Abstract: An annular position detection method provides a plurality of light emitters on a first imaginary circle centered on an axis, the emitters directing individual, well-defined, overlapping light beams to a pair of light detectors positioned on a second imaginary circle centered on that axis. The detectors include pairs of diametrically opposite photosensors producing outputs depending upon the areas thereof exposed to light from the emitters. A light blocker is rotatably mounted on the axis so that the blocker blocks light to different extents of the photosensors depending upon its orientation about the axis. The outputs from all of the photosensors are processed to produce a position signal that varies with the angular position of the blocker and the relative intensities of the emitters are adjusted so that the position signal is substantially linear at all operative angles of the blocker. Apparatus for practicing the method is also disclosed.

Abstract: An annular position detection method provides a plurality of light emitters on a first imaginary circle centered on an axis, the emitters directing individual, well-defined, overlapping light beams to a pair of light detectors positioned on a second imaginary circle centered on that axis. The detectors include pairs of diametrically opposite photosensors producing outputs depending upon the areas thereof exposed to light from the emitters. A light blocker is rotatably mounted on the axis so that the blocker blocks light to different extents of the photosensors depending upon its orientation about the axis. The outputs from all of the photosensors are processed to produce a position signal that varies with the angular position of the blocker and the relative intensities of the emitters are adjusted so that the position signal is substantially linear at all operative angles of the blocker. Apparatus for practicing the method is also disclosed.

Abstract: A method and apparatus for a slide loading/unloading system is described. A slide storage cassette is provided to store slides in which the slides are stored with an end protruding from the slide storage cassette. A slide feeder is described having grippers, which grip the end of a slide and transport the slide to a sample holder. The sample holder receives and retains the transported slide.

Abstract: A microarray storage device includes a cassette having top, bottom and opposite side walls, the front and rear of the cassette being open. The side walls are formed with a multiplicity of parallel rails spaced along the heights of the walls which define compartments in the cassette for supporting a multiplicity of microarrays one above the other. The depth of the cassette is such that the microarrays supported in the compartments project appreciably from the front and/or rear of the cassette. Integral springs are formed in the side walls of the cassette which press down directly on the side edge margins of the microarrays so as to releasably retain the microarrays in their respective compartments.