Tx/Rx Aperture Sharing Element for Open-Loop Optical Pointing
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Solution Overview
Problem
Gimbaled optical sensors used in guided munitions and autonomous vehicles face challenges in controlling pointing without relying on measuring and locating the active signal return, especially when combining passive and active systems, as existing systems often require closed-loop feedback from active signal returns for accurate targeting.
Innovation Solution
The optical sensor design incorporates a common Tx/Rx telescope with an off-gimbal aperture sharing element (ASE) that blocks the return of active signals, allowing only passive emissions to reach the detector, enabling open-loop pointing control using passive returns, and uses dichroic or polarization beam splitters to separate active and passive signals based on wavelength or polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a common Tx/Rx telescope with ASE is used to block active signal returns, then open-loop pointing control is enabled and passive emissions detection is improved, but the ability to perform closed-loop active signal tracking is lost
Solution Approach 1:
The optical path is segmented into separate channels using wavelength division. The ASE separates active signal wavelengths from passive emission wavelengths, directing them to different detection paths. This allows the system to selectively block active signal returns while preserving passive emissions detection, enabling open-loop pointing control without losing the ability to detect passive target characteristics.
Solution Approach 2:
The Aperture Sharing Element (ASE) acts as an intermediary component in the common Tx/Rx aperture. It mediates between the transmitted active signal and the received passive emissions by selectively filtering and directing different wavelength components. This intermediary enables the system to maintain a single aperture while achieving separate functional paths for active and passive operations.
2Measurement precision
If an ASE is positioned in the common Tx/Rx aperture to separate wavelength bands, then passive emissions can be detected across multiple wavelengths, but the transmitted active signal wavelength must be blocked from reaching the detector
Solution Approach 1:
The common Tx/Rx telescope and aperture serve multiple functions: transmitting active signals, receiving passive emissions across multiple wavelengths, and enabling both open-loop and potential closed-loop operation modes. The ASE provides universal wavelength separation functionality that supports various detection and control modes without requiring separate dedicated optical paths for each function.
Solution Approach 2:
The system uses spectral copying where the ASE creates separate optical copies for different wavelength bands. The active signal wavelength is copied to a separate path that can be blocked or processed independently, while passive emission wavelengths are copied to the detection path. This spectral copying enables multi-wavelength passive detection without interference from the active signal.
3Ease of operation
If open-loop pointing control is used without measuring active signal return, then the system can operate without closed-loop feedback, but pointing accuracy may be reduced compared to closed-loop systems
Solution Approach 1:
The system uses passive target emissions to self-correct and verify pointing accuracy without requiring active signal return feedback. The detector captures passive emissions from the target area, and the system automatically processes this information to maintain accurate pointing. This self-service approach enables open-loop operation to function with accuracy comparable to closed-loop systems by utilizing available passive target information.
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 configuration enables effective open-loop pointing control and target detection without the need for active signal feedback, maintaining high image quality and optical performance, suitable for use in guided munitions and autonomous vehicles.
Implementation Method 1
The ASE free-space couples the optical transmit signal from the off-gimbal access point into the free-space optical path and to the common Tx/Rx telescope
Implementation Method 2
uses dichroic or polarization beam splitters to separate active and passive signals based on wavelength or polarization
Implementation Method 3
A common Tx/Rx telescope mounted on the inner gimbal along the optical axis collects light from the target to form an intermediate image
Implementation Method 4
An off-gimbal detector responsive to a band of wavelengths e.g. Visible or IR (SWIR, MWIR, NIR, LWIR, etc.)
Data Source
AI summary
Optical sensors and particularly gimbaled optical sensors transmit an active signal at a given wavelength and receive passive signals over a range of wavelengths while controlling pointing without benefit of measuring and locating the active signal return. The sensor includes a Tx/Rx Aperture Sharing Element (ASE) is configured to block the received active signal (e.g. reflections off a target in a scene) and process only the passive emissions. These optical sensors may, for example, be used with guided munitions or autonomous vehicles.