Un-Cooled Ultra-High Sensitivity Imaging

In the annals of infrared detection and imaging, heightened sensitivity and noise reduction is usually accompanied by cooling and/or purifying the sensing elements. Both the photonic (such as HgCdTe and superlattices) and microbolometer (such as semiconductors) detectors need the required cooling and material purity which incurs high cost and structural complexity, both are undesirable for portable military systems and even more so for commercial systems.

However, our Micro Fabry-Perot Interferometry (MFPI) based detectors are capable of extraordinarily high sensitivity either in the uncooled or cooled state, as illustrated in the graph below on detectivity vs. temperature. This graph shows that the sensitivity of our MFPI detector is superior to all other detectors, except at extremely low temperatures. This is due primarily to the exploitation of interferometry as the sensing mechanism which, unlike conventional detectors, is independent of material purity.

Detectivity of our MFPI detector compared to other common detector types

Detectivity of our MFPI detector compared to other common detector types (click to enlarge)

 

For un-cooled sensors or FPAs, such as bolometers and our MFPI sensor, employed for thermal imaging, the conventional Figure of Merit describing the sensor's ability to image the minute temperature changes in a thermal scene or target is the so-called Noise Equivalent Delta Temperature (or NEDT). This NEDT is usually plotted against the thermal conductance of the support that isolates the sensors thermally from its surroundings as shown in the figure below. The graph highlights the high NEDT performance of our MFPI sensor compared to the conventional bolometer sensors.

uncooled2

Comparison of NEDT performance. (click to enlarge)

 

 

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