Plane Grating Laser Interferometer Phase Detection
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Solution Overview
Problem
Traditional phase detection technologies based on time measurement suffer from low accuracy and inability to meet the requirements for displacement measurement with small measuring ranges and high precision.
Innovation Solution
A high-resolution phase detection method and system using a dual-frequency plane grating laser interferometer, which outputs a standard sine signal and a sine-like signal to solve for the integer and decimal portions of phase changes, allowing for precise displacement measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional phase detection technology based on time measurement is used, then the measurement range can be large, but the measurement precision is low
Solution Approach 1:
The patent segments the phase detection process into two independent parts: integer portion detection using a first interferometer and decimal portion detection using a second interferometer. This segmentation allows each interferometer to be optimized for its specific function, achieving high precision without requiring excessive complexity in a single system.
Solution Approach 2:
The patent transitions from traditional time-based phase detection to a dual-frequency spatial domain approach. By using two different laser frequencies and separating the detection into integer and decimal portions, the system achieves higher precision measurement through dimensional transformation in the frequency and phase domains.
2Manufacturing precision
If traditional time-based phase detection is used, then the system is simple, but it cannot meet the requirements for small measuring range and high precision
Solution Approach 1:
The measurement task is segmented into integer period detection and decimal portion detection. The first interferometer handles integer periods while the second interferometer handles decimal portions, allowing the system to achieve high manufacturing precision for small displacement measurements without overwhelming complexity.
Solution Approach 2:
The patent changes the operating parameters by using dual-frequency lasers instead of single-frequency or time-based methods. This parameter change enables the system to achieve ultra-precision displacement measurement by solving for both integer and decimal portions of phase changes simultaneously.
3Measurement precision
If dual-frequency plane grating laser interferometer is used, then high-resolution phase detection is achieved, but the device complexity increases
Solution Approach 1:
The system segments the high-resolution phase detection into two specialized interferometers: one for integer portion and one for decimal portion. This segmentation achieves high resolution by dividing the complex measurement task into manageable, optimized sub-tasks rather than requiring a single overly complex system.
Solution Approach 2:
The dual-frequency interferometer system provides multi-functionality by simultaneously measuring both integer and decimal portions of phase changes. This universal approach allows the system to handle various measurement ranges and precision requirements through a unified dual-interferometer architecture.
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 achieves high-resolution phase detection, enabling ultra-precision measurement of both integer and decimal portions of the measured signal, thereby addressing the limitations of traditional phase detection technologies.
Implementation Method 1
high-resolution phase detection method and system based on a plane grating laser interferometer
Data Source
AI summary
A high-resolution phase detection method and system based on a plane grating laser interferometer. The method uses a dual-frequency interferometer to measure the displacement, and the measurement signal processing comprises an integral part and a decimal portion, a phase equation set of a displacement measurement signal is constructed according to a measurement optical path principle of a heterodyne plane grating laser interferometer; a non-linear equation set for which the unknowns are instantaneous phase, interval phase and signal amplitude is established; and the equation sets above are solved by using the least squares method, so as to realize phase discrimination, thereby realizing precise displacement measurement. The method can solve the problems in the traditional time measurement-based phase detection technology, such as low measurement accuracy, and failing to satisfy small measuring range measurement. The measurement method can be applied to systems such as precision manufacturing equipment and lithography machine.