Optical Position Measuring Device Tilted Scale Six-DOF
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Solution Overview
Problem
Current optical position measuring devices fail to accurately measure movements in all six degrees of freedom, particularly along the vertical direction (z-axis), and are sensitive to environmental fluctuations such as temperature and humidity changes, which affects their precision and independence from light wavelength variations.
Innovation Solution
An optical position measuring device with crossed scales, where each scale has a measuring graduation with periodically arrayed grating regions, and a light source splits the illumination beam into sub-beam bundles that are tilted and back-reflected, generating phase-shifted signals for relative movements along multiple directions, ensuring wavelength-independent measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional distance sensors are used to measure movements along the vertical direction, then measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing optical measuring device perform multiple functions by adding the tilting element, enabling it to measure not only horizontal positions but also vertical movements and angles, thereby eliminating the need for separate distance sensors
Solution Approach 2:
The patent changes the orientation parameter of the second scale by tilting it relative to the horizontal plane, which enables the device to detect vertical movements through the modified light path geometry
2Adaptability or versatility
If the second scale is tilted relative to the horizontal plane, then measurement of vertical movements is enabled, but device complexity increases
Solution Approach 1:
The patent extends the measurement capability from two dimensions (horizontal plane) to three dimensions by tilting the second scale, allowing the device to capture vertical movements through the added angular dimension
3Reliability
If grating-based measurement is used, then environmental influence resistance is improved, but measurement of vertical movements cannot be achieved
Solution Approach 1:
The patent extends the functionality of the grating-based optical measuring device to include vertical movement measurement while preserving the environmental resistance benefits of the original grating-based approach
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
This solution enables highly accurate position measurement along all six degrees of freedom, including the vertical direction, while being insensitive to environmental fluctuations, reducing the complexity and cost of the device by minimizing required components and allowing the use of less stringent light sources.
Implementation Method 1
an illumination beam emitted by a light source is split into at least two sub-beam bundles at a first one of the two scales
Implementation Method 2
The sub-beam bundles subsequently impinge on a second one of the two scales, which is tilted about the direction of the longitudinal extent thereof relative to the horizontal plane of movement. The sub-beam bundles are back-reflected toward the first scale at the second scale
Implementation Method 3
The back-reflected sub-beam bundles impinge again on the first scale and are recombined there such that a resulting signal beam is subsequently propagated
Data Source
AI summary
An optical position measuring device for recording a relative position of two scales includes the scales. The longitudinal extents of the scales are oriented parallel to a first and second measuring direction. A horizontal plane of movement is spanned by these measuring directions. A light source is configured to emit an illumination beam that is split into at least two sub-beam bundles at the first scale. The sub-beam bundles subsequently impinge on the second scale, which is tilted about the direction of the longitudinal extent thereof relative to the horizontal plane of movement, and are back-reflected to impinge again on the first scale and are recombined there such that a resulting signal beam is subsequently propagated toward a detection unit, via which phase-shifted scanning signals are generatable with respect to a relative movement of the scales along a third perpendicular measuring direction and the first or second measuring direction.