Depth Profiling via Temporal Range Gating for Standoff Detection
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Solution Overview
Problem
Existing methods for detecting concealed objects like explosives or contraband are limited in field applications due to safety concerns and the inability to safely position beam sources and detectors on opposite sides of the volume, especially in combat or civilian locations where close proximity may lead to explosion risks.
Innovation Solution
A method and apparatus using pulsed electromagnetic beams and range-gated detection windows to generate depth profiles of backscattered energy, allowing for non-contact detection of concealed objects from a safe standoff distance, utilizing a mobile unit to convey the beam source and detector to selected locations and processing the backscattered beams to determine the material composition and presence of objects within obscurants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If beam source and detector are placed close to the volume for detailed inspection, then measurement precision is improved, but safety is compromised due to explosion risk
Solution Approach 1:
The patent transitions from spatial proximity (placing source and detector close to the volume) to temporal resolution (using pulsed beams and time-gated detection). By resolving depths in the time dimension through flight-time measurements of backscattered photons, the system achieves detailed depth profiling while maintaining a safe standoff distance, thus eliminating the explosion risk associated with close placement.
Solution Approach 2:
The patent replaces the mechanical approach of physically moving the source and detector close to the volume with an optical/temporal approach using ultrafast pulsed beams and time-correlated single photon counting. This substitution allows the system to achieve high-resolution depth profiles without mechanical proximity, thereby maintaining safety while preserving measurement precision.
2Measurement precision
If beam source and detector are placed on opposite sides of the volume, then material composition profiling is improved, but ease of operation deteriorates due to inability to safely position equipment in field locations
Solution Approach 1:
The patent inverts the conventional transmission geometry (source on one side, detector on the other) by using backscattering geometry where both source and detector are on the same side of the volume. The detector collects photons that backscatter from various depths within the material, enabling composition profiling without requiring equipment placement on opposite sides, thus greatly simplifying field operations while maintaining analytical capability.
Solution Approach 2:
The patent uses the backscattered photons themselves as intermediaries that carry information from deep within the volume to the detector. Instead of requiring direct line-of-sight transmission through the entire volume, the backscattered photons act as mediators that emerge from interaction points throughout the material and can be detected from a safe distance, enabling both accurate profiling and easy field deployment.
3Measurement precision
If pulsed beam with short duration is used to achieve high depth resolution, then measurement precision is improved, but use of energy increases due to need for high peak power pulses
Solution Approach 1:
The patent employs periodic pulsed illumination with ultrafast laser pulses at appropriate repetition rates. By using short-duration pulses separated by sufficient time intervals, the system achieves high depth resolution through precise time-of-flight measurements while allowing thermal management and energy recovery between pulses, thereby balancing measurement precision with acceptable energy consumption.
Solution Approach 2:
The patent optimizes the pulse duration, repetition rate, and peak power parameters of the laser source to achieve the desired depth resolution with minimal energy consumption. By carefully selecting these parameters—using the shortest pulses necessary for the required resolution and appropriate repetition rates—the system maximizes measurement precision while minimizing overall energy usage, avoiding excessive power consumption.
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 safe and effective detection of concealed objects from a distance, providing depth profiles that indicate the presence and composition of materials within volumes, enhancing safety and practicality in various environments such as combat zones or large-scale inspections.
Implementation Method 1
receiving, at a detector or a plurality of detectors with a temporal response providing a desired range gate depth resolution, a plurality of backscattered beams generated from a plurality of depths within the volume in response to interactions of the directed pulsed beam at the plurality of depths
Implementation Method 2
performing range gating of the plurality of backscattered beams to obtain a depth profile of backscattered intensity within the volume
Data Source
AI summary
A method, apparatus and system for profiling a material composition of a volume is disclosed. A beam source directs a pulsed beam of electromagnetic energy from into the volume. A plurality of backscattered beams is received at a detector. The plurality of backscattered beams is generated from a plurality of depths within the volume in response to interactions of the directed pulsed beam at the plurality of depths. A processor performs range gating of the plurality of backscattered beams to obtain a depth profile of backscattered intensity within the volume and estimates a material composition at different depths of the volume from the generated depth profile.