Bc. Johnson et al., HEAT-TRANSFER ANALYSIS AND MODELING OF A CRYOGENIC LASER RADIOMETER, Journal of thermophysics and heat transfer, 12(4), 1998, pp. 575-581
This study investigates the laser optimized cryogenic radiometer (LOCR
) recently acquired by the National Institute of Standards and Technol
ogy in Boulder, Colorado, to calibrate laser power meters and detector
s. The objectives are to evaluate potentially significant sources of u
ncertainty in the radiometric measurements and to develop transient mo
dels that efficiently and accurately predict the behavior of this radi
ometer. The analysis suggests that radiation from the Brewster window
assembly may cause the total power entering the radiometer to drift mo
re than 130 nW for a room temperature variation of 0.2 K, Steady-state
modeling of the LOCR with finite element analysis software indicates
a relative inequivalence between optical and electrical heating of 4 x
10(-6) at the 1-mW power level. A new thermal model has been develope
d to simplify transient predictions by combining lumped parameter and
one-dimensional elements. This model outperforms single-time-constant
exponential models and can be expanded to simulate the complete radiom
eter system.