Patent ID: 6628373
Filing Date: 2003-09-30
Classification: G01C

Abstract:
A transmitter for projecting a beam of laser light, comprising:a source of a beam of laser light, a projection arrangement for directing the beam of laser light at a selected grade, said projection arrangement including a level vial which provides an electrical signal indicating that said laser light is being projected at said selected grade, said level vial including a quantity of electrically conductive fluid; a temperature sensor for detecting the temperature of said vial, said temperature sensor including a current sensor circuit for sensing the resistivity of said quantity of electrically conductive fluid in said level vial, and a temperature correction circuit, including a look-up table, responsive to said temperature sensor, for adjusting said projection arrangement in dependence upon offset grade values that are stored in said look-up table for a plurality of transmitter temperature ranges, such that temperature induced errors in the direction of said beam of laser light are compensated.