A new gonioreflectometer has been developed at the National Research Council of Canada to measure spectral bidirectional reflectance distribution functions (BRDF). It incorporates a five-axis robot manipulator that holds the sample, and a rotation stage that holds an extended uniform light source of precisely known emitting solid angle. An array spectroradiometer is used to measure the reflected spectral radiance from the sample, which is compared to the spectral radiance of the source itself, allowing the calculation of the BRDF from first principles. The system has been designed in anticipation of a growing demand for traceable spectral BRDF measurements from sectors such as machine vision, remote sensing and color imaging. Capabilities of the system are demonstrated for diffuse reflectance material, vapor-blasted aluminum, and light interference pigments.

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For highest accuracy fluorescence colorimetry, standardizing organizations recommend the use of a two-monochromator method with a bidirectional illumination and viewing geometry (45:0 or 0:45). For this reason, reference fluorescence instruments developed by National Measurement Institutes (NMIs) have largely conformed to this bidirectional geometry. However, for many practical applications in colorimetry where the samples exhibit texture, surface roughness or other spatial non-uniformities, the relevant standard test methods specify a sphere geometry with diffuse illumination or viewing (e.g. d:8 or 8:d) which gives improved measurement precision. This difference in the measurement geometry between the primary instrument used to realize the fluorescence scale and the secondary testing instruments used for practical measurements, compromises the traceability of these fluorescence calibrations. To address this metrology issue, a two-monochromator goniospectrofluorimeter instrument has been developed at the National Research Council of Canada (NRC). This instrument can be configured for different illumination and viewing geometries to conform with international standards for different colorimetric applications. To improve the traceability chain for measurements using different geometries, the instrument has been thoroughly characterized and validated by means of comparison measurements with NRC's other spectrophotometric and fluorescence reference instruments. This uncertainty analysis has been carried out in a step-wise manner; first, for a bidirectional geometry (45:0) and then for a sphere geometry (8:d) to provide an uninterrupted traceability to primary radiometric scales. The first paper in this two paper series reviews the background to this work and provides details of the basic design of the new instrument and its characterization for measurements using a bidirectional geometry (45:0), including a representative uncertainty budget. In part 2, the major sources of sphere error are described and minimized in a modified sphere design. The instrument characterization and validation are then extended to a sphere geometry (8:d) to provide direct traceability for practical fluorescence colorimetry.

We describe the most recent implementation of the data acquisition system which we have developed for fast time-resolved (FTR) Fourier transform spectroscopy (FTS) and report spectra that were obtained by using this instrument. This FTRPTS data system operates in conjunction with any continuous-scan Michelson interferometer, giving it the capability to record many time-delayed spectra of a transient event, with a minimum time resolution of 1 µs. The sensitivity and the spectral resolution of the complete system are the same as those that would be obtained if the interferometer were used in conventional steady-state spectroscopy. To illustrate the performance of the FTRPTS system, we recorded emission spectra from the products of transient chemical reactions of H atoms with CF(3)Cl, CF(2)Cl(2), CFCL(3), and NO(2). These are laser-initiated reactions involving atoms with energies that correspond to a temperature of approximately 27,000 K and lifetimes of a few microseconds, but the FTRPTS system records the time evolution of their products with high signal-to-noise ratio.