Hyperspectral Imaging Device Using Micro Lens Array
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Solution Overview
Problem
Existing spectral imaging devices are bulky due to the focusing distance between the lens and the image sensor, which limits their use in mobile applications, and attempting to reduce this distance compromises the spectral resolution of the Fabry-Perot interferometer.
Innovation Solution
The use of optical micro-structures, specifically a micro lens array, to reduce the length of the imaging device while maintaining spectral resolution, achieved by employing a telecentric or afocal system and a combination of a modulator array and filter array to control light transmission through the Fabry-Perot interferometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lens system is used to focus light onto the image sensor, then the spectral resolution of the Fabry-Perot interferometer is maintained, but the length of the imaging device becomes too large for mobile applications
Solution Approach 1:
The patent divides the imaging device into multiple segments: a microlens array that captures light from different field angles, a Fabry-Perot interferometer that spectrally filters the light, and an image sensor that detects the filtered light. This segmentation allows each component to be optimized independently, reducing the overall device length while maintaining spectral resolution
Solution Approach 2:
The patent transitions from a conventional single-lens focusing system to a microlens array system where multiple micro-lenses operate in parallel. This dimensional change from 2D image plane to 3D spatial-spectral space allows simultaneous capture of multiple wavelength bands across the field of view, reducing the required focusing distance and overall device length
2Length of moving object
If the focusing distance between the lens and image sensor is reduced to make the device compact, then the device size becomes suitable for mobile applications, but the divergence of light beams increases and spectral resolution deteriorates
Solution Approach 1:
The patent applies local quality by using a microlens array where each microlens is optimized for its specific position in the array. Each microlens captures light from a specific field angle and directs it through the Fabry-Perot interferometer at the appropriate angle, ensuring that local optical paths maintain the required beam divergence characteristics even when the overall device is compact
Solution Approach 2:
The Fabry-Perot interferometer acts as an intermediary between the microlens array and the image sensor. It receives light from multiple microlenses with different divergence angles and performs spectral filtering, effectively decoupling the focusing distance requirement from the spectral resolution requirement. This intermediary component allows compact device design without compromising spectral measurement accuracy
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 allows for a significant reduction in the size of the imaging device, typically to a length of 3 mm to 15 mm, while maintaining the spectral resolution and enabling the device to capture multispectral or hyperspectral images efficiently.
Implementation Method 1
The Fabry-Perot interferometer FPI may operate as an adjustable optical passband filter
Implementation Method 2
a Fabry-Perot interferometer FPI
Implementation Method 3
The lens FLNS may form an image IMG2 of an object on the image sensor SEN1, by focusing light LB1 received from the object to the image sensor SEN1
Data Source
AI summary
A spectral imaging device comprises:an optical modifier system (SYS1) to form axial light beams (LB2) from received light beams (LB1), the axial light beams (LB2) being parallel with an optical axis (AX1) of the imaging device (500),a Fabry-Perot interferometer (FPI) to provide filtered axial light beams (LB3) by filtering light of the axial light beams (LB2),an image sensor (SEN1), andan array (ARR1) of lenses (LNS0,0, LNS0,1) to form a plurality of sub-images (S0,0, S0,1) on the image sensor (SEN1) by focusing light of the filtered light beams (LB3).