Fast Steering Mirror Jitter Correction for High Energy Laser Systems
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Solution Overview
Problem
High energy laser beam propagation through the atmosphere is affected by atmospheric jitter and broadband interference, leading to reduced power on target and decreased target kill probability in tactical engagements, as well as signal-to-noise ratio degradation in laser communications and imaging systems.
Innovation Solution
A system and method utilizing fast steering mirrors and a beacon illuminator to spatially and angularly offset a high energy laser beam and a beacon illuminator beam, with a Coude path FSM simultaneously correcting for atmospheric jitter while maintaining the offset, ensuring precise pointing and separation of beams to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single beam path is used for both HEL and BIL, then system complexity is reduced, but atmospheric jitter correction becomes inaccurate due to different propagation paths
Solution Approach 1:
The optical system is segmented into separate beam paths for HEL and BIL, allowing independent optimization of each path. The BIL path is offset spatially and angularly from the HEL path, enabling separate atmospheric propagation and independent wavefront sensing, which resolves the contradiction between system simplicity and measurement accuracy.
Solution Approach 2:
A beam combining/distributing optical element acts as an intermediary that receives the BIL beam at a first location and directs it to a second location offset from the HEL beam path. This intermediary component enables spatial separation of the two beams while maintaining a unified optical system architecture.
2Ease of operation
If BIL beam is co-aligned with HEL beam, then optical alignment is simplified, but BIL signal is degraded by HEL broadband interference
Solution Approach 1:
The BIL beam is extracted from the common optical path and spatially offset from the HEL beam using steering mirrors. This separation removes the BIL signal from the region affected by HEL broadband interference while maintaining independent control of each beam's pointing and wavefront correction.
Solution Approach 2:
Different regions of the optical system are assigned different functions: the HEL beam path is optimized for high-power transmission, while the offset BIL beam path is optimized for sensitive wavefront sensing. This local differentiation allows each beam to operate in its optimal regime without mutual interference.
3Manufacturing precision
If atmospheric jitter compensation is applied to both beams separately, then pointing accuracy is maximized, but system complexity and control difficulty increase
Solution Approach 1:
The wavefront correction functions are merged into a single deformable mirror that corrects atmospheric disturbances for both HEL and BIL beams simultaneously. The tip-tilt correction is applied through a common fast steering mirror, reducing the number of independent control systems while maintaining separate beam paths for accurate atmospheric sensing.
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 effectively compensates for atmospheric jitter and broadband interference, maximizing power-on-target for high energy laser systems and improving signal-to-noise ratios in laser communications and imaging, thereby enhancing target engagement efficiency and system performance.
Implementation Method 1
atmospherically induced beam tip-tilt or jitter
Implementation Method 2
fast steering mirrors configured to receive a beacon illuminator beam and steer the beam
Implementation Method 3
correct for atmospheric jitter of the high energy laser beam and the beacon illuminator beam
Implementation Method 4
Coude path FSMs to simultaneously receive both the high energy laser beam and the BIL beam and steer the beams
Data Source
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AI summary
A system includes a high energy laser (HEL) (205) configured to transmit a HEL beam (322) aimed at a first location on an airborne target (240). The system also includes a beacon illuminator laser (BIL) (215) configured to transmit a BEL beam (320) aimed at a second location on the target, wherein the second location is offset from the first location. The system also includes at least one fast steering mirror (FSM) (302, 304) configured to steer the BIL beam to be spatially and angularly offset from the HEL beam. The system also includes at least one Coudé path FSM (312, 314) configured to simultaneously receive both the HEL beam and the BIL beam and steer the HEL beam and the BIL beam to correct for atmospheric jitter of the HEL beam and the BIL beam while maintaining the offset of the BIL beam from the HEL beam.