Quarterwaveplate and Fresnel rhomb compared in the 10-microm CO(2) laser emission region

A comparison is made between the use of the quarterwaveplate and Fresnel rhomb over the 10-microm emission region of the CO(2) laser. From 9.24 to 10.74microm a quarterwaveplate for the 10.6-microm CO(2) spectra line can give rise to a total phase shift of 97-176 degrees for the respective lines. A Fresnel rhomb exhibits virtually no phase variation from the desired 90 degrees phase shift over this region. Both devices exhibit phase shifts for light not normally incident on them.