Off-Axis Beam Director With Auto-Alignment Wavefront Correction
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Solution Overview
Problem
Conventional beam directors for high-power laser systems face challenges in accurately tracking moving objects and correcting for wavefront errors due to atmospheric disturbances and optical aberrations, particularly in on-axis telescope designs which are obscured and less effective at high laser powers.
Innovation Solution
A high-performance beam director is developed, incorporating a wavefront sensor and an auto-alignment system with a telescope and fast steering mirrors. This system estimates wavefront errors and adjusts the line-of-sight to compensate for internal and external disturbances, using auto-alignment illumination to correct internal line-of-sight errors without requiring a separate beacon laser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If on-axis telescope design is used, then the beam director can be compact and easy to manufacture, but the secondary mirror and its support structures are illuminated by high-power laser beams causing damage or performance degradation
Solution Approach 1:
The patent extracts the harmful secondary mirror and its support structures from the optical path by using an off-axis telescope design. This removes the component that was being damaged by high-power laser illumination, allowing the system to operate at high powers without compromising the secondary mirror.
Solution Approach 2:
The patent employs asymmetric off-axis telescope geometry where the optical axis is deliberately offset from the telescope's central axis. This asymmetric configuration allows the primary mirror to illuminate the target without the secondary mirror intercepting the high-power beam, resolving the damage issue while maintaining compact design.
2Device complexity
If on-axis telescope design is used, then the telescope structure is simplified, but the central obscuration reduces the effectiveness of focused beams on remote objects
Solution Approach 1:
The patent removes the central obscuration problem by extracting the secondary mirror from the center of the optical path. The off-axis configuration eliminates the blocking effect that reduced beam effectiveness, allowing full aperture utilization for focusing energy on remote objects.
Solution Approach 2:
The asymmetric off-axis design positions the secondary mirror laterally offset from the optical axis, eliminating central obscuration. This allows the full aperture of the primary mirror to contribute to beam focusing, significantly improving energy delivery effectiveness to remote targets.
3Measurement precision
If a separate beacon laser is used for wavefront sensing, then wavefront error estimation can be performed, but the system complexity and cost increase
Solution Approach 1:
The patent merges the wavefront sensing function with the existing illuminator laser by using a beam splitter to direct a portion of the illuminator's output to the wavefront sensor. This eliminates the need for a separate beacon laser, reducing system complexity while maintaining wavefront error estimation capability.
Solution Approach 2:
The illuminator laser is given multiple functions: it serves both as the primary illumination source for the target and as the reference source for wavefront sensing. This multi-functionality eliminates redundant components and simplifies the overall system architecture.
4Measurement precision
If auto-alignment system is added to correct internal line-of-sight errors, then tracking precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements a self-aligning system where the wavefront sensor detects internal misalignments and automatically corrects them using controllable optical elements. The system serves itself by detecting and correcting its own alignment errors, improving tracking precision without requiring external alignment equipment.
Solution Approach 2:
The auto-alignment system uses feedback from the wavefront sensor to continuously monitor and correct internal line-of-sight errors. The sensor provides real-time information about alignment deviations, and controllable optical elements adjust the optical path to compensate, maintaining high tracking precision dynamically.
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 solution enables precise tracking and focusing of high-power laser beams on moving objects, effectively correcting for wavefront errors and maintaining high-performance beam direction without the need for additional lasers or complex systems, thus reducing size, weight, cost, and power requirements.
Implementation Method 1
receive coherent flood illumination that is reflected from a remote object
Implementation Method 2
generate auto-alignment illumination that passes through the telescope, is reflected off a mirror, and returns through the telescope
Data Source
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AI summary
An apparatus includes a wavefront sensor (109, 111, 203-208, 210-214, 305-309, 402-404) configured to receive coherent flood illumination (105) that is reflected from a remote object (101) and to estimate wavefront errors associated with the coherent flood illumination. The apparatus also includes a beam director (202, 215, 410-422, 802, 804) optically coupled to the wavefront sensor and having a telescope (215, 406-408) and an auto-alignment system (202). The auto-alignment system is configured to adjust at least one first optical device (410-422, 802, 804) in order to alter a line-of-sight of the wavefront sensor. The wavefront errors estimated by the wavefront sensor include a wavefront error resulting from the adjustment of the at least one first optical device. The beam director could further include at least one second optical device (410-422, 802, 804) configured to correct for the wavefront errors. The at least one second optical device could include at least one deformable mirror.