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Proceedings Paper

Theoretical model for the heat diffusion in an electrically calibrated laser power meter
Author(s): Dan G. Sporea; Nicolae Miron; Gabriel Dumitru; Bogdan Timus
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Paper Abstract

The theoretical model for the heat diffusion in the case of a high power IR electrically calibrated laser powermeter, developed at the Institute for Atomic Physics in Bucharest, is presented. The IR laser beam falls onto a laser detector, a special design copper disc wafer which absorbs the laser beam, heats its center. A daisy-chain of thermocouple elements having one set of junctions thermally connected to the central region of the disc and the other ones to the disc's boundary is used to detect temperature rise induced by the exposure to the laser beam. For calibration, the copper disc is electrically heated and the electric power that produces the same temperature rise as one induced by an incident laser beam, should equal the laser beam power. The electric heater is designed to provide a uniform heating of the copper disc. The solution for heat diffusion equation was searched as a series of Bessel functions of zero order, the cold junction's temperature was imposed as boundary condition and the heat induced by the laser beam in the disc's center was regarded as input data. To find the correct solutions, there must be taken into account the designing elements of the copper disc: termic material's properties (caloric capacity, termic conductibility), laser detector's geometry, copper's density. The electric power for calibration was injected using a precision power injection circuit which allows a stability of the calibration power, better than 0.1%.

Paper Details

Date Published: 26 September 1995
PDF: 9 pages
Proc. SPIE 2550, Photodetectors and Power Meters II, (26 September 1995); doi: 10.1117/12.221418
Show Author Affiliations
Dan G. Sporea, Institute for Atomic Physics (Romania)
Nicolae Miron, Institute for Atomic Physics (Romania)
Gabriel Dumitru, Institute for Atomic Physics (Romania)
Bogdan Timus, Institute for Atomic Physics (Romania)


Published in SPIE Proceedings Vol. 2550:
Photodetectors and Power Meters II
Kathleen Muray; Kenneth J. Kaufmann, Editor(s)

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