INTERNATIONAL ROUND-ROBIN IN INFRARED ALPHA-MEASUREMENTS ON SLICES OFSYNTHETIC QUARTZ

An International Round Robin (IRR) has been completed in the measureme nt of three infrared extinction coefficients (alphas) used in the rece nt quality specification for synthetic quartz as revised and augmented by the International Electrotechnical Commission (IEC), to be known a s the Second Edition of IEC Publication 758 [1]. These results, more c omprehensive than from earlier round robins, have enabled an improved standardization and coordination of alpha test limits at the three wav enumbers in international use: 3410, 3500, and 3585 cm-1. The IRR reve aled that among the 17 participating infrared instruments used each ha d its individual three long term biases (within the claimed ranges of instrument accuracy). t,ow range corrections to the alphas for partici pating instruments have been reported by the IRR committee to particip ants and at a 1992 US Electronic Industries Association meeting [2], [ 3]. The alpha interrelationships from this round robin also enable imp roved coordination of 5 MHz Q indication formulas in the three measure d 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 tes t use, bypass Q calibrations and other potential sources of grading co nfusion. The convergence of alpha averages as the IRR results were rec orded suggests that they are stable and will contribute to improved co ordination of synthetic quartz grading.