OFR Variable Retarder

Variable Retarders and Soleil-Babinet Compensator
Whereas the traditional application of the Soleil-Babinet Compensator is as an instrument for the analysis of polarized light, we have introduced its use as an adjustable retarder, with emphasis in the laser lab where many wavelengths are employed.

The heart of the OFR Variable Retarder and Soleil-Babinet Compensator is the set of crystal quartz wedges: a longer wedge moves with respect to a fixed shorter wedge. The combination of the wedges comprises a zero-order retarder which is adjustable from 0 to 2p of phase retardation at any wavelength from 190 nm to 1.0 µm. Operation at longer wavelengths is possible, however at less than 2p of phase retardation. These instruments are useable with high-power lasers, and available upon request with antireflection coatings.

The fast axis of the Retarder is parallel to the long base of the instrument. In operation, the plane of polarization will normally be at ±45° with respect to this axis. The S-B Compensator is actually a variable retarder that can be adjusted from 0 to 2p of phase retardation. When used as the Variable Retarder, a 2" diameter x ½" black-anodized aluminum plate is attached on the rear face of the instrument. This plate fits into any standard 2" mirror mount, which allows full rotation to correspond to any plane of polarization orientation. For full capability as a classic Soleil-Babinet Compensator, the instrument is mounted onto the Divided Circle Rotator which allows full 360° of rotation, with locking at any angle therein, as well as 2-axis tilting. It has the additional feature of ±45° detents for ease of setting.

ELECTRONIC DIGITAL READOUT
is a feature of the micrometer actuator. This, along with "zero reset" and memory, simplifies operation. An RS-232 Port can be accessed for data acquisition and processing. Resolution is 0.001 of the wavelength.