Electrically based spectral power measurements through use of a tunable cw laser

A new approach to radiant power measurements is described. A continuously tunable cw dye laser was used to measure the absolute spectral response of a silicon photodiode and narrow band−pass filter by comparison with an electrically calibrated pyroelectric detector. The filtered photodetector was then used to measure the spectral power density from a standard lamp that had been calibrated by the classical technique. The agreement of better than 1% between the two measurements is well within the uncertainties identified with each measurement individually, of the order of 1%. A number of advantages in the new technique are identified.