Rotating Mirror Calibration via Laser Tracker Automation
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Solution Overview
Problem
Calibrating rotating mirror systems for laser applications is challenging due to the need for high accuracy, which is difficult to achieve with existing theodolite-based methods that are complex, time-consuming, and require significant technician time and skill.
Innovation Solution
A method involving precise measurement of mirror normals and vectors using a laser tracker, followed by calculation of axes of rotation and creation of coordinate systems using least squares fits, allowing for automation and significant reduction in calibration and processing time while achieving high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If theodolite-based calibration methods are used, then measurement precision can be achieved, but device complexity and time consumption increase significantly
Solution Approach 1:
The patent replaces traditional theodolite-based mechanical measurement systems with a laser tracker and automated mirror rotation system. The laser tracker uses optical time-of-flight measurement instead of mechanical theodolite observation, and the mirror rotation is controlled by automated motors with encoders rather than manual adjustment, thereby reducing device complexity while maintaining precision.
Solution Approach 2:
The calibration system uses the mirror system itself to reflect laser beams back to the laser tracker, creating a self-measuring configuration. The mirrors under calibration actively participate in the measurement process by reflecting the laser beam, eliminating the need for separate measurement apparatus and reducing overall system complexity.
2Measurement precision
If theodolite-based calibration methods are used, then measurement precision can be achieved, but calibration time increases from hours to days
Solution Approach 1:
The patent implements continuous automated measurement by rotating the mirrors through multiple positions and having the laser tracker continuously measure the reflected beam positions. The system automatically collects data at each mirror position without interruption, eliminating the manual setup and measurement time associated with theodolite methods, thereby reducing calibration time from days to hours while maintaining precision.
3Measurement precision
If theodolite-based calibration methods are used, then measurement precision can be achieved, but operator skill requirements and operational complexity increase
Solution Approach 1:
The patent replaces manual theodolite operation with automated motor-driven mirror rotation and encoder-based position tracking. The computer-controlled system automatically calculates calibration parameters from the collected data, eliminating the need for highly skilled operators to perform complex manual measurements and calculations, thereby improving ease of operation while maintaining measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables highly accurate pointing of laser systems with less than one arcsecond accuracy, reducing calibration time from days to hours and simplifying the process through automation, while providing greater precision and reduced complexity.
Implementation Method 1
measuring, with a laser tracker, a normal of a first fiducial of the mirror system
Implementation Method 2
measuring, with the laser tracker, vectors to a second fiducial of the mirror system at several angles of rotation
Data Source
AI summary
Methodology for calibrating a rotating mirror system includes: measuring a normal of a first fiducial of the mirror system; measuring vectors to a second fiducial of the mirror system, each vector being measured at a different angle of rotation about an azimuth axis of rotation of the mirror system; calculating the azimuth axis of rotation using the measured vectors; creating a base coordinate system from the measured first fiducial normal and the calculated azimuth axis of rotation; and for each of a first mirror and a second mirror of the mirror system, measuring normals of the mirror at multiple angles of rotation, calculating an axis of rotation of the mirror using the measured normals, creating a mirror coordinate system from the measured normals and the calculated axis of rotation of the mirror, and calculating a translation and rotation matrix from the mirror coordinate system to the base coordinate system.