Telescope Wavefront Control via Segmented Mirrors
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Solution Overview
Problem
Modern high-energy laser applications face challenges in maintaining imaging performance and focusing accuracy across various target ranges due to the degradation of wavefront error when adjusting focus away from the nominal design point in Mersenne-style telescope designs with a moving secondary mirror.
Innovation Solution
A telescope design featuring a primary mirror, a secondary mirror moving along a first linear axis, and a tertiary mirror moving along a second linear axis in synchronized motion, combined with an anamorphic deformable mirror and a fast steering mirror to achieve wavefront control and correction of optical aberrations, while avoiding intermediate images and maintaining boresight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single secondary mirror is moved in multiple axes to focus the laser beam, then the telescope can focus high-energy laser at range, but the wavefront error degrades when focusing away from the nominal design point
Solution Approach 1:
The patent divides the single secondary mirror into two separate mirrors: a secondary mirror for focusing along the optical axis and a tertiary mirror for fine wavefront control. This segmentation allows each mirror to be optimized for its specific function, enabling focus adjustment while maintaining wavefront precision across multiple ranges
Solution Approach 2:
The patent adds a new dimension of control by introducing the tertiary mirror that moves perpendicular to the optical axis, while the secondary mirror moves along the optical axis. This dimensional separation allows independent optimization of focus range and wavefront precision without mutual interference
2Adaptability or versatility
If the secondary mirror is moved along the optical axis to adjust focus, then the laser can be focused at different ranges, but beam walk occurs on the primary mirror
Solution Approach 1:
The fast steering mirror acts as an intermediary component that compensates for beam walk by making rapid angular adjustments. It mediates between the focus-adjusting secondary mirror and the primary mirror, maintaining beam pointing accuracy on the primary mirror while allowing focus adjustment at different ranges
Solution Approach 2:
The system uses wavefront sensing to detect beam walk and provides real-time feedback control through the fast steering mirror and deformable mirror, continuously correcting pointing accuracy and wavefront errors as the secondary mirror is repositioned for different target ranges
3Adaptability or versatility
If a moving secondary mirror design is used, then the telescope can focus laser at range, but the device complexity increases
Solution Approach 1:
By segmenting the focusing function between secondary and tertiary mirrors, each with simpler single-axis movement, the overall system complexity is reduced compared to moving a single mirror in multiple axes, while maintaining the same focus capability
Solution Approach 2:
The system uses dynamic wavefront control through the deformable mirror and fast steering mirror to compensate for the added mechanical complexity, allowing the mirrors to be moved along simple linear axes while maintaining optical performance through real-time adaptive adjustments
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 design achieves excellent on-axis wavefront error across target ranges, particularly at closer ranges, with reduced root mean square wavefront error and controlled beam walk, enabling high-energy laser focus and imaging performance from 0.3 km to infinity.
Implementation Method 1
a primary mirror configured to receive and reflect electromagnetic radiation along an optical path
Implementation Method 2
a secondary mirror configured to receive electromagnetic radiation from the primary mirror and to reflect electromagnetic radiation along the optical path
Implementation Method 3
a tertiary mirror configured to receive electromagnetic radiation from the secondary mirror and to reflect electromagnetic radiation along the optical path
Implementation Method 4
an anamorphic deformable mirror configured to achieve wavefront control and correction of optical aberrations
Implementation Method 5
a fast steering mirror configured to reflect electromagnetic radiation from the deformable mirror to an off-axis parabolic objective
Data Source
AI summary
A telescope includes a primary mirror, a secondary mirror configured to move along a first axis, and a tertiary mirror configured to move along a second axis. The secondary and tertiary mirrors are configured to move along respective axes in a synchronized manner to focus a beam of electromagnetic radiation from the primary mirror. The telescope further may include an anamorphic deformable mirror configured to achieve wavefront control and correction of optical aberrations. The telescope further may include a first linear actuator configured to move the secondary mirror along the first axis and a second linear actuator configured to move the tertiary mirror along the second axis.