COHERENT AND INCOHERENT OPERATION IN OPTICAL VIBRATION MICROSCOPY

We present an experimental and theoretical analysis of vibration micro scopy using an arbitrarily defined detection aperture. For the two lim iting cases, incoherent operation (no aperture) offers intensity-gradi ent 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 harmon ic. The possibilities of phase microscopy, when the system is used in a coherent mode of operation, are discussed. (C) 1997 Optical Society of America.