Polarisers, Polarising Prisms and Beamsplitters

Generate linear or circular polarised light or split light into its polarised components.

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When choosing a polariser it is normally a balance of several key considerations: cost, wavelength range, aperture size, acceptance angle, damage threshold, transmission efficiency, and extinction ratio.

For more information please read the section Polariser Selection “Guide” in our blog Polarisation & phase manipulation with retarders (waveplates)

Polarisers come in three main forms: Linear; Beam-splitting and Circular.

Linear Polarisers
Ideal linear polarisers transmit 100% of the light when the incoming light is polarised and aligned with the polarisation axis or 50% if the incoming light is unpolarised.

The ratio between the transmission of the desired polarisation direction and the undesired orthogonal polarisation direction is the contrast or extinction ratio.

Beamsplitting Polarisers
Beamsplitting polarisers separate the incoming unpolarised light into two (usually) orthogonally polarised beams. Most commonly this is done via birefringent crystals such as Calcite via beam splitting cubes or polarising prisms.

Other beamsplitters such as wire grid polarisers contructed of a thin layer of aluminium microwires allow for durability, contrast and a wide field of view through to IR wavelengths.

Laser 2000 offer laser line and broadband beamsplitters.

Circular Polarisers
Mainly used for optical isolation with two main designs:

1) Dichroic circular polarisers/zero-order retarder
2) Beamsplitting polariser/zero-order retarder

Both designs take advantage of the handedness change of a circularly polarised beam upon reflection. By changing the handedness of the circularly polarised beam, back reflections are blocked by the polariser.

Showing all 4 results

Products	Product Code	Description
	Linear and Circular Dichroic Polarisers	A dichroic has selective absorption of one polarisation state, transmitting the other. Available in lower cost polymers and higher precision glass. Suitable for lower power (~W's), larger aperture applications
	Wire Grid Reflective Polarisers	A reflective polariser transmits the desired polarisation and reflects the rest. Available as plates, cubes or prisms. Suitable for higher damage thresholds (>50kW), larger acceptance angle (±22.5°)
	Thin Film Polarisers	Thin-film polarisers in plate or cube form, utilising a multilayer dielectric coating which works on interference effects. The majority of designs are such that the incidence angle is 45°, such that the transmitted and reflected beams. These optics are ideal for high transmission, low loss and specific laser lines or narrow bands.
	Birefringent Polarisers	Birefringent polarisers transmits the desired polarisation and scatters/deviate's the rest. This utilises the fundamental property of birefringence, where the refractive index depends on its polarisation. Commonly in the form of joined prisms this type of polariser offers higher extinction ratios, higher damage thresholds, broad wavelength ranges but are more expensive.

Founded in 1979 by Tom Baur a pioneer in the field, awarded the SPIE G.G.Stokes award in 2018, Meadowlark optics are polarisation experts, providing polarisation components, liquid-crystal devices, spatial light modulators and polarisation instrumentation.

In the twenty-first century, Meadowlark products help position customers worldwide to pioneer their own innovations. These include advances in liquid crystals with one-of-a-kind polarization controllers and the Liquid Crystal Stokes Polarimeter. In other areas, they measure there waveplate product line to subnanometer precision. One thousandth of a wave of retardance is our standard accuracy.

OptoSigma is a leading global manufacturer of Optical Systems, Optical Assemblies, Optical Coatings, Opto-Mechanics, Manual and Motion Control Stages, and a variety of complimentary Photonics products. With over 19,000 standard items, they provide a wide range of high-quality products and they also manufacture custom solutions to support various industries including Life Sciences, Bio-Medical, Semiconductor, Displays, Research, Telecommunications, Aerospace and Defense.