Abstract
A spectrometer has been constructed to scan portions of the infrared spectrum at repetition rates up to 20 spectra per second. The optics are basically those of a Perkin-Elmer Model 12 C prism spectrometer. The electrically driven mechanical system used to oscillate the Littrow mirror provides for changing the repetition rate, the scanning interval, and the spectral region independently of one another while the instrument is in operation. A Golay pneumatic detector with a time constant of 1.2 milliseconds extends the spectral range to 14 microns with a NaCl prism. The resolving power is low by conventional standards, but is satisfactory for broad bands such as those exhibited by gases under high pressure. The spectra are displayed on a cathode-ray oscillograph and are recorded photographically. Reference marks corresponding to definite orientations of the Littrow mirror are obtained by a subsidiary optical system and are indicated as blanked spots on the oscillograph trace. A synchronized radiation beam chopper serves to indicate the zero radiation signal during the unusable portion of the scanning period. The spectrometer was designed for the study of solid propellant flames, but will also be useful for the study of fast, but not explosive, gas reactions.
© 1951 Optical Society of America
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