17 February 1987 Low-Cost Reflective Optical Switches Applied To Non-Contact Liquid Level Set-Point Control
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Abstract
Commercial reflective optical switches, tilted strongly off-axis, can provide better than ±0.03 mm sensitivity in controlling the refill of a quiescent fluid container to some desired set-point level. The optics of this increased sensitivity is derived geometrically and a control sensor described and tested. Both set-point control sensitivity and sensor-surface working distance (inversely) are functions of tilt angle, so can be chosen or changed as required. Two such sensors, adjusted to give peak signals at two slightly different liquid levels (0.2 mm apart, e.g.), can then control not only a two-stage (fast/ slow) refill process but also provide high-sensitivity monitoring of any ripples or waves on the liquid surface after refill is complete.
© (1987) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John N. Pike, "Low-Cost Reflective Optical Switches Applied To Non-Contact Liquid Level Set-Point Control", Proc. SPIE 0814, Photomechanics and Speckle Metrology, (17 February 1987); doi: 10.1117/12.941702; https://doi.org/10.1117/12.941702
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