A computer-controlled spectrometer has been built for measuring high-reflectance mirrors in the
visible region (380 800 nm). The instrument is designed to scan high-reflectance mirrors (greater
than 50%) on a surface up to 32 x 50 in. Plots of complete reflectance scans are available in minutes
and are used for process control. The reflectometer can be set to any desired incidence angle in the
range of 15 to 60° and four different polarization modes can be selected: P, S, P&S, and No
The instrument incorporates several techniques in order to perform as an absolute system with an
overall accuracy of better than 1% . The optical system features double-bounce reflection, a
special integrating-sphere light source, a double-stage monochromator, and a high-uniformity,
9-stage, side-on photomultiplier tube.
This paper will focus on the electronics, controls and computer system used in the reflectometer.