Abstract: An optical microscope for examining surface features of a target surface, at a resolution, in one dimension, in the picometer-to-nanometer range. The microscope includes a laser for use in producing a coherent output light beam, a lens for focusing the output beam onto a target, and a photodetector for measuring the power output of the beam. The focused beam is moved relative to the target surface in a defined position-dependent pattern, with a portion of the light reflected from the target surface being reflected back into the laser. Changes in the measured power of the laser are converted to position-dependent surface displacements, in the direction of the output beam.

Abstract: An optical data storage apparatus and disc in which information is stored in the form of multiple submicron depths at information-storage sites on the disc surface. The depth information is read by directing a focused laser beam onto the storage sites, back reflecting a portion of the reflected beam into the laser cavity, and converting power fluctuations in the laser beam to submicron distance measurements.

Abstract: Method and apparatus for measuring nanometer or picometer surface displacements in a target surface. A laser beam is directed against the target surface, and time-dependent variations in laser output power are measured. These variations, which are due to non-specular reflection of the incident beam by the target and reentry of the retroreflected light into the laser cavity, are used to determine time-dependent displacements at the target surface, based on a linear relationship between the measured power variations and surface displacements. The invention is useful for determining microscopic surface features of a surface, for high-density laser optical disc data storage and retrieval, and as an ultrasensitive transducer for sound or mechanical vibrations.