Abstract

For accurate DIAL measurements, the detector output should have a linear response to the input light signal. In addition to good linearity, the detector should also have good gain stability and negligible signal-induced noise.

The requirement for gain stability is less stringent compared to the other requirements as long as the gain stability pattern is preserved between the pair of on-line and off-line pulses. The linearity of the detector response is critical in the sense that the nonlinear behavior of the PMT responsivity is normally dependent upon the signal amplitude itself. Therefore, for off line and on-line signals which are not identical, the effect of the non-linearity is not cancelled in the DIAL signal processing. The same argument applies for the signal-induced noise term. The cause and characteristics of the signal-induced noise which appears as a bias is not well understood.

© 1987 Optical Society of America