초록 ▼

A thermal detector comprises a row of thermal detector elements each connected to a common bus line via the gate of a high impedance input preamplifier and a switch. The line output from the bus line is taken across a load resistance providing a common source follower load for the prepamplifiers. Th

A thermal detector comprises a row of thermal detector elements each connected to a common bus line via the gate of a high impedance input preamplifier and a switch. The line output from the bus line is taken across a load resistance providing a common source follower load for the prepamplifiers. The signal across the load is passed through an anti-aliasing low-pass filter to a sample-and-hold. Signals then pass to a high-pass digital filter arranged to substract successive signals from each detector element corresponding to open and closed positions of a radiation modulator. This attenuates 1/f noise. The filters are located outside the row. Bulky filter components may accordingly be employed giving good noise performance without affecting detector element spacing. The preamplifiers and the switches are preferably MOSFETs. The detector may incorporate many rows of detector elements to provide a two-dimensional array.

대표청구항 ▼

A thermal detector including: (1) a row of thermal detector elements disposed to receive radiation from a scene, (2) a row output line arranged to relay detector element signals to a common row output, (3) a respective power amplifier associated with each detector element, each power amplifier being

A thermal detector including: (1) a row of thermal detector elements disposed to receive radiation from a scene, (2) a row output line arranged to relay detector element signals to a common row output, (3) a respective power amplifier associated with each detector element, each power amplifier being arranged to amplify detector element signals for output to the row output line and to decouple detector element capacitance from that of the row output line, (4) modulating means arranged to modulate radiation from the scene such that each detector element experiences alternate light and dark time intervals and becomes illuminated in sequence along the row, (5) addressing means synchronised with the modulating means and arranged to address the power amplifiers sequentially and sample their signals to the common row output to provide alternate light and dark sets of signals, and (6) a band pass filter arranged to receive light and dark sets of signals from the common row output, the filter having transmission characteristics to pass detector element output signals and including both an anti-aliasing low pass filter and a high pass filter arranged to extract respective difference signals from each detector element\s light and dark output signals.