Theory of Isoperibol Calorimetry for Laser Power and Energy Measurements

Abstract

Laser power and energy measurements are commonly made in calorimeters operating in a constant temperature environment. Calorimeters of this type are analyzed in terms of the first law of thermodynamics and the boundary value problem describing heat flow in the calorimeter. This theory of the measurement suggests design features of the calorimeter, sources of error to be avoided in design and operation, and tests to demonstrate experimentally the adequacy of the design. The analysis shows how time—temperature data can be used to allow for the temperature gradient on the calorimeter and the heat exchange due to transients in the temperature.

Nbs Laser Power And Energy Measurements

“…Volume absorbing transfer standards have also been calibrated and characterized for measuring pulsed laser radiation at a wavelength of 10.6 pm using a transversely excited, atmospheric pressure (TEA) CO2 laser source. 1 This NBS TEA laser is used in single mode configuration to measure pulse energy and detector responsivity as summarized in Table 4. …”

Effects of Air Flow On the Isoperibol Calorimetric Measurements

“…In all these applications, the air flow through the calorimeter during measurement has been fixed at an arbitrarily selected rate, in most cases, at a fairly high flow rate to insure quick calorimetric response and consistent burning of the material. The theory of isoperibol calorimeter [1,2] implies that varying air flow would affect the rate of calorimetric response, but not the total work (heat input) done on the calorimeter. However, this has not been substantiated experimentally.…”

“…in considerable detail and applied extensively in thermochemistry [1][2][3]. Its subsequent applications in the area of polymer and textile combustion has demonstrated that the technique is a unique and effective tool in the evaluation of material flammability [4,5] and efficiency of flame retardants [6][7][8][9], and on the study of the mechanism of flame retardant action [10][11][12].…”

Laser power measurement standards: A comparison of two scales

“…1 J/ crrr' for shorter pulses). The C-series calorimeters and the theory of isoperibol calorimetry have been described elsewhere [4], [6]. The Center for Devices and Radiological Health (CDRH) of the Food and Drug Administration (FDA) also maintains a C-series calorimeter.…”