Micro-mirror array optical pattern generation

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Solution Overview

Problem

Existing optical pattern generation technologies face challenges with light absorption leading to inefficiencies, particularly in creating patterns with high contrast and precise control of light intensity, and require complex control data and expensive micro-mirror arrays for high resolution and sharpness.

Innovation Solution

A system using a micro-mirror array with tiltable micro-mirrors that adjust the direction of centroid beams to ensure coherent light interference in the image plane, allowing for precise control of optical path lengths to generate high-resolution, high-intensity image points without absorption-based losses, using partially coherent light beams to achieve constructive superposition and sharp image points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If absorption-based slide projection is used to generate optical patterns, then high resolution is achieved, but light output is significantly reduced and heating problems occur

Engineering Contradiction:

Improvepattern resolutionVSAvoidlight output

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical absorption-based slide system with a diffractive optical element that modulates light phase rather than absorbing it. The DOE creates interference patterns through constructive and destructive interference of diffracted light, achieving high-resolution patterns without the light loss and heating issues of absorption-based methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention uses phase modulation of light through the diffractive optical element to control pattern formation. By varying the phase of incident light across the DOE surface, the system directs light constructively to bright regions and destructively to dark regions, achieving pattern generation without absorption and associated energy loss.

Inventive Principle:

Principle #36Phase transitions

2Loss of energy

If diffractive optical elements are used for pattern generation, then light loss due to absorption is avoided, but extremely small pixels with dimensions close to light wavelength are required for good image quality

Engineering Contradiction:

Improvelight output efficiencyVSAvoidpixel size and number

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent employs a spatial light modulator in conjunction with the diffractive optical element, allowing dynamic reconfiguration of the pattern without physical changes to the DOE structure. The SLM can programmatically adjust phase and amplitude of light across different regions, enabling flexible pattern generation with fewer physical elements while maintaining high efficiency.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If incoherent pattern generation with beam steering is used, then fewer pixels are needed, but diffraction at individual micro-mirrors limits resolution and image sharpness

Engineering Contradiction:

Improvenumber of pixelsVSAvoidimage sharpness

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent combines diffractive optical elements with spatial light modulators to merge the advantages of both approaches. The DOE provides efficient light redirection while the SLM adds programmable control and enhances resolution through coherent interference effects, achieving both reduced pixel requirements and improved image sharpness.

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 approach enables efficient generation of optical patterns with high resolution and precision, minimizing light loss and complexity in control data, suitable for applications requiring bright, adjustable light points, such as material processing and lithography.

Implementation Method 1

a micro-mirror array (3) for reflecting light beams (LS) incident on the micro-mirror array (3) in a planar manner

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a focusing means (6) for focusing onto the image plane (BE) the light beams (LS) reflected at the multitude of micro-mirrors (4)

Methodology Applied

Scientific EffectFocusing: Focusing

Implementation Method 3

allowing for precise control of optical path lengths to generate high-resolution, high-intensity image points without absorption-based losses, using partially coherent light beams to achieve constructive superposition

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS11067953B2Apparatus and method for generating an optical pattern from image points in an image plane

Publication Date: 2021.07.20 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

Apparatus for generating an optical pattern from image points in an image plane, including: a control unit; a micro-mirror array; an illumination unit controllable by the control unit; a focusing unit; the control unit being configured to control one or several micro-mirror groups formed of several micro-mirrors of the multitude of micro-mirrors such that the centroid beams reflected at the micro-mirrors of one of the micro-mirror groups meet in the image plane, and such that optical path lengths of the centroid beams reflected at the micro-mirrors of the respective micro-mirror group are equal from the illumination unit up to the image plane or differ by an integer multiple of a wavelength of the light beams in order to generate an image point of the image points in such a way.