APPARATUS AND PROCESSES FOR DETECTION, GENERATION AND FREQUENCY MEASUREMENTS OF ELECTRO-MAGNETIC RADIATION IN THE INFRARED AND VISIBLE DOMAIN

摘要

A metal to metal point contact diode with an extremely fast response comprising a metal base and an extremely thin metal wire, a cat whisker, with an end point about the order of a thousand angstroms (0.1 micron) or less in diameter at its junction with the diode's base. Detection of low power radiation is accomplished by detecting a voltage across the diode when incident radiation impinges on the cat whisker. Alternatively, the weak signal to be detected is coupled to the diode, together with a strong laser radiation at a frequency in the vicinity of the weak signal to be detected, thereby developing an alternating voltage signal at the difference frequency of the laser and the weak signal. This superheterodyne process is capable of detecting infrared signals below 10-15 watts. Frequency measuring is accomplished by hesterodyning an induced current in the whisker with the unknown frequency with a harmonic of a known lower frequency and a known microwave difference frequency to produce a strong beat note. The unknown frequency to be measured can be determined from the known lower frequency and the known microwave difference frequency. Generating radiation in the infrared and visible region is accomplished by subjecting the diode to an incident laser radiation. The cat whisker emits radiation at integral multiples of the laser frequency.