Integrated optical waveguide coupler

An integrated optical waveguide coupler for coupling energy in one direction to illuminate an optical stylus tip and for carrying reflected energy received by said tip in the opposite direction, the coupler comprising,

• a substrate including a first relatively low refractive index material portion having a face and a tip opposite said face and a second relatively high refractive index material portion formed on said face, said substrate having a planar top surface at an angle with respect to said face and defining a light corner within said second material portion at said surface, said second substrate further having a light receiving surface defined by a plane intersecting said face and said planar top surface at a predetermined angle with respect to said top surface,
• a layer of relatively low refractive index material formed on said planar top surface having a thickness ranging from 1/8 to 1/4 of the equivalent vacuum wavelength at the coupler operating wavelength,
• and an optical waveguide formed along the upper surface of said layer extending to said tip and overlapping and extending beyond said light corner,
• so that when light energy of a predetermined operating wavelength is incident said light receiving surface at a predetermined entrance angle with respect to said top surface it illuminates a portion of said planar top surface adjacent said corner and is coupled to said waveguide and travels to said tip to illuminate an associated surface and light energy reflected from said associated surface is coupled to said waveguide and travels along said waveguide to a point beyond said light corner.