Patent ID: 8339584
Filing Date: 2012-12-25
Classification: G01P,G01S

Abstract:
1. An apparatus for noncontact open channel fluid flow measurement comprising: a laser; and an optical system, the optical system and laser being positioned and constructed to focus light from the laser to at least one predetermined effective focal point within the flowing stream and to return back scattered light from scatterers at the effective focal point within the flowing stream to a system for obtaining a Doppler beat signal from light generated by the laser and the back scattered light; and at least one system for protecting the optical system from an environment, said at least one system for protecting the optical system from the environment includes at least one of a long tube having an inner surface that is coated with a hydrophilic material that draws moisture away from optics in the apparatus; a system that provides a short air blast from a compressed air source that clears any residual condensation from the optics; a flat optical quality window oriented at Brewster's angle; a shutter positioned at the end of the coated tube that is only opened for brief periods when data is collected to limit exposure of the optics to the outside environment; an optical coating applied to the optics to inhibit moisture condensation; and a mechanical vibrator attached physically to the window to shake off debris and condensation droplets.