Triangulation Laser Line Intensity Compensation

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Solution Overview

Problem

Conventional triangulation measurement systems face challenges with non-uniform light intensity distribution along the laser line due to optical properties, leading to reduced readout quality and increased dynamic range issues in camera detection.

Innovation Solution

The method involves adjusting the intensity distribution of the emitted light to compensate for expected losses, particularly at the ends of the laser line, using cylindrical or acylindrical lens arrays and filtering techniques to ensure uniform light intensity across the line, thereby improving detection conditions and reducing exposure time variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional light emitting is used in triangulation measurement, then the measurement process is simple, but the light intensity decreases along the line leading to reduced readout quality

Engineering Contradiction:
Improvereadout qualityVSAvoidlight intensity distribution
Core Design Contradiction:
Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent applies local quality by adjusting the light intensity distribution non-uniformly across the laser line. Specifically, the light source is configured to emit higher intensity at regions where light loss is expected (ends of the line) and lower intensity at regions where light is stronger (center), compensating for the cos4(α) effect and achieving uniform detected intensity across all measurement points.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of light intensity distribution by using optical elements (cylindrical lenses, beam shaping elements) to modify the spatial distribution of light intensity. The emission parameters are adjusted so that the intensity profile along the laser line follows a specific distribution pattern that compensates for optical losses, transforming the conventional uniform emission into a compensated non-uniform emission.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If light intensity is increased to compensate for losses, then readout quality improves, but dynamic range issues increase in camera detection

Engineering Contradiction:
Improvereadout qualityVSAvoiddynamic range management
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by differentiating the light intensity requirements for different regions of the measurement line. Instead of uniformly increasing light intensity across the entire line (which would cause dynamic range issues), the system locally adjusts intensity only where needed to compensate for optical losses, maintaining appropriate intensity levels for the camera's dynamic range while improving readout quality.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If uniform light intensity is achieved across the laser line, then measurement precision improves, but exposure time variations increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoidexposure time variations
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-configuring the light source to emit light with a compensated intensity distribution before measurement begins. The system预先 (in advance) calculates and sets the appropriate intensity profile based on the expected optical losses, so that when measurement occurs, uniform intensity is already achieved without requiring real-time exposure time adjustments during the measurement process.

Inventive Principle:
Principle #10Preliminary action

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 approach results in a more uniform light intensity distribution across the detected laser line, enhancing measurement precision and dynamic range, and allowing for consistent signal amplitudes across the sensor, thus improving the overall triangulation measurement process.

Implementation Method 1

a light source for emitting light, in particular laser light, and a beam forming assembly for shaping the light emitted by the light source

Methodology Applied
Scientific EffectLight emission and shaping: Light

Implementation Method 2

at least one cylindrical or acylindrical lens array arranged to receive the light emitted by the light source and arranged to provide diffraction of the light emitted by the light source

Methodology Applied
Scientific EffectDiffraction and focusing of light: Diffraction

Implementation Method 3

a filter element arranged with the sensor unit and arranged to filter the intensity distribution of received measuring light

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 4

a sensor unit for detecting light, in particular laser light, reflected from the object to be measured

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP3165872B1Compensation of light intensity across a line of light providing improved measuring quality
Publication Date: 2020.04.15 HEXAGON TECH CENT GMBH
  • EP3165872B1 patent drawingFigure 1~2
  • EP3165872B1 patent drawingFigure 3a~4b
  • EP3165872B1 patent drawingFigure 5~6

AI summary

Method of providing measuring light for triangulation-based distance measurement to an object to be measured, wherein distance information is derivable by detecting at least portions of the measuring light reflected at the object. The method comprises emitting light and shaping the light so that the measuring light is provided in form of a line having a midpoint and two opposite ends. The intensity distribution of the light across the line is adjusted so that a respective light intensity at the ends of the line is at least 10% higher than light intensity around the midpoint.