Split beam spectrophotometer.

A single light source-single detector spectrophotometer has been constructed to record continuously transmissivity or reflectivity as a function of wavelength. This instrument is especially useful for thin film samples of small areas glued to substrates, when it is difficult to produce a similar glue layer for the reference beam. Measurements on samples 1 mm(2) and smaller have been performed. Except for the simple custom-made chopper blade, commercially available components were used throughout. Through the use of reflecting optics no wavelength limitations are encountered.