Hyperspectral Optical Module Using DMD Scanning Without Grating Rotation
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Solution Overview
Problem
Conventional hyperspectral imaging methods face challenges with increased measurement time and instability due to high-speed rotational movements of grating units, misalignment of optics, and fluctuations in light source intensity, particularly when achieving high wavelength resolution.
Innovation Solution
The use of a toroidal diffraction grating to eliminate high-speed rotational movements, combined with a digital micromirror array (DMD) for Fourier transform and real-time light source intensity compensation, allows for stable and efficient hyperspectral imaging without increasing measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional grating units perform high-speed rotational movements to achieve hyperspectral imaging, then wavelength resolution can be obtained, but facility stability deteriorates and measurement time increases
Solution Approach 1:
The patent replaces the conventional mechanical rotating grating system with a fixed grating unit combined with a DMD (Digital Micromirror Array). The DMD performs rapid electronic switching to direct different wavelengths to the detector, eliminating high-speed mechanical rotation while maintaining spectral resolution capability. This substitution of mechanical motion with electronic control resolves the stability issue.
Solution Approach 2:
The patent introduces a DMD device that dynamically switches optical paths for different wavelengths without moving the grating. The DMD mirrors can be electronically controlled to redirect light at different angles, enabling rapid wavelength scanning through electronic rather than mechanical dynamics, thus maintaining measurement capability while improving system stability.
2Measurement precision
If conventional grating units perform high-speed rotational movements to achieve hyperspectral imaging, then spectral data can be collected, but measurement time increases
Solution Approach 1:
The DMD's electronic switching capability enables much faster wavelength selection compared to mechanical grating rotation. The electronic control allows for microsecond-scale switching between wavelengths, dramatically reducing the time required to collect spectral data while maintaining data quality through precise optical path control.
Solution Approach 2:
The patent enables continuous spectral measurement by using the DMD to rapidly and continuously switch between different wavelength channels without the mechanical acceleration and deceleration cycles inherent in rotating grating systems. This continuous electronic switching maintains measurement throughput while reducing total acquisition time.
3Measurement precision
If conventional systems lack real-time light source intensity monitoring, then system complexity is reduced, but measurement accuracy deteriorates due to light source fluctuations
Solution Approach 1:
The patent incorporates a feedback mechanism where a portion of the light source output is directed to a reference detector that continuously monitors light source intensity. This reference signal is used to normalize the spectral measurements, compensating for any fluctuations in light source output and improving measurement accuracy through real-time feedback correction.
Solution Approach 2:
The patent introduces a reference light path as an intermediary measurement channel. This reference path captures light source intensity variations independently of the sample measurement, serving as a mediator that allows for post-processing normalization of the spectral data to correct for light source fluctuations.
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
The solution enhances facility stability, reduces measurement time, and compensates for light source fluctuations, enabling high-speed acquisition of hyperspectral data with improved reproducibility and accuracy.
Implementation Method 1
a diffraction grating configured to split a beam that is incident on a slit and rotate and focus a beam path on a Fourier plane
Implementation Method 2
a digital micromirror array (DMD), which is configured to assign a natural frequency for each wavelength of the focused beam and perform Fourier transform for each frequency
Implementation Method 3
a first optical fiber, which is configured to pass a beam reflected at the DMD back to an incident path after having passed through the diffraction grating
Data Source
AI summary
An optical module includes: a diffraction grating configured to rotate and focus a beam, which is incident thereon from an incident path, onto a Fourier plane, a digital micromirror array (DMD) configured to assign a frequency for each wavelength of the focused beam received at the Fourier plane, and perform a Fourier transform for each frequency, and a first optical fiber configured to receive a beam that is reflected back from the DMD back and the diffraction grating, and along the incident path.