Polarizer Selection Guide

Authors: Stefaan Vandendriessche

For more information on polarization read Introduction to Polarization.

Polarization is an important characteristic of light. Polarizers are key optical elements for controlling your polarization, transmitting a desired polarization state while reflecting, absorbing or deviating the rest. There is a wide variety of polarizer designs, each with its own advantages and disadvantages. To help you select the best polarizer for your application, we will discuss polarizer specifications as well as the different classes of polarizer designs.

Polarizer Characteristics

Polarizers are defined by a few key parameters, some of which are specific to polarization optics. The most important characteristics are:

Extinction Ratio and Degree of Polarization: The polarizing properties of a linear polarizer are typically defined by the degree of polarization or polarization efficiency, P, and its extinction ratio, ρ_p. Following the formalism given in the Handbook of Optics, the principal transmittances of the polarizer are T₁ and T₂. T₁ is the maximum transmission of the polarizer and occurs when the axis of the polarizer is parallel to the plane of polarization of the incident polarized beam. T₂ is the minimum transmission of the polarizer and occurs when the axis of the polarizer is perpendicular to the plane of polarization of the incident polarized beam.

The extinction performance of a linear polarizer is often expressed as 1 / ρ_p : 1. This parameter ranges from less than 100:1 for economical sheet polarizers to 10⁶:1 for high quality birefringent crystalline polarizers. The extinction ratio typically varies with wavelength and incident angle and must be evaluated along with other factors like cost, size, and polarized transmission for a given application.

Transmission: This value either refers to the transmission of light polarized linearly in the direction of the polarization axis, or to the transmission of unpolarized light through the polarizer. Parallel transmission is the transmission of unpolarized light through two polarizers with their polarization axes aligned in parallel, while crossed transmission is the transmission of unpolarized light through two polarizers with their polarization axes crossed. For ideal polarizers transmission of linearly polarized light parallel to the polarization axis is 100%, parallel transmission is 50% and crossed transmission is 0%. This can be calculated with Malus’ law as described in Introduction to Polarization.

Acceptance angle: The acceptance angle is the largest deviation from design incidence angle at which the polarizer will still perform within specifications. Most polarizers are designed to work at an incidence angle of 0° or 45°, or at Brewster’s angle. The acceptance angle is important for alignment but has particular importance when working with non-collimated beams. Wire grid and dichroic polarizers have the largest acceptance angles, up to a full acceptance angle of almost 90°.

Construction: Polarizers come in many forms and designs. Thin film polarizers are thin films similar to optical filters. Polarizing plate beamsplitters are thin, flat plates placed at an angle to the beam. Polarizing cube beamsplitters consist of two right angle prisms mounted together at the hypotenuse. Birefringent polarizers consist of two crystalline prisms mounted together, where the angle of the prisms is determined by the specific polarizer design.

Clear aperture: The clear aperture is typically most restrictive for birefringent polarizers as the availability of optically pure crystals limits the size of these polarizers. Dichroic polarizers have the largest available clear apertures as their fabrication lends itself to larger sizes.

Optical path length: The length light must travel through the polarizer. Important for dispersion, damage thresholds, and space constraints, optical path lengths can be significant in birefringent polarizers but are usually short in dichroic polarizers.

Damage threshold: The laser damage threshold is determined by the material used as well as the polarizer design, with birefringent polarizers typically having the highest damage threshold. Cement is often the most susceptible element to laser damage, which is why optically contacted beamsplitters or air spaced birefringent polarizers have higher damage thresholds.

Cost: Some polarizers require large, very pure crystals, which are expensive, while others are made of stretched plastic, which make them more economical.  

Dichroic polarizers transmit the desired polarization and absorb the rest. This is achieved via anisotropy in the polarizer; common examples are oriented polymer molecules and stretched nanoparticles. This is a broad class of polarizers, going from low cost laminated plastic polarizers to precision high cost glass nanoparticle polarizers. Most dichroic polarizers have good extinction ratios relative to their cost. Their damage thresholds and environmental stability are often limited, although glass dichroic polarizers outperform plastic dichroic polarizers in this aspect. Dichroic polarizers are well suited for microscopy, imaging and display applications, and are often the only choice when very large apertures are necessary.

