Fluorescence > Accessories > Polarizers

Polarizers

UV Glan-Thompson Prism Polarizers   

10x10 mm aperture (100 mm² view area)
14x14 mm aperture (196 mm² view area)

Glan-Thompson polarizers are made of two calcite crystals cemented together with optical cement with transmission in the UV (such as Sylgard by Dow Corning Corp.). The entrance and exit faces are normal to the direction of light propagation; the prism is cut at an angle such that the ordinary beam is totally reflected (by total internal reflection) at the first face.

UV Glan-Taylor Prism Polarizers   

10x10 mm aperture

Glan-Taylor prism polarizers are made of the same material as the Glan-Thompson polarizers. The two halves of the polarizers are not cemented, but they are separated by an air gap. Glan-Taylor polarizers should be used when the excitation source is a strong laser emitting more than 800 mW of power. The cement that holds the two halves of the Glan-Thompson polarizer together may slightly absorbs radiation at such high power levels and may cause it to heat up and to release substances which reduce the transmission of the polarizer.

What is the useful field angle?

The useful acceptance angle of a prism polarizer with L/A = 2.5 varies from about 14 at 350 nm to about 16 at 1000 nm. It is important that the radiation beam impinging onto it be as parallel as possible. In fact, ray beams arriving at angles larger than 16 are reflected back. Spectrofluorometers featuring parallel beam geometry (beam between the collecting lens and the focusing lens is parallel) help to minimize reflections at the polarizer's entrance face.