Study of precipitant systems by computerised simulation. Influence of optical elements on the noise associated with the transmittance

The transmittance signal of a precipitant system measured with a focused la ser beam carries associated noise coming from several sources. In this work , we have studied the influence of the focal parameters (wavelength, focal length and prefocused radius of the beam) on the maximum noise reached in e quivalent nucleation processes. For this purpose, a-simulation program of p recipitating systems, designed in FORTRAN 90, has been developed. The progr am generates simulated transmittances, which are processed by another compu ter program to extract associated noise. Wide ranges of values of the focal parameters have been analysed, finding relationships between the maximum n oise and the focal parameters. They have been justified in connection with the changes observed in the radial parameters, which define the size and sh ape of the focused path. (C) 2001 Elsevier Science Ltd. All rights reserved .