| 摘要 |
PURPOSE:To increase diffraction efficiency and to improve analytic accuracy by arranging an acoustic lens made of a metallic thin film on the surface acoustic wave propagation path between interdigital electrodes and a light surface wave propagation path. CONSTITUTION:This Bragg cell has the acoustic lens 10 made of the metallic thin film on the propagation path for a surface acoustic wave 5 between the interdigital electrodes 4 and propagation path for a light surface wave 8. Consequently, the surface acoustic wave 5 consisting of a divergent beam is reconverted into a parallel beam to reduce the component of the surface acoustic wave 5 which is propagated in a direction where angle relation required to diffract the light surface wave 8 is not obtained. Consequently, the diffraction efficiency increases and a high-accuracy frequency analysis is made.
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