Heterodyne Starring Array Imager Waveguide Segmentation
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Solution Overview
Problem
Current imaging technologies lack small, inexpensive, power-efficient, eye-safe, and solid-state active imagers that provide range-gated imagery unaffected by bright sunlit backgrounds, and are not capable of multi-spectral, real-time imagery with high sensitivity, especially in poor atmospheric conditions.
Innovation Solution
The implementation of a heterodyne starring array active imager (HSAAI) using continuous wave laser diodes as illuminators and waveguide components for efficient heterodyne sensing, which separates light collection from photo detection, and employs a novel means of gating the optical receiver to reduce noise and speckle, allowing for high signal-to-noise ratio and multi-pulse imaging with uniform illumination across ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional active imaging systems are used, then they can provide range-gated imagery, but they are affected by bright sunlit backgrounds and produce speckle noise
Solution Approach 1:
The invention segments the detection process by separating signal collection from photo detection through waveguide components. Each pixel's returned light is guided through individual waveguides to heterodyne detection elements, allowing selective frequency mixing that rejects broad-spectrum background light while preserving the modulated signal.
Solution Approach 2:
The invention changes the detection parameter from direct intensity measurement to heterodyne frequency mixing. By modulating the illuminator and detecting only at the modulated frequency through heterodyne mixing, the system achieves immunity to bright sunlit backgrounds that contain unrelated frequency components.
2Object-affected harmful factors
If heterodyne detection with narrowband illuminators is used, then background immunity is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts the spectral filtering function from external optical cavities and integrates it into compact waveguide components at each pixel. The waveguides inherently provide spatial and spectral selectivity, eliminating the need for separate external optical cavities while maintaining narrowband detection capabilities.
Solution Approach 2:
The invention nests multiple functions within the waveguide structure: light collection, spatial filtering, spectral filtering, and guidance to detection elements all occur within the integrated waveguide component, reducing overall system complexity despite the advanced detection capability.
3Use of energy by moving object
If continuous wave laser diodes are used as illuminators, then power efficiency and eye safety are improved, but spectral bandwidth control becomes more difficult
Solution Approach 1:
The invention replaces the mechanical/optical cavity system used for spectral control with electrical modulation of continuous wave laser diodes. The spectral bandwidth is controlled through the modulation process rather than physical cavity constraints, enabling easier tuning and integration with heterodyne detection.
4Measurement precision
If external optical cavities are used to tailor illuminator spectrum, then spectral precision is improved, but device size and cost increase
Solution Approach 1:
The invention extracts the spectral precision function from large external optical cavities and implements it through compact waveguide structures integrated at each pixel. The waveguides provide inherent spatial and spectral selectivity without requiring bulky external cavity assemblies.
Solution Approach 2:
The invention transitions from controlling spectrum through one-dimensional cavity length adjustments to utilizing the spatial dimension of waveguide propagation. The waveguide geometry and coupling conditions provide spectral selectivity through spatial confinement rather than longitudinal cavity resonance, reducing overall device volume.
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 HSAAI provides speckle-free, high signal-to-noise ratio imagery over extended range gates, improved performance in bright backgrounds, and enhanced ability to penetrate scattering media like fog and smoke, while being compact, power-efficient, and cost-effective.
Implementation Method 1
Each light collection site contains waveguide components for guiding and combining light fields
Implementation Method 2
Heterodyne detection of active radiation in a starring imager configuration
Implementation Method 3
detected with a CCD, CMOS or focal plane array (FPA) detector
Data Source
AI summary
A heterodyne starring array active imager for producing an image. The imager comprises a light source and a component for segregating the light into frequency bands, each band intermittently illuminating a region of a scene and an array of light collecting sites, each comprising: a coupling component optically coupling scene light into a first waveguide and a local oscillator light coupled into a second waveguide. First and second waveguides coupled to a third waveguide with scene light and local oscillator light propagating into the third waveguide. A square law photo detector at each light collecting site receives the merged light for heterodyning the scene light and the local oscillator light. Components receive and process the heterodyned light from the photo detectors to produce a frame signal for each light collecting site. A read-out device produces an array signal responsive to the frame signal from each light collecting site.