Optical Position Measuring Device Using Conical Illumination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical position measuring devices require additional polarization-optical components in the scanning beam path, which pose challenges in limited space, mechanical fixation, and evenness of support structures, and restrict the dimensioning range of gratings and the width of the illuminated region.
Innovation Solution
The optical position measuring device generates phase-displaced scanning signals without additional polarization-optical components by configuring the scanning beam path with a splitting and combination grating, where the illumination beam bundle is conically incident and the scanning beam paths are arranged in mirror symmetry, allowing polarization crosstalk and orthogonal polarization at recombination, eliminating the need for separate polarization-optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional polarization-optical components are placed in the scanning beam path, then phase-displaced scanning signals can be generated, but the device complexity increases and space requirements are not met
Solution Approach 1:
The invention extracts the polarization-optical functionality from separate discrete components and integrates it directly into the grating structures. The grating elements are designed with specific polarization properties, eliminating the need for separate lambda quarter-wave plates and polarizers in the scanning beam path, while still enabling generation of phase-displaced scanning signals for precise position measurement
Solution Approach 2:
The invention merges the polarization-optical functions with the grating structures by designing gratings with position-dependent polarization characteristics. The high-frequency grating and low-frequency grating are combined in a single measuring standard, with the high-frequency grating providing both measurement function and polarization functionality, thereby reducing the total number of optical components
2Measurement precision
If additional polarization-optical components are placed in the scanning beam path, then scanning signals can be generated, but the area occupied in the scanning gap increases
Solution Approach 1:
The invention removes discrete polarization-optical components from the scanning beam path and integrates their functionality into the grating structures themselves. This extraction eliminates the need for additional space in the scanning gap, as the polarization functions are embedded within the existing grating elements rather than requiring separate physical components
Solution Approach 2:
The invention transitions from using separate spatial components for polarization control to encoding polarization information in the dimensional structure of the grating elements themselves. The high-frequency grating lines are oriented at specific angles (e.g., 45 degrees) to provide polarization functionality through their geometric arrangement rather than through separate optical elements
3Measurement precision
If discrete polarization-optical components are used, then scanning signals can be generated, but integration into movable measuring standards is not possible
Solution Approach 1:
The invention combines the polarization-optical functions with the grating structures in the measuring standards. The high-frequency grating is integrated directly into the measuring standard with position-dependent polarization characteristics, allowing the entire assembly to move together as a single unit without requiring separate fixation of polarization components
Solution Approach 2:
The grating structures serve multiple functions simultaneously: they provide the measurement function through their periodic structure and also provide the polarization-optical function through their specific orientation and design. This multi-functionality allows the measuring standards to be self-contained and movable without requiring additional polarization components
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 configuration allows for precise position measurement without additional polarization-optical components, reducing restrictions on grating periodicities and illuminated region width, enabling operation in compact setups where mechanical fixation is not possible.
Implementation Method 1
At a splitting grating, one of the illumination beam bundles emitted by a light source is split up into at least two partial beam bundles
Implementation Method 2
the scanning beam paths of the partial beam bundles are arranged in mirror symmetry with the plane of incidence between the splitting and recombination... allowing polarization crosstalk and orthogonal polarization at recombination
Implementation Method 3
after the differently polarized partial beam bundles are recombined at a combination grating, multiple phase-displaced, phase-dependent scanning signals are able to be generated
Implementation Method 4
When passing through scanning beam paths, the partial beam bundles undergo different polarization-optical effects... multiple phase-displaced, phase-dependent scanning signals are able to be generated
Data Source
AI summary
In an optical position measuring device for detecting the relative position of a first measuring standard and a second measuring standard, movable relative to each other along at least one measuring direction, at a splitting grating, a beam bundle emitted by a light source is split up into at least two partial beam bundles. When passing through scanning beam paths, the partial beam bundles undergo different polarization-optical effects. After the differently polarized partial beam bundles are recombined at a combination grating, a plurality of phase-displaced, displacement-dependent scanning signals is able to be generated from the resulting beam bundle. No polarization-optical components are arranged in the scanning beam paths of the partial beam bundles between the splitting and recombination. To generate the different polarization-optical effects on the partial beam bundles, a conically incident illumination beam bundle impinges upon the splitting grating, the incident illumination beam bundle extending in a plane perpendicular to the measuring direction at an angle other than 0°, the plane of incidence being defined by the grating normal to the splitting grating and the direction of incidence of the illumination beam bundle. The scanning beam paths of the partial beam bundles are arranged in mirror symmetry with respect to the plane of incidence between the splitting and recombination.