Reflectance/Transmittance Spheres

Reflectance/Transmittance spheres are designed for the purpose of measuring total hemispherical reflectance or total transmittance of solid materials located on the sphere wall. Typically, a spectrometer is used to illuminate the sample and non-filtered detector is used to collected the integrated flux. By using a 'white' light source and a photopically filter silicon detector, photometric measurements can be accomplished. Finally, if a broadband source is used to illuminate the sample, a dispersive device and a diode- or CCD- array can also provide spectral transmittance or reflectance measurements. The general purpose reflectance/transmittance spheres are configured to accommodate any of these types of measurement. The spheres are also configured to allow double-beam comparison type measurements, which are more accurate than simple 'substitution-sphere' measurements. (ref http://physics.nist.gov/Divisions/Div844/facilities/specphoto/references.html).

Systems include spun or machined aluminum sphere with four ports at 90 degrees from each other along the equator of the sphere (drawing 2), a 1/4-20 mounting boss, and a mounting stand. The ports include two 25 mm reflectance sample/reference ports, a 25 mm entrance/transmittance port, and a 10 mm= detector port. Detector port is screened from reflectance and transmittance port.