Stray Light Correction in Spectrometer Quantum Yield Measurement
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Solution Overview
Problem
Spectroscopic measurement apparatuses using multi-channel spectrometers generate significant stray light, which affects the accuracy of luminescence quantum yield measurements in organic EL elements, as excitation light is diffusely reflected and detected as a wavelength component other than the excitation light, leading to reduced measurement accuracy.
Innovation Solution
A spectroscopic measurement apparatus and method that utilize an integrating sphere with defined aperture settings and data analysis to separate excitation light and emission light by wavelength spectrum, using reference and sample measurements to calculate luminescence quantum yield, correcting for stray light effects with factors β and γ, thereby reducing its impact on measurement results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-channel spectrometer is used to simultaneously measure the entire wavelength range, then measurement efficiency is improved, but stray light increases due to the spectrometer structure causing diffused reflection of excitation light
Solution Approach 1:
The patent extracts and separates the excitation light component from the emission light component by defining distinct wavelength ranges (first wavelength range for excitation light, second wavelength range for emission light). This allows the multi-channel spectrometer to simultaneously measure both components without interference, maintaining high measurement efficiency while eliminating stray light effects on accuracy.
Solution Approach 2:
The patent segments the measurement process into two distinct wavelength range measurements: one for excitation light and another for emission light. By dividing the spectral analysis into separate segments, the system can accurately quantify and subtract stray light contributions from each segment, thereby improving measurement precision while using a multi-channel spectrometer for efficient simultaneous measurement.
2Ease of operation
If the excitation light is diffusely reflected inside the spectrometer, then the measurement process becomes simpler, but the excitation light is detected as a wavelength component other than the excitation light wavelength, reducing measurement accuracy
Solution Approach 1:
The patent introduces an intermediary calculation step that uses the measured intensity in the first wavelength range (excitation light) to quantify the stray light contribution in the second wavelength range (emission light). This intermediary measurement and calculation process allows the system to maintain operational simplicity while correcting for stray light interference to preserve measurement accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the measured excitation light intensity is used to calculate and subtract the stray light contribution from the emission light measurement. This feedback loop ensures that the final luminescence quantum yield calculation is corrected for stray light effects, maintaining high measurement precision despite the simple diffused reflection measurement process.
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 method effectively reduces the effect of stray light in spectrometer measurements, allowing for accurate determination of luminescence quantum yield by correcting measurement values using β and γ factors, improving measurement accuracy without the need for physical modifications to the spectrometer.
Implementation Method 1
The inner wall of the integrating sphere is made out of a coating or a material having a high reflectance and excellent in diffuseness, and light incident on the inner wall surface is multi-diffusely-reflected
Implementation Method 2
spectroscopic means dispersing the light to be measured output from the exit aperture of the integrating sphere and obtaining a wavelength spectrum
Implementation Method 3
the diffused light from the sample enters a photodetector through an exit aperture provided at a predetermined position of the integrating sphere to be detected
Implementation Method 4
Photons are generated by holes injected from the anode and electrons injected from the cathode being recombined in the light emitting layer, and the light emitting layer emits light
Implementation Method 5
a sample of a luminescent material located in the integrating sphere is irradiated with excitation light of a predetermined wavelength, and a luminescence quantum yield defined by a ratio of the number of photons of light emission from the sample to the number of photons of the excitation light absorbed by the sample is measured
Data Source
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AI summary
A spectroscopic measurement apparatus 1A comprises an integrating sphere 20 in which a sample S is located, a spectroscopic analyzer 30 dispersing the light to be measured from the sample S and obtaining a wavelength spectrum, and a data analyzer 50. The analyzer 50 includes an object range setting section which sets a first object range corresponding to excitation light and a second object range corresponding to light emission from the sample S in a wavelength spectrum, and a sample information analyzing section which determines a luminescence quantum yield of the sample S, determines a measurement value Φ0 of the luminescence quantum yield from results of a reference measurement and a sample measurement, and determines, by using factors β, γ regarding stray light in the reference measurement, an analysis value Φ of the luminescence quantum yield with the effect of stray light reduced by Φ = βΦ0+γ. This realizes a spectroscopic measurement apparatus, a measurement method, and a measurement program which can reduce the effect of stray light generated in a spectrometer.