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alpha-BBO Glan-Laser Polarizers

  • Designed for High-Power Laser Applications
  • Extinction Ratio: 100,000:1
  • Laser Quality α-BBO Crystal




GLB10 Polarizer and 
SM1PM10 Mount on a 
PRM1 Rotation Mount

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Alpha-BBO Glan-Laser Polarizers Divert Ordinary Rays, Leaving Highly Polarized Extraordinary Rays (Aligned with the "Polarization Axis" Mark on the Housing) Passing Through the Polarizer

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  • Extinction Ratio for Output Beam: 100,000:1
  • Fabricated from the Highest-Grade, Laser-Quality α-BBO
  • Three Available Coatings
    • 210 - 450 nm (centered at 266 nm), Ravg < 1.5%
    • 220 - 370 nm, Ravg < 0.5%
    • VAR for 405 nm, Ravg < 0.25%
  • High Damage Threshold: 5 J/cm2 (10 ns pulse, 10 Hz, Ø0.347 mm Spot Size, @ 355 nm)
  • Low Scatter
  • Wavefront Distortion ≤ λ/8 Over Clear Aperture (Excluding Side Ports)
  • Surface Quality
    • 20-10 Scratch-Dig on AR-Coated Input and Exit Faces
    • 40-20 Scratch-Dig on Uncoated Side Ports
  • Glan-Taylor Design (Air-Spaced Birefringent Crystal Prisms)

Our Glan-Laser α-BBO Polarizers are specifically designed to deal with high-energy, short-wavelength laser light. Like our Glan-Taylor and Glan-Laser Calcite Polarizers, these polarizers are ideal for applications requiring extremely high polarization purity (100,000:1), high damage threshold (5 J/cm2, 10 ns pulse, 10 Hz, 0.347 mm Spot Size, @ 355 nm), and transmisison in the UV (210 - 450 nm). A significant amount of reflected light escapes the polarizers through the side port, including all of the ordinary ray and some of the extraordinary ray. As such, the escape beam is not fully polarized, and only the transmitted extraordinary ray should be used for applications that require a high-quality, polarized beam.

The input and output faces of these polarizers are polished to a laser quality 20-10 scratch-dig surface finish to minimize scattering of the transmitted extraordinary polarization component of the incident laser beam or light field. The ordinary polarization component is reflected and exits the polarizer at a 61° angle (wavelength dependent) through one of the two uncoated side ports, which are provided to allow bidirectional use of the polarizer. The escape ray is not fully polarized and the side escape ports have a lower surface quality of 40-20 scratch-dig. In addition, the hygroscopic nature of α-BBO may cause these uncoated side faces may become hazy over time as the crystal absorbs water from the air, further decreasing the beam quality of the escape ray.

The polarizers are available with three antireflection coatings: a single-layer MgF2 antireflection coating (SLAR-MgF2), a UV AR coating, or a V Coating optimized for 405 nm. The SLAR coating features good broadband UV performance with low reflectance (<1.5%) from 210 to 450 nm while the UV AR coating provides exceptionally low reflectance (<0.5%) from 220 to 370 nm. The 405 nm V coating provides even less reflectance (<0.25%) than the UV coating at 405 nm. These coatings also serve as a protective layer that prevents the hygroscopic α-BBO substrate from interacting with moisture in the environment. Please see the Graphs tab for more information about the reflectance of these coatings.

For compatibility with Thorlabs' selection of rotation mounts and other optomechanics, these polarizers can be mounted in our Polarizing Prism Mounts, which are available for both 5 mm (SM05PM5) and 10 mm polarizers (SM1PM10). Thorlabs also provides Glan-Taylor polarizers.

Item #GLB5GLB10
Extinction Ratioa 100,000:1
Substrate Laser Quality α-BBOb
(Low Scatter)
Design High Laser Damage Threshold
Air-Spaced Design
Transmission Range 210 - 450 nm
Available AR Coatingsc SLAR MgF2 (210 - 450 nm), Ravg< 1.5%
UV (220 - 370 nm), Ravg< 0.5%
V-Coat (405 nm), Ravg< 0.25%
Damage Threshold 5 J/cm2 (10 Hz, Ø0.347 mm Spot Size, 10 ns Pulses @ 355 nm)
Wavefront Distortion ≤ λ/8 Over Clear Aperture
Surface Quality (Input and Output Faces) 20/10 Scratch/Dig
Surface Quality (Side Ports) 40/20 Scratch/Dig
Aperture 5 mm x 5 mm 10 mm x 10 mm
Prism Dimensions (W x L) 6.5 mm x 7.5 mm 12 mm x 13.7 mm
  • Extinction ratio is only for the output ray (see drawing below). Measured at 405 nm and 355 nm. The extinction ratio (ER) is the ratio of the maximum transmission of a linear polarized signal when the polarizer’s axis is aligned with the signal to the minimum transmission when the polarizer is rotated by 90°.
  • Click Link for Detailed Specifications on the Substrate
  • The escape windows (perpendicular to input / exit faces) are not coated. See the Graphs Tab for more information.
Note: Since α-BBO is a relatively soft material, care must be taken when cleaning. The coated faces of the polarizer can be gently cleaned with solvent and air. The escape faces (perpendicular to the input / exit faces) are also extremely delicate. Do not touch any faces if possible. Cleaning should be light and at a glancing angle. If these surfaces must be wiped, use only solvent-moistened cotton or untreated facial tissues.