Figure 1: Dichroic polarizers absorb the unwanted polarization state

	Type	Applications	Substrate	Wavelength Range (nm)	Extinction Ratio	Transmission (%)	Cost
	High Contrast Glass Linear Polarizers	Imaging, Microscopy, Display, Intensity Adjustment	B270 & Polymer Film	400 - 700	10,000:1	25	\$​$$
High Contrast Glass Linear Polarizers High Contrast Glass Linear Polarizers offer very high extinction ratios and have exceptional surface flatness for optical grade wavefront qualities. They are anti-reflection (AR) coated to minimize light loss from reflection and achieve a transmission of approximately 25% for randomly polarized visible light (400 – 700nm). High Contrast Glass Linear Polarizers are available in a large variety of sizes. View Product Specifications Wavelenth Range (nm) 400 - 700 Extinction Ratio 10,000:1 Transmission (%) 25.00 Operating Temperature (°C) -25 to +65 Thickness (mm) 2.00 Thickness Tolerance (%) ±2 Substrate B270 Transmitted Wavefront Quality <1λ Parellelism (arcmin) <4 AR Coating Specification Ravg <0.5% @ 400 - 700nm
	High Contrast Plastic Linear Polarizers	Imaging, Microscopy, Display, Intensity Adjustment	PMMA & Polymer Film	400 - 700	9000:1	Single: 42 Parallel: 36 Crossed: <0.004	\$​\$
High Contrast Plastic Linear Polarizers Due to their high extinction ratios, along with their exceptional transmission in the visible spectrum (400 – 700nm), High Contrast Linear Polarizers are an ideal choice for applications involving imaging. Aside from surface flatness and extinction ratio, these plastic substrate polarizers are a high performance and cost-effective alternative to High Contrast Glass Linear Polarizers with more durability than polarizing film. View Product Specifications Wavelength Range (nm) 400 - 700 Extinction Ratio 9000:1 Transmission (%) Single: 42 Parallel: 36 Crossed: <0.004 Operating Temperature (°C) -40 to +80 Substrate PMMA Thickness (mm) 2.20 Thickness Tolerance (%) ±10
	High Contrast Linear Polarizing Film	Imaging, Microscopy, Display, Intensity Adjustment	Polymer Film	400 - 700	9000:1	Single: 42 Parallel: 36 Crossed: <0.004	$
High Contrast Linear Polarizing Film Similar to the High Contrast Plastic Linear Polarizers, High Contrast Linear Polarizing Film is another option for imaging applications requiring polarizers with flexibility in shape and rigidity. Polarizing Film is available in sheets with a variety of thicknesses, and can be cut to size or fashioned to a desired shape. View Product Specifications Wavelength Range (nm) 400 - 700 Extinction Ratio 9000:1 Transmission (%) Single: 42 Parallel: 36 Crossed: <0.004 Operating Temperature (°C) -40 to +80
	Linear Glass Polarizing Filters	Imaging, Microscopy, Display, Intensity Adjustment	B270 & Polymer Film	400 - 700	100:1	Single: 30  Parallel: 20  Crossed: 0.15	$
