Contactless Six-DOF Positioning via Laser and PSD Sensors
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Solution Overview
Problem
Current object positioning systems for six degrees of freedom in space, such as those used in lithography machines, face challenges with cable interference affecting precision, high costs, and complex structures, necessitating a contactless system with high precision, rapid response, and reduced complexity.
Innovation Solution
A two-dimensional position-sensitive sensor-based system utilizing a semiconductor laser, optical fibers, and PSD sensors, where the laser is split into three paths and filtered before being received by sensors fixed on an object, allowing for contactless positioning without cables, enabling precise and rapid object positioning with a simple structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photoelectric encoder, grating ruler, magnetic encoder, or other traditional positioning sensor is used, then positioning function is achieved, but cable connection interferes with movement precision or the system has high cost and large volume
Solution Approach 1:
The patent extracts and removes the cable connection from the positioning system. By using a contactless laser-based measurement system, the physical cable that connects the sensor to the moving object is eliminated, thereby eliminating the source of interference with movement precision while maintaining the positioning function
Solution Approach 2:
The patent replaces the mechanical cable connection system with an optical field-based measurement system. Instead of using physical cables to transmit signals, the system uses laser beams and optical fields to achieve contactless measurement, substituting mechanical connection with optical field interaction
2Reliability
If traditional positioning sensors with cable connections are used, then positioning is achieved, but movement precision is affected by cable interference
Solution Approach 1:
The patent converts the potential harm of cable interference into a benefit by completely eliminating the cable from the system. The contactless optical measurement approach transforms the problem of cable interference into an opportunity to achieve higher reliability by using non-contact optical fields that do not physically interfere with the moving object
Solution Approach 2:
The patent introduces an optical field as an intermediary between the measurement system and the moving object. Instead of direct cable connection, the laser beam and optical field serve as the mediator to transmit measurement information without physical contact, thereby eliminating cable interference while maintaining measurement capability
3Measurement precision
If conventional positioning systems are used, then positioning function is provided, but cost and volume are high
Solution Approach 1:
The patent employs relatively simple and cost-effective optical components such as lasers, photodetectors, and lenses to build the positioning system. These components are more affordable and compact compared to traditional precision encoders and grating rulers, reducing both system cost and volume 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 system achieves high precision, rapid response, and reduced cost by eliminating cable interference and simplifying the structure, ensuring accurate six degrees of freedom positioning without compromising movement precision.
Implementation Method 1
A two-dimensional position-sensitive sensor-based system for positioning an object having six degrees of freedom in space, characterized in that the system comprises a semiconductor laser
Implementation Method 2
laser emitted by the semiconductor laser is irradiated onto the optical fiber collimator, divided into three paths via the optical fiber splitter after being coupled into the input optical fiber by the optical fiber collimator
Implementation Method 3
received by the first PSD sensor, the second PSD sensor, and the third PSD sensor after being filtered out by the first filter plate, the second filter plate, and the third filter plate, respectively, while the positions of laser spots on the three PSD sensors are processed by the signal processing system
Data Source
AI summary
A two-dimensional, position-sensitive sensor-based system for positioning an object having six degrees of freedom in space, used for positioning of a silicon table and mask table of a lithography machine. The system comprises mainly a semiconductor laser 1, an optical fiber collimator 2, optical fibers 3, 7, 10, and 13, an optical fiber splitter 4, filter plates 6, 9, and 12, three PSD sensors 5, 8, and 11, and a signal processing system. Laser emitted by the semiconductor laser 1 is irradiated onto the optical fiber collimator 2, then transmitted respectively via three paths, and received by the PSD sensors 5, 8, and 11 after having background light filtered out by the filter plates 6, 9, and 12, while the positions of laser spots on the three PSD sensors 5, 8, and 11 are processed by the signal processing system to acquire the position and orientation.