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Soleil-Babinet Compensators

  • Continuously Variable Wave Plate with Uniform Retardance over Full Aperture
  • Models for Visible or IR Spectral Ranges
  • Graduated Rotation Ring



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Soleil-Babinet Compensator Drawing
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SBC-IR Drawing


  • Uniform Retardance Over Full Aperture
  • Continuously Variable Retardance from 0 to 2π
  • Graduated Rotation Ring and Digital Micrometer Aid Repeatability
  • 45° Detent Index Stops
  • Options for 365 - 800 nm or 740 - 1650 nm


  • Measurement of Unknown Retardances
  • High-Resolution Ellipsometry
  • Birefringence Compensation

The Soleil-Babinet Compensator is a continuously variable, zero-order retarder (wave plate) that operates over a broad wavelength range. The classical design of the compensator consists of a long birefringent wedge and a fixed wedge mounted to a compensator plate. The retardance is adjusted by moving the position of the long wedge relative to the short wedge using the included precision digital micrometer. This allows the retardance to vary continuously while maintaining a uniform retardance across the aperture at any given setting.

Crystalline quartz optics are used in both Soleil-Babinet Compensator models. The visible (SBC-VIS) and infrared (SBC-IR) models are designed for the 365 - 800 nm and 740 - 1650 nm spectral ranges, respectively.

Our standard Soleil-Babinet Compensators are uncoated for broad spectral operation. To minimize reflection losses when using the compensator over narrow wavelength ranges, we offer AR-coated versions upon request. Please contact Technical Support for more information on this option.

The optional SBC-COMM offers cables to provide an RS-232 interface to a PC. GUI software and LabVIEW VIs are provided to allow for easy calibration and readout of the retardance of the compensator. A CD with the software is included; the software may also be downloaded from the link on the Software tab.

The included digital micrometer has a Ø3/8" (Ø9.5 mm) mounting barrel and offers 1" (25.4 mm) of travel. To motorize an SBC, a Z825B DC servo motor can be used in place of the standard micrometer. Alternatively, Thorlabs' Liquid Crystal Variable Retarders may be a suitable alternative to a motorized SBC.

The Soleil-Babinet Compensator can be mounted on a post using one of the six #8 (M4) counterbores. These counterbores are arranged to allow for a vertical or horizontal orientation.

Wavelength Range 365 - 800 nm 740 - 1650 nm
Retardance Adjustment 0 to 2π (Full Wave)
Clear Aperture Ø10 mm
Beam Deviation <1 arcmin
Transmitted Wavefront Error <λ/4
Surface Quality 40-20 Scratch-Dig
Digital Readout Resolution 0.001 mm
Repeatability Valuesa @ 405 nm: 0.0016 waves
@ 633 nm: 0.001 waves
@ 800 nm: 0.0008 waves
@ 1064 nm: 0.0012 waves
@ 1550 nm: 0.0008 waves
Rotation 360°, Continuous
Rotation Division Scale 1° Increments
Detent Index Stops Every 45°
Mounting Holes #8 (M4) Counterbore (6 Places)
  • Individual results may vary.

Software for the SBC-COMM


Software Version 2.0.4

GUI and Libraries for the SBC-COMM RS-232 Interface

Software Download

Posted Comments:
nettony  (posted 2017-12-12 22:15:19.477)
Dear person in charge I just got SBC-IR, and it doesn't work for "45 Dentent Stops". The manual says, 'see Appendix C', but I cannot find such Appendix section from my manual and that from this website.
nbayconich  (posted 2017-12-19 08:48:47.0)
Thank you for contacting Thorlabs. The SBC has knob on the top that can loosen the detent spring tension. I will reach out to you directly to help troubleshoot your problem. We have corrected the manual that has no references to the non-existent appendix.
evan.meyer.scott  (posted 2017-03-07 14:24:01.117)
I would like to know the transmission of the SBC-IR at 1550 nm please, not just the reflectance of the AR coatings.
tfrisch  (posted 2017-03-13 06:45:04.0)
Hello, thank you for contacting Thorlabs. Our stock compensators are uncoated so that they can be used over the whole defined wavelength range, so with 6 uncoated surfaces, the transmission would be roughly 78%. It looks like you are already in contact with our Technical Support Team about a quote for a coated version.
user  (posted 2016-03-17 10:36:38.58)
What kind of mount to you need for the SBC?
besembeson  (posted 2016-03-17 12:12:46.0)
Response from Bweh at Thorlabs USA: There are counter bore holes by the kinematic mount for #8 or M4 cap screws to connect the unit to our TR series post and post holders: and
user  (posted 2014-04-10 17:01:48.82)
Has the person who designed this ever heard anything about the laws of the lever? Works in principle, but the mechanical periphery is highly awkward!
besembeson  (posted 2014-04-10 01:37:53.0)
Response from Bweh E at Thorlabs:Hello, Thanks for contacting Thorlabs. I believe you are alluding to the actuator that sticks out of the SB Compensator? I can see your concern but we have tested this arrangement and we found that it doesn't affect the performance of the unit. If you think this is suitable for your application and you would like to probably get a loan unit to test this or you want an alternate actuator, please contact and we will gladly assist you regarding this.
Adam  (posted 2010-04-07 12:16:22.0)
A response from Adam at Thorlabs to dgtlc: The crystals inside the SBC-VIS are not AR coated. We currently have not considered adding a VIS-NIR version to our catalog. I will recommend this to our engineering team as a customer inspired idea. Theoretically, the SBC-VIS should be useable up to 1064nm. At 800nm, the retardance is > 1.75 waves, so at 1064nm, the retardance will be > 1.3 waves. I will contact you directly with more information about the product.
apalmentieri  (posted 2010-03-02 16:48:39.0)
A response from Adam at Thorlabs to a.bruni: I would like to get more information about your setup and how you intend to use the CCD camera. I will email you directly to get this information.
a.bruni  (posted 2010-03-02 13:56:31.0)
Dear, I am Eng. Bruni from Loccioni Group, I would like to have some information about your babinet compesator. I have to performed a polariscope using CCD Camera and light sorce, please send me same information if it is possible to use this compesator with a CCD camera. All the best Andrea
klee  (posted 2009-11-03 10:02:35.0)
A response from Ken at Thorlabs to teng3123: The optics in the SBC-VIS and SBC-IR are not anti-reflection coated. However, we can make them with AR coating as specials. Please let us know if you would like to have a quotation.
teng3123  (posted 2009-11-03 02:48:37.0)
Was the crystal inside the SBC-VIS anti-reflection coated? About 30% of the laser power was lost after passed through SBC-VIS.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SBC-VIS Support Documentation
SBC-VISSoleil-Babinet Compensator, 365 - 800 nm
SBC-IR Support Documentation
SBC-IRSoleil-Babinet Compensator, 740 - 1650 nm
SBC-COMM Support Documentation
SBC-COMMRS-232 Interface & LabVIEW Driver for Soleil-Babinet Compensator
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