Gap measurement by position-sensitive detectors

Abstract

A system for measuring the gap in a proximity exposure tool of a plasma display panel (PDP) is developed that uses single or dual position-sensitive detectors (PSD's). The resolution of the gap distance is 0.5 mum, with a capture range of 500 mum. Signal processing is simple and fast and easy because analogous PSD's are used as the position sensors. One PSD is used to detect the position of the reference beam, which is reflected from the upper surface of the gap; the other PSD is used to detect the position of the signal beam, which is reflected from the lower surface of the gap. A charge-coupled-device sensor is also employed to monitor the reflected beams and the region of measurement. In the gap-measurement system that uses a single PSD, first the reference beam is incident upon the PSD and then the signal beam is incident upon the same PSD. Then the separation between the two beams is calculated from the position of the reference beam and from the average beam position.

<title>Silicon quadrant detector in CMOS technology</title>

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Vibration Measurement Method of a String in Transversal Motion by Using a PSD

“…There have been extensive studies on PSDs because of their numerous applications in the field of engineering. Devices used for human eye movement monitoring, machine tool alignment, vibration analysis and path tracking all utilize PSDs [ 20 , 21 , 22 , 23 , 24 , 25 ]. Unlike discrete element detectors such as charge-coupled device (CCD), a PSD can provide continuous position data and features a high position-resolution.…”

Design and Characterization of a Birefringent-Type Compact Displacement Sensor for Improving Measurement Sensitivity by a Guided-Wave Beam

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