Apparatus and method for determining an inclination of an elongate object contacting a plane surface

Abstract

An apparatus and method for determining an inclination angle θ between an axis of an elongate object such as a cane, a pointer or a jotting implement such as a pen, pencil, stylus or the like and a normal to a plane surface at times when a tip of the elongate object is contacting that plane surface. The apparatus has an emitter mounted on the object for illuminating the plane surface with a probe radiation at an angle σ with respect to the axis of the object. The apparatus also has a detector mounted on the elongate object for detecting a radiation characteristic of a scattered portion of the probe radiation returning from the plane surface and a computing unit for deriving the inclination angle θ from the radiation characteristic. A scanning arrangement, such as a uniaxial or biaxial scanner, or a light guiding optic can be used for varying angle σ, and the probe radiation can be emitted in the form of a scan beam. Preferably, the emitter and detector of the scattered portion of the probe radiation are integrated and the scattered portion of the probe radiation whose characteristic is being measured is the back-scattered portion. The radiation characteristic detected by the detector can be the intensity, polarization, time-of-flight or any combination thereof.