Patent ID: 6384913
Filing Date: 2002-05-07
Classification: G01C

Abstract:
A laser transmitter comprising:a housing; a laser light source coupled to said housing and operative to generate a beam of laser light; an optical projecting device positioned to direct said beam of laser light to define a reference beam of light projected out of said housing; a compensator assembly arranged to provide an optical correction for misalignment of said housing relative to a vertical axis; a compensator assembly suspension arranged to couple said compensator assembly to said housing, wherein said suspension defines three degrees of freedom in which said compensator assembly is free to move, and wherein said three degrees of freedom include movement along an X-axis orthogonal to said vertical axis, movement along a Y-axis orthogonal to said X-axis and said vertical axis, and rotation through an angle &thgr; in a plane parallel to said X and Y axes; a compensator assembly position detector arranged to detect a position X1 of said compensator assembly with respect to said X-axis, and a position Y1 of said compensator assembly with respect to said Y-axis; a compensator assembly damping mechanism including an X-axis magnetic damping mechanism, a Y-axis magnetic damping mechanism, and a rotational damping mechanism, wherein said rotational damping mechanism is arranged to magnetically damp movement of said compensator assembly through said angle &thgr;; and an active feedback circuit, wherein said active feedback circuit is arranged to drive said X-axis magnetic damping mechanism so as to increase a damping force generated by said X-axis magnetic damping mechanism as a rate of change of said signal indicative of the position x1 increases, and drive said Y-axis magnetic damping mechanism so as to increase a damping force generated by said Y-axis magnetic damping mechanism as a rate of change of said signal indicative of the position Y1 increases.