Hidden Object Imaging via Scattering Surface Interference
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Solution Overview
Problem
Image sensing technologies are limited in detecting objects hidden from view, as they typically require line-of-sight and rely on scattering surfaces, which may not provide practical information diversity, especially in situations where movement of the scattering surface is not feasible.
Innovation Solution
An imaging system utilizing a narrow-band light source, beam splitters, and frequency modulators to create an illumination and probe beam, which interferes with scattered light to generate an interference pattern on a scattering surface, allowing a lock-in camera to detect and calculate the complex-valued light field representing the hidden object, enabling the recovery of its geometry or image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image sensing devices are optimized for line-of-sight operations, then measurement precision for visible objects is improved, but the ability to detect hidden objects deteriorates
Solution Approach 1:
The patent introduces a scattering surface as an intermediary between the light source and the hidden object. This scattering surface redirects light to illuminate objects that are not directly visible, enabling the imaging system to detect hidden objects without requiring direct line-of-sight while maintaining measurement precision through controlled light scattering and temporal gating
2Adaptability or versatility
If scattering surfaces are used to illuminate hidden objects, then hidden object detection is enabled, but device complexity increases due to required surface movements
Solution Approach 1:
The patent employs temporal gating and time-resolved detection to dynamically separate scattered light from direct light based on their different arrival times. This dynamic temporal filtering eliminates the need for mechanical movement of scattering surfaces, reducing device complexity while maintaining the ability to detect hidden objects
Solution Approach 2:
The patent replaces mechanical movement of scattering surfaces with optical and temporal methods. By using ultrashort laser pulses and time-correlated single photon counting, the system achieves hidden object detection without mechanical actuators, simplifying the overall system configuration
3Loss of information
If light scattering is exploited to recover hidden object information, then information recovery is enabled, but loss of information increases due to noise and signal degradation
Solution Approach 1:
The patent uses periodic modulation of the light source at specific frequencies and employs lock-in detection to recover hidden object information. The periodic action allows the system to distinguish the scattered signal from background noise through frequency discrimination, maintaining measurement precision while enabling information recovery from scattered light
Solution Approach 2:
The patent implements feedback through time-correlated single photon counting and histogram analysis. By continuously monitoring photon arrival times and adjusting the detection window based on measured flight time distributions, the system optimizes signal-to-noise ratio and recovers hidden object information with high precision despite information loss in scattering
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 the detection and recovery of hidden objects by isolating latent information from corrupting noise, using the scattering surface as a virtual detector to sense the obscured object's information, even when the object is behind a diffuser or opaque barrier.
Implementation Method 1
Technologies for sensing hidden objects normally rely on a scattering surface, such as a wall to scatter light that can illuminate the hidden objects
Implementation Method 2
the probe beam may interfere with the light field and create a first interference pattern on a second scattering surface
Implementation Method 3
The frequency modulator may shift the temporal frequency of at least one of the first beam or the second beam
Implementation Method 4
a lock-in camera may detect an irradiance of the interference pattern, monitor temporal variations of the irradiance caused by the temporal frequency shift introduced by the frequency modulator, and identifies a complex-valued light field that represents information of the hidden object
Data Source
AI summary
The present disclosure describes an imaging system, method, and apparatus for identifying a latent image of a hidden object. A light source generates a first beam of narrow-band light and a second beam of narrow-band light that has temporal fluctuations correlated with the first beam. A frequency modulator shifts a temporal frequency of at least one of the first beam or the second beam. The first beam is directed towards a first scattering surface and the second beam is directed towards a second scattering surface. The first scattering surface scatters the first beam to a scattered light that illuminates a hidden object. The hidden object reflects at least a portion of the scattered light towards the second scattering surface, the reflected light interferes with the second beam and produces an interference pattern on the second scattering surface. A lock-in camera detects an irradiance of the interference pattern, monitors temporal variations of the irradiance caused by the temporal frequency shift introduced by the frequency modulator, and identifies a complex-valued light field that represents information of the hidden object based on the temporal variations of the irradiance.