Compound Mirror Laser Line-Beam Generator

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Solution Overview

Problem

Existing optical devices, such as diffractive optical elements and Powell lenses, suffer from severe chromatic aberration and power losses when transforming polychromatic laser radiation with a Gaussian intensity distribution into a beam with uniform intensity distribution, particularly for applications requiring flat-top or line-beam illumination.

Innovation Solution

A compound mirror surface with a rounded apex is used to reflect the laser radiation, transforming a beam with a non-uniform intensity distribution into one with an approximately uniform intensity distribution, effectively addressing chromatic aberration issues by maintaining uniformity across different wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If diffractive optical elements are used to transform Gaussian beam into line-beam, then beam shaping is achieved, but chromatic aberration increases and power losses occur

Engineering Contradiction:

Improvebeam intensity distributionVSAvoidpower losses

Core Design Contradiction:

ShapeVSLoss of energy

Solution Approach 1:

The patent replaces diffractive optical elements (which rely on light interference and diffraction) with a reflective optical system using a compound mirror surface. This substitution eliminates chromatic aberration because reflection does not suffer from wavelength-dependent effects like diffraction does, while still achieving the desired beam shaping function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent modifies the mirror surface geometry by introducing a compound shape with a rounded apex, transforming it from a conventional flat or simple curved surface. This parameter change in the mirror's geometric profile enables the specific beam shaping function while maintaining reflectivity across all wavelengths, thus avoiding power losses associated with diffractive elements.

Inventive Principle:

Principle #35Parameter changes

2Shape

If Powell lens is used to transform Gaussian beam into line-beam, then beam shaping is achieved, but chromatic aberration increases

Engineering Contradiction:

Improvebeam intensity distributionVSAvoidchromatic aberration

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the Powell lens (a refractive optical element) with a reflective compound mirror surface. Reflection-based optics inherently avoid chromatic aberration since the law of reflection is wavelength-independent, whereas refraction through lenses introduces wavelength-dependent focal shifts. This substitution maintains beam shaping capability while eliminating the harmful chromatic effect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a compound mirror surface featuring a rounded apex, utilizing curved geometries to achieve beam shaping. The spherical curvature at the apex enables the mirror to redirect and distribute laser radiation uniformly, achieving the desired line-beam profile without the chromatic aberration problems of refractive curved surfaces like Powell lenses.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Shape

If diffractive optical elements are used to create line-beam, then beam shaping is achieved, but image quality degrades

Engineering Contradiction:

Improvebeam intensity distributionVSAvoidimage quality

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent substitutes diffractive optical elements with a reflective compound mirror system. Reflection optics provide superior image quality and beam uniformity compared to diffractive elements, which suffer from higher-order diffraction losses and chromatic aberration. The compound mirror design achieves precise beam shaping with minimal degradation of optical quality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution achieves a beam with an isotropic intensity distribution, providing improved uniform illumination with minimal variation (within 10%) across the beam axis, reducing chromatic aberration and power losses, and is applicable for both monochromatic and polychromatic laser sources.

Implementation Method 1

The compound mirror-surface has a rounded apex and is reflective to the beam of laser-radiation having the non-uniform intensity distribution. The beam of laser-radiation having the non-uniform intensity distribution is incident on the compound mirror-surface. The beam of laser-radiation having the about uniform intensity distribution is reflected from the compound mirror-surface.

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS9971159B2Reflective laser line-beam generator

Publication Date: 2018.05.15 COHERENT INC

AI summary

A mirror is used to form a beam of laser-radiation having a uniform intensity distribution from a beam of laser-radiation having a non-uniform intensity distribution. The mirror has a reflective surface that has a compound shape, which is two inclined surfaces joined by a rounded apex. The compound-mirror is achromatic and can form a uniform intensity distribution from a polychromatic beam of laser-radiation. The uniform intensity distribution may be an isotropic distribution or a flat-top distribution in a plane. The non-uniform intensity distribution may be a Gaussian distribution from a laser source.