Gimbaled Optical Sensor ASE Layout for Passive-Only Signal Detection
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Solution Overview
Problem
Existing gimbaled optical sensors face challenges in integrating active and passive capabilities without relying on closed-loop feedback from active signal returns, which are often distorted and difficult to measure accurately.
Innovation Solution
A gimbaled optical sensor design that transmits an active signal at a specific wavelength and receives passive emissions across a range of wavelengths, using an off-gimbal aperture sharing element (ASE) to block active signal returns and process only passive emissions, enabling open-loop pointing control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common Tx/Rx telescope is used to transmit active signals and receive passive emissions, then the device complexity is reduced, but the measurement precision of active signal returns deteriorates due to distortion and difficulty in accurate measurement
Solution Approach 1:
The optical system is segmented into separate transmit and receive paths using a beam splitter. The transmit path directs the active signal through the common telescope, while the receive path separately collects passive emissions and blocked active returns. This segmentation allows the system to maintain structural simplicity while improving measurement precision by isolating the detection path from transmit signal interference.
2Adaptability or versatility
If active signal returns are used for closed-loop pointing control, then the adaptability of the system is improved, but the reliability deteriorates due to distorted and difficult-to-measure active returns
Solution Approach 1:
A beam splitter acts as an intermediary element that separates the active signal returns from the passive emissions while directing both to appropriate detectors. This intermediary allows the system to maintain closed-loop pointing control capability by providing reliable active return data, while simultaneously enabling passive imaging functionality without the reliability issues caused by signal distortion in the detection path.
3Measurement precision
If an ASE is positioned in the receive path to separate wavelength bands, then the measurement precision of passive emissions is improved, but the device complexity increases due to additional optical elements
Solution Approach 1:
The beam splitter is designed to perform multiple functions: it separates active signal returns from passive emissions, directs different wavelength bands to appropriate detectors, and maintains the common telescope architecture. This multi-functionality improves passive emission detection precision while minimizing the increase in device complexity by using a single optical element for multiple purposes.
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
Enables effective passive imaging and target detection without closed-loop feedback, maintaining high optical performance and image quality, suitable for guided munitions and autonomous vehicles.
Implementation Method 1
An aperture sharing element (ASE) is positioned in a receive aperture to separate the incident light into different wavelength bands e.g. Visible and IR and direct the light to different detectors
Implementation Method 2
A telescope mounted on the inner gimbal along the optical axis collects light from the target to form an intermediate image
Implementation Method 3
An off-gimbal optical source e.g., a laser, emits light in a narrowband around a specified wavelength
Data Source
Figure 1A~1B
Figure 2
Figure 3
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.