SemaDyne - Strength in Sensing

Infrared Imagers

Bimorph Technology
Infrared imaging is essential for a variety of applications for the government, commercial and civilian sectors including, fire fighting, law enforcement, national defense, automated inspection, automobiles, aviation, hunting and camping. The market for high-end models is highly developed, so more and more companies are looking to the low-end market to take advantage of the high elasticity of the IR imaging market. Using SemaDyne’s patented thermal bimorph sensors, SemaDyne has the capability to produce imagers with low-end prices that can match the performance of the most sensitive high-end photon-based IR imagers. The cantilever-based sensors employ a bimorph approach as the sensing mechanism. The sensing structure is made of two materials, which are bonded together. When the sensor is infrared radiation, the two materials thermally expand by different amounts; it is this expansion mismatch that causes the cantilever to bend. We have developed polymeric coatings that are highly responsive and the thermal-based sensors based on these coatings have an NETD that approaches 1mK. This is orders of magnitude more sensitive compared to conventional metal-ceramic based bimorphs, which have NETDs around 60-100mK. The highly optimized sensitivity approaches the theoretical limits of bimorph-based thermal sensors.

Features

Thermal-based sensor
Very High sensitivity (<1mK NETD)
Economical Sensor Design
High reliability
Fast response (few msec, capable of tv-rate)
Large dynamic range (10°C-100°C)
Long term stability (years)
Low drift
Low hysteresis
Easy operation
Easy to replace the sensor chips
Low calibration and recalibration requirements
Miniature size

Golay Imager Technology
SemaDyne has also focused on developing extremely cheap IR imagers developed using SemaDyne’s patented Golay cell technology. The Golay sensor is composed of a membrane that is freely suspended over a cavity. When the encapsulated gas absorbs radiation the temperature of the gas increases. The increased gas temperature results in an increased pressure, which deflects the freely suspended membrane. SemaDyne has developed a fabrication technique capable of producing freely-suspended polymeric membranes with thicknesses from 20-50 nm. We have developed these sensors for infrared and far-infrared based imagers. We have demonstrated that with little optimization the polymeric Golay cells are in fact very sensitive, reaching better than 100mK NETD, which is comparable to other commercially available thermal based sensors. We have demonstrated two methods to transduce the membrane deflection, optically and piezo-resistively. The membrane deflection is transduced optically by bouncing a laser off the membrane into a position sensitive photo-diode. With the inclusion of oriented conductive nanoparticles these nanomembranes are piezo-resistive and have a very good gauge factor. These sensors also have very fast response times, well within TV-rate scanning speeds. These sensors are very promising for extremely cheap applications because the microfabrication is extremely simple.

Features

Thermal-based sensor
Good sensitivity (~50mK NETD)
Very Simple Economical Design
High reliability
Fast response (few msec, capable of tv-rate)
Large dynamic range (10°C-100°C)
Long term stability (years)
Low drift
Low hysteresis
Easy operation
Easy to replace the sensor chips
Low calibration and recalibration requirements
Miniature size