Air spaced etalon with mechanism for adjusting parallelism of reflecting surfaces

摘要

An air spaced etalon for wavelength selection including a spacer comprised of two hollow cylindrical members abutting each other in end-to-end aligned relation. A high degree of parallelism of two seconds or less can be easily obtained between the opposite end surfaces of the compound spacer by adjusting the relative angular position of the spacer members irrespective of the parallelism of the end surfaces of the individual spacer members. This enables production of high performance etalons with reduced cost and high yield.