Linear Glass Polarizing Filters Linear Glass Polarizing Filters are ideal for OEM integration and prototyping. With a fair surface flatness, they balance exceptional polarization performance (95% polarization efficiency) with a less robust extinction ratio, and feature a single filter transmission of 30%. View Product Specifications Wavelength Range (nm) 400 - 700 Extinction Ratio 100:1 Transmission (%) Single: 30 Parallel: 20 Crossed: 0.15 Polarizing Efficiency (%) 95 Surface Quality 80-50 Operating Temperature (°C) -15 to +70 Thickness Tolerance (mm) ±0.2 Substrate B270 Transmitted Wavefront  4 - 6λ/1
	Mounted Linear Glass Polarizing Filters	Imaging, Microscopy, Display, Intensity Adjustment	Float Glass	400 - 700	19:1	Single: 30 Crossed: 0.15	$
Mounted Linear Glass Polarizing Filters Mounted Linear Glass Polarizing Filters come in a variety of standard thread sizes and are able to be threaded into imaging systems to reduce glare and hot spots. Additionally, they can be stacked for variable optical density effects. View Product Specifications Wavelength (nm) 400 - 700 Extinction Ratio 19:1 Transmission (%) Single: 30 Crossed: 0.15 Operating Temperature (°C) -15 to +70 Substrate Float Glass Coating Uncoated
	Circular Polarizers	Imaging, Microscopy, Display, Intensity Adjustment	PMMA & Polymer Film	400 - 700	-	42	\$​\$
Circular Polarizers Circular polarizers are not a separate type of polarizer, as they are the combination of a linear polarizer with a correctly aligned quarter waveplate. The polarizer linearly polarizers the incident light, and the quarter waveplate at 45° turns this linearly polarized light into circularly polarized light. The advantage is that the polarizer and waveplate axes are always aligned correctly relative to each other so no alignment is necessary and there is no concern of generating elliptically polarized light. They are ideal for reducing flare in imaging applications and are available in left and right-handed versions. View Product Specifications Wavelength Range (nm) 400 - 700 Transmission (%) 42 Thickness (mm) 0.30 2.20 Thickness Tolerance (%) ±10 Substrate Plastic Efficiency of Linear Component (%) 99.98 Operating Temperature (°C) -40 to +80
	NIR Linear Polarizers	NIR Lasers, LEDs, Telecommunication	B270 & Polymer Film	450 - 750 1000 - 2000	1000:1	30 33	\$​$$
NIR Linear Polarizers Consisting of a polymer polarization film layered between two flat pieces of optical glass, NIR Linear Polarizers are ideal for NIR sources including low power lasers and LEDs. View Product Specifications Wavelength Range (nm) 750 - 850 1000 - 2000 Extinction Ratio 1000:1 Transmission (%) 30 33 Transmission Tolerance (%) ±3 Substrate B270 Thickness (mm) 2.00 Thickness Tolerance (%) ±10

