Off-axis Reflective Transmit Telescope for DIRCM Dome Aberration
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Solution Overview
Problem
Current DIRCM systems face challenges in effectively countering MANPADS threats, particularly when missiles are launched from close range or in simultaneous attacks, due to limitations in detecting and jamming infrared seekers, and existing technologies do not adequately address the distortion issues caused by the off-axis mounting of transmit telescopes through the aircraft dome.
Innovation Solution
An off-axis reflective transmit telescope is designed for DIRCM systems, featuring a reflective optical assembly with an off-axis mirror segment and a second optical element that precompensates the laser beam for dome aberrations, allowing the optical port and folding mirrors to be positioned without obscuring the reflected laser beam, thus maintaining beam collimation and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the transmit telescope is mounted off-axis from the optical axis of the receive telescope, then the laser beam transmission path is separated from the detection path to avoid backscatter, but optical distortion and aberrations are introduced through the dome
Solution Approach 1:
The patent employs an off-axis reflective transmit telescope design where the transmit telescope is deliberately positioned off the optical axis of the receive telescope. This asymmetric mounting separates the laser transmission path from the detection path, preventing backscatter from the laser beam from entering the detector while accepting the resulting optical distortion through the dome as a trade-off that is managed through conformal optics
Solution Approach 2:
The patent uses conformal optics (multi-element on-axis refractive optics) to compensate for the optical distortion introduced by the off-axis mounting through the dome. By adjusting and optimizing the parameters of the conformal optics system, the distortion is minimized while maintaining the benefits of the off-axis configuration
2Device complexity
If the transmit telescope is mounted off-axis, then the optical path is simplified to avoid backscatter, but the system complexity increases due to the need for conformal optics to minimize distortion
Solution Approach 1:
The off-axis mounting of the transmit telescope creates an asymmetric optical path that simplifies the system by eliminating the need for beam separation mechanisms while avoiding backscatter. This asymmetric configuration, combined with conformal optics, manages the distortion issue without requiring overly complex optical arrangements
Solution Approach 2:
The conformal optics system serves multiple functions: it minimizes distortion through the dome, maintains beam quality, and works seamlessly with the off-axis mounting configuration. This multi-functional approach reduces overall system complexity by combining several optical correction functions into a unified subsystem
3Productivity
If the optical port and folding mirrors are positioned to accommodate off-axis mounting, then the laser beam can be transmitted effectively, but the positioning becomes more complex to avoid obscuring the reflected beam
Solution Approach 1:
The patent positions the optical port and folding mirrors in three-dimensional space to accommodate the off-axis mounting configuration. By utilizing spatial arrangement in multiple dimensions, the design achieves effective laser beam transmission while avoiding component obscuration, transforming a two-dimensional layout problem into a three-dimensional spatial solution
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 enhances the DIRCM system's ability to transmit a collimated laser beam effectively through the dome, improving its agility and capability to counter near-simultaneous MANPADS threats by minimizing distortion and maintaining high throughput across multiple wavelengths.
Implementation Method 1
a reflective optical assembly that reflects the laser beam through the dome
Implementation Method 2
a second optical element that together precompensate the laser beam for dome aberrations
Data Source
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AI summary
An off-axis reflective transmit telescope for a DIRCM system is mounted on the gimbal along a transmit-axis offset laterally from the optical axis of the receive telescope but nominally aligned with the line-of-sight of the receive telescope to transmit a laser beam. The telescope comprises an optical port optically coupled to a laser to receive and direct the laser beam away from the dome and a reflective optical assembly that reflects the laser beam through the dome. The reflective optical assembly comprises an off-axis mirror segment and a second optical element that together precompensate the laser beam for dome aberrations induced by the lateral offset of the transmit telescope's transmit axis from the optical axis. The off-axis mirror segment comprises a segment of a parent mirror having an aspheric curvature (e.g. parabolic, elliptical or higher-order asphere) about an axis of symmetry. The segment is offset so that it is not centered on the axis of symmetry of the parent mirror. The use of the off-axis mirror segment allows the optical port and any folding mirror to be positioned so that they do not obscure the reflected laser beam. The second optical element may be a segment of a dome corrector parent lens, a prism or a refractive lens formed on the front surface of the off-axis mirror segment.