Coherent and incoherent operation in optical vibration microscopy

Abstract

We present an experimental and theoretical analysis of vibration microscopy using an arbitrarily defined detection aperture. For the two limiting cases, incoherent operation (no aperture) offers intensity-gradient information in the amplitude of higher harmonics of the vibration frequency, whereas coherent operation (pinhole aperture) reflects the phase of the object being scanned in the amplitude of the first harmonic. The possibilities of phase microscopy, when the system is used in a coherent mode of operation, are discussed.