초록 ▼

The thickness of a semi transparent layer, such as ice, is determined by supporting the layer atop or above a light transmissive window and directing multiple light beams through the light transmissive window and into the layer. The light transmissive window has a higher index of refraction than the

The thickness of a semi transparent layer, such as ice, is determined by supporting the layer atop or above a light transmissive window and directing multiple light beams through the light transmissive window and into the layer. The light transmissive window has a higher index of refraction than the layer or any intermediate layer directly above the semi-transparent layer. Light beams are directed at an angle to the surface that results in total internal reflection from the outer surface of the supported semi-transparent layer. The light reflected to the rear of the window at the same but opposite angle is monitored and correlates to the thickness of the monitored layer. The spatial distribution of reflected light along the longitudinal axis of the window changes in dependence upon the thickness of the supported layer. Quantitative indications of that thickness are displayed and should that thickness exceed a prescribed level an alarm may be generated. The monitoring system has application as a non-intrusive ice detection system for aircraft airfoil surfaces.

대표청구항 ▼

[ What is claimed is:] [1.] Apparatus for monitoring the thickness of a semi-transparent material within a gaseous environment, comprising:a detector window, having front and back sides, and being of a first predetermined thickness;said front side of said detector window for supporting the semi-tran

[ What is claimed is:] [1.] Apparatus for monitoring the thickness of a semi-transparent material within a gaseous environment, comprising:a detector window, having front and back sides, and being of a first predetermined thickness;said front side of said detector window for supporting the semi-transparent material whose thickness is to be monitored;light beam directing means for directing a plurality of individual light beams at said detector window at a first predetermined angle to said back side of said detector window;said light beam directing means comprising a plurality of first optical fibers displaced in position relative to one another so as to be distributed longitudinally along the back side of said detector window;light beam detector array means spaced from said light beam directing means;said light beam detector array means comprising:a plurality of second optical fibers for receiving light propagating at a second predetermined angle to said back side of said detector window, said second predetermined angle being opposite in direction relative to said back side of said detector window as said first predetermined angle; andsaid second optical fibers being displaced in position from one another relative to said back side of said detector window so as to be distributed longitudinally along said detector window; andat least a plurality of longitudinally displaced light detectors optically coupled to respective ones of said plurality of second optical fibers whereby light propagating into a second optical fiber is coupled to a corresponding one of said light detectors;each said light detector producing an electrical output signal in dependence upon the intensity of incident light; andmeans for monitoring the spatial distribution of light represented by said light detectors to indicate the thickness of said semi-transparent material.