Product category:
Probes and sensors
News Release from: BEI Technologies | Subject: Linear Gap Displacement Transducer
Edited by the Manufacturingtalk Editorial
Team on 19 May 2003
Measurements made accurately over short
distances
Linear gap displacement transducer makes non-contact, highly accurate, short distance measurements over a small range, very precisely, using fibre-optic technology.
The new LGDT (Linear Gap Displacement Transducer) from BEI Precision Systems is a unique concept in non-contact, highly accurate, short distance measurement Using fibre-optic technology, it measures target surface distance over a small range, very precisely
This article was originally published on Manufacturingtalk on 30 Jul 2001 at 8.00am (UK)
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A 360 degree, sealed, non-contacting rotary sensor from is only 8mm thick and is ideal for heavy equipment, oil field, medical instrumentation, factory automation and aerospace applications.
The measurement probe is only 9mm in diameter and consists of three concentric fibre-optic bundles, feeding into an electronics module, which processes the data providing an analogue output.
The probe length is typically 600mm long, but as an option can be up to 9 metres long for applications where remote operation is required.
A long-life, infrared LED illuminates the target surface via the central bundle and the two outer fibre bundle rings detect reflected light.
As the distance to the target increases, so the outer ring receives more reflected light, whilst the inner receives less.
Detectors in the electronics module measure the resulting light levels and an analogue divider calculates the ratio of the detected signals.
An offset voltage, proportional to the mid point distance is subtracted to give the final output.
Since the LGDT works on ratiometric principles, the reflectivity of the target surface is not important.
The electronics module is less than 250cu cm and requires a +/-12 volts DC supply at 2.4 watts.
Connection is via a standard D type 9-way connector.
Different versions of the LGDT are available for stand-off distances of between 4 to 12mm, with 1% linearity over a 2 to 4mm range.
They provide sensitivities of between 2 to 6V/mm with resolutions of 0.1 to 0.5 micron.
This non-contacting technology opens up many possibilities for accurate measurement of material thickness, real time concentricity, mechanical flexure under load conditions, bearing run-out and as a feedback sensor for dynamic control applications.
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