Lensless Laser Imager Using Diffraction for Wearable Threat Detection
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Solution Overview
Problem
Existing laser detection systems are too large, heavy, and costly for wearable personal protection, lacking the ability to rapidly identify laser threats from broadband light sources.
Innovation Solution
A compact, lightweight laser detection device using diffraction optics with planar surfaces and semiconductor fabrication, employing an image sensor array, diffraction gratings, and control logic to identify laser wavelength and direction without conventional lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional refractive optical systems with large curved lenses are used, then wide field-of-view laser detection is achieved, but device size and weight increase making it unsuitable for wearable applications
Solution Approach 1:
The patent replaces conventional refractive optical systems (curved lenses, reflectors) with a lensless diffraction-based system. The diffraction grating creates angularly-resolved spectra directly on the sensor array, eliminating the need for heavy curved optical components while maintaining wide field-of-view capability through computational analysis of diffraction patterns.
Solution Approach 2:
The system changes the fundamental optical parameter from refraction-based imaging to diffraction-based spectral encoding. By using a diffraction grating instead of curved lenses, the system achieves wide field-of-view through the angular dependence of diffraction orders, mapping different incident angles to different positions on the sensor array.
2Reliability
If conventional laser detection systems are used, then accurate laser detection is achieved, but cost and complexity increase making it unacceptable for personal protection
Solution Approach 1:
The patent replaces complex conventional laser detection systems with a simplified lensless diffraction system. The diffraction grating combined with standard image sensor array and computational algorithms provides accurate laser detection without requiring complex optical benches, alignment mechanisms, or specialized detectors.
Solution Approach 2:
The system uses a diffraction grating that simultaneously provides spatial encoding (angular information) and spectral encoding (wavelength information) on a single sensor array. This multi-functional approach eliminates the need for separate components for different detection functions, reducing overall system complexity.
3Adaptability or versatility
If broadband light sources are present, then environmental monitoring is achieved, but laser identification becomes difficult due to light source confusion
Solution Approach 1:
The patent applies local quality analysis by examining the specific spatial-spectral signature of each light source in the field-of-view. The diffraction pattern's angular and spectral characteristics are analyzed locally to distinguish laser sources from broadband sources, with each source's diffraction order distribution providing unique identification information.
Solution Approach 2:
The system exploits the wavelength-dependent diffraction angles to create spectral separation. Lasers produce sharp, well-defined diffraction orders at specific wavelengths, while broadband sources produce continuous spectra. The control logic processor analyzes these spectral differences to accurately identify laser sources even in the presence of broadband illumination.
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
Accurately distinguishes laser light from broadband sources, providing rapid and reliable personal laser threat detection at a lower cost and size, enabling wearable applications.
Implementation Method 1
a diffraction grating disposed in each of the incident light paths and configured to form, on the image sensor array, for each corresponding light source, a light pattern having at least a zeroth diffraction order and a first diffraction order of light from the light source
Data Source
AI summary
An apparatus for characterization of one or more light sources, has an image sensor array that defines an image plane having an imaging area. An aperture spaced apart from the image plane defines the field of view that includes, for each of the one or more light sources, a corresponding incident light path that lies along a central ray beginning at the corresponding light source, extending through a center of the aperture, and terminating at the image plane. A diffraction grating forms, on the image sensor array, for each corresponding light source, a light pattern having at least a zeroth diffraction order and a first diffraction order, wherein the zeroth diffraction order is a geometrical projection of the aperture along the central ray. A control logic processor identifies a wavelength range and angular direction within the field of view for at least one of the light sources.