Spectrophotometer with Variable Dimming Plates for High-Absorbance Samples
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Solution Overview
Problem
Conventional double beam spectrophotometers face challenges in accurately measuring samples with absorbance that greatly varies by wavelength due to increased measurement time and reduced accuracy when dimming control light across the entire wavelength range, especially when high absorbance and low absorbance coexist.
Innovation Solution
A spectrophotometer with a light source, spectroscope, optical path switch, detector, and multiple dimming plates with different dimming rates, along with a controller that adjusts dimming plates and scanning speed for each wavelength range, allowing for simultaneous scanning of the entire measurement wavelength range with optimized measurement conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control light is dimmed in the entire measurement wavelength range to improve accuracy in high absorbance regions, then measurement accuracy is improved, but measurement time increases and accuracy in low absorbance regions deteriorates
Solution Approach 1:
The measurement wavelength range is divided into multiple wavelength ranges (first wavelength range with high absorbance, second wavelength range with low absorbance). Different dimming plates with different dimming rates are selectively applied to different wavelength ranges. This segmentation allows optimized measurement conditions for each wavelength range, improving accuracy without unnecessarily increasing measurement time across the entire spectrum.
Solution Approach 2:
Different dimming rates are applied locally to different wavelength ranges based on their specific absorbance characteristics. The control light is dimmed more strongly in the high absorbance wavelength range and less strongly in the low absorbance wavelength range. This local quality approach ensures that each wavelength range receives the appropriate amount of dimming for accurate measurement, avoiding over-dimming in low absorbance regions.
2Measurement precision
If measurement is performed multiple times with changed conditions to obtain favorable spectrum across entire wavelength range, then measurement accuracy is improved, but operator burden increases
Solution Approach 1:
The spectrophotometer automatically determines the absorbance spectrum of the measurement sample in advance and based on this spectrum, automatically determines the boundary wavelength between different wavelength ranges and selects appropriate dimming plates for each range. This self-service capability eliminates the need for operators to manually perform multiple measurements with different conditions, significantly reducing operator burden while maintaining measurement accuracy.
Solution Approach 2:
The system uses the absorbance spectrum obtained in advance as feedback to automatically determine the boundary wavelength and select appropriate measurement conditions for each wavelength range. This feedback mechanism allows the system to adaptively optimize measurement parameters based on the actual sample characteristics, ensuring accurate measurement across the entire wavelength range without requiring manual intervention.
3Measurement precision
If wavelength scanning speed is reduced and integration times are increased to reduce noise in high absorbance regions, then signal-to-noise ratio is improved, but measurement time increases
Solution Approach 1:
Different scanning speeds and integration times are applied to different wavelength ranges based on their absorbance characteristics. In the high absorbance wavelength range, slower scanning speed and longer integration time are used to improve signal-to-noise ratio. In the low absorbance wavelength range, faster scanning speed and shorter integration time are sufficient. This local optimization reduces the overall measurement time while maintaining high signal-to-noise ratio where needed.
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 configuration enables efficient high-accuracy measurements with a high signal-to-noise ratio and fewer scans across the entire wavelength range, reducing operator burden and improving measurement efficiency for samples with varying absorbance.
Implementation Method 1
a spectroscope that splits light from the light source
Implementation Method 2
a plurality of dimming plates having different dimming rates
Data Source
AI summary
When a measurement sample whose absorbance greatly changes depending on a wavelength range is measured, measurement with a high S/N ratio and accuracy can be efficiently performed in a short time.For a plurality of wavelength ranges in wavelength scanning measurement of a measurement sample, based on measurement conditions including one of a plurality of dimming plates (16a to 16e) to be disposed in each wavelength range and a scanning speed of a wavelength to be set in each wavelength range, when wavelength scanning measurement in which the entire measurement wavelength range including all of the plurality of wavelength ranges is scanned at once is performed, a spectrophotometer (100) changes one of the plurality of dimming plates (16a to 16e) and the scanning speed according to the measurement conditions for each wavelength range.