Micronor and Optocon AG have collaborated to create the FOTEMP1-OEM-MNT—a small form factor, single channel signal conditioner PCB (printed circuit board) interface module that seamlessly integrates fiber optic temperature sensing into any industrial control system, medical instrumentation, or other OEM design. It is designed for low cost insertion of high precision GaAs-based fiber optic temperature sensor technology into OEM applications where common electrical temperature sensors and thermocouples cannot be used.
The FOTEMP1-OEM-MNT controller works with all TS series fiber optic temperature sensors and standard built-in USB, RS232, and SPI interfaces.
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 fiber which illuminates a GaAs crystal mounted on the TS series sensor’s fiber 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 analyzer 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 fiber Bragg gratings. Monitoring the internal temperature of oil-filled transformers, with life expectancies of 20+ years, is one example of why GaAs-based temperature sensors are suitable for high reliability, mission critical applications. This sensing and interrogation method allows for lower cost, greater accuracy (±0.2ºC), and wider measurement range (-328°F to 572°F) compared to other fiber optic sensor techniques.
The FOTEMP1-OEM-MNT provides a discrete temperature monitoring solution that operates in challenging environments where electronics-based temperature sensors (e.g., thermocouples, RTDs) cannot function. The fiber 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, the GaAs fiber optic signal conditioner enables 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 fiber allows interference-free, remote temperature monitoring up to approximately 6,560′. Such distances are characteristic of mines, tank farms, and downhole applications.
The FOTEMP1-OEM-MNT controller measures 3.93 x 3.15 x 1.18 and weighs 4.94 ounces with an operating temperature of 32°F to 122°F.