Disclosed is an integrating sphere for measuring the diffuse reflectivity
of material samples in the infrared. The sphere is disposed in an airtight vacuum
chamber under an atmosphere that does not absorb in the infrared. The sphere has
two positions at which a sample may be mounted, one on a rod at the sphere's center,
another on the sphere's wall, each mounting position corresponding to two different
modes of testing samples. The rod acts as a mounting pedestal for a center mounted
sample, and is rotatably mounted about its elongate vertical axis so that the sample
can rotate with the rod in a horizontal plane. The rod penetrates the sphere and
the chamber, and terminates in a knob or handle by which the rod can be rotated
to position the sample at a preselected angle. Adjacent to the position for wall
mounting, there is a sample heater. This configuration allows one to measure diffuse
reflectance of a sample as a function of incidence angle and temperature. In the
center-mount configuration, the handle enables one to anglularly reposition a center
mounted sample without the need to vent and replenish the chamber's atmosphere
after each test.
