Reduced Pupil Optical System Using Matched Pathlength Waveguides
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Solution Overview
Problem
Traditional optical imaging systems are limited in compactness due to the requirement of a focal length equal to the aperture size, which restricts their performance and efficiency, especially in phased array systems where beam steering and focusing are necessary.
Innovation Solution
A reduced pupil imaging system using matched pathlength combining waveguide arrays with input and output couplers, along with phase shifting systems, allows for compact optical systems with improved light collection and interference reduction, enabling precise pathlength control and field-of-view steering through micro-fabrication and active tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional lens systems are used for imaging, then the aperture size determines the focal length, but this results in large system size and reduced compactness
Solution Approach 1:
The patent creates a reduced-scale copy of the wavefront at the output coupler array, where the output couplers reproduce the incident wavefront characteristics at a smaller aperture. This copying approach allows the focal length to be decoupled from the aperture size, enabling compact system design while maintaining imaging performance.
Solution Approach 2:
The patent changes the fundamental parameter relationship between aperture and focal length by using waveguide pathlength control. Instead of focal length being determined by aperture size as in traditional lenses, the focal length is now controlled by the optical pathlengths in the waveguides, allowing independent optimization of both aperture and focal length for compact design.
2Device complexity
If the number of output couplers is reduced through combining waveguides, then integration is improved, but pathlength matching precision becomes more challenging
Solution Approach 1:
The patent merges multiple waveguide paths into combined output couplers using H-tree combining networks. This merging reduces the total number of output couplers required, improving integration and reducing device complexity while maintaining the ability to control optical paths through the combining network structure.
Solution Approach 2:
The patent incorporates trimming mechanisms and active tuning capabilities that provide feedback control for pathlength matching. These mechanisms allow precise adjustment of waveguide pathlengths after fabrication, compensating for manufacturing variations and ensuring accurate pathlength matching even as the number of output couplers is reduced.
3Adaptability or versatility
If matched pathlength waveguides are used for beam steering, then field-of-view control is improved, but device complexity increases due to pathlength control mechanisms
Solution Approach 1:
The patent implements dynamic field-of-view steering by making the waveguide pathlengths adjustable rather than fixed. Phase shifters and active tuning mechanisms allow the optical pathlengths to be dynamically changed during operation, enabling electronic beam steering and field-of-view control without mechanical movement, thus improving adaptability while managing complexity through integrated control.
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 results in a highly efficient and compact optical system capable of maintaining resolution while significantly reducing the number of output couplers, allowing for a much smaller minimum practical focal length, thus overcoming the limitations of traditional lens-based systems.
Implementation Method 1
a matched pathlength combining waveguide array including input optical couplers for receiving light, combining waveguides for combining the light received from different input optical couplers and relaying the light to output optical couplers
Implementation Method 2
combining waveguides for combining the light received from different input optical couplers
Data Source
AI summary
An imaging system comprises a matched pathlength combining waveguide array including input optical couplers for receiving light, combining waveguides for combining the light received from different input optical couplers and relaying the light to output optical couplers. A lens system is also provided for imaging the light from the output optical couplers. Compared to imaging systems, this imaging system can be much more compact. A standard imaging system requires a focal length at least equal to the aperture (width) of the lens. Because the aperture size of a lens determines the performance of a system (resolution and collected light) there is a limit to how compact a traditional high performance imaging system can be. In contrast, the present system removes that limitation because the minimum practical focal length is now determined by the size of the aperture of the outputs, which can be significantly smaller (by factors of more than 10×, typically).