| 摘要 |
A system is described in which a laser beam is diffracted or deflected into at least 1,500 resolvable positions. The system includes an acoustooptic device comprising a block of acoustooptic material, such as lead molybdate, with an array of piezoelectric transducers bonded to one side or surface. In order to acheive operation over a wide bandwidth, it is necessary to steer the direction of propagation of the acoustic wave so that the Bragg diffraction condition is approximately satisfied. This can be accomplished by providing an array of steps which is cut into an edge surface of the acoustooptic block, each step being of a particular width and height which are related to the wavelength of the acoustic wave at the designed frequency of the device. A transducer is bonded to each step, the transducers being serially connected to an oscillator means which generates a series of electrical signals within a predetermined frequency range for causing sound waves to be radiated or propagated by each transducer. Since the transducers are serially connected, they are oppositely poled and radiate in phase. Hence the electrical field direction alternates.
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