Optical Angle Measuring Apparatus with Linear Scanning Grating

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Solution Overview

Problem

High-resolution optical angle measuring devices with low mounting tolerances are limited in their ability to universally scan different graduation radii and applications, requiring significant adjustments to the scanning optics.

Innovation Solution

An optical angle measuring device with a linear scanning grating and combined radial-circular gratings on the graduated disk, which allows for universal scanning of curved and linear measuring graduations with varying radii without the need for significant adjustments to the scanning optics, enabling high-resolution angle measurements with large mounting tolerances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a wavefront corrector is optimized for a specific graduation radius, then high measurement precision is achieved, but the device cannot be used universally for different graduation radii

Engineering Contradiction:
Improvemeasurement precisionVSAvoiduniversal usability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces the optimized wavefront corrector with a linear scanning grating that can universally scan different graduation radii. The linear scanning grating performs the function of both wavefront correction and scanning for any radius, making the device adaptable to different measurement applications without requiring optimization for specific radii.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts the wavefront correction function from the dedicated wavefront corrector and integrates it into the linear scanning grating. This eliminates the separate optimized component and allows a single element to handle multiple functions across different graduation radii.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If retroreflectors and wavefront correctors are used to minimize wavefront distortions, then high measurement precision is achieved, but the scanning optics require significant adjustments for different applications

Engineering Contradiction:
Improvemeasurement precisionVSAvoidscanning optics adjustment
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the wavefront correction function with the scanning function into a single linear scanning grating. This combination eliminates the need for separate retroreflectors and wavefront correctors, reducing the number of components and the complexity of adjustments required when changing applications.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If dedicated scanning optics are used for specific graduation radii, then high measurement precision is achieved, but the device cannot be used for different graduation radii without significant adjustments

Engineering Contradiction:
Improvemeasurement precisionVSAvoidgraduation radius adaptability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The linear scanning grating is designed to universally scan different graduation radii while maintaining measurement precision. Its linear geometry and scanning mechanism allow it to adapt to various radii without requiring optimization or significant adjustments, achieving both precision and versatility.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 high-resolution, universal scanning of curved measuring graduations with different graduation radii and simultaneous detection of rotational and linear movements, providing accurate angle measurements and position determination with reduced caliper size and drift, suitable for various applications including polar coordinate kinematics.

Implementation Method 1

an incident beam of rays at the scanning grating is first split into two partial beams of rays

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

The partial beams of rays then propagate in the direction of the first combined radial-circular grating and are diffracted there

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 3

The diffracted partial beams of rays then propagate in the direction of the mirror and are reflected there

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 4

The partial beams of rays then propagate in the direction of the second combined radial-circular grating and are diffracted there

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 5

The first combined radial-circular grating can be designed in such a way that, in addition to a longitudinal and a transverse deflection effect on the partial beams of rays, the partial beams of rays are also focused on the mirror

Methodology Applied
Scientific EffectFocusing: Focusing

Data Source

PatentEP2450672B1Optical angle measuring apparatus
Publication Date: 2016.01.20 DR JOHANNES HEIDENHAIN GMBH
  • EP2450672B1 patent drawingFigure 1~2b
  • EP2450672B1 patent drawingFigure 3a~3b
  • EP2450672B1 patent drawingFigure 4a~5

AI summary

The present invention relates to an optical angle measuring device for detecting the relative motion between at least one scanning grating and a partial disk with at least one measuring division. The scanning grating is designed as a linear scanning grating, and the partial disk comprises, as measuring divisions, a first and a second combined radial circular grating and includes a mirror. Thus, an incident beam of light is first split into two partial beams at the scanning grating. The partial beams then propagate towards the first combined radial circular grating and are diffracted there. The diffracted partial beams propagate towards the mirror and are reflected there towards the second combined radial circular grating. The partial beams then propagate towards the second combined radial circular grating and are diffracted there.The diffracted partial beams propagate towards the scanning grating, where a superposition of the partial beams results (Fig. 2a).