Abstract: An apparatus and method for direct measurement for head/disc interface dynamics in a head/disc assembly is described incorporating two light beams positioned to reflect off two surfaces, two position sensitive detectors for receiving reflected light beams, and a processor for determining the displacement of the surfaces. The processor may further include circuitry for determining the change of displacement as a function of time of the two surfaces and for correlating displacement signals and change of displacement signals with themselves or with other predetermined stored signals to provide an indication of the operating status of the head/disc assembly. The invention overcomes the problem of experiencing unexpected head crashes and of predicting timely preventive maintenance of the head/disc assembly.

Abstract: An atomic force microscope includes a tip mounted on a micromachined cantilever. As the tip scans a surface to be investigated, interatomic forces between the tip and the surface induce displacement of the tip. A laser beam is transmitted to and reflected from the cantilever for measuring the cantilever orientation. In a preferred embodiment the laser beam has an elliptical shape. The reflected laser beam is detected with a position-sensitive detector, preferably a bicell. The output of the bicell is provided to a computer for processing of the data for providing a topographical image of the surface with atomic resolution.

Abstract: Successive minute regions (13) along a scan path on a coal sample (11) are individually analyzed, at a series of different depths if desired, to determine chemical composition including the locations, sizes and distributions of different maceral inclusions (12). A sequence of infrared light pulses (17) of progressively changing wavelengths is directed into each minute region (13) and a probe light beam (22) is directed along the sample surface (21) adjacent the region (13). Infrared wavelengths at which strong absorption occurs in the region (13) are identified by detecting the resulting deflections (.phi.) of the probe beam (22) caused by thermally induced index of refraction changes in the air or other medium (19) adjacent the region (13). The detected peak absorption wavelengths are correlated with known characteristic peak absorption wavelengths of specific coal constituents to identify the composition of each such minute region (13) of the sample (11).

Abstract: Predetermined amounts of heat are generated within a coal sample (11) by directing pump light pulses (14) of predetermined energy content into a small surface region (16) of the sample (11). A beam (18) of probe light is directed along the sample surface (19) and deflection of the probe beam (18) from thermally induced changes of index of refraction in the fluid medium adjacent the heated region (16) are detected. Deflection amplitude and the phase lag of the deflection, relative to the initiating pump light pulse (14), are indicative of the calorific value and the porosity of the sample (11). The method provides rapid, accurate and non-destructive analysis of the heat producing capabilities of coal samples (11).

Abstract: A method and apparatus that significantly increases the sensitivity and flexibility of laser optoacoustic spectroscopy, with reduced size. With the method, it no longer is necessary to limit the use of laser optoacoustic spectroscopy to species whose absorption must match available laser radiation. Instead, "doping" with a relatively small amount of an optically absorbing gas yields optoacoustic signatures of nonabsorbing materials (gases, liquids, solids, and aerosols), thus significantly increasing the sensitivity and flexibility of optoacoustic spectroscopy. Several applications of this method are demonstated and/or suggested.