Noise Reduction in Time-Gated Spectroscopy

Abstract

Systems and methods for reducing fluorescence and systematic noise in time-gated spectroscopy are disclosed. Exemplary methods include: a method for reducing fluorescence and systematic noise in time-gated spectroscopy may comprise: providing first light using an excitation light source; receiving, by a detector, first scattered light from a material responsive to the first light during a first time window; detecting a peak intensity of the first scattered light; receiving, by the detector, second scattered light from the material responsive to the first light during a second time window; detecting a peak intensity of the second scattered light; recovering a spectrum of the material by taking a ratio of the peak intensity of the first scattered light and the peak intensity of the second scattered light; and identifying at least one molecule of the material using the recovered spectrum and a database of identified spectra.

1 . A method for reducing fluorescence and systemic noise in time-gated spectroscopy, the method comprising:
 providing first light using an excitation light source;   receiving, by a detector, first scattered light from a material responsive to the first light during a first time window having a first duration, the first scattered light having substantial Raman signal, the first scattered light having a first wavelength;   detecting a peak intensity of the first scattered light;   receiving, by the detector, second scattered light from the material responsive to the first light during a second time window having a second duration, the second scattered light having little Raman signal, the second scattered light having the first wavelength;   detecting a peak intensity of the second scattered light;   providing second light using the excitation light source;   receiving, by the detector, third scattered light from the material responsive to the second light during a third time window having the first duration, the third scattered light having substantial Raman signal, the third scattered light having a second wavelength;   detecting a peak intensity of the third scattered light;   receiving, by the detector, fourth scattered light from the material responsive to the second light during a fourth time window having the second duration, the fourth scattered light having little Raman signal, the fourth scattered light having the second wavelength;   detecting a peak intensity of the fourth scattered light;   recovering a spectrum of the material; and   identifying at least one molecule of the material.   
     
     
         2 . The method of  claim 1  further comprising:
 providing third light using the excitation light source; 
 receiving, by the detector, fifth scattered light from the material responsive to the third light during a fifth time window having the first duration, the fifth scattered light having substantial Raman signal, the fifth scattered light having a third wavelength; 
 detecting a peak intensity of the fifth scattered light; 
 receiving, by the detector, sixth scattered light from the material responsive to the third light during a sixth time window having the second duration, the sixth scattered light having little Raman signal, the sixth scattered light having the third wavelength; and 
 detecting a peak intensity of the sixth scattered light; 
 wherein the recovering the spectrum of the material further includes taking a ratio of the peak intensity of the fifth scattered light and the peak intensity of the sixth scattered light. 
 
     
     
         3 . The method of  claim 1 , further comprising:
 normalizing the recovered spectrum to produce a normalized recovered spectrum; and   identifying at least one molecule of the material using the normalized recovered spectrum and a database of identified spectra.   
     
     
         4 . The method of  claim 3 , wherein normalizing the recovered spectrum includes:
 fitting the recovered spectrum to a baseline using at least one of linear regression and polynomial curve fitting; and   subtracting the baseline from the recovered spectrum to produce the normalized recovered spectrum.   
     
     
         5 . The method of  claim 1 , wherein the substantial Raman signal is 80%-100% of peak intensity of a respective Raman signal. 
     
     
         6 . The method of  claim 5 , wherein the little Raman signal is 0%-20% of peak intensity of the respective Raman signal. 
     
     
         7 . The method of  claim 1 , wherein:
 the first duration is shorter than the second duration;   the second time window begins after the first time window ends; and   the fourth time window begins after the third time window ends.   
     
     
         8 . The method of  claim 19 , wherein the detector is at least one of a single-photon avalanche diode (SPAD), micro-channel plate (MCP), photomultiplier tube (PMT), silicon photomultiplier (SiPM), and avalanche photodiode (APD), and the detector is disposed on at least one of a scanning motor driven rail, SPAD array, and an intensified CCD (ICCD). 
     
     
         9 . The method of  claim 1 , wherein the systemic noise arises from spectrometer components producing multiple reflections that interfere with each other to generate an interference pattern. 
     
     
         10 . The method of  claim 1 , wherein the material has a strong fluorescence background. 
     
