, or Custom Displacements Available
• Outputs Parallel to Input
• 350 nm to 2.3 μm Operation
• Highest Grade Optical Calcite
• Ø1" Housing

Beam displacing prisms are used to separate an input beam into two orthogonally polarized output beams and can be used as polarizing beamsplitters in applications where the 90° separation of the beams is not possible. Fabricated from a single piece of the highest quality optical grade calcite, our beam displacers can be used with wavelengths from 350 nm up to 2.3 μm. Since calcite is a soft crystal that can be easily damaged, our calcite polarizers are housed in a Ø1" metal housing that can be mounted into our optomechanical rotation mounts. For further information on the properties of calcite, please see the Calcite tab above. Our mounted beam displacers are offered in two versions, which provide a beam displacement of either 2.7 mm or 4.0 mm.

In both versions both output beams are parallel to the input beam to within 30 arcsec. In addition Thorlabs also offers a complete line of Calcite Polarizers,Polarization, Optics Components and Polarization Measurement Equipment.

Polarization-Dependent Refraction - Glan Laser Calcite Polarizer

Our calcite polarizers are all based on high-grade, birefringent, calcite crystals. Due to the birefringent structure of calcite, a differential delay is created between two orthogonally polarized waves traveling in the crystal. As shown in the image to the right, this birefringent structure creates a polarization-dependent refraction that effectively steers the polarization planes in two angles. While the ordinary plane will travel straight through the crystal, the extraordinary plane will exit the crystal at an angle proportional to the wavelength as well as the length of the crystal.

A calcite polarizer can be designed as either a polarization splitter/combiner or as a polarizer element that removes the angled, orthogonally polarized component of a beam. Our calcite polarizers are typically built out of two prisms, as shown in the drawing to the right. Since calcite is a soft crystal that is easily damaged, almost all of our calcite polarizers are offered in metal housings. With convenient threadings and adapters, these housings can easily be mounted into our opto-mechanical products.

Calcite Polarizer Field of View (FOV)

Frame B

Frame A

Frame D

Frame C

Beam Displacer Mounting

Thorlabs Calcite Beam Displacers can be mounted to a PRM1 rotation mount by using a SM1L20 lens tube:

1. Remove the SM1RR retaining ring that comes with the PRM1 rotation mount.
2. Screw the threaded end of the lens tube into the rotation mount as shown in Frame A.
3. Once the lens tube is threaded (Frame B), insert the mounted beam displacer into the other end of the lens tube (see Frame C)
4. Secure the beam displacer into place using the retaining ring included with the lens tube.
5. A SPW602 spanner wrench can be used to tighten the retaining ring (Frame D).

Note: The SM1P1 Ø1" to SM1 adapter can be used in place of the SM1L20 lens tube when space is not available for the extra length of the lens tube.