 Thin Film polarizers utilize a thin-film dielectric coating to separate a beam into s- and p-polarization, commonly at a 45 degree AOI. They are often specified for optimal transmission/reflection performance at laser line wavelengths. 

	Type	Substrate	Wavelength Range / Design Wavelength (nm)	Extinction Ratio	Transmission (%)	Cost
	Ultrafast Thin Film Polarizers	UV Grade Fused Silica	750 - 850 980 - 1090	Transmissive 20:1 Reflective 60:1	Tp >85 / Ts <4	$
Ultrafast Thin Film Polarizers With Damage Thresholds up to 0.3 J/cm2 @ 200 fs @ 800nm, these Ultrafast Thin Film Polarizers are ideal for high powered Ti:Sapphire and Ytterbium doped lasers in the NIR range. These polarizers impart minimal dispersion when separating S and P polarizations and are available in transmissive and reflective versions. View Product Specifications Wavelength Range (nm) 750 - 850 980 - 1090 Extinction Ratio Transmissive 20:1 Reflective 60:1  Transmission for Transmissive (%) Tp >85 / Ts <4 Reflection for Reflective (%) Rs >85 / Rp <1 Angle of Incidence (°) 72 Damage Threshold, Pulsed 5 J/cm2 @ 1064nm, 10ns Thickness (mm) 3.00 Thickness Tolerance (mm) ±0.2 Substrate UV Grade Fused Silica Transmitted Wavefront Quality λ/6 Parallelism (arcsec) <30
	High Energy Laser Line Polarizers	UV Grade Fused Silica	355, 532, 633, 1064	10,000:1	Tp >98	$
High Energy Laser Line Polarizers TECHSPEC High Energy Laser Line Polarizers are used to transmit P-polarized light while reflecting S-polarized light. With high laser damage thresholds and extinction ratios for optimal performance, these polarizers are ideal for a wide range of laser applications. The UV grade fused silica substrate maximizes performance, while the hard anti-reflection coating makes these durable polarizers easy to clean and simple to align. View Product  Specifications Design Wavelength (nm) 355 532 633 1064 Extinction Ratio 10,000:1 P-Polarization Transmission  (%) >98 Angle of Incidence (°)  45±2 Damage Threshold, Pulsed  2 J/cm2 @ 532nm, 10ns Thickness (mm)  6.00 Thickness Tolerance (mm)  ±0.25 Substrate  UV Grade Fused Silica Transmitted Wavefront Quality  λ/4 @ 633nm Surface Quality  40 - 20

