Telescope based calibration of a three dimensional optical scanner
AssigneeLeica Geosystems AG
InventorGregory Charles Walsh
Life of this patent
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Abstract
An embodiment of the invention includes using a set of telescopes to calibrate a three dimensional optical scanner. Three separate calibrations are disclosed for a survey grade calibration: (1) angular calibration, implemented using at least one anti-podal pair of telescopes, (2) range calibration, implemented using at least one telescope mounted fiber recirculator, and (3) tilt calibration, implemented using at least one pair of telescopes not mounted in anti-podal configuration and an integral tilt table. Methods for aligning or measuring the mis-alignment between anti-podal telescope pairs are also described.
Claims17
A method for calibrating a tilt sensor of a three dimensional optical scanning system comprising:
- locating the scanning system on a tilt table within an antipodal calibration rig, wherein the antipodal calibration rig includes two or more telescopes mounted on the antipodal calibration rig, wherein the two or more telescopes are used to measure the tilt of the three dimensional optical scanning system;
- performing an angular calibration on the three dimensional optical scanning system;
- solving for a tilt index of the three dimensional optical scanning system;
- performing a set of steps including:
- moving the tilt table to a next tilt position;
- obtaining an actual output of the tilt sensor;
- measuring the position of the two or more telescopes;
- and
- computing the expected output of the tilt sensor using the measured position of the two or more telescopes;
- repeating the set of steps for a total of three or more tilt positions of the three dimensional optical scanning system;
- and
- computing an estimated tilt sensor model using the measurements.
A method for determining a range scale of a three dimensional optical scanning system comprising:
- transmitting a beam from the three dimensional optical scanning system to a range calibration rig;
- splitting the beam at the range calibration rig, wherein:
- a first portion of the beam enters a recirculating fiber loop to be returned to the beam splitter;
- and
- a second portion of the beam enters a transmitting lens;
- transmitting the second portion of the beam from the transmitting lens to the scanning system;
- measuring the time between pulses at the scanning system;
- and
- calculating the range scale from the time between pulses.
Dependencies are inferred from the claim text.