Method for measuring light scattering by low-frequency modulation of a halogen lamp, and a scatterometer embodying said method

摘要

The diffusion of light due to particles of liquid in a gas or in air is measured by determining the coefficient of extinction of an emitted beam in an open volume (5) formed by the intersection of emitted and detecting beams. A halogen lamp (6) modulated at low frequency in the range 10-100 Hz is used with an optical system (7) as emitter and a photodiode (8) with reception optics (9) is used as detector. The emitter and receiver are orientated at an angle of 35 degrees and are 1.22 m apart. A microprocessor controls the modulation and synchronises measurements.