Abstract :
Present beam splitters allow a maximum beam separation of about 12º, and an electronically-controlled scanner for lasers is non-existent. Design variables are presented for a beam splitter (yielding up to 90º or more beam separation), and for an electronic scanner. Voltage control is obtained by changing input polarization components with a voltage-controlled KDP crystal. The beam splitter consists of two doubly-refracting crystals, either optically clamped or cemented, so as to form an oblique boundary at which one component is totally reflected, and the other, totally transmitted. The beam-separation angle determines the angle of incidence, which in turn specifies the maximum ratio (n1/n2) of indices of refraction for the totally-reflected component and the exact ratio of indices required for total transmission of the other. Experimental measurements of the relative transmission intensities for the two beams are presented for a first experimental model. The scanner makes use of one of the conical refraction phenomena found in biaxial crystals. Here, each direction of vibration has a unique and "continuous" direction of refraction; so a "continuous" scan then results from a "continuous" change in the input vibration direction. Shaping of the output surface, or of some external media properly directs each particular ray. The beam splitter may prove especially useful in sampling, feedback, logic, and intensity-control systems, and the scanner in high-speed sweeping systems, including optical radar and television.
