Fabry-Perot Spectrometer Calibration Using Narrowband and Broadband Light
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Solution Overview
Problem
Current spectrometer calibration methods are inefficient, particularly with narrowband calibration being time-consuming and providing only approximate results, while broadband calibration is faster but less accurate, and there is a need for a method to accurately calibrate spectrometers for fast spectral analysis at high resolution.
Innovation Solution
A method involving a Fabry-Perot interferometer with adjustable mirror gap, using both narrowband and broadband calibration lights to determine calibration parameters, where the mirror gap is adjusted to match spectral sensitivities of detector pixels, allowing for simultaneous measurement of spectral intensities at multiple wavelengths, and the calibration parameters are refined using broadband light for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If narrowband calibration light is used for spectrometer calibration, then measurement precision is improved, but loss of time increases due to the time-consuming scanning process
Solution Approach 1:
The patent applies preliminary action by performing a broadband calibration first to establish initial calibration parameters, and then performing narrowband calibration only at selected wavelengths to refine specific parameters. This staged approach prepares the system in advance with coarse calibration, reducing the time needed for subsequent precise calibration while maintaining accuracy where needed.
Solution Approach 2:
The patent applies local quality by applying narrowband calibration selectively at specific wavelengths where high precision is required, rather than uniformly across the entire spectrum. The calibration parameters are determined locally at selected wavelengths and then interpolated to other wavelengths, providing high measurement precision only where necessary and reducing overall calibration time.
2Productivity
If broadband calibration light is used for spectrometer calibration, then productivity is improved due to faster calibration, but measurement precision deteriorates as it provides only approximate results
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into two distinct stages: broadband calibration to determine initial parameters quickly, and narrowband calibration to refine specific parameters for accuracy. This segmentation allows the system to benefit from both fast broadband calibration and precise narrowband calibration without combining them into a single time-consuming process.
Solution Approach 2:
The patent applies parameter changes by using different calibration light sources (broadband vs. narrowband) with different spectral characteristics to determine different sets of calibration parameters. The broadband light provides initial parameter estimates, while narrowband light refines specific parameters, and the system dynamically switches between calibration modes based on the required precision and speed.
3Measurement precision
If the mirror gap is adjusted to match spectral sensitivities of detector pixels, then measurement precision is improved for simultaneous spectral analysis, but device complexity increases due to additional adjustment mechanisms
Solution Approach 1:
The patent applies dynamics by making the mirror gap adjustable rather than fixed, allowing the interferometer to be dynamically tuned to match the spectral sensitivities of the detector pixels. This dynamic adjustment enables the system to optimize spectral resolution for different operating conditions while maintaining a relatively simple overall device structure through controlled adaptability.
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 rapid and accurate spectral analysis with high resolution by calibrating the spectrometer to match spectral sensitivities of detector pixels, improving the accuracy of spectral intensity measurements and reducing the need for frequent recalibration.
Implementation Method 1
a Fabry-Perot interferometer, and an image sensor. The Fabry-Perot interferometer comprises a first semi-transparent mirror and a second semi-transparent mirror, which are arranged to form an optical cavity. The Fabry-Perot interferometer may provide two or more transmission peaks.
Implementation Method 2
The Fabry-Perot interferometer comprises a first semi-transparent mirror and a second semi-transparent mirror, which are arranged to form an optical cavity
Implementation Method 3
The distance between mirrors may be adjusted e.g. by using a piezoelectric actuator
Implementation Method 4
Spectral components transmitted at different transmission peaks of the interferometer may be discriminated by using at least two types of detector pixels, which have maximum sensitivities at different wavelengths
Data Source
Figure 1
Figure 2a~2d
Figure 3~4
AI summary
An imaging spectrometer (500) comprises a Fabry-Perot interferometer (100) and an image sensor (200) having color-sensitive pixels. The interferometer (100) has a first transmission peak (PEAK1) and a second transmission peak (PEAK2). A method calibrating the spectrometer (500) comprises: - providing first calibration light (LB11), which has a narrow spectral peak (MPEAK), - obtaining first detector signal values (SR, SG) from the image sensor (200) by coupling the first calibration light (LB11) into the spectrometer (500) when the reference spectral peak (MPEAK) is near a first spectral position (λ0), - obtaining second detector signal values (SR, SG) from the image sensor (200) by coupling the first calibration light (LB11) into the spectrometer (500) when the reference spectral peak (MPEAK) is near a second spectral position (λ1), - providing second calibration light (LB20), which has a broad bandwidth, and - obtaining third detector signal values (SR, SG) from the image sensor (200) by coupling the second calibration light (LB20) into the spectrometer (500).