Raman Radiation Measurement Using Single-Photon Timing Discrimination
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Solution Overview
Problem
Current methods for measuring Raman radiation are impractical due to low duty cycle of gating devices, high-energy requirements, and complexity, making them unsuitable for field applications and limiting the accuracy and reliability of fluorescence and Raman scattering measurements.
Innovation Solution
An apparatus and method that eliminate the need for gating devices by time-labeling each detection, allowing for accurate estimation of fluorescence and Raman scattering strength using a semiconductor single-photon avalanche diode detector array and a time-to-digital conversion circuit, with optical filters or dispersers to separate Raman and fluorescence signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gating devices (Kerr-gate or image intensifier) are used to separate Raman radiation from excitation and fluorescent radiation, then measurement reliability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the timing information from each detected photon and uses it to identify whether the photon belongs to Raman radiation, fluorescent radiation, or excitation radiation. By separating the timing measurement function from the detection function, the system eliminates the need for complex gating devices while maintaining measurement reliability through time-based discrimination.
Solution Approach 2:
The patent replaces the mechanical/optical gating system (Kerr-gate or image intensifier) with an electronic timing-based discrimination system. Instead of using physical gates to block or pass photons, the system measures the arrival time of each photon and uses timing windows to distinguish between different radiation types, thereby eliminating complex mechanical components.
2Reliability
If Kerr-gate is used to suppress excitation and fluorescent radiation, then Raman radiation detection is improved, but the duty cycle becomes very low making measurement impractical
Solution Approach 1:
The patent enables continuous detection of all photons without the need to close gating devices between excitation pulses. By continuously measuring photon arrival times and using timing windows to distinguish Raman photons from fluorescent and excitation photons, the system maintains 100% duty cycle while still achieving effective Raman radiation detection.
3Reliability
If image intensifier with short gate period is used, then fluorescent radiation suppression is improved, but high voltage requirements and operational complexity increase
Solution Approach 1:
The patent replaces the high-voltage image intensifier system with a simple timing-based discrimination approach. Instead of using high-voltage switched intensifiers with picosecond gate periods, the system uses standard detectors combined with timing measurements and software-based time window analysis to suppress fluorescent radiation, dramatically simplifying operation.
4Measurement precision
If gating devices are used to measure Raman radiation, then measurement accuracy is improved, but the system becomes slow and unsuitable for field applications
Solution Approach 1:
The patent enables continuous, real-time measurement of Raman radiation by continuously detecting photon arrival times and immediately processing the timing information to distinguish Raman photons from fluorescent and excitation photons. This eliminates the sequential gating process and enables fast, continuous measurement suitable for field applications.
5Ease of operation
If high-energy optical pulses are used to operate Kerr-gate, then gating function is achieved, but the energy available for the measured object is drastically limited
Solution Approach 1:
The patent extracts the timing information from detected photons and uses this timing data to identify Raman radiation, thereby removing the need for high-energy optical pulses to operate Kerr-gate. This allows nearly all optical energy to be directed to the measurement object while the gating function is achieved through electronic timing discrimination.
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 approach enables reliable and efficient measurement of Raman radiation without gating devices, improving measurement accuracy and reducing complexity, making it suitable for field applications and on-line measurements with low background noise and cost.
Implementation Method 1
a semiconductor single-photon avalanche diode detector array
Implementation Method 2
The apparatus may also comprise a disperser 202 which may comprise a prism, a diffraction grating or a spectrograph. The disperser 202 may disperse different bands 210 to 214 of wavelengths
Implementation Method 3
with optical filters or dispersers to separate Raman and fluorescence signals
Data Source
AI summary
An apparatus comprises a semiconductor single-photon avalanche detector, and a counter. The detector performs detections of photons of optical radiation caused by an optical excitation pulse to the object. The counter measures timing of each detection made in the detector with respect to the excitation pulse causing the detected photons, and performs at least one of the following: forming a number of Raman detections, forming a number of fluorescence detections. Forming the number of the Raman detections is performed by eliminating an estimate of a number of fluorescence photons in the measurement. Forming the number of the fluorescence detections is performed by eliminating an estimate of a number of Raman photons in the measurement. The estimates are formed in a predetermined manner from the number and timing of the detections.