EXAMINATION OF THE DIFFERENCES BETWEEN OFDA AND LASERSCAN ON ULTRAFINE WOOLS

Previous submissions to IWTO have shown that the OFDA and Laserscan gi ve compatible results over the normal working range, but systematic an d commercially-significant differences have been observed on ultrafine lots. Detailed investigation has been carried out to establish the re asons for this. Evidence is presented which indicates that the OFDA ha s been providing accurate results, but that at very fine diameters, th e extrapolated non-linear calibration of the Laserscan has led to erro r. An empirical procedure has been developed and tested to overcome th is problem, and it is recommended that other laboratories verify the p rocess.