Active Multispectral Imaging With Amplitude-Modulated Narrowband Light
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Solution Overview
Problem
Existing remote sensing technologies face limitations due to atmospheric interference and ambient illumination conditions, which affect the accuracy of multispectral and hyperspectral imaging, particularly in terrestrial and aquatic environments, and cannot capture wavelength-dependent reflectance information across the full visible optical spectrum.
Innovation Solution
An active multispectral imaging system using a transmitter to emit amplitude-modulated narrowband light and a receiver to capture and decode reflectance data, enabling self-calibration and reconstruction of multispectral or hyperspectral images, as well as 3D characterization of objects, without requiring prior knowledge of the color band order or synchronization with the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If passive remote sensing using Sun's reflected radiation is used, then material identification through spectral analysis is enabled, but measurement accuracy deteriorates due to atmospheric absorption and ambient illumination limitations
Solution Approach 1:
The patent introduces an active illumination source as an intermediary between the sensor and target. This controlled light source emits known spectral signatures that penetrate the atmosphere and reflect off the target, allowing the sensor to measure reflectance without being affected by atmospheric absorption of ambient sunlight. The intermediary active source bypasses the harmful atmospheric filtering effect.
Solution Approach 2:
The system changes the parameter of illumination control by using amplitude-modulated narrowband light sources with known spectral characteristics. By actively controlling the illumination parameters (wavelength, intensity, modulation pattern) rather than passively relying on solar radiation, the system achieves accurate reflectance measurements independent of atmospheric conditions and ambient illumination.
2Adaptability or versatility
If active remote sensing using RADAR or LiDAR is used, then independence from ambient illumination conditions is achieved, but wavelength-dependent reflectance information across the full visible optical spectrum is lost
Solution Approach 1:
The active illumination source is segmented into multiple narrowband channels, each emitting at a specific wavelength across the visible and near-infrared spectrum. This segmentation allows the system to independently control and measure reflectance at different wavelengths, recovering the spectral information that would be lost in broadband active sensing while maintaining independence from ambient illumination.
Solution Approach 2:
The active multispectral illumination system serves multiple functions simultaneously: it provides controlled illumination independent of ambient conditions, enables wavelength-dependent reflectance measurement across the visible spectrum, and allows for material identification through spectral analysis. This multi-functional approach combines the advantages of passive and active sensing.
3Measurement precision
If narrowband filters are applied over sensor arrays to detect reflectance in tens of spectral bands, then material identification is enabled, but the system remains limited by atmospheric interference and ambient illumination spectrum
Solution Approach 1:
Instead of using narrowband filters to select wavelengths from ambient sunlight (passive approach), the system inverts the approach by using narrowband light sources to emit controlled wavelengths directly at the target. This active inversion bypasses atmospheric filtering of solar radiation and enables spectral measurement in bands that may be absorbed by the atmosphere, achieving both precision and adaptability.
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 system achieves efficient, radiometrically calibrated, high signal-to-noise ratio active multispectral imaging across multiple channels, allowing for accurate material identification and 3D reconstruction, even in challenging environments like deep sea or space, with the ability to dynamically change color bands and intensities in real-time.
Implementation Method 1
Light emitting diodes (LEDs), laser sources, and quantum dot LEDs are examples of sources that emit narrowband light
Implementation Method 2
The receiver includes a camera or digital sensor configured to capture image data from a scene
Data Source
AI summary
Provided is a system and method for active multispectral imaging having a transmitter that uses narrowband optical radiation to dynamically illuminate an object with modulated structured light in multiple spectral bands, and a receiver that includes an independent panchromatic imager. The transmitter and receiver can be operated in a bistatic decoupled configuration to enable passive multispectral synthesis, illumination-invariant sensing, optical communications, and the ability for the transmitter to emit a sequence of spectral bands in an order that is unknown to the receiver, and the receiver is able to passively decode the spectral identity from a band identifier embedded in the modulated structured light. The receiver passively decodes embedded high-bandwidth simplex communications while reconstructing calibrated multispectral images at video frame rates.