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The OPM reflectometer measures the total hemispherical reflectance of test materials over the spectral range from 250 nm to 2500 nm. The OPM reflectometer is an enhanced version of the reflectometer flown on the Long Duration Exposure Facility (LDEF) Thermal Control Surfaces Experiment (TCSE) and AZ Technology's LPSR-200 commercial reflectometer.

The OPM reflectometer will measure total hemispherical reflectance of OPM test materials with the following performance:

• Accuracy: 3%
• Repeatability: 1%
• Wavelength range: 250 nm to 2500 nm
• Spectral resolution: better than 5% of wavelength
• Number of spectral measurements: 100 points for a full scan

The reflectometer design is integrated into the overall OPM design to work with the sample carousel and the DACS. The OPM reflectometer is a standard optical design that is used routinely in the laboratory. Two light sources, tungsten and deuterium lamps, are used with a scanning prism monochromator with selectable slit widths to provide the monochromatic energy for the spectral measurement. A 115 mm (4.5 inch) diameter integrating sphere collects both the specularly- and diffusely-reflected light from a wall mounted sample providing the angularly integrated measurement capability. A UV enhanced silicon photodiode detector and a lead sulfide detector are used with the integrating sphere to cover the required 250 nm to 2500 nm spectral range.

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Revised: November 12, 1996