Microlens Array Structured Light Pattern Generation

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Solution Overview

Problem

Existing structured light systems face challenges in producing high contrast patterns over a wide range of distances with minimal components, requiring precise alignment and complex manufacturing processes, while also achieving high intensity and manufacturability.

Innovation Solution

A structured light apparatus comprising a microlens array and an illumination unit with specifically selected lens pitch, distance, and wavelength relationships, where the lens pitch squared equals twice the product of the distance and wavelength divided by an integer, allowing for high contrast patterns without the need for precise alignment and complex manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional structured light systems use multiple optical components to achieve high contrast patterns, then the pattern contrast is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvepattern contrastVSAvoidnumber of optical components
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent combines the functions of multiple optical components (grating, lens, aperture) into a single microlens array where each microlens acts as both the aperture and the focusing element. This integration maintains the ability to produce high contrast structured light patterns while reducing the total number of components and simplifying the optical system.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Each microlens in the array serves multiple functions simultaneously: it acts as an aperture stop, a focusing lens, and a spatial light modulator. This multi-functionality eliminates the need for separate components for each function, reducing device complexity while maintaining pattern contrast performance.

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

2Illumination intensity

If precise alignment of optical components is implemented to achieve high contrast patterns, then the pattern contrast is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvepattern contrastVSAvoidalignment precision
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

By merging the aperture and lens functions into a single integrated microlens structure, the patent eliminates the need for precise alignment between separate aperture and lens components. The microlens array can be manufactured as a monolithic structure where all elements are inherently aligned, dramatically reducing manufacturing precision requirements while maintaining high pattern contrast.

Inventive Principle:
Principle #5Merging (Combining)

3Illumination intensity

If complex manufacturing processes are used to produce high quality structured light, then the optical quality is improved, but the ease of manufacture decreases

Engineering Contradiction:
Improveoptical qualityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent achieves high optical quality by optimizing key parameters of the microlens array (lens pitch, focal length, aperture diameter, and wavelength relationships) rather than through complex manufacturing processes. The specific parameter relationship P² = 2Dλ/N allows for high quality pattern production using standard microlens fabrication techniques, significantly improving ease of manufacture.

Inventive Principle:
Principle #35Parameter changes

4Illumination intensity

If multiple optical components are used to achieve high intensity structured light, then the light intensity is improved, but the loss of energy increases

Engineering Contradiction:
Improvestructured light intensityVSAvoidenergy loss through optical components
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

By integrating the aperture and lens functions into a single microlens element, the patent eliminates energy losses that would occur at the interfaces between separate components. Light passes through only one optical element rather than multiple interfaces, reducing reflection losses and absorption while maintaining high structured light intensity.

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

The apparatus achieves high contrast structured light patterns over a wide range of distances with reduced component complexity and improved manufacturability, maintaining high intensity and simplicity in design.

Implementation Method 1

a microlens array (MLA) including a multitude of microlenses (2) which are regularly arranged at a lens pitch P

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

Light from the VCSEL array is focused through a collimating micro-lens array consisting of a plurality of lenses, one lens for each VCSEL. The micro-lens array serves to focus and direct the beams from the VCSEL array to a DOE.

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP3250882B1Apparatus for producing patterned illumination
Publication Date: 2019.11.27 HEPTAGON MICRO OPTICS PTE LTD
  • EP3250882B1 patent drawingFigure 1~3
  • EP3250882B1 patent drawingFigure 4~7
  • EP3250882B1 patent drawingFigure 8~12

AI summary

An apparatus for producing structured light comprises a first optical arrangement which comprises a microlens array (L1) comprising a multitude of transmissive or reflective microlenses (2) which are regularly arranged at a lens pitch P and an illumination unit for illuminating the microlens array. The illumination unit comprises an array (S1) of light sources (1) for emitting light of a wavelength L each and having an aperture each, wherein the apertures are located in a common emission plane which is located at a distance D from the microlens array. For the lens pitch P, the distance D and the wavelength L, the following equation applies P2 = 2LD/N, wherein N is an integer with N ≥ 1. High- contrast high-intensity light patterns can be produced. Devices comprising such apparatuses can be used for depth mapping.