Homogenizing Laser Beam Using Dual Cylindrical Lens Arrays

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Solution Overview

Problem

Existing devices for homogenizing laser beams require an additional Fourier lens to achieve a homogeneous intensity distribution in the working plane, which is inefficient.

Innovation Solution

A device with two lens arrays where the center distances of the cylindrical lens means in the first lens array are greater than those in the second lens array, allowing for a homogeneous intensity distribution without a Fourier lens, by aligning central lens apices and increasing lateral offsets for other lenses, enabling the partial beams to superimpose correctly in the working plane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an additional Fourier lens is provided to obtain homogeneous intensity distribution, then the intensity distribution becomes homogeneous, but the device complexity increases

Engineering Contradiction:
Improveintensity distribution homogeneityVSAvoidnumber of optical components
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the Fourier lens from the traditional homogenization system. By carefully designing the lens arrays with specific pitch ratios and configurations, the system achieves homogeneous intensity distribution without requiring the additional Fourier lens that would normally be needed to transform angular distribution to intensity distribution.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the functions of angular distribution homogenization and intensity distribution homogenization into a single integrated system. The lens arrays are designed to simultaneously perform both functions that were traditionally separated into distinct stages requiring additional optical components.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If the center distances of cylindrical lens means are made different between first and second lens arrays, then homogeneous intensity distribution is achieved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveintensity distribution homogeneityVSAvoidlens array configuration complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies local quality by making the center distances (pitch) of cylindrical lens means position-dependent. Specifically, the pitch of the first lens array is designed to be different from the pitch of the second lens array, creating a controlled asymmetry that enables the overlapping of partial beams to produce homogeneous intensity distribution. This local variation in geometric parameters is precisely what achieves the homogenization effect.

Inventive Principle:
Principle #3Local quality

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 homogeneous intensity distribution in at least one direction without the need for an additional Fourier lens, improving beam quality and allowing for adjustable angular distribution and line length in the working plane.

Implementation Method 1

a first lens array having a plurality of cylindrical lens means which can refract the laser beam to be homogenized and divide it into a plurality of partial beam bundles

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

a second lens array having a plurality of cylindrical lens means which can refract the partial beams transmitted through the second lens array

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2976672B1Device for homogenizing a laser beam
Publication Date: 2020.05.06 LIMO GMBH
  • EP2976672B1 patent drawingFigure 1
  • EP2976672B1 patent drawingFigure 2
  • EP2976672B1 patent drawingFigure 3

AI summary

Device for homogenizing a laser beam including a first substrate with a first lens array including a plurality of cylindrical lenses and a second substrate with a second cylindrical lens array, which is arranged in the beam path downstream of the first substrate and includes a plurality of cylindrical lenses. Exactly one of the cylindrical lenses of the second lens array is assigned to each of the cylindrical lenses of the first lens array. Center-to-center distances between the cylindrical lenses of the first lens array are greater than the center-to-center distances between the cylindrical lenses of the second lens array. A lens vertex of a central one of the cylindrical lenses of the first lens array is aligned with a lens vertex of a central one of the cylindrical lenses of the first lens array that is assigned thereto. Lens vertices of the other cylindrical lenses of the second lens array and the lens vertices of the cylindrical lenses of the first lens array that are assigned thereto have an outwardly increasing vertex offset proceeding from the center of the second lens array.