Ladar 3D Imaging Phase Compensation for Target Acquisition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LADAR systems face limitations in spatial coverage and target acquisition time due to the narrow beam angle and sensitivity to signal-to-noise ratios, which can result in lengthy search times and potential misses of fast-moving targets.
Innovation Solution
A LADAR system with a laser transmitter modulated by a frequency, using a receiver with isothermal contours and a plurality of lenses optically connected to detectors, where calibration reflections are used to measure relative phase shifts and apply phase compensation for target reflections, allowing for parallel operation and improved target detection and tracking within a volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LADAR uses tightly collimated narrow LASER energy for detection, then measurement precision is improved, but area of stationary object deteriorates
Solution Approach 1:
The receiver is divided into multiple detector elements (e.g., 4x4 array) with associated optical paths, allowing simultaneous detection across multiple spatial zones. Each detector element processes a specific portion of the illuminated volume, enabling parallel measurement that increases both precision and coverage area
Solution Approach 2:
The patent transitions from single-point detection to volumetric detection by adding spatial dimensions through multiple detector elements arranged in arrays. This dimensional expansion allows the system to cover larger solid angles while maintaining the precision of individual detector measurements through coherent processing
2Reliability
If LADAR emits multiple pulses for redundant detection, then reliability is improved, but loss of time worsens
Solution Approach 1:
A calibration reflector is positioned in the illuminated volume before actual target detection begins. This preliminary calibration establishes reference phase relationships and signal characteristics, allowing the system to achieve reliable detection with fewer subsequent pulses since the statistical properties are pre-characterized
Solution Approach 2:
Multiple detector elements operate continuously in parallel, constantly monitoring the illuminated volume. This continuous multi-point detection maintains reliable signal acquisition without requiring repeated pulsed illumination, as the parallel detectors provide ongoing coverage of the entire detection volume
3Device complexity
If LADAR uses single detector for target detection, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The receiver is segmented into multiple detector elements with associated optical paths, where each detector processes a specific spatial zone. This segmentation enables parallel measurement of different portions of the illuminated volume, improving overall detection precision through spatial diversity while keeping individual detector elements relatively simple
Solution Approach 2:
Multiple detector elements are combined through coherent processing that integrates their outputs. The phase relationships between detectors are maintained and processed together, merging the information from multiple simple detectors to achieve the precision equivalent to a single complex detector while distributing the hardware complexity across multiple simpler components
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 approach enhances the spatial coverage and reduces target acquisition time by enabling phase compensation, thereby improving the efficiency and accuracy of target detection and tracking in LADAR systems.
Implementation Method 1
a laser transmitter for illuminating said volume with a laser beam modulated with a frequency
Implementation Method 2
Each of the detectors mix the incoming optical input from its associated lens with a signal from the local oscillator
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A LADAR system for coherently imaging a target within a volume has a mod¬ ulated laser transmitter at a frequency and a receiver. The receiver has a plurality of lenses, each with its own detector. Each detector is supplied by a centrally located local oscillator tuned to the frequency. The paths from the local oscillator to each detector, as well as the delay within each lens/detector combination are measured during a calibration. A calibrating reflector reflects a test signal during the calibra¬ tion at many frequencies, temperatures and accelerations. Measurements of paths and delays obtained during the calibration are stored, and used to phase compensate subsequent target reflections for coherent processing.