Frequency Agile Ladar Backscatter Noise Suppression
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Solution Overview
Problem
Photon counting LADAR sensors face performance limitations due to atmospheric optical backscatter noise, which increases with range and can blind the sensor, limiting its operational range and accuracy in detecting targets.
Innovation Solution
A frequency agile LADAR system that uses a tunable transmitter and receiver to hop between optical frequencies, blocking backscatter noise and reducing range ambiguity by ensuring the optical frequency of the last transmitted pulse is different from the received signal, thereby enhancing optical isolation and reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon counting LADAR uses high laser pulse energy to detect targets at long ranges, then the detection capability is improved, but the atmospheric optical backscatter noise increases and can blind the sensor
Solution Approach 1:
The patent changes the optical frequency parameter of the laser transmitter dynamically. By hopping between different optical frequencies for transmitted pulses and tuning the receiver to match only the expected return frequency, the system distinguishes target returns from backscatter noise that remains at the original transmit frequency, thereby improving target detection capability while suppressing backscatter interference
Solution Approach 2:
The patent converts the harmful backscatter noise into a useful frequency discrimination mechanism. By intentionally using frequency offset between transmitted and received signals, the system makes backscatter noise at the original frequency distinguishable from target returns at the shifted frequency, effectively turning the harmful noise into a separable signal component
2Reliability
If LADAR operates at a fixed optical frequency, then the system simplicity is maintained, but the ability to distinguish target returns from backscatter noise is limited
Solution Approach 1:
The patent introduces dynamic frequency tuning capability to the LADAR system. The transmitter dynamically changes optical frequency between pulses, and the receiver dynamically tunes its detection frequency to match the expected return. This dynamic behavior enables reliable signal discrimination while managing complexity through coordinated frequency hopping rather than continuous sweeping
Solution Approach 2:
The frequency agile components (transmitter and receiver) serve multiple functions: they enable both long-range target detection and backscatter noise suppression using the same frequency hopping mechanism. The ability to operate at multiple frequencies provides universal adaptability to different detection scenarios while maintaining a unified system architecture
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 frequency agile LADAR system effectively attenuates backscatter noise, increases operational range, and improves the ability to detect targets by minimizing interference from atmospheric and internal backscattered photons, allowing for more accurate 3D imaging.
Implementation Method 1
a laser transmitter that generates an optical waveform
Implementation Method 2
a frequency agile optical filter to transmit light at a specific optical frequency
Implementation Method 3
a photon sensitive imaging receiver to detect the light collected by the receive optics
Data Source
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AI summary
In one aspect, a frequency agile LADAR (laser detection and ranging) sensor includes a transmitter configured to provide laser pulses towards a target, a receiver configured to receive a reflected signal from the target and control circuitry configured to tune an optical frequency of a first laser pulse of the laser pulses to be different from an optical frequency of a second laser pulse of the laser pulses and tune an optical frequency of the receiver to be different than an optical frequency of a laser pulse most recently transmitted by the transmitter.