Heterodyne Interferometer Absolute Positioning via Cyclic Error Phase
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Solution Overview
Problem
Existing interferometer systems require additional hardware and substantial processing time to determine the absolute position of movable objects, and existing methods are complex and sensitive to movement.
Innovation Solution
A method and system that utilize cyclic error phase components from a heterodyne interferometer to determine absolute position without additional hardware, by splitting a light beam into measurement and reference beams, guiding them to reflective surfaces, measuring phase signals, and separating cyclic error phase components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate zeroing sensor is provided to determine absolute position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the absolute position determination function into the existing interferometer system by utilizing the measurement beam and reference beam interference patterns. The cyclic error phase component, which was previously considered a disturbance, is now extracted and used to determine absolute position, merging multiple functions into a single integrated system without requiring separate zeroing sensors.
Solution Approach 2:
The patent converts the harmful cyclic error phase component, which was traditionally viewed as measurement noise or distortion, into a beneficial signal for determining absolute position. By extracting and analyzing this cyclic error component, the system transforms a disadvantage into a useful measurement resource, eliminating the need for additional hardware.
2Measurement precision
If traditional interferometer methods are used to determine absolute position, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent enables continuous determination of absolute position by processing the cyclic error phase component in real-time as the measurement beam and reference beam continuously interfere. The system maintains continuous measurement capability without requiring periodic returns to a reference position, eliminating time loss associated with traditional zeroing procedures.
Solution Approach 2:
The patent performs preliminary extraction and analysis of the cyclic error phase component during the normal measurement process itself, rather than requiring separate post-processing steps. The absolute position information is derived concurrently with the primary measurement, eliminating additional processing time.
3Measurement precision
If a zeroing sensor is used to determine absolute position, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent makes the interferometer system universal by enabling it to determine absolute position across its entire measurement range without being constrained by the limited range of a separate zeroing sensor. The system can measure absolute position at any location within the interferometer's operational range, providing multi-functional capability that eliminates the need to return to a specific reference point.
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
Enables accurate determination of absolute position without additional hardware or substantial processing time, using cyclic error phase components to correct for polarization leakage and determine the object's position with high precision.
Implementation Method 1
measuring a phase signal based on the measurement beam and the reference beam received by the detector
Implementation Method 2
guiding the measurement beam along a measurement path towards a reflective measurement surface on the object; guiding the reference beam along a reference path towards a reflective reference surface on a reference object
Implementation Method 3
A method and system that utilize cyclic error phase components from a heterodyne interferometer to determine absolute position
Data Source
AI summary
The invention provides a method to determine an absolute position of an object using an interferometer system, comprising the steps of: providing a light beam; splitting the light beam in a measurement beam and a reference beam; guiding the measurement beam along a measurement path towards a reflective measurement surface on the object; guiding the reference beam along a reference path towards a reflective reference surface on a reference object; receiving the measurement beam after reflection on the reflective measurement surface and the reference beam after reflection on the reflective reference surface at a detector; measuring a phase signal based on the measurement beam and the reference beam received by the detector, separating a cyclic error phase component from the phase signal, determining the absolute position of the object on the basis of the cyclic error phase component.