Acoustic microscope

US5675075A · kind A · utility

Assignee

• Max-Planck-Gesellschaft zur Föderung der Wissenschaften e.V. · US

Inventors

• Walter Arnold · Saarburg, DE
• Ute Rabe · Saarburg, DE

Key dates

• Filing date: Nov 13, 1995
• Grant date: Oct 7, 1997
• Expiry date: Nov 13, 2015

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S977/87
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An acoustic microscope allowing both the topography and the elasticity of a sample to be measured at the same time. To this end the displacement of a cantilever with a tip is measured by the deflection of a laser beam. In order to measure the topography, the average deviation of the tip is held constant by a regulation circuit. The regulation circuit consists of a split-photodiode which supplies a neutral signal to the output of a normalizing amplifier which delivers a neutral value. Deviations from this neutral signal are compensated by a z-electrode of a piezocrystal. The elastic properties of the sample are measured by coupling ultrasound into the sample by means of a transducer and the high-frequency displacements of the cantilever with the tip are detected by a second detection device that consists of knife-edge detector and a fast photodiode. The detection device may also consist of a heterodyne time-of-flight interferometer or a capacitive detection scheme.