Field of View Angle Orientation

A significant amount of scattered unpolarized light escapes the polarizers. As a result, the escape ray (o-ray) is not purely polarized and should not be used for polarization dependent applications.

The typical transmission and reflectivity of the α-BBO Glan-Laser polarizers are shown in the graphs below. The blue shading indicates the region for which the AR coating is optimized (see Specs tab for more information). The reflectivity plots represent the performance of the coating only, not including internal losses of the polarizer. The transmission plots include both both reflectivity and transmission through the polarizer (including any internal losses).

The plots below apply to the GLB10 and GLB5 α-BBO Glan-Laser polarizers.

The plots below apply to the GLB10-UV and GLB5-UV α-BBO Glan-Laser polarizers.

The plots below apply to the GLB10-405 and GLB5-405 α-BBO Glan-Laser polarizers.

Note: Short wavelength cutoff is due to the cut angle of the α-BBO prism, not the reflectivity or transmission of the material.

UV Glan-Laser Polarizer Schematic Diagram

Glan Laser Specifications

Item #GLB5GLB10
W 6.5 mm 12 mm
L 7.5 mm 13.7 mm
A 9.5 mm 16 mm
B 12.7 mm 19.2 mm

Polarization-Dependent Refraction - Glan Laser α-BBO Polarizer

Polarization-Dependent Refraction

Thorlabs' α-BBO polarizers are all based on high-grade, birefringent α-BBO crystals. Due to the birefringent nature of α-BBO, waves polarized in the direction of the optical axis propagate with a different index of refraction than waves polarized orthogonally to the optical axis. In our Glan-Laser polarizers, this birefringence causes the ordinary polarization component of an incident beam to undergo total internal reflection at an internal glass-to-air interface. The light transmitted through the polarizer then consists of only the remaining extraordinary polarization component. While these transmitted extraordinary rays are highly polarized, the reflected ordinary rays are only partially polarized.

Our Glan-Laser and Glan-Taylor polarizer are designed as polarizer elements that remove the reflected, partially polarized component of a beam. These polarizers are typically built out of two prisms, as shown in the drawing to the right. They are only designed to work with well collimated light beams; converging and diverging input beams will not exhibit proper polarization and incidence angle at the internal interface. Since α-BBO is a soft crystal that is easily damaged, all of our α-BBO polarizers are offered in metal housings. With convenient threadings and adapters, these housings can easily be mounted into our opto-mechanical products.

Field of View
α-BBO polarizers feature a field of view (FOV) that varies with both wavelength and entrance orientation. The FOV of these prisms must be considered during alignment and collimation procedures. The side of the polarizer with the escape window has an FOV that decreases with increasing wavelength (FOV 1). The opposite side has an FOV that increases at longer wavelengths (FOV 2).

Field of View Angle Orientation


Thorlabs uses only the highest quality synthetic α-BBO in our polarizing prisms. The transmission curves of the α-BBO polarizers are shown on the Overview tab. These curves also represent the transmission of the GLB5, GLB5-UV, and GLB5-405. Variations during the manufacturing of the α-BBO crystal affect the transmission curve and the damage threshold rating.

