Spectral Camera Sensor Array With Integrated Fabry-Perot Filters

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Solution Overview

Problem

Current hyperspectral cameras face challenges in achieving high spatial and spectral resolution due to limitations in sensor array utilization, crosstalk between optical channels, and the need for physical barriers, which restricts the size of projected image copies and increases acquisition time.

Innovation Solution

The integration of thin film Fabry-Perot filters and an optical duplicator with lenses, eliminating the need for physical barriers between sensor elements, allows for larger image copies and improved light throughput, enabling higher resolution and flexible reconfiguration of image projections without crosstalk, and facilitating snapshot imaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If physical barriers are used to prevent crosstalk between adjacent optical channels, then crosstalk is reduced, but sensor area utilization decreases and image copy size is restricted

Engineering Contradiction:
Improvecrosstalk reductionVSAvoidsensor area utilization
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent replaces physical mechanical barriers with an optical filtering solution. Instead of using opaque walls between sensor elements, the invention integrates wavelength-selective filters that allow light of specific wavelengths to pass through while blocking other wavelengths. This substitution eliminates the need for physical barriers that block light, thereby increasing sensor area utilization while maintaining channel isolation through spectral separation rather than spatial separation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the isolation parameter from spatial separation (physical barriers) to spectral separation (wavelength filtering). By assigning different spectral passbands to adjacent optical channels, the system achieves channel isolation without requiring physical walls. This parameter change allows the sensor array to be fully utilized for capturing image copies across different spectral bands rather than having inactive barrier regions between channels.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If physical barriers are placed between sensor elements, then crosstalk is prevented, but acquisition time increases due to restricted image copy size

Engineering Contradiction:
Improvecrosstalk preventionVSAvoidacquisition time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces physical mechanical barriers with an optical filtering solution. Instead of using opaque walls between sensor elements, the invention integrates wavelength-selective filters that allow light of specific wavelengths to pass through while blocking other wavelengths. This substitution eliminates the need for physical barriers that block light, thereby increasing sensor area utilization while maintaining channel isolation through spectral separation rather than spatial separation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates multiple spectral copies of the same spatial scene simultaneously across the sensor array. Each sensor element captures an image copy filtered to a specific wavelength band, allowing parallel acquisition of spectral information without temporal sequencing. This copying approach enables the entire spectral cube to be captured in a single exposure rather than requiring sequential scanning, dramatically reducing acquisition time.

Inventive Principle:
Principle #26Copying

3Measurement precision

If pixels are made smaller to improve spatial resolution, then spatial resolution increases, but signal-to-noise ratio decreases due to lower energy capture

Engineering Contradiction:
Improvespatial resolutionVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent adds a spectral dimension to the imaging system, transforming it from a 2D spatial sensor to a 3D spectral-spatial sensor. By capturing information across multiple wavelength bands, the system compensates for the reduced signal per pixel in smaller pixels. The spectral redundancy provides additional information that improves overall measurement precision and reliability, allowing smaller pixels to achieve adequate signal-to-noise ratios through spectral integration rather than requiring large pixel areas.

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

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 configuration enhances spatial and spectral resolution, reduces acquisition time, and allows for more efficient use of sensor area, enabling the capture of hyperspectral data cubes with improved accuracy and detail.

Implementation Method 1

integration of thin film Fabry-Perot filters

Methodology Applied
Scientific EffectFabry-Perot interference: Fabry-Perot Interferometer

Implementation Method 2

optical duplicator with lenses, allows for larger image copies and improved light throughput

Methodology Applied
Scientific EffectOptical imaging: Lens

Implementation Method 3

array of sensors arranged to simultaneously detect the filtered image copies

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP2776798B1Spectral camera with integrated filters and multiple adjacent image copies projected onto sensor array
Publication Date: 2023.12.13 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)
  • EP2776798B1 patent drawingFigure 1
  • EP2776798B1 patent drawingFigure 2
  • EP2776798B1 patent drawingFigure 3~4

AI summary

A spectral camera for producing a spectral output has an objective lens (10) for producing an image, an optical duplicator (20), an array of filters (30) and a sensor arrays (40) arranged to detect the filtered image copies simultaneously on different parts of the sensor array. A field stop (50) defines an outline of the image copies projected on the sensor array. The filters are integrated on the sensor array, which has a planar structure without perpendicular physical barriers for preventing cross talk between each of the adjacent optical channels. The field stop enables adjacent image copies to fit together without gaps for such barriers. The integrated filters mean there is no parasitic cavity causing crosstalk between the adjacent image copies. This means there is no longer a need for barriers between adjacent projected image copies, and thus sensor area can be better utilised.