| 摘要 |
1,186,359. Measuring the energy of electromagnetic radiation. A.J. SCHMIDT. Dec. 14, 1967 [Dec. 19, 1966], No.56608/66. Heading G1A. In a method and apparatus for measuring the energy of electromagnetic radiation, a hollow body, the walls of which are sufficiently opaque to the radiation and sufficiently non-reflective to cause substantially complete absorption, and which is thermally insulated, has the radiation beam directed into its interior and the resulting change of eletrical resistance of the body is measured as an indication of the absorbed energy. The body is of the tangled wire or "rats nest" type using enamelled copper for low powers or oxide coated aluminium for higher powers, and may be spherical with a small hole for the admission of radiation, formed by two cones base to base, of spirally wound wire, or by a single cone of wound wire. Two layers may be sufficient. The radiation may be directed into the hole by a lens the focal plane of which is at the hole, and the body may be suspended by nylon cords or supported in thermal insulation such as foamed polystyrene in a chamber which may be evacuated. The instrument or chamber may include two such hollow bodies which may be connected in different arms of a Wheatstone bridge to compensate for ambient conditions. The apparatus may be used for measuring the energy content of a laser beam and may be calibrated by comparing the resistance charge with that, arising from the passage of a known current. Wire winding and sphere forming arrangements are described. |