Reflective polarizers transmit the desired polarization and reflect the rest. They either use a wire grid, Brewster’s angle, or interference effects. Brewster’s angle is the angle at which, based on the Fresnel equations, only s-polarized light is reflected. Because the p-polarized light is not reflected while the s-polarized light is partially reflected, the transmitted light is enriched in p-polarization.

Figure 2: Reflective polarizers, available as cube beamsplitters, plate beamsplitters, or thin films, reflect the unwanted polarization state

	Type	Applications	Wavelength Range (nm)	Laser Damage Threshold	Cost
	Brewster Windows	Laser Cavities	200 - 2200	High	$
Brewster Windows Brewster windows are uncoated windows that are placed at Brewster’s angle. A single Brewster window has a relatively poor extinction ratio. While this extinction ratio is sufficient for many laser cavity applications due to the many round trips in this cavity, for other applications it can be enhanced by placing multiple Brewster windows in succession (also called a pile of plates). Due to the dependence on the Fresnel equations the acceptance angle is very small for Brewster windows, limiting their use to tightly collimated beams. View Product Specifications Wavelength Range (nm) 200 - 2200 Design Wavelength (nm) 632.8 Surface Quality 10 - 5 Clear Aperture (%) ≥90 Thickness (mm) 2.00 Thickness Tolerance (%) ±0.20 Substrate Fused Silica Transmitted Wavefront, P-V λ/10 @ 632nm Parellelism (arcmin) ≤10 Coating Uncoated
	Broadband Polarizing Plate Beamsplitters	Space/Weight Constrained Applications, Low Cost & Low Extinction Ratio Applications, Femtosecond Laser Applications	250 - 1550	Low to High	$
Broadband Polarizing Plate Beamsplitters Broadband polarizing plate beamsplitters are coated windows, placed at an angle, that transmit p-polarization and reflect s-polarization. The coating on the plate generally works in either interference or internal Brewster’s angle principles. In contrast to many birefringent polarizers, both the reflected and transmitted beams are usable. These beamsplitters are useful in weight or space constrained applications and where laser damage threshold and a short optical path length are important. A disadvantage is the appearance of ghost reflections from the second surface and beam deviation. These also exist in ultrafast versions which are ideal for femtosecond pulsed lasers. View Product Specifications Wavelength Range (nm) 400 - 670 Surface Quality 80 - 50 Operating Temperature (°C) -40 to +200 Thermal Expansion ( m m°C ) 37.6 × 10-7 Thickness (mm) 0.70 Dimensional Tolerance (mm)  ±0.2 Angle of Incidence (°) 45 ±10 Angle Tolerance (°) ±1 Substrate Corning Eagle XG Parellelism (arcmin) ≤10 Coating Uncoated
	Broadband Polarizing Cube Beamsplitters	Beam Combining	400 - 1100	Low to High	$$
Broadband Polarizing Cube Beamsplitters Broadband polarizing cube beamsplitters are similar to polarizing plate beamsplitters, but the coating is placed in between two right angle prisms. Mounting and aligning polarizing cube beamsplitters is easier than plate beamsplitters and there is less beam deviation, but they have a longer optical path length, take up more space and weigh more. They are ideal for collimated light sources and are more efficient than wire grid polarizing cube beamsplitters. (Non-polarizing cube beamsplitters exist as well; for more information on these, please read What are Beamsplitters?) View Product Specifications Wavelength Range (nm) 420 - 680 700 - 1100 Surface Quality 40 - 20 Surface Flatness λ/8 Extinction Ratio 500:1 S-Polarization Reflection (%) >99 P-Polarization Reflection (%) >90 Clear Aperture (%) 90
	Wire Grid Polarizers	Demanding Environments, Broadband Applications, Infrared, Uncollimated Light	300 - 15000	Low to High	\$​\$ - \$​$$
Wire Grid Polarizers Wire grid polarizers consist of many thin wires arranged parallel to each other. Light that is polarized along the direction of these wires is reflected, while light that is polarized perpendicular to these wires is transmitted. Because the principle of parallel wires is wavelength independent, wire grid polarizers cover a very large wavelength range well into the IR, limited by material or AR coating absorption. This design is very robust, with excellent environmental stability and a large acceptance angle. While most wire grid polarizers use glass substrates, thin film wire grid polarizers offer a more economical solution. View Product Specifications Wavelength Range (nm) 420 - 700 Surface Quality 80 - 50 Operating Temperature (°C) -40 to + 200 Thermal Expansion ( m m°C ) 31.7 x 10-7 Alignment Tolerance (°) ±1 Transmission (%) 85 (typical @ 550nm) Angle Tolerance (°) ±1 Substrate Corning Eagle XG Parellism (arcmin) ≤10 AR Coating Specification <1% reflectance for 400 - 700nm on back of substrate and both side of cover glass
	Wire Grid Polarizing Cube Beamsplitters	Broadband Applications, Uncollimated Light	400 - 700	Low to High	\$​\$
Wire Grid Polarizing Cube Beamsplitters Wire Grid Polarizing Cube Beamsplitters are polarizing cube beamsplitters that use a wire grid polarizer in between the hypotenuses of the two prisms. These polarizers combine the easy alignment of polarizing cube beamsplitters with the large angle acceptance and environmental stability of wire grid polarizers. View Product Specifications Wavelength Range (nm) 400 - 700 Transmission Tp >75% (for a ±25° cone of light) Efficiency (Tp × Rs) ≥65% Surface Quality 40 - 20 Transmitted Wavefront Distortion (RMS) <λ/3 Extinction Ratio 1100:1 Beam Deviation (arcmin) <5 Clear Aperture (%) >90 AR Coating Specification Ravg <0.5% @ 400 - 700nm Substrate N-BK7

