Optical Sensor Astigmatism Compensation Curved Housing

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Solution Overview

Problem

Conventional optical sensors have a large beam cross-section due to astigmatism caused by the curvature of the housing wall, which makes it difficult to reliably detect small objects in the monitored area.

Innovation Solution

The optical sensor incorporates optical correction means to compensate for astigmatism by shaping the housing wall and using additional components like correction lenses or mirrors to ensure that axial and transverse components of the transmitted light have the same focal positions, thereby maintaining a small beam cross-section.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the housing wall is curved to guide the light beam through the housing, then the structural integrity and light guidance are improved, but astigmatism occurs causing beam cross-section expansion

Engineering Contradiction:
Improvehousing wall curvatureVSAvoidbeam focus precision
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

An optical correction element is introduced as an intermediary component between the curved housing wall and the light beam. This element specifically compensates for the astigmatism induced by the curved housing wall, restoring the beam's focal properties without altering the housing's structural curvature.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical correction element modifies the optical parameters of the light beam by introducing opposite astigmatism. Through precise control of the correction element's optical properties (such as cylindrical lens power), the harmful astigmatism from the curved housing is compensated, restoring the beam cross-section to its intended dimensions.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the beam direction is rotated to monitor different sections of the area, then the coverage area is improved, but the beam cross-section expands due to housing wall curvature

Engineering Contradiction:
Improvemonitoring area coverageVSAvoidobject detection precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The optical correction element serves as a mediator that remains effective across multiple beam directions. As the beam rotates to cover different monitoring sections, the correction element continuously compensates for astigmatism, ensuring consistent beam cross-section and detection precision throughout the entire monitoring area.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the housing wall curvature is increased to improve light guidance, then the light path control is improved, but the astigmatism and beam expansion worsen

Engineering Contradiction:
Improvelight path controlVSAvoidbeam cross-section shape
Core Design Contradiction:
Ease of operationVSShape

Solution Approach 1:

The optical correction element acts as a compensating intermediary that counterbalances the astigmatistic effect of the curved housing wall. This allows the housing to maintain its advantageous curved shape for light guidance while the correction element restores the beam cross-section to a proper circular or rectangular shape at the target.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 allows for reliable detection of small objects even at long distances by maintaining a small beam cross-section, reducing astigmatism and ensuring accurate focus across the monitoring area.

Implementation Method 1

optical correction means (70) in a beam path of the transmitted light (15), the optical correction means (70) being designed to compensate for or avoid an astigmatism caused by a curvature of the housing wall (51)

Methodology Applied
Scientific EffectAstigmatism: Lens

Implementation Method 2

the housing wall (51) acts as a dispersing lens for transmitted light in this direction, i.e. the focus position for such components of the transmitted light is changed

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2653883B1Optical sensor
Publication Date: 2014.11.19 PEPPERL & FUCHS GMBH
  • EP2653883B1 patent drawingFigure 1
  • EP2653883B1 patent drawingFigure 2
  • EP2653883B1 patent drawingFigure 3

AI summary

The invention relates to an optical sensor with a light source for emitting transmitted light into a monitoring area, with a rotating device for rotating a beam direction of the transmitted light about a rotation axis oriented transversely to the beam direction, with a detector for measuring light to be detected that is reflected back from an object in the monitoring area, and with a housing for separating a sensor interior from the monitoring area, wherein the housing has a housing wall that is transparent to the transmitted light and the light to be detected and through which the light passes during measurement operation. The sensor is characterized according to the invention in that optical correction means are provided in a beam path of the transmitted light, which are designed to compensate for or avoid astigmatism caused by a curvature of the housing wall.