A PRECISION SPECTROPHOTOMETER FOR THE 0.2 TO 2.7 MICRON REGION
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Publisher:Ohio State University
Recent developments in solid state physics as well as in chemical analysis have created a need for extending the range of photoelectric spectrophotometers into the near infrared. An instrument is described which meets the requirements for good resolving power, very low scattered light, and high photometric accuracy. The spectrophotometer employs a prism-grating double monochromator which combines the high resolving power of the grating at longer wavelengths with the high efficiency and low scattered light of the prism. The photometer system employs a single photoreceiver which measures the relative absorbance of the sample and reference paths on a time-sharing basis. A multiplier phototube is used in the 2000 to 6000 Angstrom range and a lead sulfide cell in the 0.6 to 2.7 micron range. A novel optical system using a cylindric lens and toric mirrors directs radiation through the sample space in order to reduce sample volume and to minimize photometric errors arising from sample refraction, diffraction at the exit slit, and nonuniform photo-surface sensitivity. To take advantage of the high photometric accuracy a two-pen recorder is employed giving an effective chart width of 20 inches for an absorbance range of 0 to 2.0.
Author Institution: Applied Physics Corporation