Diffractive Grating Light Sensor Module for Spectral Analysis

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Solution Overview

Problem

Current light sensor modules and spectrometers face challenges in efficiently detecting and analyzing the spectral characteristics of optical radiation, particularly in ambient light and light reflected by objects, with limitations in compactness, cost-effectiveness, and interference prevention.

Innovation Solution

The development of optoelectronic modules with a diffractive grating structure that separates light into spectral components and directs them to photosensitive elements, using multiple sections of the grating tuned to specific wavelengths or narrow bands, along with features like sub-wavelength structures and color filters to prevent stray light interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a diffractive grating with multiple sections is used to separate light into spectral components, then spectral analysis capability is improved, but device complexity increases

Engineering Contradiction:
Improvespectral analysis capabilityVSAvoidgrating structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The diffractive grating is divided into multiple sections, with each section tuned to diffract a specific wavelength or narrow band of wavelengths to a corresponding photosensitive element. This segmentation allows precise spectral analysis by assigning dedicated grating sections to specific wavelength ranges, improving measurement precision while maintaining manageable complexity through functional specialization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the diffractive grating have different local properties - each section is designed with specific grating parameters (such as groove spacing and depth) optimized for its target wavelength range. This local quality variation enables each section to excel at detecting its designated spectral components, achieving high spectral analysis capability through specialized local optimization.

Inventive Principle:
Principle #3Local quality

2Reliability

If color filters and opaque spacers are added to prevent stray light interference, then measurement reliability is improved, but device complexity increases

Engineering Contradiction:
Improveinterference preventionVSAvoidmodule structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Color filters are positioned over photosensitive elements to preemptively block stray light of wavelengths that would cause interference before it reaches the sensors. Opaque spacers are strategically placed to prevent cross-talk between adjacent optical channels. These measures take preliminary anti-action against potential interference, ensuring measurement reliability by preventing stray light issues before they affect the detection process.

Inventive Principle:
Principle #9Preliminary anti-action

3Measurement precision

If multiple photosensitive elements are used to detect different wavelengths, then spectral detection capability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvespectral detection capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The diffractive grating structure serves multiple functions simultaneously - it acts as both a wavelength-separating element and a directing element that guides different spectral components to their respective photosensitive elements. This multi-functionality reduces the need for additional separate components, thereby improving spectral detection capability while controlling manufacturing costs through component consolidation.

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

4Volume of moving object

If a compact optoelectronic module design is implemented, then device size is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvemodule sizeVSAvoidgrating fabrication precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The diffractive grating and the light guide structure are merged into an integrated component, with the grating formed directly on or within the light guide. This merging eliminates the need for separate alignment of grating and sensor arrays, significantly reducing the overall module size while managing manufacturing precision requirements through integrated fabrication processes rather than assembly of multiple precision components.

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 solution provides a compact, cost-efficient method for detecting spectral components of light, enhancing the analysis of optical radiation characteristics and preventing interference, suitable for various applications including spectrometry and imaging.

Implementation Method 1

The light guide has a diffractive grating that includes multiple sections, each of which is tuned to a respective wavelength or narrow band of wavelengths

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

multiple photosensitive elements, each of which is arranged to receive light diffracted by a respective one of the sections of the diffractive grating

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3191815B1Light sensor modules and spectrometers including an optical grating structure
Publication Date: 2019.12.04 HEPTAGON MICRO OPTICS PTE LTD
  • EP3191815B1 patent drawingFigure 1
  • EP3191815B1 patent drawingFigure 2
  • EP3191815B1 patent drawingFigure 3

AI summary

An optoelectronic module includes a light guide arranged to receive light, such as ambient light or light reflected by an object. The light guide has a diffractive grating that includes multiple sections, each of which is tuned to a respective wavelength or narrow band of wavelengths. The module further includes multiple photosensitive elements, each of which is arranged to receive light diffracted by a respective one of the sections of the diffractive grating. The module can be integrated, for example, as part of a spectrometer or other apparatus for optically determining characteristics of an object.