Conference Report: SIXTH BIENNIAL SYMPOSIUM ON OPTICAL FIBER MEASUREMENTS Boulder, CO September 11–12, 1990

The development of lightwave communications over the last 2 decades has been particularly dependent on careful metrology to support product specification and standardization. Some estimates have suggested that as much as 20% of the selling price of a fiber is associated with measurements. This perhaps explains the continuing success of the biennial Symposium on Optical Fiber Measurements as an international forum for the discussion of lightwave measurement problems. The sixth in this series of symposia sponsored by the National Institute of Standards and Technology (NIST) in cooperation with the Institute of Electrical and Electronics Engineers (IEEE) and the Optical Society of America (OSA) was held September 11-12, 1990 at NIST in Boulder. The 2 day meeting drew about 250 attendees; 30 percent came from 16 countries outside of the United States. In addition, several committees of the International Electrotechnical Commission (lEC) and the Telecommunications Industry Association (TIA) concerned with standards for optical fiber measurements took the opportunity to hold meetings on the day before and the 2 days following the Symposium. Attendees saw and heard a total of 45 papers, 9 invited and 36 contributed, slightly more than half from abroad. As a result of the large number of papers submitted, the committee elected for the first time to schedule a poster session. The topics of contributed papers at the Symposium have historically been a good measure of current problems facing the industry. At the 1990 meeting there were enough papers on each of three topics to require separate sessions. One of those was geometric measurements on single mode fiber. Maintaining a high degree of circularity in the cladding of a fiber, an accurate cladding diameter, and good concentricity between the core and cladding are essential in achieving low connector losses. Current measurement agreement for cladding diameter as determined by international comparisons is about 0.4 jjim (1 standard deviation). For manufacturers to further reduce geometric tolerances on fiber, primary standards and measurement methods with uncertainties approaching 0.1 [ISO. are needed. To achieve that accuracy it has become necessary to revisit the capabiHties of existing methods and to investigate new approaches. Keith Emig of Corning, Inc. presented data indicating that transverse interferometric techniques, based on Fizeau and Michelson interferometers, could achieve the required 0.1 |xm accuracies in cladding diameter measurements. He regards these techniques as suitable for measuring samples to be used for calibrating measurement systems based on microscopic end-viewing. End-viewing is an easy and popular technique, but suffers from difficulty