Patent ID: 6191856
Filing Date: 2001-02-20
Classification: G01N

Abstract:
An optical device for establishing a spatial orientation for a drill bit, the drill bit defining a longitudinal axis and having a primary facet with a normal inclined at an angle .alpha. to the axis and having a margin extending generally on a helical path around the axis, said device comprising:a first light source for generating a first light beam for silhouetting said drill bit;a second light source for generating a second light beam for reflection from said primary facet at an angle of reflection a for travel substantially along said axis, wherein .alpha.=cos.sup.-1 (1/(1+tan.sup.2 (.phi.)+tan.sup.2 (.psi.))), and where, in a cartesian coordinate system, .alpha. is an angle with the z axis (said longitudinal axis), .phi. is an angle of rotation about the x axis, and .psi. is an angle of rotation about the y axis;a third light source for generating a third light beam for reflection from said margin;a means for responding to said first light beam to establish an axial position for the drill bit on said axis;a means for responding to said second light beam to establish a gross rotational position for the drill bit on said axis; anda means for responding to said third light beam to establish a precise rotational position for the drill bit on said axis to establish said spatial orientation.