DESIGN AND TESTING OF A 2-MONOCHROMATOR REFERENCE SPECTROFLUOROMETER FOR HIGH-ACCURACY TOTAL RADIANCE FACTOR MEASUREMENTS

A two-monochromator reference spectrofluorimeter has been developed at the National Research Council of Canada in accordance with Internatio nal Commission on Illumination and American Society for Testing and Ma terials colorimetry standards to permit high-accuracy total spectral r adiance factor measurements of fluorescent materials. This fully autom ated instrument employs a xenon-are light source, all-reflective optic s, two grating monochromators with order-sorting filters, a cooled pho tomultiplier tube analyzing detector, and a calibrated silicon photodi ode monitor detector. The instrument operating range is 250-1050 nm wi th a selectable bandpass (optimized for a 5-nm resolution), and the me asurement geometry is 45 degrees annular illumination and 0 degrees vi ewing (45/0). We describe the instrument's design, testing, and verifi cation procedures. Systematic errors that have been determined and cor rected for include instrument polarization, beam nonuniformity, wavele ngth shifts, stray light, and system drift. The wavelength accuracy an d reproducibility are estimated to better than +/-0.1 and +/-0.03 nm, respectively. The photometric short-term repeatability and long-term r eproducibility are estimated to be better than +/- 0.15% and +/- 0.5%, respectively. The overall photometric accuracy is better than 1% of t he value over a wide range of reflectances, and the reproducibility of the color specification of a fluorescent material is better than 0.25 Delta E(ab) units. (C) 1997 Optical Society of America