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Measuring the Spectral Dependence of the Intensity of a Radiation

IP.com Disclosure Number: IPCOM000096780D
Original Publication Date: 1963-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Hora, H: AUTHOR

Abstract

The measuring device and its associated control system electrically determine the spectral intensity distribution of an unknown light source directly electrically rather than by using complicated and expensive optical analyzers. The measuring device which is exposed to an impinging light source comprises a vacuum tube 1 consisting of photocathode 2, plate 3 and a glass envelope. Photo cathode 2 is connected to plate 3 through free running multivibrator 4, the frequency of which is dependent upon the applied voltage. Free running multivibrator 5 converts the plate current flowing in the system into frequency values. Sawtooth generator 15 connects to cathode 2 and through multivibrator 5 to plate 3. Radiation 8, comprising an unknown frequency spectrum, impinges on cathode 2 and releases from 2 a number of electrons.

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Measuring the Spectral Dependence of the Intensity of a Radiation

The measuring device and its associated control system electrically determine the spectral intensity distribution of an unknown light source directly electrically rather than by using complicated and expensive optical analyzers. The measuring device which is exposed to an impinging light source comprises a vacuum tube 1 consisting of photocathode 2, plate 3 and a glass envelope. Photo cathode 2 is connected to plate 3 through free running multivibrator 4, the frequency of which is dependent upon the applied voltage. Free running multivibrator 5 converts the plate current flowing in the system into frequency values. Sawtooth generator 15 connects to cathode 2 and through multivibrator 5 to plate 3. Radiation 8, comprising an unknown frequency spectrum, impinges on cathode 2 and releases from 2 a number of electrons. This is determined by the total energy or wavelength of that radiation. These electrons have different exit speeds, as the individual frequency regions depending upon the cathode 2 have different energy levels, and thus impart such different exit speeds to the released electrons.

At the start of a saw tooth wave, the potential difference between plate 3 and cathode 2 is zero. All electrons reach the plate 3. Therefore, the maximum current is flowing. The farther the potential of plate 3 is shifted negatively with respect to that of cathode 2, the lower is the number of electrons the spee...