A black body cavity radiometer is provided by a radiation receiving isothermal body having a short hollow cylinder with a hollow cone at one end. The cylinder is spun down at the other end to a smaller hollow cylinder of short length to form a radiation cavity having an aperture. A thermal guard surrounds the cavity, except over the aperture. The annular wall of the guard around the short cylindrical extension of the cavity is provided with an internally blackened groove which functions as an annular radiation trap for radiation from the internal surface of the guard and the external surface of the cavity. Glass rods or fibers maintain a thin annular space between the guard and the cylindrical extension of the cavity. A guard temperature sensing coil is provided on a hollow cylinder disposed in space between the guard and the cavity. The hollow cylinder is thermally connected to the guard by a flange. A heating and temperature sensing coil is wound directly on the main cylindrical portion of the cavity. A voltage is applied across the latter coil in sufficient amplitude to maintain the temperature of the latter coil equal to the temperature of the guard sensing coil. The magnitude of that voltage is a measure of radiation into the cavity through the aperture thereof.
3838282 - SENSORS - Owned by National Research Development Corporation (London,EN)
The invention concerns a sensor for measuring ultra-violet radiation over long periods. Interference filters remove unwanted radiation and a phosphor selected from zinc cadmium sulphide activated by copper and having a hexagonal crystal structure or strontium chlorosilicate activated by divalent europium with the phosphor matrix having an orthorhombic crystal structure, which converts the transmitted ultra-violet into radiation acceptable to a selenium photovoltaic cell.
A method and apparatus for measuring thermal properties of electronic components (25) encapsulated in packaging is described. The method can be used to measure a junction temperature T.sub.j of the electronic component (25), without removing the package (30), and during operation of the electronic component (25) by a power supply. The method comprises the steps of (a) positioning the electronic component (25) in a field of view of an infrared sensor (90), during operation of the electronic component (25) by the power supply; (b) focusing the infrared sensor (90) on the electronic component (25) inside the package (30) to obtain (i) a sharp outline of the component, and (ii) a maximum temperature reading; (c) removing the electronic component (25) from the field of view of the infrared sensor (90); (d) positioning a blackbody source (65) capable of emitting infrared radiation at different wavelengths at substantially the same focal point as the electronic component (25); (e) calibrating the infrared sensor (90) using the blackbody source (65); (f) replacing the blackbody source (65) by the electronic component (25) while continuing to operate the electronic component (25) by the power supply; (g) adjusting the focus of the calibrated infrared sensor (90) by an amount F.sub.c sufficient to compensate for a thermal expansion movement of the electronic component (25) and package (30) caused by a rise in temperature of the electronic component (25) resulting from operation of the component by the power supply; and (h) measuring the junction temperature T.sub.j of the electronic component (25) to an accuracy of greater than 5% without removing the package (30) of the electronic component (25).
