Laser Heterodyne Interferometer Six DOF Error Compensation
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Solution Overview
Problem
Current laser heterodyne interferometric straightness measurement apparatuses are unable to simultaneously determine six degrees of freedom (DOFs) error parameters of a measured object, as they fail to eliminate the influence of rotational errors on measurement results, leading to decreased accuracy in straightness and position determination.
Innovation Solution
A laser heterodyne interferometric straightness measurement apparatus and method that utilizes a dual-frequency laser, nonpolarizing and polarizing beam-splitters, a Wollaston prism, reflecting prism, and photodetectors to detect and compensate for rotational errors, enabling simultaneous determination of six DOFs motion parameters and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional laser heterodyne interferometer is used for straightness measurement, then the measurement setup is simple and operates at one DOF, but it cannot eliminate the influence of rotational errors and cannot simultaneously determine six DOFs error parameters
Solution Approach 1:
The optical path is segmented into multiple independent measurement channels, each equipped with its own beam-splitter, Wollaston prism, and photodetector assembly. This segmentation allows simultaneous measurement of different DOFs while maintaining the simplicity and accuracy characteristics of traditional heterodyne interferometry for each individual channel.
Solution Approach 2:
The measurement system is designed with multi-functional capability to simultaneously determine all six DOFs error parameters (three linear displacements and three rotational angles) of the measured object. Each optical channel is configured to measure specific combinations of DOFs, and the integrated system provides comprehensive six-DOF measurement functionality.
2Measurement precision
If rotational errors are not compensated in straightness measurement, then the measurement system remains simple, but the measurement accuracy decreases due to the influence of rotational errors on straightness results
Solution Approach 1:
The system employs feedback mechanisms where the measured rotational error parameters are processed and used to compensate the straightness measurement results. The computer calculates the straightness errors by integrating the differential equations that relate the six DOFs parameters, effectively using the measured rotational information to correct and improve the straightness measurement accuracy.
Solution Approach 2:
The measurement approach transitions from traditional one-DOF straightness measurement to six-DOF comprehensive measurement, adding dimensional complexity to capture rotational errors. By measuring in multiple dimensions (all six DOFs simultaneously), the system gains the ability to separate and compensate rotational effects from linear displacement measurements.
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 allows for the simultaneous measurement of six DOFs error parameters, effectively eliminating the impact of rotational errors and enhancing the accuracy of straightness and position determination in precision machinery and instruments.
Implementation Method 1
laser heterodyne interferometric straightness measurement apparatus
Implementation Method 2
laser heterodyne interferometric straightness measurement apparatus
Implementation Method 3
Wollaston prism
Implementation Method 4
first photodetector and a second photodetector
Implementation Method 5
V-shaped retroreflector
Data Source
AI summary
A laser heterodyne interferometric straightness measurement apparatus and method with six DOFs determination includes a part for determining the straightness and its position based on laser heterodyne interferometry and a part for error determination and compensation. The optical path for determination of four DOFs errors including three common beam-splitters, a polarizing beam-splitter, a planar mirror, a convex lens, a position-sensitive detector and two quadrant detectors is added in the optical configuration of the part for determining the straightness and its position based on laser heterodyne interferometry.