Multi-channel Array Spectrometer Stray Light Rejection
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Solution Overview
Problem
Existing multi-channel array spectrometers face limitations in dynamic range linearity and stray light rejection, leading to measurement errors and reduced accuracy, particularly in applications with line spectrum emissions and broadband light sources.
Innovation Solution
A multi-channel array spectrometer design incorporating a reference detector with wide linear dynamic range, a bandpass filter wheel for stray light rejection, and a microprocessor for data processing and filter control, allowing for precise and quick measurements with spectral correction factors for similar test light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a narrow dynamic range photoelectric device (CCD or PDA) is used in multi-channel array spectrometer, then the measurement speed is high (several milliseconds), but the linearity and dynamic range are limited causing measurement errors
Solution Approach 1:
The patent combines a reference detector with wide linear dynamic range (silicon photodiode) and an array detector for spectral measurement. The reference detector measures total light intensity while the array detector measures spectral distribution, allowing the system to achieve both high speed and wide dynamic range by merging the advantages of both detector types.
Solution Approach 2:
The patent introduces a reference detector as an intermediary device that measures the total light intensity separately. This reference measurement is then used to normalize and correct the spectral measurements from the array detector, compensating for the narrow dynamic range limitation of the array detector and extending the overall dynamic range of the system.
2Object-affected harmful factors
If filters are introduced to reject stray light, then stray light rejection improves, but device complexity and optical path length increase
Solution Approach 1:
The patent places a longpass filter at the entrance of the optical path, before the light enters the spectrometer. This preliminary action blocks higher order diffraction light and stray light from entering the system in the first place, rather than trying to remove them after they have contaminated the measurement. This approach achieves effective stray light rejection without adding complexity to the internal optical path.
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 achieves high linearity, accurate radiometric and photometric measurements across a wide dynamic range while effectively reducing stray light, enabling quick and precise measurements of test light sources with similar spectral characteristics.
Implementation Method 1
Pixels of the array detector detect the entire spectrum simultaneously, and convert them to electrical signals
Implementation Method 2
at least one grating for optical dispersion
Implementation Method 3
The longpass filters are usually used to reject higher order responses
Data Source
AI summary
A multi-channel array spectrometer combines a spectral measurement system and a reference detector which measures photometric or radiometric qualities. High accuracy photometric or radiometric measurement of a wide dynamic range can be achieved by correcting measurement results of the reference detector with a spectral correction factor. The multi-channel array spectrometer comprises a bandpass filter wheel holding a set of bandpass filters and an open hole. The wheel is placed between an entrance slit and gratings. A test light beam passes through a turret of the bandpass filters. The test light beam can be precisely measured band by band. The spectrometer can also quickly and accurately measure a plurality of test light sources having similar spectral characteristics by using the stray light correction factor.