An optical homodyne technique for measurement of amplitude and phase of subangstrom ultrasonic vibrations

Abstract

An optical homodyne technique is utilized to measure sub-angstrom dynamic mechanical deformations. For measurement in the frequency domain, where synchronous detection is used both the amplitude and phase of the mechanical signal can be measured with a high sensitivity; displacements less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> Å were measured with normal environment acoustic noise. Measurement in the time domain is also feasible with reduced sensitivity.