Phase Retardation Reflectors Series PRR: Silicon for CO2 Lasers and 10.6μm 

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These mirrors create a 90° Phase Shift with the aid of specially constructed thin film coating x-layers applied to the surface, when hit with a linear polarized beam at 45° to the plane of incidence. Commonly called Phase Shifters, Polarizers, or Circular Polarizing Mirrors, they tranform the incoming beam into a circular polarized state. They typically are only used external to the laser cavity as a beam delivery mirror. These operate only with a true 10.6μm laser wavelength and will not work at other wavelengths such as 9.2 or 9.6μm without special modifications to the thin film coating design. We offer non-standard wavelength Phase Retardation Reflectors at these other wavelengths as custom parts.

Specifications:

Material: Silicon (Si) Single Crystal
Diameter Tolerances: +.000" -.005" 
Thickness: ±.010" 
Flatness: 1/40 wavelength
Parallelism: < 3 minutes of arc
Surface Quality: < 40/20 scratch dig Laser Finish

Spectral Performance:

Phase Shift: 90° ± 3.0° between p and s polarization for 10.6μm operation only  45° Angle Of Incidence
Reflectance: > 99.0% average  10.6μm
Absorption: < .40%  10.6μm
Coating optimized to create 90° phase shift from a linear polarized beam. Used in beam delivery systems where cutting circles in materials is required