Abstract: A heater includes at least one heating element having a resistance that varies non-linearly with respect to a temperature of the heating element. The heating element includes a first surface, a second surface opposite the first surface, a third surface extending between the first and second surfaces, and a fourth surface extending between the first and second surfaces, opposite the third surface. The heating element has a height defined between the first and second surfaces, and a width defined between the third and fourth surfaces, and wherein the width is less than the height. The heater also includes at least one electrode coupled to the first surface and configured to generate an electric field across the heating element and cause a current to flow through the heating element.

Abstract: A dielectric bolometer thermal detector of infra-red radiation comprises a layer of dielectric bolometer material, a thermally insulating layer therebelow, a pair of electrodes located on one and the same side of said layer of dielectric bolometer material, a source of bias voltage for providing a bias voltage to said electrode so as to provide a bias field in said layer of bolometer material and a pair of read out contacts respectively connected to said electrodes. A signal which appears between said contacts in response to the application of radiation to said layer of dielectric bolometer material constitutes an output of the detector.

Abstract: In order to overcome problems in an active noise reduction system of sound buffets at low frequency and signal enhancement caused by imperfect transfer functions of a noise cancelling sound generator and a microphone, one or more high pass filters for reducing low frequency signals are provided in a feedback loop between the sound generator and microphone. A low pass filter is provided for extending the bandwidth of the system but which does not introduce unduly large phase shifts.