シリコン音響レンズの開発

概要

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In order to develop Scanning Acoustic Microscope(SAM) having high resolving power, the acoustic lens for a high acoustic frequency range which has very small spherical concave has been fabricated by micromachining. Silicon single crystal is used as the material for the acoustic lens. Suitable etching conditions to obtain excellent sphericity and minimal surface roughness demanded for a lens profile, have been investigated. The optimum etchant was mixture of hydrofluoric, nitric and acetic acids in the ratio of 2 : 3 : 3,at 50℃. The influence of the aperture diameter of the etching mask and etching time on the spherical lens profile was examined. The etched concave profile for 1 GHz range lens fabricated under the above conditions showed a maximum deviation from a perfect sphere of less than 0.2 μm. Silicon lens designed for frequency 1 GHz exhibited the theoretical resolution expected from the wave length.
公益社団法人精密工学会の論文
1993-01-05