Luminescence Decay Time Measurement Using Frequency-Modulated Laser
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Solution Overview
Problem
Current time-resolved photoluminescence measurement techniques are limited by requiring expensive equipment, being mono-wavelength, and needing repetitive measurements for each wavelength, making them inefficient for multi-wavelength analyses and costly.
Innovation Solution
A method using a slot-modulated laser source and a linear sensor with spectral separation to determine decay times across multiple wavelengths without the need for repetitive measurements, replicating streak camera functionality at a significantly lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct measurement technique is used, then implementation is simple, but measurement chain must be fast, sensitive and linear which are difficult to meet simultaneously
Solution Approach 1:
The patent replaces the direct measurement approach with a frequency-domain measurement technique. Instead of directly measuring the time-resolved luminescence signal which requires fast and sensitive detection, the invention uses frequency-modulated excitation and measures the amplitude and phase of the luminescence response at different frequencies. This substitution transforms the measurement problem from time-domain to frequency-domain, avoiding the need for fast, sensitive, and linear measurement chains while maintaining measurement accuracy.
2Ease of manufacture
If single-wavelength measurement method is used, then measurement is simple, but spectrum covering multiple wavelengths requires repeated measurements
Solution Approach 1:
The patent implements a measurement system that simultaneously measures luminescence decay times at multiple wavelengths. By using frequency-modulated excitation and detecting the luminescence response across a spectral range with a spectrometer coupled to a linear sensor array, the system obtains multi-wavelength decay time information in a single measurement sequence. This multi-functional approach eliminates the need for repeated single-wavelength measurements while maintaining measurement simplicity.
3Measurement precision
If TCSPC method is used, then single photon counting is achieved, but low luminescence intensity and long measurement time are required
Solution Approach 1:
The patent employs periodic frequency modulation of the excitation source to stimulate luminescence. By modulating the excitation frequency and measuring the steady-state luminescence response at each frequency, the system accumulates signal information over multiple excitation cycles. This periodic action allows the use of higher luminescence intensities compared to TCSPC, reducing measurement time while maintaining precision through frequency-domain signal analysis.
4Adaptability or versatility
If streak camera is used, then time-domain and multi-wavelength measurements are achieved, but equipment cost is extremely high
Solution Approach 1:
The patent creates a functional copy of the streak camera's time-resolved multi-wavelength measurement capability using simpler, less expensive components. Instead of using a streak camera with its complex time-scanning mechanism and two-dimensional sensor, the invention uses frequency-modulated excitation combined with a spectrometer and linear sensor array. This copying approach replicates the essential measurement functionality at a fraction of the cost by measuring frequency response rather than direct time evolution.
5Measurement precision
If phase-shift method is used, then lifetime calculation is achieved, but method is limited to simple exponential decays
Solution Approach 1:
The patent implements a dynamic measurement approach that sweeps through multiple excitation frequencies to map the frequency response of the luminescence system. Instead of relying on a single phase-shift measurement at one frequency, the system varies the excitation frequency and measures the corresponding luminescence response at each point. This dynamic frequency sweeping enables the extraction of decay time information from complex, multi-exponential decay profiles by analyzing the frequency-dependent amplitude and phase response across the entire spectrum.
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 cost-effective, multi-wavelength measurements of luminescence decay times, allowing for indirect determination of lifetimes across various transitions with a simple linear sensor, reducing the need for expensive two-dimensional sensors.
Implementation Method 1
excitation of said region of interest by means of a laser source periodically modulated in square wave
Implementation Method 2
separating said luminescence signal into a plurality of luminescence signals each associated with a given wavelength
Data Source
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AI summary
The invention relates to a method for determining the decay times of a luminescence signal from a region of interest 106 of a sample 107 comprising the following steps: - Excitation of the region of interest by means of a square-modulated laser source 101 at a given frequency; - Spectral separation of the emitted luminescence signal into a plurality of single-wavelength signals; - Transmission of the single-wavelength signals to a linear sensor 105 comprising a plurality of single-sensors 111 arranged linearly; - Determination of the average intensity of each of the single-wavelength signals received by the linear sensor 105;the preceding steps being repeated for a plurality of modulation frequencies of the laser source, the process further comprising a step of determining the decay times of the luminescence signal of the region of interest, each decay time being determined, for a given wavelength, from the evolution of the average intensity of the single-wavelength signal at said wavelength as a function of the modulation frequency of the laser.