Monolithic Beam Shaper for Homogeneous Ring Illumination

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Solution Overview

Problem

Ring illumination systems based on optical fibers exhibit large light divergence, and annular LED arrangements create inhomogeneous illumination fields, failing to achieve the required degree of homogeneity for precision applications, particularly in machine vision and inspection where maximum light intensity is crucial.

Innovation Solution

The use of beam shapers, specifically a configuration including a light collector, a homogenizing rod with total internal reflection, and a lens, which are manufactured as a single piece to simplify assembly and enhance light homogeneity, replaces traditional shaping optics like TIR lenses and aspheric condenser lenses, ensuring a more focused and homogeneous illumination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If optical fibers are used for ring illumination, then light can be transmitted to the illumination area, but large light divergence occurs

Engineering Contradiction:
Improvelight transmissionVSAvoidlight divergence
Core Design Contradiction:
Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

A beam shaper is introduced as an intermediary optical element between the light source and the illumination area. This beam shaper includes a light collector, homogenizing rod, and lens that work together to reshape the divergent light from optical fibers or LEDs into a controlled, homogeneous illumination pattern with reduced divergence

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the optical parameters of the light beam by using a homogenizing rod with specific refractive index and geometry, combined with a lens of particular focal length. These parameter changes transform the light from a divergent state to a controlled illumination state with homogeneous intensity distribution

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If annular LED arrangements are used, then light sources can be positioned in a ring configuration, but inhomogeneous illumination fields are created

Engineering Contradiction:
Improvering configuration assemblyVSAvoidillumination homogeneity
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The beam shaper acts as an intermediary that receives light from the annular LED arrangement and transforms it into a homogeneous illumination pattern. The homogenizing rod and lens combination redistributes the light evenly across the illumination area, eliminating the inhomogeneities inherent in direct LED arrangements

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent explicitly applies the homogeneity principle by designing the beam shaper to produce uniform light distribution. The homogenizing rod with its specific geometry and refractive index, combined with the lens, ensures that light from multiple LED sources is evenly distributed across the entire illumination area, achieving homogeneous illumination intensity

Inventive Principle:
Principle #33Homogeneity

3Illumination intensity

If multiple optical elements are used for beam shaping, then light can be directed and focused, but device complexity increases

Engineering Contradiction:
Improvelight focusingVSAvoidnumber of optical components
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges multiple optical functions into a single integrated beam shaper component. The light collector, homogenizing rod, and lens are combined into one monolithic optical element that performs beam shaping, homogenization, and focusing simultaneously, thereby reducing the total number of separate components while maintaining effective light control

Inventive Principle:
Principle #5Merging (Combining)

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 configuration achieves a significantly more homogeneous and intense illumination pattern with clearly defined edges, improving the light collection efficiency and reducing the divergence of light, thereby meeting the high precision requirements of machine vision and inspection applications.

Implementation Method 1

The light integrator homogenizes and constrains the light, based on reflection of the light within the integrator. The light integrator may be a hollow tube with reflective inner surface or a solid rod of an optically transparent material, where the reflection of light within the light integrator is due to total internal reflection.

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The condensing section combines refraction and reflection in order to direct light from the light source into the transmitting section.

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

The light from the LED is introduced into the rod lens by a condensing lens.

Methodology Applied
Scientific EffectLens focusing: Lens

Implementation Method 4

the rod lens and condensing lens are provided as sections of an optical unit, the rod lens constituting a light transmitting section

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2564111B1Ring light illuminator and beam shaper for ring light illuminator
Publication Date: 2022.01.05 KLA CORP
  • EP2564111B1 patent drawingFigure 1a~1b
  • EP2564111B1 patent drawingFigure 2~3
  • EP2564111B1 patent drawingFigure 4~5

AI summary

A ring light illuminator with annularly arranged light sources is disclosed. To each light source there corresponds a beam shaper comprising a light collector, a homogenizing means for light from the light source, and an imaging means for imaging an output of the homogenizing means into an area to be illuminated. The homogenizing means in embodiments is a rod, into which light from the light collector is directed. The end of the rod opposite the light collector is imaged by the imaging means into the area to be illuminated.