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Proceedings Paper

A new type of optical microphone
Author(s): Yongchen Xu
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Paper Abstract

The invention of scanning near-field optical microsopy(SNOM)[1-2] has opened a new era of optical resolution beyond the diffraction limit of conventional optical instruments. The SNOM is using a near-field optical probe to confine the lateral space of the optical field within a subwavelength scale. The probe is made of glasses, quartz or metals, being formed into a tip[2]. The light from a big entrance travels to the small end of the tip, total internal reflection inside the wall of the tip, makes almost the whole entered energy pass through the small tip end. In this case at the small tip end the energy density increases greatly. This we call a focussing effect. Microphones[3] are commonly using a membrane that vibrates with audiowave frequency in the air next to it. The present design is based on a tip divided into two parts. One side of the tip is a membrane, the other side together with the entrance of the tip are fixed. The end area will vary with the vibration of the membrane. Therefore the signal of the light detector provides a measure of the vibration.

Paper Details

Date Published: 1 September 1996
PDF: 2 pages
Proc. SPIE 2778, 17th Congress of the International Commission for Optics: Optics for Science and New Technology, 2778G1 (1 September 1996); doi: 10.1117/12.2316266
Show Author Affiliations
Yongchen Xu, Ruhr Univ. Bochum (Germany)


Published in SPIE Proceedings Vol. 2778:
17th Congress of the International Commission for Optics: Optics for Science and New Technology
Joon-Sung Chang; Jai-Hyung Lee; ChangHee Nam, Editor(s)

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