Optically-Steered RF Imaging Receiver for Sub-Pixel Resolution
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Solution Overview
Problem
RF imaging receivers, particularly those using sparse phased arrays, lack the angle-angle location precision required for certain applications due to limited resolution, which is less than traditional optical imaging receivers and cannot provide sub-pixel resolution.
Innovation Solution
An optically-steered RF imaging receiver using photonic spatial beam processing is configured to convert received RF signals into modulated optical signals, with an optical beam steerer inducing individual phase delays to steer the composite optical signal, allowing for precise beam steering and improved resolution by varying the relative effective path lengths or refractive indices of the modulated optical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RF imaging receivers use sparse phased arrays, then device complexity is reduced, but measurement precision deteriorates due to limited angle-angle location precision
Solution Approach 1:
The patent replaces electronic beam steering with optical beam steering. An optical beam steerer uses optical components (such as spatial light modulators or prism pairs) to steer the optical beam that carries the RF signal information. This optical steering mechanism provides finer control over beam direction and enables sub-pixel resolution, thereby improving angle-angle location precision without requiring a denser RF antenna array, thus maintaining low device complexity.
Solution Approach 2:
The patent employs a hybrid RF-optical system that combines RF phased array technology with optical beam steering technology. The RF signals are modulated onto optical carriers, and the optical beams are steered using optical components. This composite approach leverages the advantages of both domains: the RF domain for wide bandwidth and the optical domain for precise beam control, achieving high measurement precision with a sparse array configuration.
2Measurement precision
If traditional optical imaging receivers are used, then measurement precision is improved, but device complexity increases compared to RF imaging receivers
Solution Approach 1:
The patent replaces traditional optical imaging receivers with an RF-to-optical conversion system. Instead of using complex optical imaging components to achieve high precision, the system converts RF signals to optical signals and uses optical beam steering to achieve the desired precision. This substitution simplifies the overall system by using a sparse RF array combined with optical steering, rather than requiring a full optical imaging receiver architecture.
3Device complexity
If RF imaging receivers lack sub-pixel resolution capability, then device complexity is reduced, but measurement precision deteriorates for applications requiring high location accuracy
Solution Approach 1:
The patent introduces optical beam steering to enable sub-pixel resolution in RF imaging receivers. The optical beam steerer can precisely control the beam direction and focus, allowing the system to achieve sub-pixel resolution by steering the optical beam to sub-pixel positions on the detector. This optical control mechanism provides the fine resolution capability without requiring a denser RF array, thus maintaining device simplicity while achieving high measurement precision.
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 angle-angle location precision and resolution of RF imaging receivers, enabling sub-pixel resolution and addressing the limitations of existing RF imaging systems by leveraging optical beam steering for precise focusing and wavefront correction.
Implementation Method 1
an optical beam steerer is configured to act on the individual modulated optical signals to induce individual phase delays that produce a phase delay with a linear term across a two-dimensional wavefront of the composite optical signal to steer the composite optical signal
Implementation Method 2
Detector optics are configured to focus the composite optical signal into a spot on an optical detector array to form an image of the RF scene
Implementation Method 3
The received RF signals from each of the plurality of antenna elements are electronically amplified via low noise amplifiers (LNAs) and modulated onto an optical carrier to generate a plurality of modulated optical signals
Data Source
AI summary
An RF imaging receiver using photonic spatial beam processing is provided with an optical beam steerer that acts on the individual modulated optical signals to induce individual phase delays that produce a phase delay with a linear term, and possibly spherical or aspherical terms, across a two-dimensional wavefront of the composite optical signal to steer the composite optical signal and move the location of the spot on the optical detector array. The optical beam steerer may change the path length or a refractive index for each of the modulated optical signals to induce the requisite phase delays. The optical beam steerer may be implemented, for example, with a Risley prism or liquid crystal or MEMs spatial light modulator.