Birefringent polarizers transmit the desired polarization and deviate the rest. They rely on birefringent crystals, where the refractive index of light depends on its polarization. Unpolarized light at non-normal incidence will split into two separate beams upon entering the crystal, as the refraction for s- and p-polarized light will be different. Most designs consist of two joined birefringent prisms, where the angle they are joined at and the relative orientation of their optical axes determine the functionality of the polarizer. Because these polarizers require optically pure crystals they are expensive, but have high laser damage thresholds, excellent extinction ratios and broad wavelength ranges.

Figure 3: Crystalline polarizers, such as the Glan-Taylor polarizer, transmit a desired polarization and deviate the rest, using birefringent properties of their crystalline materials

Figure 4a: Glan-Taylor Polarizers

Figure 4b: Glan-Laser Polarizers

Figure 4c: Glan-Thompson Polarizers

	Type	Applications	Wavelength Range (nm)	Laser Damage Threshold	Cost
	Glan-Thompson	Laser Applications, High Quality Imaging and Microscopy	220 - 2200	Medium	\$$$
Glan-Thompson Polarizers Glan-Thompson polarizers have the largest acceptance angle of the Glan-type polarizers. Cement is used to join the prisms together, which causes a low optical damage threshold. View Product Specifications Wavelength Range (nm) 350 - 2200 Housing Diameter (mm) 25.4 Extinction Ratio 20,000:1 Laser Damage Threshold (MW/cm2) >100 Substrate Calcite Surface Quality 20 - 10 Transmitted Wavefront Distortion  λ/2 @ 632.8nm (RMS) Beam Deviation (arcmin) <3 Coating Specification Ravg <1.75% @ 400 - 700nm (MgF2)
	Glan-Taylor	Laser Applications, Spectroscopy	220 - 2200	High	\$​$$
Glan-Taylor Polarizers Glan-Taylor polarizers have a higher optical damage threshold than Glan-Thompson due to an air gap instead of cement in between the two constituent prisms. They have a shorter optical path length but also a smaller acceptance angle than Glan-Thompson polarizers. View Product Specifications Wavelength Range (nm) 220 - 350 350 - 2200 Housing Diameter (mm) 25.4 Extinction Ratio 200,000:1 20,000:1 Laser Damage Threshold (MW/cm2) >200 Substrate α-BBO Calcite Surface Quality 20 - 10 Transmitted Wavefront Distortion  λ/2 @ 632.8nm (RMS) λ/2 @ 632.8nm (P-V) Beam Deviation (arcmin) <3 Coating Specification Ravg <1.75% @ 400 - 700nm (MgF2)
	Glan-Laser	Laser Applications, Q-Switching Lasers	220 - 2200	Very High	\$$$
Glan-Laser Polarizers Glan-Laser polarizers are special versions of Glan-Taylor polarizers with a high laser damage threshold. These typically have higher quality crystals, better polished surfaces and the rejected beam is allowed to escape via escape windows, decreasing unwanted internal reflections and thermal damage due to the absorption of the rejected beam. View Product Specifications Wavelength Range (nm) 220 - 350 350 - 2200 Housing Diameter (mm) 25.4 Extinction Ratio 200,000:1 20,000:1 Laser Damage Threshold (MW/cm2) >500 Substrate α-BBO Calcite Surface Quality 20 - 10 Transmitted Wavefront Distortion λ/2 @ 632.8nm (RMS and P-V) Beam Deviation (arcmin) <3 Coating Specification Ravg <1.75% @ 400 – 700nm (MgF2)
	Wollaston Prisms	Laboratory Experiments, where both polarizations need to be accessed	190 - 4000	High	\$$$
Wollaston Prisms Wollaston prisms are birefringent polarizers that are designed to transmit but separate both polarizations. In contrast with the Glan-type polarizers, both beams are completely polarized and usable. The orthogonally polarized beams exit the polarizer symmetrically at a wavelength dependent angle from the incident beam. View Product Specifications Housing Diameter (mm) 25.4 Extinction Ratio 200,000:1 20,000:1 Laser Damage Threshold (MW/cm2) >500 Surface Quality 20 - 10 Transmitted Wavefront Distortion λ/2 @ 632.8nm (P-V) Beam Deviation (arcmin) <3
	Rochon Prisms	Laboratory Experiments, where both polarizations need to be accessed	130 - 7000	High	\$​$$
Rochon Prisms Rochon prisms are similar to Wollaston prisms in that both beams are transmitted, but in this polarizer one beam is transmitted undeviated while the other is transmitted at wavelength dependent angle. View Product Specifications Laser Damage Threshold (MW/cm2) >500 @ 1064nm Surface Quality 20 - 10 Transmitted Wavefront Distortion λ/4 @ 632.8nm (P-V) Beam Deviation (arcmin) <3

Insert main image shown at top of tool here Looking for a custom polarizer? Edmund Optics® offers custom polymer polarizers and retarders in a wide range of film types, sizes, and shapes. Products include linear and circular polymer polarizers, and retarders. To obtain pricing information for our most popular laser-cut polarizing films please enter your requirements below. If you cannot find what you are looking for please contact our product support team and we will be happy to assist you with your enquiry.

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ITOS GmbH is a division of Edmund Optics that has provided both custom and off-the shelf polarization solutions to the German and European markets since 1993. The ITOS division expands EO's polarization manufacturing and metrology capabilities, providing customers with a wider range of standard and custom polarization optics.

References

1. Bass, Michael, Casimer DeCusatis, Jay Enoch, Vasudevan Lakshminarayanan, Guifang Li, Carolyn MacDonald, Virendra Mahajan, and Eric Van Stryland, eds. Handbook of Optics: Geometrical and Physical Optics, Polarized Light, Components and Instruments. 3rd ed. Vol. 1. New York, NY: McGraw-Hill Education, 2010.
2. Goldstein, Dennis. Polarized Light. 2nd ed. New York, NY: Marcel Dekker, 2003.