International round robin in infrared alpha measurements on slices of synthetic quartz

An International Round Robin (IRR) has been completed in the measurement of three infrared extinction coefficients (alphas) used in the recent quality specification for synthetic quartz as revised and augmented by the International Electrotechnical Commission (IEC), to be known as the Second Edition of IEC Publication 758. These results, more comprehensive than from earlier round robins, have enabled an improved standardization and coordination of alpha test limits at the three wavenumbers in international use: 3410, 3500, and 3585 cm/sup -/. The IRR revealed that among the 17 participating infrared instruments used each had its individual three long term biases (within the claimed ranges of instrument accuracy). Low range corrections to the alphas for participating instruments have been reported by the IRR committee to participants and at a 1992 US Electronic Industries Association meeting. The alpha interrelationships from this round robin also enable improved coordination of 5 MHz Q indication formulas in the three measured alphas for those who need to refer to alpha-indicated Q´s. The grade test limits as stated in alphas, now accepted for direct standard test use, bypass Q calibrations and other potential sources of grading confusion. The convergence of alpha averages as the IRR results were recorded suggests that they are stable and, will contribute to improved coordination of synthetic quartz grading.<>