Multispectral Imaging Filter Wheel Synchronization

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing multispectral step-and-stare imaging techniques face challenges with multiple cameras or fixed spectral filters, which increase volume, weight, and cost, while limiting flexibility and image overlap for complete area coverage.

Innovation Solution

A multispectral image capture device using a filter wheel with n spectral filters covering the entire imaging area, synchronized with the image sensor's capture rate and the movement of the imaging platform, allowing for high-speed, high-resolution imaging with overlapping frames.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple cameras are used to capture different spectral wavelengths, then multispectral imaging capability is improved, but device volume, weight, and cost increase

Engineering Contradiction:

Improvemultispectral imaging capabilityVSAvoiddevice volume, weight, and cost

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple spectral filtering functions into a single camera system by using a filter wheel mechanism that sequentially blocks different spectral wavelengths through a single lens and sensor assembly, eliminating the need for multiple separate cameras while maintaining multispectral imaging capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single camera system is designed to perform multiple spectral imaging functions by rotating through different spectral filters, making the imaging device universal across different spectral bands without requiring separate dedicated cameras for each wavelength range

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If fixed spectral filter strips are applied onto a single focal plane array, then multispectral imaging is enabled, but system flexibility is limited

Engineering Contradiction:

Improvemultispectral imaging capabilityVSAvoidsystem flexibility

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent replaces fixed spectral filter strips with a dynamically rotatable filter wheel that can be controlled to present different spectral filters at different times, allowing flexible switching between spectral bands during the imaging process and enabling adaptive control over which wavelengths are captured

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The filter wheel rotates periodically to sequentially present different spectral filters to the image sensor, creating a time-multiplexed spectral imaging system that maintains flexibility by controlling the timing and sequence of filter presentation during the imaging cycle

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If filter wheel rotates at variable speed to synchronize with image capture, then imaging precision is improved, but system complexity increases

Engineering Contradiction:

Improvesynchronization precisionVSAvoidcontrol system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The filter wheel rotates at a constant velocity throughout the imaging process, maintaining continuous and uniform motion that simplifies control while achieving precise synchronization through timing control of the image capture rate to match the constant rotational speed

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system achieves synchronization through the inherent relationship between the constant rotational speed of the filter wheel and the capture rate of the image sensor, where the timing is self-regulating and does not require complex external control mechanisms to maintain precision

Inventive Principle:

Principle #25Self-service

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

Enables high-frequency, high-resolution multispectral imaging with sufficient overlap for post-processing combination, improving flexibility and reducing system size and cost compared to traditional methods.

Implementation Method 1

a drive system configured to rotate the filter wheel at a constant velocity so as to bring each of the spectral filters into a line of sight between the image sensor and the imaging target

Methodology Applied

Scientific EffectConstant velocity rotation:

Implementation Method 2

an image sensor comprising a photosensitive surface

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS20250203180A1Multispectral step-and-stare imaging with single sensor

Publication Date: 2025.06.19 RAFAEL ADVANCED DEFENSE SYST LTD

AI summary

A multispectral image capture device includes an imaging platform having arranged thereon an image sensor comprising a photosensitive surface and an optical unit, a gimbals system for controlling a line of sight of the image sensor, a filter wheel comprising a series of n spectral filters arranged between the image sensor and an imaging target; and a drive system configured to rotate the filter wheel at a constant velocity so as to bring each of the spectral filters into a line of sight between the image sensor and the imaging target. A controller is adapted to synchronize movement of the imaging platform, control of line of sight of the image sensor with the gimbals, and constant rotation of the filter wheel, such that the image sensor captures a sequence of overlapping step-and-stare images through the series of rotating spectral filters without changing a speed of rotation of the filter wheel.