Patent ID: 6173609
Filing Date: 2001-01-16
Classification: G01F,G02B

Abstract:
A method for detecting a level of a liquid, the method comprising:providing a waveguide extending from a first end to a second end along an axis, the axis extending into said liquid, said waveguide having a surface for contacting said liquid such that light traveling in said waveguide at certain angles relative to said axis undergoes total internal reflection from said surface where said surface is not in contact with said liquid but undergoes significant transmission through said surface into said liquid where said surface is in contact with said liquid;injecting light into said waveguide so as to travel in a direction having a component along said axis, said light being injected at locations along a significant length of said waveguide;detecting an amount of light reaching one of said ends of said waveguide; andconverting a signal representing said amount of light, so detected, to a representation of said level of liquid.