| 摘要 |
1,116,169. Digital light measurement. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. 2 Nov., 1966 [11 Nov., 1965; 16 Dec., 1965; 24 Dec., 1965; 18 Feb., 1966], No. 49213/66. Heading G4H. [Also in Divisions G1 and H1] In a Gunn effect oscillator or amplifier apparatus including a semi-conductor element adapted to exhibit negative resistance when an electric field in excess of a certain critical value is applied, light is employed to produce a photocurrent which is superimposed on the current already present in the element to control its operation. The light may be applied directly to the element or to a separate light sensitive device connected in circuit with the element. In a Gunn effect oscillator adapted to oscillate when biased by an electric field exceeding a critical value U k , the oscillations may be initiated or stopped by means of the photocurrent which causes the actual bias U applied to the element to rise above or fall below U k , the photo-current being a function of the light intensity E. Consequently, by employing a number of Gunn elements biased to different extents above U k , the intensity of the light may be determined by noting which of the elements cease to oscillate. The elements preferably have the same oscillating frequency and are parts of the same semi-conductor body, although different frequencies and materials may be used. The invention may also be used to demodulate light of modulated intensity providing the period of the modulation is greater than the period of the oscillations but not more than twice this period. If the photo-current is produced by a separate light-sensitive device, this may be a photo-diode, photo-transistor or photo-resistor. In Gunn effect amplifier apparatus, the invention provides means to modify the gain or the frequency at which maximum gain is exhibited. The light employed may be a laser beam. |
