Lighting Device with Beam Splitters for Edge Illumination Compensation

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Solution Overview

Problem

Conventional illumination devices for three-dimensional image capture suffer from a homogeneous brightness distribution that leads to a natural light fall-off, particularly at the edges, resulting in reduced image quality due to insufficient lighting in peripheral areas.

Innovation Solution

A lighting device that uses a reflective pattern generator illuminated by a light source via two beam splitters and an optical retarder, where the light components are polarized differently to compensate for edge light drop by projecting light outward with one projection optics and centrally with the other, allowing for dynamic adaptation of the illumination pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a homogeneous brightness distribution is used for illumination, then the lighting device is simple to manufacture, but the edge areas of the image suffer from insufficient lighting due to natural light fall-off

Engineering Contradiction:
Improvesimplicity of lighting deviceVSAvoidbrightness at edge areas
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies local quality by varying the brightness distribution across different regions of the illumination pattern. Specifically, it increases the brightness in edge areas while maintaining or reducing brightness in central areas, compensating for the natural cos^4 light fall-off. This is achieved through a programmable pattern generator that can dynamically adjust the intensity distribution to match the specific requirements of the scene being captured.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by using a programmable pattern generator that can dynamically adapt the illumination pattern in real-time. The system can change the brightness distribution according to different scenes, capture modes, and lighting conditions. This dynamic adaptation allows the lighting device to optimize edge area illumination for each specific recording situation rather than using a fixed homogeneous pattern.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If the illumination pattern is dynamically adapted to the scene, then the three-dimensional image data quality is improved, but the device complexity increases

Engineering Contradiction:
Improvequality of three-dimensional image dataVSAvoidcomplexity of lighting device
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a programmable pattern generator that can produce multiple different illumination patterns for various applications. The same hardware component can generate structured light patterns for 3D scanning, dot patterns for featureless surface scanning, or adaptive patterns optimized for specific scenes. This multi-functionality reduces the need for multiple specialized lighting devices while maintaining high measurement precision.

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

Solution Approach 2:

The patent implements parameter changes by allowing dynamic modification of the illumination pattern parameters such as brightness distribution, pattern type, and spatial frequency. The system can adjust these parameters based on scene analysis, camera settings, and desired measurement accuracy. This flexibility enables high-quality 3D imaging across diverse applications without requiring complex hardware changes for each scenario.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If higher currents or higher density emitters are used outdoors, then the edge light drop is compensated, but the arrangement of individual emitters becomes fixed during manufacture

Engineering Contradiction:
Improvebrightness at edge areasVSAvoiddynamic adjustment capability
Core Design Contradiction:
Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical/physical approach of using higher current or denser fixed emitters with an electronic control system. Instead of physically modifying the emitter arrangement or operating conditions, the system uses a programmable pattern generator to dynamically control which emitters are activated and at what intensity. This substitution enables flexible, real-time adaptation of the illumination pattern without permanent hardware modifications.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements dynamics by enabling real-time reconfiguration of the illumination pattern through electronic control. The system can dynamically adjust the activation and intensity of individual emitters based on scene requirements, allowing the same physical array to adapt its effective configuration for different applications. This dynamic control provides versatility that fixed emitter arrangements cannot achieve.

Inventive Principle:
Principle #15Dynamics

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 enables efficient redistribution of light, improving the detection of low-contrast and dark areas, enhancing the precision of camera-captured images by maintaining or increasing brightness at the edges, thus improving the overall quality of three-dimensional image data.

Implementation Method 1

The first beam splitter (18a) generates from the incident light beam a reflected first light component and a transmitted second light component, which are polarized differently from one another

Methodology Applied
Scientific EffectPolarization: Polarisation

Implementation Method 2

The transmitted second light component is then incident on an optical retarder (28), in particular a half-wavelength plate or λ/2 plate, arranged behind the first beam splitter (18a) in the direction of the light

Methodology Applied
Scientific EffectOptical retardation: Birefringence

Implementation Method 3

the pattern generator changes properties of the reflected light and in particular its polarization, for example through a pixel arrangement

Methodology Applied
Scientific EffectPolarization modulation: Polarisation

Implementation Method 4

so that only the light components corresponding to the desired illumination pattern are projected by the respective projection optics assigned to the beam splitters

Methodology Applied
Scientific EffectOptical projection: Lens

Data Source

PatentEP3021072B1Lighting device and method for projecting an illumination pattern
Publication Date: 2016.09.28 SICK AG
  • EP3021072B1 patent drawingFigure 1~3
  • EP3021072B1 patent drawingFigure 4~6
  • EP3021072B1 patent drawingFigure 7~8

AI summary

A lighting device (10) for projecting a lighting pattern is described, comprising a light source (12) in whose beam path a first beam splitter (18a) and a second beam splitter (18b) with an optical delay element (28) between them are arranged, a reflective pattern generator (22), and a first projection optic (24a) associated with the first beam splitter (18a) and a second projection optic (24b) associated with the second beam splitter (18b). The first projection optic (24a) projects light outwards and the second projection optic (24b) projects light centrally.