Showing papers on "Responsivity published in 1969"

The pyroelectric detector of infrared radiation

Abstract: The pyroelectric detector is a thermal sensor of infra-red radiation requiring no bias. While in principle a pure capacitor (hence theoretically noiseless), the detector has a varying noise contribution as a function of frequency due to a load resistor, series loss resistance, and amplifier. The actual sensor is a pyroelectric crystal exhibiting spontaneous polarization. The spontaneous polarization and dielectric constant of the crystal are temperature-dependent. A change in incident power raises the detector temperature causing an electric charge to appear across the electroded surfaces cut perpendicular to the crystal's ferroelectric axis. Under open circuit conditions, a voltage is obtained which is ultimately neutralized by current flow through the leakage resistance or load resistor. The evacuated detector package incorporates an electroded flake of triglycine sulfate mounted on a substrate of low thermal and electrical conductivity, a field effect transistor, load resistor, and an infrared transparent window. Data on the detectivity, responsivity, and noise as a function of frequency and area are presented. Polycrystalline pyroelectric detectors of TGS are feasible and simplify the construction of arrays and mosaics. Applications of the pyroelectric detector to date have been in a multielement line scanner, thermal imaging camera, spectrometer, and laser calorimeter.

A Rocket-Borne Liquid Helium-Cooled Infrared Telescope. II: Photoconductive Detectors.

Abstract: In the absence of a thermal radiation background, it is possible to obtain a very high responsivity with far ir extrinsic photoconductive detectors. Using a low noise liquid helium-cooled preamplifier, we have obtained an NEP of 10(-14) W Hz(-(1/2)) for Ge: Ga at 100 micro in an instrument designed for rocket ir astronomy. The limiting noise factor appears to be generation recombination noise due to thermal excitation of other impurities present in the germanium.

A fast room-temperature millimeter and submillimeter electric-tunnel effect detector

Abstract: It is well known that current can flow between two metal electrodes, separated by a thin oxide or insulator layer of the order of 50A thick, by means of the electric-tunnel effect. Estimates have been made that it requires 10-16sec for an electron to tunnel from one electrode to the other. Calculations by Simmons and others have shown that for low voltages dissimilar electrode junctions are to a first approximation ohmic. We show in this paper that to a second approximation an asymmetry square law dependence appears for an ideal trapezoidal barrier, Which can lead to detection. The I-V curves and responsivity (volts/watt) of the detector are calculated for typical parameters.

Optimization of bias in thermistor radiation detectors. I: bias conditions and performance figures.

Abstract: Equations defining the bias conditions for thermistor radiation detectors, and the dependence of responsivity, time constant, and noise equivalent power on these conditions are derived for two bias networks. By choosing bias temperature as the independent variable, a set of curves applicable to bias optimization of all thermistors of a given material type are constructed. Detector noise is discussed in detail.