Computerized Spectrum Analysis

Abstract

A system to automatically reduce and analyze the data on a spectrogram is in current use. The techniques used and the system are described. The system's principal components consist of a scanning densitometer with a built-on linear encoder, a 16-kc word rate analog-to-digital converter, and an IBM 1800 process computer with magnetic disk memory. The photomultiplier signal, which is proportional to the relative transmissivity of the spectrogram, is sampled at intervals of 2 or 4 μ. For a typical dispersion, this corresponds to approximately 0.025 Å. The sampled data are permanently stored on the disk memory. Typical processing time to scan one 12-cm spectrogram is 3 to 5 min. The stored data are further processed to locate all significant lines, to assign wavelengths to each line, and to determine relative intensities of the lines. The spectrum is plotted for visual interpretation and further analysis.