Design and characterization of adaptive microbolometers

We report the first practical results on design and characterization of adaptive microbolometers with a thermally tuned responsivity. Such devices are needed to simultaneously image scenes that contain objects at ambient and extremely hot temperatures. In the high detectivity state, the microbolometers are operated similar to standard commercial devices. In the low detectivity state, portions of the support beams are brought in contact with the substrate, which thermally shorts the devices on a pixel-by-pixel basis. This is the first time this concept has been practically implemented in a microbolometer device architecture as opposed to simple cantilever beams and plates. The maximum actuation voltage is set to 17 V, and the thermal conductances, responsivities and detectivities of a typical device can be switched more than an order of magnitude between 1.65 × 10−5 W K−1 and 2.99 × 10−4 W K−1, between 1.5 V W−1 and 0.2 V W−1 and between 1.8 × 106 cm Hz1/2 W−1 and 1.5 × 105 cm Hz1/2 W−1, respectively. This extends the dynamic range of the device more than an order of magnitude. The device pixel size is 100 μm ×100 μm.