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Dichroic Polarizers

Dichroic refers to the polarization selective absorption of the anisotropic polarizing material. Meadowlark Optics offers an extensive line of dichroic sheet polarizers. These polarizers are constructed by laminating a thin, stretched, and dyed polymer film between two polished and antireflection coated glass windows. The resulting compact component offers excellent value and is often the best choice for flux densities below 1 watt/cm

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.Selecting the appropriate dichroic polarizing materialenables excellent extinction ratio performance over the wavelength range from 310 to 2300 nm for small apertures. Due to small material variations in the polarization axis direction, extinction ratios degrade over larger apertures for all dichroic polarizers.Meadowlark Optics has improved the transmission ofdichroic sheet polarizers with high-efficiency, broadband antireflection coatings on the glass windows used in our product construction. Sturdy glass construction contributes to a substantial improvement in transmitted wavefront distortion. Our polarizer construction greatly improves the product durability, allowing for easy and repeated cleaning.Meadowlark Optics also offers a line of high contrastdichroic glass polarizers for the near infrared region of the spectrum. High throughput and contrast makes these polarizers an excellent choice for near infrared requirements.Key advantages of dichroic polarizers include superiorangular acceptance and extreme flexibility for custom shapes and sizes. Please call our Sales Department for assistance.

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olarizers allow the transmission of only one polarizationstate. A linear (or plane) polarizer transmits lightpolarized in a single plane. The output polarization axis orientation is independent of the input beam polarization state. The plane of polarization is changed by rotating the linear polarizer about its beam axis. A “perfect” linear polarizer transmits 50% of anunpolarized input beam. Two perfect polarizers with their transmission axes crossed will totally extinguish an incident beam.When choosing a linear polarizer, several key factors must be considered, including: cost, wavelength range, aperture size, acceptance angle, damage resistance, transmission efficiency, and extinction ratio.Extinction ratio is defined as the ratio of transmittedintensity through crossed polarizers to the transmitted intensity through parallel polarizers. Meadowlark Optics offers polarizers with extinction ratios as low as 10

Fig. 2-1 Regardless of input polarization, a linear polarizer transmits onlylinearly polarized light.

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overthe operating wavelength range. Meadowlark Optics offers four types of linear polarizers:dichroic, dielectric coating (beamsplitting polarizers), calcite crystal, and wire grid. Page 2

Tel (303) 833-4333

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Fax (303) 833-4335

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e-mail: sales@meadowlark.com