Spectral Imaging Refractive Element Noise Filtering
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Solution Overview
Problem
Existing spectral microscopes generate spectral images of insufficient quality due to lack of optical frequency modulation during image capture, limiting effective analysis of samples such as human tissue and explosive residues.
Innovation Solution
A spectral imaging device with a tunable optical source, optical assembly, and control system that generates discrete optical frequencies within a desired tuning range, using refractive elements with specific thickness and spacing to inhibit noise sources outside the measurement passband, and applies filters to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a swept wavelength imaging optical interrogation system is used to generate spectral images, then spectral data can be captured, but the image quality and resolution are insufficient due to lack of optical frequency modulation during capture
Solution Approach 1:
The patent applies periodic modulation of the optical frequency during the capture of spectral images. The tunable optical source is modulated to sweep through a range of frequencies multiple times during image capture, which enhances the spectral resolution and image quality by ensuring complete spectral sampling at each spatial location.
Solution Approach 2:
The system dynamically adjusts the optical frequency during image capture rather than using a static wavelength. The tunable optical source continuously sweeps through frequencies, and the system coordinates this dynamic frequency change with the image capture process to achieve high-resolution spectral imaging.
2Reliability
If refractive elements are added to the optical assembly to inhibit noise sources, then signal-to-noise ratio improves, but device complexity increases
Solution Approach 1:
The patent converts the harmful effect of parasitic etalon noise into a beneficial filtering mechanism. By carefully selecting the thickness and spacing of refractive elements, the system allows noise frequencies to fall outside the measurement passband, effectively using the noise-generating elements themselves to reject noise through spectral filtering.
Solution Approach 2:
The system changes the physical parameters of refractive elements (thickness and spacing) to control the spectral position of noise frequencies. By adjusting these parameters, the noise frequencies are shifted outside the measurement passband, achieving noise reduction without requiring complex active filtering mechanisms.
3Measurement precision
If multiple discrete optical frequencies are captured to improve spectral resolution, then measurement precision improves, but measurement time increases
Solution Approach 1:
The patent implements continuous sweeping of the optical frequency during image capture, rather than sequentially capturing images at discrete frequencies. The tunable optical source continuously modulates through the spectral range, and the image sensor captures the complete spectral information in a continuous process, maintaining high spectral resolution while minimizing capture time.
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 device produces high-resolution spectral cubes with improved image quality and signal-to-noise ratio, effectively reducing noise interference and enhancing analysis capabilities for various materials.
Implementation Method 1
The optical assembly includes a plurality of refractive elements that are positioned along the beam path between the tunable optical source and the image sensor
Implementation Method 2
the Fourier space components of the optical frequency dependent transmittance function of each refractive element fall outside a measurement passband
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A spectral imaging device (12) includes an image sensor (28), a tunable light source (14), an optical assembly (17), and a control system (30). The optical assembly (17) includes a first refractive element (24A) and a second refractive element (24B) that are spaced apart from one another by a first separation distance. The refractive elements (24A) (24B) have an element optical thickness and a Fourier space component of the optical frequency dependent transmittance function. Further, the element optical thickness of each refractive element (24A) (24B) and the first separation distance are set such that the Fourier space components of the optical frequency dependent transmittance function of each refractive element (24A) (24B) fall outside a Fourier space measurement passband.