Measuring level of liq. steel in ladles etc. - using laser beam directed at surface at angle to axis of imaging system

摘要

A method of determining the position of the free surface of the steel involves illuminating it and forming an image of the illumination on a photoelectric receiver. It is improved wrt. similar methods to enable its use with surfaces much larger than the beam cross-section and whose position varies in the direction of propagation of the beams. A laser beam is used and is inclined at an angle to the axis of the imageing system. The beam is directed at a surface region perpendicular to the optical axis at a point which is at the correct temp. to radiate in the same visible wavelength region as the laser. The reflected and radiated light from the surface passes to the receiver via a narrow band filter passing the laser wavelength.