A light source with a programmable spectral output was designed and constructed following the identification of limitations in current display calibration techniques. Current calibration of a display measurement instrument compares the measured spectral output of a pre-calibrated reference light source with the calibration data traceable to national standards. This allows correction factors to be calculated for each wavelength and entered into the measurement instrument. However, the reference light source used to create these correction factors is very dissimilar in spectral output to test displays such as cathode ray tubes (CRT) or liquid crystal displays (LCDs). The dissimilarity between the reference calibration spectrum and the spectrum of the test display gives errors at some wavelengths, which leads to inaccurate measurement of colour and luminance, and inter-instrument disagreement. The development of a light source with a programmable spectrum, will allow display measurement instruments to be calibrated against a reference source that mimics the spectrum of the device under test, improving the accuracy of measurements and the agreement between display measurement instruments. This paper describes the prototype programmable source and demonstrates the feasibility of mimicking both CRT and LCD spectra. The programmable source could be used as a transfer standard to assess display measurement techniques in international laboratories.

Abstract— A double‐monochromator spectroradiometer with a photon‐counting detector will be described. The system captures spectroradiometric data with near‐perfect linearity over six decades of intensity and with wavelength uncertainties of under 0.05 nm. It enables accurate measurement of spectral radiance data and small‐area contrast with an uncertainty less than 0.002 in chromaticity (x,y) and 2% in luminance for a typical CRT spectrum.

In earlier papers, NIST proposed a standard illumination source and optical filter targets with which to assess the state-of-the-art of display measurement. The Display Measurement Assessment Transfer Standard (DMATS) was designed to present the display metrologist with a rectangular anay of targets such as color filters, polarizers, and grilles, back-lighted by uniform illumination, to be measured using methods and instruments typically used in display performance measurement. A "round robin" interlaboratory measurement exercise using the "standard" artifact suite would enable a first order assessment of display measurement reproducibility, i.e., measurement variability within the electronic display community. The rectangular array design of the DMATS was anticipated to present stray light and color contamination challenges to facilitate identification of error sources deriving from measurement protocols, laboratory environment, and equipment. However, complications in dealing with heating problems threatened to delay the planned laboratory intercomparison. The Gamut Assessment Standard (GAS) was thus designed as an interim solution to enable the NIST scientists and participating measurement laboratories to begin collecting data. The GAS consists of a 150 mm diameter integrating sphere standard illumination source with a stray light elimination tube (SLET) mounted at the exit port. A dual six-position filter wheel is mounted at the SLET exit port. One wheel holds a series ofneutral density filters and a second interchangeable wheel holds various color filters. This paper describes the design and construction ofthe GAS, its initial performance characterization by NIST, and comparison measurements made at NPL. Possible design changes suggested by the results of the preliminary intercomparison are discussed, as are plans for future interlaboratory comparisons and potential use of the GAS as a transfer standard for laboratory self-certification.

This paper describes a double monochromator spectroradiometer with a photon counting detector. The system captures spectroradiometric data with near perfect linearity over six decades of intensity and with wavelength uncertainties of under 0.05 nm. It enables very accurate measurement of spectral radiance data from small areas of displays and thus calculation of luminance, chromaticity and small area contrast.

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