Local Stabilization of Laser Radiation Spot via Image Analysis
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Solution Overview
Problem
High energy laser beams used for remote target destruction are affected by atmospheric turbulence, leading to deflection and non-linear changes in the radiation spot, which impairs the target image and stabilization, especially with extended targets and non-homogeneous illumination, causing noise and blurring that conventional methods fail to adequately compensate.
Innovation Solution
A method and device that utilize an image acquisition device to analyze and compare images of the target object with prior images or a database, generating correction signals for an optical correction device to stabilize the radiation spot by compensating turbulence effects without additional sensors, using a combination of filter and fine tracking controller to predict and correct displacement, thereby minimizing noise and contouring errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image processing methods (center of gravity, four quadrant detector) are used for stabilization, then the radiation spot can be stabilized to some extent, but temporal variations in surface brightness are interpreted as virtual turbulent tip-tilt movement, producing significant noise that deteriorates stabilization
Solution Approach 1:
The patent introduces an illumination beam as an intermediary that reflects off the target object to provide a stable reference signal. This reflected illumination serves as a mediator between the target and the image acquisition device, allowing turbulence measurement without being affected by the target's own brightness variations. The illumination beam creates a known reference pattern that can be distinguished from actual target features.
2Measurement precision
If additional sensors and transmitters are used for turbulence detection (guidestars, tip-tilt laser spots, adaptive optics), then turbulence can be detected and compensated, but the device complexity increases significantly
Solution Approach 1:
The patent makes the illumination device serve multiple functions: it illuminates the target for imaging purposes while simultaneously providing a reference beam for turbulence detection. The same optical path and image acquisition device are used for both target observation and turbulence measurement, eliminating the need for separate sensors and transmitters. This multi-functionality reduces system complexity while maintaining turbulence compensation capability.
3Loss of information
If image acquisition is used to observe the target, then the radiation spot position can be monitored, but non-homogeneous temporal variation in surface brightness, speckle effects, and blurring impair the image quality and worsen stabilization
Solution Approach 1:
The patent separates the turbulence measurement function from the target imaging function. By using the reflected illumination beam specifically for turbulence detection rather than relying on target image analysis, the system segments the measurement tasks. This allows high-quality target imaging for destruction purposes while using a dedicated reference signal for precise turbulence compensation, avoiding the interference between these functions.
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 effective power of the radiation spot on the target by compensating turbulence effects in real-time, reducing radiation time and avoiding the need for complex technical wavefront measurements, while maintaining robustness against surface intensity changes and distortions.
Implementation Method 1
The propagation of high energy laser beams in the atmosphere is subject to turbulent disturbances that are caused by temperature fluctuations, and thus minor fluctuations in the refractive index of the air
Implementation Method 2
fluctuations in the refractive index of the air
Implementation Method 3
radiation reflected by the target object that is illuminated by the illumination beam
Data Source
AI summary
A method for local stabilization of a radiation spot formed by a high energy laser beam includes receiving radiation reflected by the target object, where the radiation reflected by the target object passes through the same optical path as the high energy laser beam. An image processing is performed by analyzing and comparing the image of the illuminated target object or part of the illuminated target object to at least one image of the illuminated target object or part of the illuminated target object produced at a prior point in time. A correction signal is computed, with which an optical correction device is actuated. A filter correction signal is produced by a filter device, while a controller correction signal is produced by a fine tracking controller. Finally, the correction signal is formed from the filter correction signal and the controller correction signal.