Multi-spectral Camera Using Segmented Microlens Array

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Solution Overview

Problem

Existing multi-spectral cameras face challenges in achieving high spatial, spectral, and temporal resolution simultaneously due to complexity, cost, size, weight, power consumption, and reliability issues, particularly when capturing moving images or requiring adaptable spectral resolution.

Innovation Solution

A multi-spectral camera design that includes a user-input controlled microlens array and image sensor positioning, allowing for instantaneous image capture without sequential scanning or filter changes, using a conventional image sensor with a dedicated configuration of a main lens, micro-lens array, and dispersive element to generate detailed multi-spectral images through post-processing, enabling flexible trade-offs between spatial and spectral resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sequential scanning with dispersive element is used, then spectral resolution is improved, but temporal resolution and reliability deteriorate

Engineering Contradiction:
Improvespectral resolutionVSAvoidreliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The camera divides the sensor into multiple spectral bands, with each band having dedicated microlenses that focus specific wavelength ranges onto corresponding sensor regions. This segmentation allows simultaneous capture of multiple spectral bands without sequential scanning, improving both reliability and temporal resolution while maintaining spectral resolution.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent adds a spectral dimension to the traditional 2D sensor by incorporating microlens arrays that spatially encode spectral information. Each pixel group captures light from different spectral bands, transforming the imaging process from capturing only spatial information to capturing both spatial and spectral information simultaneously in a single exposure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If variable spectral filter is used, then spectral resolution is improved, but light efficiency and temporal resolution deteriorate

Engineering Contradiction:
Improvespectral resolutionVSAvoidlight efficiency
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Instead of using a single variable filter that blocks most light, the patent segments the optical path into multiple fixed spectral bands, each with dedicated microlenses. This allows all spectral bands to be captured simultaneously without blocking light, dramatically improving light efficiency while maintaining spectral resolution.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The microlens arrays are pre-configured to focus specific wavelength ranges onto corresponding sensor regions before the light reaches the sensor. This preliminary spectral sorting eliminates the need for sequential filtering, allowing all spectral information to be captured in a single exposure without light loss.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If high spectral resolution is achieved through sequential methods, then measurement precision is improved, but productivity and temporal resolution deteriorate

Engineering Contradiction:
Improvespectral resolutionVSAvoidtemporal resolution
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The sensor is divided into multiple spectral bands with dedicated microlenses for each band. This segmentation enables simultaneous capture of all spectral bands in a single exposure, achieving high spectral resolution without sequential scanning, thereby improving temporal resolution and productivity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The camera captures all spectral bands continuously in a single exposure rather than sequentially. The microlens arrays ensure that light from all spectral bands reaches the sensor simultaneously, maintaining continuous capture of spectral information without interruption or time delay between bands.

Inventive Principle:
Principle #20Continuity of useful action

4Measurement precision

If scanning mechanism is implemented, then spectral resolution is improved, but device complexity and size increase

Engineering Contradiction:
Improvespectral resolutionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The camera uses static microlens arrays segmented into multiple spectral bands rather than a single movable scanning mechanism. This segmentation eliminates the need for complex scanning hardware while maintaining spectral resolution, significantly reducing device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical scanning system with a static optical system using microlens arrays. Instead of mechanically moving components to capture different spectral bands, the microlenses optically separate and focus different wavelength ranges onto corresponding sensor regions, eliminating mechanical complexity.

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

This approach enables high temporal and spatial resolution while reducing complexity, cost, size, and power consumption, allowing for simultaneous local spectral information capture, making it suitable for capturing moving objects or video with improved reliability and flexibility.

Implementation Method 1

a dispersive element which separates incident light in a wavelength dependent manner into different directions

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

a microlens array which receives light from the lens and distributes light onto the image sensor, each microlens in the array receiving light at an identical angle

Methodology Applied
Scientific EffectOptical focusing: Lens

Data Source

PatentEP2464952B1Multi-spectral imaging
Publication Date: 2018.10.10 KONINKLIJKE PHILIPS NV
  • EP2464952B1 patent drawingFigure 1
  • EP2464952B1 patent drawingFigure 2
  • EP2464952B1 patent drawingFigure 3

AI summary

A multi-spectral camera comprises a blocking element (201) having at least one hole (203) allowing light to pass through. A dispersive element (205) spreads light from the at least one hole (203) in different wavelength dependent directions and a lens (207) focuses light from the dispersive element (205) on an image plane (209). A microlens array (211) receives light from the lens (207) and an image sensor (213) receives the light from the microlens array (211) and generates a pixel value signal which comprises incident light values for the pixels of the image sensor (213). A processor then generates a multi-spectral image from the pixel value signal. The approach may allow a single instantaneous sensor measurement to provide a multi-spectral image comprising at least one spatial dimension and one spectral dimension. The multi- spectral image may be generated by post-processing of the sensor output and no physical filtering or moving parts are necessary.