Wavelength-Dependent Optical Element for Compact Hyperspectral Imaging
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Solution Overview
Problem
Hyperspectral cameras face challenges with large size due to long optical path lengths and scanning mechanisms in line scan-type cameras, and complex optical systems with multi-stage lithography in compressive sensing-type cameras, leading to high manufacturing costs and restrictions on light transmittance and F-number.
Innovation Solution
An imaging device with a transparent substrate and structured optical element that outputs light with a different point spread function for each wavelength, using a simple device configuration and compressive sensing to reconstruct hyperspectral images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a line scan-type hyperspectral camera uses a spectroscopic element for wavelength separation, then measurement precision of wavelength spectrum is improved, but device complexity and size increase due to long optical path length and scanning mechanism
Solution Approach 1:
The imaging sensor is divided into multiple pixel groups, where each pixel group corresponds to a specific wavelength band. This segmentation allows simultaneous capture of different wavelength regions without requiring mechanical scanning or complex spectroscopic elements, thereby reducing device complexity while maintaining wavelength measurement capability
Solution Approach 2:
The patent transitions from temporal scanning (one-dimensional time-based acquisition) to spatial parallel acquisition (two-dimensional pixel array). By arranging pixels to simultaneously capture different wavelength bands in space, the system eliminates the need for scanning mechanisms and long optical paths while preserving spectral information
2Measurement precision
If a line scan-type hyperspectral camera performs multiple photographing operations for scanning, then measurement precision of wavelength spectrum is improved, but productivity decreases due to low temporal resolution
Solution Approach 1:
The imaging sensor continuously captures hyperspectral information across all wavelength bands simultaneously in a single shot, eliminating the need for sequential scanning operations. This continuous parallel acquisition maintains high temporal resolution while preserving spectral accuracy
Solution Approach 2:
The pixel array is segmented into multiple pixel groups, each dedicated to capturing specific wavelength bands. This segmentation enables simultaneous multi-band acquisition without temporal sequencing, achieving both high temporal resolution and spectral precision
3Device complexity
If a compressive sensing-type hyperspectral camera uses multi-stage diffraction optical element, then device complexity is reduced, but manufacturing precision becomes more difficult due to multi-stage lithography requirements
Solution Approach 1:
The patent extracts the wavelength separation function from complex multi-stage diffraction optical elements and implements it through a simpler pixel group arrangement on the imaging sensor. This extraction eliminates the need for multi-stage lithography while maintaining the essential spectral discrimination capability
Solution Approach 2:
The invention replaces expensive, precision-critical multi-stage diffraction optical elements with a more affordable pixel array configuration. The simpler manufacturing process using standard lithography makes the system more cost-effective and easier to produce
4Device complexity
If a compressive sensing-type hyperspectral camera uses simplified optical system, then device complexity is reduced, but loss of information increases due to shadow effects and light transmittance restrictions
Solution Approach 1:
The patent transitions from complex optical encoding in the optical path to computational encoding through pixel group arrangements on the sensor. This dimensional shift from optical to electronic processing reduces information loss by avoiding shadow effects while maintaining compression efficiency
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 a compact and efficient hyperspectral imaging device with high accuracy and temporal resolution, overcoming size and complexity issues of existing technologies.
Implementation Method 1
an optical element (12) having a function of outputting light with a different point spread function depending on wavelength
Implementation Method 2
an imaging sensor (11) having a plurality of pixels (130), each including a photoelectric conversion element
Data Source
AI summary
An imaging device includes an optical element including a transparent substrate and a plurality of structures disposed on or in the transparent substrate in a plane direction of the transparent substrate, an imaging sensor in which a plurality of pixels each including a photoelectric conversion element are arranged, and a signal processing unit configured to generate an image signal based on an electric signal obtained from the imaging sensor, wherein the optical element outputs light with a different point spread function for each wavelength to form, on the imaging sensor, an image in which the point spread function of each wavelength is convoluted, the plurality of structures have the same height in a side view, and the signal processing unit reconstructs an image in which the point spread function of each wavelength is convoluted.