Lensless Imaging Phase Grating for Infrared Sensor Cost Reduction
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Solution Overview
Problem
Conventional image sensors require expensive lenses, particularly in infrared imaging systems, where the cost of IR lenses scales with the cube of their linear size, making them costly and large.
Innovation Solution
Integration of an optical phase grating with a photodetector array that produces an interference pattern, eliminating the need for a lens by using a phase grating to capture intensity and spatial-frequency information, which can be processed to recover images, thereby reducing the size and cost of image sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lens is used in infrared imaging systems, then image quality is maintained, but the size and cost increase significantly
Solution Approach 1:
The patent removes the lens component from the infrared imaging system entirely, extracting only the essential function of light modulation. The phase grating directly modulates incoming infrared light to create an interference pattern that encodes image information, eliminating the need for separate lens and sensor components while maintaining imaging capability.
Solution Approach 2:
The phase grating structure serves multiple functions simultaneously: it acts as both the optical element for focusing light and the modulating element for creating the interference pattern. This multi-functional design replaces what would traditionally require separate lens and aperture components, reducing overall system complexity while preserving image quality.
2Measurement precision
If lens size is increased to improve image quality, then resolution improves, but cost scales with the cube of linear size
Solution Approach 1:
The patent replaces expensive, precision-manufactured infrared lenses with a phase grating structure that can be fabricated using standard semiconductor manufacturing techniques. This approach uses inexpensive materials and processes to achieve the optical function, dramatically reducing manufacturing cost while maintaining adequate resolution through computational processing.
Solution Approach 2:
The invention changes the fundamental parameter from lens diameter (which scales cost cubically) to grating period and fill factor, which can be adjusted through standard photolithography processes. By controlling the phase modulation depth and grating geometry rather than lens size, the system achieves resolution improvement without the associated cubic cost increase.
3Device complexity
If a phase grating is used instead of a lens, then size and cost are reduced, but image resolution may be compromised
Solution Approach 1:
The patent introduces computational processing as an intermediary between the phase grating and the final image output. The raw interference pattern from the grating is processed using algorithms that decode the encoded information and reconstruct the image, compensating for the lower optical resolution and achieving high-quality images despite the simplified optical path.
Solution Approach 2:
The system combines the phase grating optical element with computational algorithms to create a composite imaging system. The grating provides the physical modulation of light while the computational component provides the information processing and image reconstruction, together achieving resolution performance that neither component could achieve alone.
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 the construction of smaller and more cost-effective imaging devices that can capture high-resolution images without the need for traditional lenses, while maintaining the ability to process and recover useful image data.
Implementation Method 1
The phase grating produces an interference pattern that is unintelligible to a human observer, but that nevertheless includes intensity and spatial-frequency information
Implementation Method 2
The phase grating produces an interference pattern... that includes intensity and spatial-frequency information that can be processed to recover an image
Data Source
AI summary
An optical phase grating produces an interference pattern rich in intensity and spatial-frequency information from the external scene. The grating includes an odd number of repeated sets of adjacent horizontal portions, separated by steps, that fill an area that radiates outward from a central region. At a given distance from the central region and within the area of the phase grating, each of the first horizontal portions is of a first width that differs from a second width of the adjacent second horizontal portions. The interference patterns produced by the grating can be processed to extract images and other information of interest about an imaged scene.