Time-Resolved Raman Spectroscopy Temporal Broadening
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Solution Overview
Problem
Time-gated Raman spectroscopy methods using angular dispersion suffer from excess temporal broadening, leading to decreased temporal resolution and signal-to-noise ratio, which hampers the effectiveness of measuring time-resolved optical spectra.
Innovation Solution
The implementation of an apparatus and method that employs optical delay elements to manipulate the optical radiation, providing a time delay to a portion of the emitted radiation while allowing another portion to bypass these elements, ensuring that each wavelength of the dispersed radiation is received by the sensor element with predetermined relative delays, thereby enhancing temporal resolution and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If angular dispersion is used in high-throughput spectrograph, then spectral resolution is improved, but excess temporal broadening occurs leading to decreased temporal resolution
Solution Approach 1:
The optical radiation is divided into a first portion and a second portion. The first portion is directed through the angular dispersion spectrograph while the second portion bypasses the spectrograph. This segmentation allows spectral analysis of only the relevant Raman scattering signal while avoiding temporal broadening effects on the entire beam, thereby resolving the contradiction between achieving spectral resolution and minimizing temporal broadening.
2Reliability
If time-gating is performed after the pulse exits the spectrograph, then fluorescence rejection is improved, but excess temporal broadening decreases signal-to-noise ratio
Solution Approach 1:
The optical radiation is segmented into two portions: the first portion undergoes spectral dispersion and then time-gating to reject fluorescence, while the second portion bypasses the spectrograph entirely. This segmentation enables fluorescence rejection through time-gating of the dispersed signal while preserving the temporal integrity of the bypassed portion, thereby maintaining signal-to-noise ratio.
Solution Approach 2:
The optical radiation is pre-split into portions before entering the spectrograph. The second portion that bypasses the spectrograph serves as a reference that has not undergone temporal broadening, allowing for improved signal-to-noise ratio measurement while the first portion undergoes the necessary spectral analysis and time-gating for fluorescence rejection.
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 substantially reduces excess temporal broadening and improves the signal-to-noise ratio, resulting in more accurate and efficient measurement of time-resolved optical spectra, particularly in high-throughput spectrographs.
Implementation Method 1
a spectrograph based on angular dispersion enables one to achieve a good spectral resolution
Implementation Method 2
at least one optical delay element to provide a time delay to the first portion of the emitted optical radiation
Implementation Method 3
a sensor element configured to receive each wavelength of the dispersed radiation on a different spatial region thereof, and to measure light intensity associated with each wavelength
Implementation Method 4
a light source for generating a pulse of light towards a target
Data Source
AI summary
An apparatus for measuring time-resolved optical spectrum includes a light source, a sensor for collecting, forming, manipulating and measuring the intensity of the optical radiation, and a controller coupled to the light source and sensor. The sensor includes at least one optical delay element to provide a time delay to a first portion of the optical radiation. The sensor arrangement further includes an optical spectral disperser to split the delayed first portion and the second portion of the optical radiation into dispersed radiation having a plurality of wavelengths, and a sensor element configured to receive each wavelength of the dispersed radiation on a different spatial region, and measure the light intensity associated with each wavelength of the dispersed radiation. The controller collects the light intensity associated with each wavelength of the dispersed radiation measured by the sensor element to form a time-resolved optical spectrum.