     
         11 . A system for reducing fluorescence and systemic noise in time-gated spectroscopy, the system comprising:
 a processor; and   a memory, the memory communicatively coupled to the processor and storing instructions executable by the processor to perform a method, the method comprising:
 providing first light using an excitation light source; 
 receiving, by a detector, first scattered light from a material responsive to the first light during a first time window having a first duration, the first scattered light having substantial Raman signal, the first scattered light having a first wavelength; 
 detecting a peak intensity of the first scattered light; 
 receiving, by the detector, second scattered light from the material responsive to the first light during a second time window having a second duration, the second scattered light having little Raman signal, the second scattered light having the first wavelength; 
 detecting a peak intensity of the second scattered light; 
 providing second light using the excitation light source; 
 receiving, by the detector, third scattered light from the material responsive to the second light during a third time window having the first duration, the third scattered light having substantial Raman signal, the third scattered light having a second wavelength; 
 detecting a peak intensity of the third scattered light; 
 receiving, by the detector, fourth scattered light from the material responsive to the second light during a fourth time window having the second duration, the fourth scattered light having little Raman signal, the fourth scattered light having the second wavelength; 
 detecting a peak intensity of the fourth scattered light; 
 recovering a spectrum of the material; and 
 identifying at least one molecule of the material. 
   
     
     
         12 . The system of  claim 11 , wherein the method further comprises:
 providing third light using the excitation light source;   receiving, by the detector, fifth scattered light from the material responsive to the third light during a fifth time window having the first duration, the fifth scattered light having substantial Raman signal, the fifth scattered light having a third wavelength;   detecting a peak intensity of the fifth scattered light;   receiving, by the detector, sixth scattered light from the material responsive to the third light during a sixth time window having the second duration, the sixth scattered light having little Raman signal, the sixth scattered light having the third wavelength; and   detecting a peak intensity of the sixth scattered light;   wherein the recovering the spectrum of the material further includes taking a ratio of the peak intensity of the fifth scattered light and the peak intensity of the sixth scattered light.   
     
     
         13 . The system of  claim 11 , wherein the method further comprises:
 normalizing the recovered spectrum to produce a normalized recovered spectrum; and   identifying at least one molecule of the material using the normalized recovered spectrum and a database of identified spectra.   
     
     
         14 . The system of  claim 13 , wherein normalizing the recovered spectrum includes:
 fitting the recovered spectrum to a baseline using at least one of linear regression and polynomial curve fitting; and   subtracting the baseline from the recovered spectrum to produce the normalized recovered spectrum.   
     
     
         15 . The system of  claim 11 , wherein the substantial Raman signal is 80%-100% of peak intensity of a respective Raman signal. 
     
     
         16 . The system of  claim 15 , wherein the little Raman signal is 0%-20% of peak intensity of the respective Raman signal. 
     
     
         17 . The system of  claim 11 , wherein:
 the first duration is shorter than the second duration;   the second time window begins after the first time window ends; and   the fourth time window begins after the third time window ends.   
     
     
         18 . The system of  claim 11 , wherein the detector is at least one of a single-photon avalanche diode (SPAD), micro-channel plate (MCP), photomultiplier tube (PMT), silicon photomultiplier (SiPM), and avalanche photodiode (APD), and the detector is disposed on at least one of a scanning motor driven rail, SPAD array, and an intensified CCD (ICCD). 
     
     
         19 . The system of  claim 11 , wherein the systemic noise arises from spectrometer components producing multiple reflections that interfere with each other to generate an interference pattern. 
     
     
         20 . A system for reducing fluorescence and systemic noise in time-gated spectroscopy, the system comprising:
 means for providing first light using an excitation light source;   receiving, by a detector, first scattered light from a material responsive to the first light during a first time window having a first duration, the first scattered light having substantial Raman signal, the first scattered light having a first wavelength;   means for detecting a peak intensity of the first scattered light;   means for receiving, by the detector, second scattered light from the material responsive to the first light during a second time window having a second duration, the second scattered light having little Raman signal, the second scattered light having the first wavelength;   means for detecting a peak intensity of the second scattered light;   means for providing second light using the excitation light source;   means for receiving, by the detector, third scattered light from the material responsive to the second light during a third time window having the first duration, the third scattered light having substantial Raman signal, the third scattered light having a second wavelength;   means for detecting a peak intensity of the third scattered light;   means for receiving, by the detector, fourth scattered light from the material responsive to the second light during a fourth time window having the second duration, the fourth scattered light having little Raman signal, the fourth scattered light having the second wavelength;   means for detecting a peak intensity of the fourth scattered light;   means for recovering a spectrum of the material; and   means for identifying at least one molecule of the material.