Spectroscopic Analyzer Amplifier Gain Control
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Solution Overview
Problem
Conventional spectroscopic analyzers face challenges in achieving high signal-to-noise (S/N) ratio and light intensity resolution due to large differences in light intensity signals between sample and reference light, leading to inaccurate concentration measurements.
Innovation Solution
Incorporating a dimming element and adjusting the amplification factor of the amplifier to ensure that both reference and sample light intensity signals remain within the full scale of the A/D converter, thereby enhancing S/N ratio and light intensity resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measurement is performed with high absorbance (1-2 Abs) to improve concentration measurement accuracy, then the concentration measurement accuracy is improved, but the transmitted light intensity becomes too small for accurate measurement
Solution Approach 1:
The invention changes the measurement parameter from absolute light intensity to absorbance ratio. By measuring the ratio of sample light intensity to reference light intensity and converting to absorbance, the system can accurately measure concentrations even when transmitted light intensity is very small (as in high absorbance measurements of 1-2 Abs or higher).
2Measurement precision
If the A/D converter full scale is set according to reference light with large intensity, then the reference light measurement is accurate, but the sample light with small intensity needs to be converted within a narrow range resulting in poor resolution
Solution Approach 1:
The invention introduces a ratio calculation as an intermediary step between light detection and A/D conversion. By calculating the ratio of sample light to reference light intensities and then converting this ratio to absorbance, the system achieves high resolution for both strong reference light and weak sample light without requiring separate optimization for each.
3Adaptability or versatility
If the sample light intensity is small, then the concentration measurement range is extended, but the S/N ratio deteriorates due to electromagnetic noise influence
Solution Approach 1:
The invention uses reference light measurement as a feedback mechanism to compensate for noise in sample light measurement. By continuously measuring reference light intensity and using it to normalize sample light intensity (through ratio calculation), the system cancels out common-mode noise including electromagnetic noise, maintaining high S/N ratio even when sample light intensity is small.
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 allows for accurate light intensity measurement and high-accuracy concentration measurement by equalizing light intensity signals and reducing noise interference.
Implementation Method 1
a light detector configured to detect sample light which has passed through the measurement cell and configured to detect reference light
Implementation Method 2
an amplifier configured to amplify an analog sample light intensity signal as outputted from the light detector during sample measurement and configured to amplify an analog reference light intensity signal outputted from the light detector during reference measurement
Implementation Method 3
an A/D converter configured to convert the analog sample light intensity signal into a digital sample light intensity signal and configured to amplify the analog reference light intensity signal into a digital reference light intensity signal
Implementation Method 4
An absorption spectroscopy method is used for concentration measurement in this spectroscopic analyzer
Implementation Method 5
concentration cj is typically calculated by multiplying an absorbance spectrum Abs (λi) by a calibration curve Mij previously obtained through calibration
Data Source
AI summary
The present invention improves an S/N ratio and light intensity resolution provided by an A/D converter, and an analyzer includes: a measurement cell irradiated with light during sample measurement; a dimming element irradiated with the light during reference measurement; an amplifier configured to amplify an analog light intensity signal outputted from a light detector; an A/D converter configured to convert the analog light intensity signal into a digital light intensity signal; and an arithmetic device configured to calculate absorbance using a digital sample light intensity signal outputted from the A/D converter during the sample measurement and a digital reference light intensity signal outputted from the A/D converter during the reference measurement, wherein an amplification factor of the amplifier is set such that the analog reference light intensity signal and the analog sample light intensity signal become less than or equal to a full scale of the A/D converter.