DWDM (dense wavelength division multiplexing) telecommunication applications depend on precise and dependable tuning and spacing of multiple optical frequencies, a task usually performed by etalons. The manufacture and quality assurance of these etalons requires an accurate, stable and deterministic measurement system. At VLOC, a JDSU swept-wavelength laser calibrated with an acetylene absorption cell was merely the starting point. By massive computerized data collection, curve-fitting, unique algorithms, and statistical methods, all performed within a custom LabView program, we were able to bootstrap the information from this system and achieve FSR measurement accuracy and stability far in excess of typical methods. In this paper we present the logical development of the technique, statistical modeling, and typical results. To date the system has been used for solid and air-gap etalons, both coated and uncoated, from 16 to 400 GHz FSR.
Specific examples of the manufacturing and testing of 1 inch diameter fused silica etalons to fractional arc second tolerances will be discussed. A step by step description of both planetary and spindle polishing processes along with the results of each will be presented. Various testing methods will be described along with the benefits of each.