Laser Radar Beam Splitter for Dynamic Sensitivity Control

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Solution Overview

Problem

Laser radar devices face challenges in monitoring large measurement ranges with varying object reflectance behaviors, leading to high signal dynamics and interference issues that affect accuracy and response speed, particularly due to external light sources and objects with high reflectance.

Innovation Solution

The integration of an optical beam splitting element in the light deflection unit to separate light pulses into a main beam and a pre-scanning beam, allowing for adjustable detection sensitivity based on reflectance measurements from the pre-scanning beam, which helps maintain response speed and reduce interference effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the light receiving arrangement is designed with high detection sensitivity to detect dark objects, then the ability to detect low-reflectance objects is improved, but interference from external light sources and saturation from high-reflectance objects occurs

Engineering Contradiction:
Improvedetection sensitivityVSAvoidmeasurement accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of the detection threshold based on the measured intensity of the pre-scanning beam. The evaluation unit continuously adapts the evaluation threshold according to the pre-scanning beam intensity, allowing the system to maintain optimal detection sensitivity across varying lighting conditions and object reflectances, thereby preventing both saturation and interference effects

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The pre-scanning beam measures the reflectance characteristics of the target object before the main measurement beam is evaluated. This preliminary measurement allows the system to predict and compensate for potential saturation or interference issues before they affect the main measurement, enabling proactive adjustment of detection parameters

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If multiple measurements are performed to suppress interference and reduce measurement error, then measurement accuracy is improved, but the response speed of the laser radar device is reduced

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidresponse speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The pre-scanning beam performs preliminary measurements of object reflectance before the main measurement beam is processed. This advance information allows the evaluation unit to immediately adjust its evaluation threshold for the main beam, achieving accurate measurements in a single pass without requiring multiple repeated measurements, thus maintaining high response speed

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses the intensity measurement from the pre-scanning beam as feedback to dynamically adjust the evaluation threshold for the main beam. This feedback mechanism enables real-time optimization of measurement accuracy without requiring multiple measurement cycles, preserving the fast response characteristics of the laser radar device

Inventive Principle:
Principle #23Feedback

3Measurement precision

If the change in light deflection direction is reduced to maintain consistent object coverage, then measurement consistency is improved, but the response speed and scanning capability are reduced

Engineering Contradiction:
Improvemeasurement consistencyVSAvoidresponse speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The patent divides the measurement process into two segments: a pre-scanning beam that measures reflectance characteristics and a main measurement beam that performs the actual distance measurement. This segmentation allows the system to maintain large angular changes for fast scanning while the pre-scanning beam ensures measurement consistency by characterizing object reflectance at each position

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The pre-scanning beam performs preliminary characterization of object reflectance at each scanning position before the main measurement is taken. This allows the system to maintain fast scanning with large angular changes while ensuring measurement consistency through adaptive threshold adjustment based on the preliminary reflectance information

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 enables accurate distance measurement by optimizing detection sensitivity and reducing noise interference, improving measurement accuracy and extending the service life of the laser radar device without compromising response speed.

Implementation Method 1

an optical beam splitting element is additionally installed in the light deflection unit of the laser radar device in order to energetically separate the light pulses emitted by the pulsed laser into a main beam and a pre-scanning beam

Methodology Applied
Scientific EffectBeam splitting: Diffraction

Implementation Method 2

The light pulses reflected from an object in the measurement area are recorded with a light receiving arrangement and fed to an evaluation unit in the form of electrical signals

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Implementation Method 3

there is a pulsed laser which, in a controlled manner, emits successive light pulses into a measurement area

Methodology Applied
Scientific EffectLaser emission: Laser

Data Source

PatentEP1865336B1Scanning laser radar with beam splitter
Publication Date: 2008.08.13 SICK AG
  • EP1865336B1 patent drawingFigure 1

AI summary

The device has a pulse laser (1) that transmits light pulse into a measuring area, and a light receiving arrangement (15) that receives the light pulse reflected at an object (12) in the area. Optical radiation unit is integrated in a light deflecting unit (5) for separating the impinged light pulse into main ray (10) and forward ray (9). A constant angular deviation is induced between the rays in the direction of light deflection using the radiation unit. An additional light receiving arrangement (17) is provided for receiving the light pulse of the forward ray reflected at the object.