|Material||High Optical Grade Calcite|
|≤λ/4 Over Clear Aperture|
|Surface Qualityb||20-10 Scratch-Dig|
|Wavelength Range||350 nm to 2.3 µm|
|Aperture||5 mm x 5 mm||10 mm x 10 mm|
|C||18 mm||33 mm|
|D||6 mm||11 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' unmounted Glan-Thompson calcite polarizers offer the widest field of view of the calcite polarizers while maintaining a high extinction ratio. These unmounted prisms are ideal for custom applications; versions mounted in a round aluminum housing are also available. The GTH5 polarizers have a 5 mm x 5 mm aperture, while the GTH10 polarizers have a 10 mm x 10 mm aperture.
Both uncoated and coated polarizers are available. The uncoated polarizers are designed for use in the 350 nm to 2.3 μm range, while coated versions are available for the 350 - 700 nm or 650 -1050 nm range. Please see the Graphs tab for coating reflectivity data.
Glan-Thompson polarizers consist of two cemented prisms made from the highest optical grade 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 reflected as shown in the diagram above. 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 extraordinary plane will travel straight through the crystal, the ordinary 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)