Patent ID: 7113270

Claim:
A method for determining at least one orientation parameter of an elongate object having a tip contacting a plane surface, the method comprising: a) illuminating the plane surface with a probe radiation beam emitted from the elongate object at an angle σ relative to an axis of the elongate object; b) varying the angle σ in accordance with a predetermined pattern so that the probe radiation beam illuminates various locations on the plane surface at various corresponding times; c) detecting at the elongate object at a first time t 1 a first scattered portion of the probe radiation beam returning from a first illuminated location along a path having a first predetermined angle τ 1 relative to the axis; d) detecting at the elongate object at a second time t 2 a second scattered portion of the probe radiation beam returning from a second illuminated location along a path having a second predetermined angle τ 2 relative to the axis; e) deriving the orientation parameter from a time difference Δt=t 2 −t 1 between detecting the first scattered portion and the second scattered portion.