Laser Spot Stabilization via Image Warping Turbulence Correction
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Solution Overview
Problem
High-energy laser beams are affected by atmospheric turbulence, causing deflection and profile changes that degrade their impact on distant targets, and existing methods for stabilization are impaired by surface brightness variations and require additional equipment.
Innovation Solution
A method and device that use an illumination beam to create images of the target, which are compared with stored or previous images using image warping techniques to predict and correct for turbulence effects, allowing for precise stabilization of the high-energy laser beam without the need for wavefront sensors or guide stars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional turbulence detection methods (guide stars, tip-tilt laser spots) are used, then turbulence can be detected, but additional sensors and transmitters are required, increasing device complexity
Solution Approach 1:
The illumination device serves dual purposes: it illuminates the target for imaging while simultaneously enabling turbulence detection through the captured image data. The same optical path and image acquisition device used for target observation are also used for turbulence measurement, eliminating the need for separate detection equipment.
Solution Approach 2:
The system uses its own illumination beam and image acquisition system to detect turbulence affecting the high-energy laser beam. By analyzing the temporal variations in the illuminated target image, the system self-diagnoses the turbulence conditions without external assistance.
2Measurement precision
If image processing methods (center of gravity, four-quadrant detector) are used for stabilization, then target position can be tracked, but temporal variations in surface brightness are interpreted as virtual turbulent tip/tilt motion, generating additional noise
Solution Approach 1:
The system employs dynamic image warping techniques that adapt to temporal variations in target surface brightness. By continuously updating the reference image and using correlation methods, the system distinguishes between actual turbulence-induced image distortions and brightness variations, filtering out false signals.
Solution Approach 2:
The system implements feedback control by continuously comparing the current illuminated target image with a reference image, detecting deviations caused by turbulence, and adjusting the beam direction accordingly. This closed-loop control compensates for turbulence effects while filtering out noise from brightness variations.
3Power
If the radiation spot is stabilized on a moving target, then laser power concentration is maximized, but atmospheric turbulence causes the radiation spot to shift across the target, reducing the effect
Solution Approach 1:
The system performs preliminary turbulence detection by analyzing the illuminated target image before the high-energy laser beam is affected. By detecting tip-tilt components in advance and predicting future turbulence effects, the system can pre-adjust the beam direction to compensate for upcoming deviations, maintaining spot stability on moving targets.
Solution Approach 2:
The illuminated target image serves as an intermediary medium that carries information about atmospheric turbulence. By analyzing distortions in this intermediate image, the system infers turbulence conditions affecting the laser beam and applies appropriate corrections, indirectly measuring beam path conditions through target image analysis.
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 enables effective turbulence estimation and compensation, increasing the active power on the target and reducing irradiation time by using image processing to predict and correct for turbulence, thus maximizing laser energy delivery.
Implementation Method 1
The propagation of high-energy laser beams in the atmosphere is subject to turbulent disturbances caused by temperature fluctuations and the resulting slight variations in the air's refractive index
Implementation Method 2
temperature fluctuations and the resulting slight variations in the air's refractive index
Implementation Method 3
the analysis of the captured image is carried out using at least one image warping method, for which a template image is used
Implementation Method 4
these disturbances result in a local deflection of the high-energy laser beam (the so-called tip/tilt component)
Data Source
Figure 1
Figure 2~3
AI summary
A method for locally stabilizing a radiation spot (S) on a distant target object (Z), wherein the radiation spot (S) is formed by a high-energy laser beam (L) directed onto the target object (Z) by a high-energy radiator (1), and wherein the target object (Z) is illuminated by an illumination beam (B) directed onto the target object (Z) by an illumination device (2), is characterized in that: - radiation (B') reflected from the target object (Z) illuminated by the illumination beam (B) is received by an image acquisition device (3); - the radiation (B') reflected from the target object (Z) to the image acquisition device (3) travels through the same optical path (P) as the high-energy laser beam (L);- that the image of the illuminated target object (Z) or part of the illuminated target object captured by the image acquisition device (3) is analyzed and compared with at least one image of the illuminated target object (Z) or part of the illuminated target object generated at a previous time or with an image stored in an object database; - that, based on this comparison, a correction signal is determined, which is applied to an optical correction device (12) arranged in the optical path (P) traversed jointly by the high-energy laser beam (L) and the reflected radiation (B').