LASER COMPONENTS has been working with Dexter Research Centre, a world leading manufacturer of thermopile detectors. We are pleased to announce the launch of a new MEMS based thermopile that can withstand operating temperatures of 300ºC. Thermopile detectors are passive radiation sensing devices that require no bias or cooling and generate an output in the range of micro to millivolts.
The ST60 has an active area of 0.61 x 0.61 mm2 and can be fitted with a low cost polysilicon resistor which is used as a positive temperature coefficient thermistor. To operate at these elevated temperatures requires careful choice of the materials used to construct the detector - one example of this is the diamond like carbon coated silicon window.
The voltage produced is proportional to the temperature gradient between junctions and, unlike pyroelectric detectors, thermopiles are very low noise devices generating no 1/f or microphonic noise. Also, thermopile detectors provide a stable output for DC radiation up to a frequency limited by the time constant of the detector.
When the detector is looking at a very hot target and installed on a cold heat sink a large temperature gradient can develop along the length of the sensor, this temperature gradient can generate a ghost signal confusing the detector. A thermopile detector can have a second, compensating, sensing element added inside the package to monitor these gradients and generate a signal that can be internally connected in opposition to the active channel, subtracting the signal generated by the gradient across the package providing an accurate temperature reading.
Applications include non-contact temperature measurements such as tympanic thermometers, automobile climate control and occupancy sensing, process temperature monitoring, household appliances, and radiometers; gas analysis in medical, automotive, and petroleum industries; hazard control including flame and explosion detection; horizon sensors for scientific and space, and applications.