DESIGN AND PERFORMANCE OF A STABLE LINEAR RETARDER

The National institute of Standards and Technology (NIST) has develope d a nominally quarter-wave linear retarder for wavelengths near 1.3 mu m that is stable within +/-0.1 degrees retardance over a range of wav elength, input angle, temperature, and environmental variations. The d evice consists of two concatenated Fresnel rhombs made from a low stre ss-optic-coefficient glass that minimizes the residual birefiringence from machining and packaging. Device machining, assembly, and antirefl ection coating tolerances are discussed, and the theoretical performan ce is compared with measurements, Humidity can modify retardance of th e total-internal-reflection surfaces; we discuss packaging that mitiga tas this effect and provides an estimated IO-Fear lifetime for the dev ice. Several measurement methods were intercompared to ensure that the device retardance can be measured with an uncertainty less than 0.1 d egrees. Similar retarders will be certified by NIST and made available as Standard Reference Materials.