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Posted Comments:
Posted Date:2016-06-17 16:45:20.063
I would like to know the damage threshold at 266 nm.
Posted Date:2016-06-21 04:14:52.0
Response from Bweh at Thorlabs USA: At 266nm, with the same beam conditions we used at 355nm (10 ns pulse, 10 Hz, 0.347 mm Spot Size), the adjusted laser induced damage threshold will be under 4.3J/cm^2. The details on this estimate can be found at the following link, under the "Damage Threshold" tab:
Posted Date:2015-10-13 03:11:45.39
Looking at the GLB10 and GLB10-UV, it seems that although the reflectivity of the GLB10-UV optic is much lower, the transmission is actually poorer at lower wavelengths than the GLB10. If the interior material is the same in both cases, I'd expect transmission to be better too. Is there some interference in the GLV10-UV that makes the transmission worse?
Posted Date:2015-10-16 11:08:11.0
Response from Bweh at Thorlabs USA: We are reviewing this and I will followup with you please.
Posted Date:2015-07-08 13:16:27.733
Can you manufacture Glan Laser prisms with larger aperture? (i.e. >20 mm?)
Posted Date:2015-09-23 09:58:11.0
Response from Bweh at Thorlabs USA: I will be contacting you regarding providing this as a special.
Posted Date:2014-12-09 12:51:59.21
I bought the GLB10 to act as a variable beamsplitter based on the specifications on your "overview" page. Once I received them I found out the "100,000:1" extinction only applies for the straight through port and the side port has awful polarization purity. Please make this clear on the "overview" page and don't bury that information as a footnote on one of the specification graphs. I expect better than this from Thorlabs. Thanks.
Posted Date:2014-12-09 03:46:00.0
Response from Mike at Thorlabs: Thank you for you feedback. I apologize for any confusion that the presentation caused. Based on your feedback we have updated the presentation to make the extinction ratio spec more clear.
Posted Date:2013-05-31 05:41:53.29
Können Sie 3 Stück a-BBO Glan-Laser Polarisatoren mit freier Apertur 5mm ohne Beschichtung anbieten?
Posted Date:2013-05-31 10:36:00.0
The coating serves as protection to the alpha-BBO. We will contact you to discuss this further along with other possible solutions.

Polarizer Selection Guide

Thorlabs offers a diverse range of polarizers, including wire grid, film, calcite, alpha-BBO, rutile, and beamsplitting polarizers. Collectively, our line of wire grid polarizers offers coverage from the visible range to the beginning of the Far-IR range. Our nanoparticle linear film polarizers provide extinction ratios as high as 100 000:1. Alternatively, our other film polarizers offer an affordable solution for polarizing light from the visible to the Near-IR. Next, our beamsplitting polarizers allow for use of the reflected beam, as well as the more completely polarized transmitted beam. Finally, our alpha-BBO (UV), calcite (visible to Near-IR), rutile (Near-IR to Mid-IR), and yttrium orthovanadate (YVO4) (Near-IR to Mid-IR) polarizers each offer an exceptional extinction ratio of 100 000:1 within their respective wavelength ranges.

To explore the available types, wavelength ranges, extinction ratios, transmission, and available sizes for each polarizer category, click More [+] in the appropriate row below.

Wire Grid Polarizers
Film Polarizers
Beamsplitting Polarizers
alpha-BBO Polarizers
Calcite Polarizers
Quartz Polarizers
Magnesium Fluoride Polarizers
Yttrium Orthovanadate (YVO4) Polarizers
Rutile Polarizers
  • Click on the graph icons in this column to view a transmission curve for the corresponding polarizer. Each curve represents one substrate sample or coating run and is not guaranteed.
  • Mounted in a protective box, unthreaded ring, or cylinder that indicates the polarization axis.
  • Available unmounted or in an SM05-threaded (0.535"-40) mount that indicates the polarization axis.
  • Available unmounted or in an SM1-threaded (1.035"-40) mount that indicates the polarization axis.
  • Available unmounted or mounted in cubes for cage system compatibility.
  • Calcite's transmittance of light near 350 nm is typically around 75% (see Transmission column).
  • Available unmounted or in an unthreaded Ø1/2" housing.
  • The transmission curves for calcite are valid for linearly polarized light with a polarization axis aligned with the mark on the polarizer's housing.
  • The 1064 nm V coating corresponds to a -C26 suffix in the item number.
  • Available unmounted or mounted in a protective box or unthreaded cylinder that indicates the polarization axis.

Glan-Laser alpha-BBO Polarizer, SLAR Coating

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
GLB5 Support Documentation
GLB5Glan-Laser alpha-BBO Polarizer, 5.0 mm CA, SLAR MgF2 (210 - 450 nm)
GLB10 Support Documentation
GLB10Glan-Laser alpha-BBO Polarizer, 10.0 mm CA, SLAR MgF2 (210 - 450 nm)

Glan-Laser alpha-BBO Polarizer, UV Coating

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
GLB5-UV Support Documentation
GLB5-UVGlan-Laser alpha-BBO Polarizer, 5.0 mm CA, UV Coating (220 - 370 nm)
GLB10-UV Support Documentation
GLB10-UVGlan-Laser alpha-BBO Polarizer, 10.0 mm CA, UV Coating (220 - 370 nm)

Glan-Laser alpha-BBO Polarizer, 405 nm V-Coated

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
GLB5-405 Support Documentation
GLB5-405Glan-Laser alpha-BBO Polarizer, 5.0 mm CA, V Coated (405 nm)
GLB10-405 Support Documentation
GLB10-405Glan-Laser alpha-BBO Polarizer, 10.0 mm CA, V Coated (405 nm)
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