Photonic Integrated Circuit Interferometer Array for Space Imaging
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Solution Overview
Problem
Traditional electro-optical imaging systems are hindered by large optics, stiff structures, and thermal control requirements, leading to high size, weight, and power (SWaP) costs that scale with the optical telescope aperture diameter, making them costly and inefficient for space-based applications.
Innovation Solution
A non-traditional imaging detector system utilizing a densely packed interferometer array based on photonic integrated circuit (PIC) technologies that samples light in the spatial-frequency domain, reconstructs images, and processes broadband light using lenslets, waveguides, and array waveguide gratings, reducing the need for large optics and complex alignment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electro-optical imaging systems use large optics and stiff structures to maintain precision free-space optical alignments, then imaging precision is improved, but size, weight, and power (SWaP) increase significantly
Solution Approach 1:
The patent replaces the traditional mechanical optical telescope system with a photonic integrated circuit (PIC) based interferometer array. Instead of using large physical optics and stiff mechanical structures to maintain alignment, the system uses integrated photonic waveguides and beam combiners fabricated on a chip. This substitution of mechanical alignment systems with integrated photonic circuits dramatically reduces weight while maintaining imaging precision through the interferometric measurement of spatial frequencies.
Solution Approach 2:
The patent transitions from direct spatial imaging to spatial-frequency domain imaging. Instead of forming images directly in the spatial domain using large optics, the system measures the visibility function (spatial frequencies) using an interferometer array and then reconstructs the image computationally. This dimensionality change from spatial domain to spatial-frequency domain allows precision imaging with a compact PIC-based system rather than requiring large physical optics.
2Measurement precision
If traditional electro-optical imaging systems use large optics to achieve high resolution, then imaging resolution is improved, but cost and manufacturing complexity increase
Solution Approach 1:
The patent replaces complex mechanical optical systems with photonic integrated circuits that can be manufactured using standard semiconductor fabrication processes. The interferometer array, beam combiners, and waveguides are all fabricated using CMOS-compatible processes, enabling high-volume, low-cost production. This eliminates the need for precision mechanical assembly and alignment of large optical components, dramatically simplifying manufacturing while achieving high imaging resolution.
Solution Approach 2:
The patent changes the fundamental operating parameters from visible/near-infrared continuous wave optics to telecom wavelength (1550 nm) pulsed laser operation. This parameter change enables the use of mature telecom photonic components and fabrication processes, significantly reducing manufacturing complexity and cost compared to traditional EO imaging systems that require specialized optics and assembly procedures.
3Measurement precision
If traditional electro-optical imaging systems use precision free-space optical alignments to maintain performance, then imaging fidelity is improved, but thermal control requirements and power consumption increase
Solution Approach 1:
The patent replaces free-space optical alignment systems with integrated photonic circuits where light propagates through confined waveguides. This eliminates the need for thermal control of large optical structures and precision mechanical alignment mechanisms. The PIC-based interferometer array maintains imaging fidelity through integrated phase control and beam combining, dramatically reducing power consumption by eliminating thermal control systems and precision alignment mechanisms.
Solution Approach 2:
The patent merges multiple optical functions (beam combining, phase modulation, signal detection) into a single integrated photonic circuit chip. Instead of separate components requiring individual thermal control and alignment, all functions are integrated on one chip with unified thermal management. This merging dramatically reduces the total power requirement for thermal control while maintaining imaging fidelity through the interferometric measurement process.
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 approach significantly reduces SWaP by at least an order of magnitude, enabling high-resolution imaging with lower mass and cost, suitable for space-based surveillance and compact designs like cubesats, while maintaining high imaging fidelity.
Implementation Method 1
The lenslets can couple light from an object with a respective plurality of waveguides on a PIC
Implementation Method 2
an array waveguide grating (AWG) built into the PIC card that can be configured to split light into spectral bins
Implementation Method 3
a plurality of interferometers arranged in a plane so as to measure at least one of an amplitude and a phase of a visibility function
Implementation Method 4
the complex spatial coherence of the object (for each field angle, frequency, and baseline) can be measured with a balanced four quadrature detection scheme
Data Source
AI summary
An imaging system can include of a plurality of pairs of lenslets and a respective plurality of two-dimensional arrays of photonic waveguides arranged in a respective plurality of photonic integrated circuits. Each waveguide can collect light in an airy-disk-size bin to cover a full field of view of the lenslet. Light from each pair of respective waveguides from each pair of lenslets can be demultiplexed into wavelength bins and combined with appropriate phase shifts to enable a measurement of the complex visibility. The complex visibilities from all of the measurements then can be processed to form an image.