Mounted Glan-Thompson Polarizers
|≤λ/4 Over Clear Aperture|
|Surface Qualitya||20-10 Scratch-Dig|
|Wavelength Range||350 nm to 2.3 µm|
|Aperture||5 mm x 5 mm||10 mm x 10 mm|
|A||21.6 mm||36.6 mm|
|B||12.7 mm||25.4 mm|
- Wide Field of View: 40° Typical
- High Extinction Ratio: 100,000:1
- 350 nm to 2.3 μm Operation for Uncoated Prisms
- AR-Coated Versions for 350 - 700 nm or 650 - 1050 nm Range
- Highest Grade Optical Calcite
- Cemented Prisms
- Damage Threshold: 1 W/cm2
Thorlabs' Mounted Glan-Thompson calcite polarizers offer the widest field of view of the calcite polarizers while maintaining a high extinction ratio. The mounts consist of a black aluminum housing; unmounted versions are also available. The mounted GTH5M polarizer has a 1/2" outer diameter and can be conveniently held inside our SM05L10 lens tube. This allows the user to easily mount this polarizer to a rotation stage, such as the PRM05 Precision Rotation Mount for Ø1/2" optics. A similar option is available for the 1" outer diameter GTH10M mounted polarizer, using the SM1L20 lens tube and PRM1 precision rotation mount. Please see the Mounting tab for more details.
Both uncoated and AR coated polarizers are available. The uncoated polarizers are designed for use in the 350 nm to 2.3 μm range, while coated versions offer Ravg < 1% per surface in the 350 - 700 nm or 650 -1050 nm wavelength range. Please see the Graphs tab for coating reflectivity data.
Glan-Thompson polarizers consist of two cemented prisms made from the highest optical grade of calcite. Unpolarized light enters the polarizer, then is split at the intersection of the two crystals allowing S-polarized (e-ray) light to continue and P-polarized light (o-ray) to be absorbed by the housing. Due to the large field of view, these polarizers can be used for highly converging or diverging beams.
Note: As with all Glan-Thompson polarizers, the maximum optical intensity is limited by the cemented prism interface. For high-power applications, Thorlabs offers Glan Laser polarizers, which can handle power densities up to 500 W/cm2 (CW).
Polarization-Dependent Refraction - Glan-Thompson 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)
|Figure 2 Figure 1 Figure 4 Figure 3
Mounting the GTH10M
The GTH10M polarizer can be mounted to a PRM1 rotation mount by using a SM1L20 lens tube:
- Remove the retaining rings that comes with the PRM1 rotation mount and the lens tube.
- Screw the threaded end of the lens tube into the rotation mount as shown in Figure 1.
- Once the lens tube is threaded (Figure 2), insert the mounted polarizer into the other end of the lens tube (see Figure 3)
- Secure the polarizer into place using the retaining ring included with the lens tube.
- A SPW602 spanner wrench can be used to tighten the retaining ring (Figure 4).
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.
Mounting the GTH5M
The GTH5M can be mounted using the directions above for the GTH10M, except substituting Ø1/2" components for the Ø1" components used for the GTH10M. The chart below lists the equivalent item numbers appropriate for mounting the GTH5M.