Ring-Shaped ASE for Gimbaled Optical Sensor Aperture Sharing
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Solution Overview
Problem
Gimbaled optical sensors face challenges in effectively combining active and passive signal processing, particularly in maintaining image quality and achieving precise pointing control for guided munitions and autonomous vehicles, due to the divergence of active signal beams and the need for separate apertures for different wavelength bands.
Innovation Solution
The implementation of a Tx/Rx Aperture Sharing Element (ASE) with an annular and center region, coupled with beam shaping elements like Axicon lenses or MEMS MMA, to form a ring-shaped energy distribution for active signals, which is corrected to maintain focus and couple both active and passive signals through a common aperture, enabling precise imaging and guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common Tx/Rx telescope is used for both transmit and receive functions, then device complexity is reduced, but image quality deteriorates due to the divergence of active signal beams and interference between active and passive signals
Solution Approach 1:
The aperture sharing element is segmented into distinct functional regions: an annular region for active signal transmission and a central region for passive signal reception. This segmentation allows each region to be optimized for its specific function while sharing the same telescope, thereby maintaining image quality without requiring separate telescopes for transmit and receive operations.
Solution Approach 2:
Different regions of the aperture sharing element have different optical properties tailored to their specific functions. The annular region is designed with characteristics optimized for active signal transmission, while the central region is optimized for passive signal reception. This local differentiation enables high-quality imaging for both active and passive modes within a single shared telescope system.
2Manufacturing precision
If separate apertures are used for active and passive signals, then image quality is maintained, but device complexity increases due to multiple apertures and wavelength separation requirements
Solution Approach 1:
The patent merges the active and passive signal paths by using a single common aperture through the aperture sharing element. This element simultaneously handles both active transmit signals and passive receive signals, eliminating the need for separate apertures and reducing overall device complexity while maintaining image quality through its segmented regional design.
Solution Approach 2:
The aperture sharing element is designed as a multi-functional component that serves dual purposes: it acts as a transmit aperture for active signals and a receive aperture for passive signals. This universal component replaces what would traditionally require separate dedicated apertures, thereby simplifying the device while preserving imaging performance.
3Use of energy by moving object
If laser energy is transmitted directly without beam shaping, then energy efficiency is improved, but image quality deteriorates due to poor energy distribution and divergence
Solution Approach 1:
The beam shaping element performs preliminary shaping of the laser energy into a ring-shaped distribution before the energy enters the aperture sharing element. This pre-shaping action ensures that the energy is optimally distributed across the annular region, preventing divergence and maintaining focus, thereby achieving both energy efficiency and high image quality in the active transmit function.
Data Source
AI summary
Optical sensors and particularly gimbaled optical sensors transmit an active signal at a given wavelength(s) and receive passive signals over a range of wavelengths and the active signal in a common aperture. The sensor includes a Tx/Rx Aperture Sharing Element (ASE) configured with an annular region that couples an active signal having a ring-shaped energy distribution to the telescope for transmission and a center region that couples the passive emissions and the returned active signal to the detector. A beam shaping element such as an Axicon lens, LCWG, Risley Prism, Unstable Optical Resonator or MEMS MMA may be used to form or trace the ring-shaped active signal onto the annular region of the ASE. A focusing optic may be used to reduce the divergence of the active signal so that it is collimated or slightly converging when transmitted such that the returned active signal approximates a spot. A filter wheel may be positioned behind the ASE to present separate passive and active images to the detector. These optical sensors may, for example, be used with guided munitions or autonomous vehicles.