OEM fibre optic temperature sensor shown at Sensors Expo 2017

12th June 2017
Anna Flockett

Sensors Expo, taking place 28-29th June, will see Micronor debuting there, after the announcement that it has collaborated with Optocon AG to create the FOTEMP1-OEM-MNT; a low cost, small form factor, single channel signal conditioner that seamlessly integrates fibre optic temperature sensing into any industrial control system, medical instrumentation or other OEM design.

The compact FOTEMP1-OEM-MNT controller works with all TS series fibre optic temperature sensors, a measurement range of -200 to 300°C, and standard built-in USB, RS232 and SPI interfaces.  The product will be demonstrated at the Micronor booth 735 at the McEnery Convention Center in San Jose, California.

On Wednesday, 28th June at 11:00am, Micronor will also be presenting a special live product presentation in the Sensors Expo Live Theatre titled; ‘Fibre Optic Temperature Sensors Outperform Thermocouples and RTDs in Challenging Environments.’

The FOTEMP methodology is based on the inherent temperature dependence of the Gallium Arsenide (GaAs) band gap. The signal conditioner couples a continuous broadband light source into the sensor’s large core 200µm optical fibre which illuminates a GaAs crystal mounted on the TS series sensor’s fibre tip. Similar to an optical filter, the crystal absorbs wavelengths below its bandgap and reflects the wavelengths above. The transition region between the reflected and transmitted spectrum, i.e. the band gap spectral position, is temperature dependent – shifting about 0.4nm/degree Kelvin. The FOTEMP controller’s internal optical spectrum analyser interrogates the reflected optical signal, and then outputs the corresponding temperature value.

This absolute measurement technique ensures stable and accurate measurements over long term usage without the need for periodic recalibration. This is one of many areas where GaAs temperature sensors outperform other optical sensor techniques, including fluorescence decay, interferometric and fibre Bragg gratings.

Monitoring the internal temperature of oil-filled transformers, with life expectancies of over 20 years, is one example of why GaAs-based temperature sensors are the sensor of choice for high reliability, mission critical applications. This sensing and interrogation method allows for lower cost, greater accuracy (±0.2°C), and wider measurement range (-200 to 300°C) compared to other fibre optic sensor techniques.

The product provides a discrete temperature monitoring solution that operates accurately and reliably in challenging environments where electronics-based temperature sensors (thermocouples, RTDs) cannot function. The fibre optic sensor’s entirely non-metallic, passive optical design provides immunity to electromagnetic interference (EMI), radio frequency interference (RFI), microwaves, high voltage, extreme magnetic fields, radiation, chemicals, and explosive atmospheres. In these environments, GaAs fibre optic temperature sensors enable new and unprecedented solutions impossible for electronic sensors.

Typical FOTEMP applications include monitoring temperature inside high voltage transformers and switchgear, MR imaging, semiconductor manufacturing, petrochemical plants, as well as microwave ovens and reactors used in food industry, material processing and bioengineering. The use of low loss optical fibre allows interference-free, remote temperature monitoring up to 2000m. Such distances are characteristic of mines, tank farms and downhole applications.

In small quantities, a complete fibre optic temperature measurement system sells for $1349, consisting of the standard FOTEMP1-OEM-MNT (calibrated -40 to 300°) at $999, and a general purpose TS2-02 GaAs fibre optic temperature sensor at $350.  

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