Abstract: A scanning confocal optical imaging system is utilized to read or measure data magnetically recorded on a magneto-optic disk. The system includes a laser for producing a linearly polarized beam and a beam splitter for directing the transmitted beam to the disk and for deflecting a portion of the reflected return beam from the disk to a photodetector. A pinhole plate is placed between the beam splitter and the disk for restricting the size of the transmitted and reflected beams, and a polarizer is positioned between the beam splitter and the photodetector to receive the deflected return beam and provide an output that discriminates between the differing directions of rotation of the polarization plane of the transmitted beam by the magnetized area on the disk so that the direction of magnetization of the magnetized area can be read by the photodetector.

Abstract: A system for determining surface profiles of specimens such as semiconductor wafers includes a drive for mounting the wafer for oscillatory movement along a line and an optical imaging system overlying the wafer for focusing a beam on a small sport on the wafer and including a photodetector for detecting the reflected sport from the wafer. The spot is scanned along the line on the wafer while the focal depth of the imaging system is progressively changed while the photodetector and connected digital circuitry generate a plurality of spaced output signals for each scan along the line so that data comprised of a series of spaced signals are provided at a plurality of focus levels extending through the surface profile of the wafer. Computer means are provided for analyzing the data and providing a graphical output of the surface profile.

Abstract: A system for determining surface profiles of specimens such as semiconductor wafers and for making linewidth measurements thereon includes a drive for mounting the wafer for oscillatory movement along a line and an optical imaging system overlying the wafer for focusing a beam on a small spot on the wafer and including a photodetector for detecting the reflected spot from the wafer. The spot is scanned along the line on the wafer while the focal depth of the imaging system is progressively changed while the photodetector and connected digital circuitry generate a plurality of spaced output signals for each scan along the line so that data comprised of a series of spaced signals are provided at a plurality of focus levels extending through the surface profile of the wafer. Computer means are provided for analyzing the data and providing a graphical output of the surface profile from which accurate linewidth measurements are made.

Abstract: A semiconductor wafer scanning system includes a confocal optical imaging system with a laser beam being focused on a small spot on the wafer surface to be scanned. The optics include an objective lens located closest to the wafer with means being provided to vary the spacing of the lens from the wafer over small distances to thus change the focal plane of the system. The wafer may be independently driven in two orthogonal directions in a plane generally perpendicular to the imaging system to bring selected portions thereof into view of the optics. During scanning, the wafer is rapidly vibrated in one of the directions while it is slowly moved in the other direction with a series of digital output signals being provided by the light reflected back from the laser spot on the moving wafer to provide precise information for constructing a three dimensional representation of the surface pattern of the wafer.

Abstract: A confocal optical imaging system includes a laser for producing a linearly polarized beam which is transmitted through the optical elements of the system, focused on a small spot on the target, and reflected back through the optical elements to a photodetector where the reflectance from the spot is determined. The optical elements include a pinhole plate for restricting the size of the transmitted and reflected beams which plate, along with other of the optical elements, can produce unwanted reflections adding optical noise to the reflected beam from the target. A retardation plate between the pinhole plate and the target alters the polarization of the transmitted beam relative to the reflected beam so that a polarizer will discriminate between the true reflected beam signal and the unwanted reflections to thereby improve the signal-to-noise ratio at the photodetector.

Abstract: Two coaxial acoustic beams, one focused and the other unfocused, are used to measure changes in temperature within a localized region in a body. The focal region of the focused beam is located at the area to be measured. Changes in the relative phase angle between the two beams are indicative of changes in acoustic properties occurring at the focal region. Since the two beams have generally the same propagation path outside of the focal region, they will be similarly affected by acoustic variations which occur there, so there will not be any relative phase change between them due to such variations.

Abstract: An acoustic microscope comprising a transducer for transmitting acoustic signals towards the surface to be studied, and means for receiving at least one reflected signal from the surface; in many embodiments of the invention, signals are received from two separate points. The signals received are passed to a synchronous phase detection system for analysis. The signals may be received at the same phase detector input and separated according to their expected time of receipt relative to their time of transmission, or they may be received at separated points on the transducer related to their separated points of transmission. The separated return signals are compared on the basis of phase (and in certain embodiments, magnitude) differential either to each other or to an internally generated reference signal to analyze the surface characteristics of the material.

Abstract: A method of sensing changes in an object comprising irradiating the object with a focused beam of acoustic radiation excited by a first alternating electric signal; receiving a beam of acoustic radiation modulated in phase and amplitude by the object in the vicinity of the focus and deriving a second alternating electric signal therefrom; providing a reference electric signal derived from the first alternating electric signal and at a known phase; mixing coherently the second signal and the reference signal to derive a first in-phase signal; mixing the second signal with the reference signal altered in phase by between 80.degree. and 100.degree.

Abstract: A confocal optical imaging system includes a laser for producing a linearly polarized beam which is transmitted through the optical elements of the system, focused on a small spot on the target, and reflected back through the optical elements to a photodetector where the reflectance from the spot is determined. The optical elements include a pinhole plate for restricting the size of the transmitted and reflected beams which plate, along with other of the optical elements, can produce unwanted reflections adding optical noise to the reflected beam from the target. A retardation plate between the pinhole plate and the target alters the polarization of the transmitted beam relative to the reflected beam so that a polarizer will discriminate between the true reflected beam signal and the unwanted reflections to thereby improve the signal-to-noise ratio at the photodete ctor.