Method and system for measuring Raman scattered light from sample

Abstract

A method for measuring Raman scattered light from a sample (102) is disclosed. The method includes emitting a train of excitation laser pulses, dividing the train of excitation laser pulses into a plurality of trains of excitation laser pulses (122), directing the plurality of trains of excitation laser pulses to a plurality of measurement points (212, 214, 216), receiving a plurality of trains of Raman scattered light pulses (124) for being directed to a plurality of pulse emission points (232, 234, 236), and capturing a plurality of Raman scattered light pulse trains from a plurality of pulse emission points at intervals of a predetermined time period (T1, T2). The method includes delaying one of a plurality of excitation laser pulse trains directed toward a plurality of measurement points or a plurality of Raman scattered light pulse trains emitted at a plurality of pulse emission points for a predetermined period of time.

Description

Technical Field

[0001] This disclosure relates to a method for measuring Raman scattered light from a sample. This disclosure also relates to a system for measuring Raman scattered light from a sample. Background Technology

[0002] Raman spectroscopy is used in many different fields, such as molecular identification, the study of chemical and intramolecular bonds, materials characterization, determination of crystal orientation, observation of low-frequency excited states of solids, and identification of active pharmaceutical ingredients and their polymorphs. Furthermore, multi-point Raman spectroscopy can rapidly acquire multiple sets of spectra on large-area samples. Multi-point Raman spectroscopy is important in industrial applications, such as those requiring Raman spectra measurements from several locations (e.g., 2-10 locations).

[0003] Typically, charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) imaging sensors are used to collect Raman spectra from multiple measurement points. Traditionally, multi-point Raman spectroscopy is achieved by using these imaging sensors at individual measurement points via a spectrometer, utilizing large CCD or CMOS sensors. Multi-point Raman spectroscopy can be achieved using these imaging sensors in continuous-wave Raman spectroscopy. However, due to limitations in the integrated circuit (IC) design layout required for operating CMOS single-photon avalanche diode (SPAD) photodetectors, the use of these imaging sensors can be difficult or even impossible for time-gated Raman spectroscopy. Specifically, the imaging sensor needs to operate in a conducting state for a period of time measured in picoseconds, making it difficult to detect time-gated Raman spectra with these sensors.

[0004] Furthermore, optomechanical fiber optic multiplexers are used in conjunction with time-gated Raman spectroscopy. However, optomechanical fiber optic multiplexers include moving parts, lenses and / or mirrors, optical stages, supports and mounts, optical tracks and carriers, bases, diffraction gratings, prisms, etc. After a period of use (e.g., more than several years), the components of the optomechanical multiplexer may undergo changes in transmission characteristics due to wear. Moreover, optomechanical fiber optic multiplexers are precision instruments, and therefore, the calibration of their measurement scales can be easily affected by coarse and / or overuse. Consequently, changes in the transmission characteristics of such optomechanical multiplexers can lead to greater errors when capturing measurement data associated with a sample.

[0005] Therefore, based on the foregoing discussion, there is a need to overcome the aforementioned drawbacks associated with multi-point time-gated Raman spectroscopy. Summary of the Invention

[0006] This disclosure seeks to provide a method for measuring Raman scattered light from a sample. This disclosure also seeks to provide a system for measuring Raman scattered light from a sample. The purpose of this disclosure is to provide a solution that at least partially overcomes the problems encountered in the prior art.

[0007] In one aspect, embodiments of this disclosure provide a method for measuring Raman scattered light from a sample, the method comprising: -Emit excitation laser pulse trains from a pulsed laser source; - The excitation laser pulse train is divided into multiple excitation laser pulse trains by a beam splitter; - Multiple excitation laser pulse trains are received by an excitation optics component so that the multiple excitation laser pulse trains are directed to multiple measurement points in the sample, wherein each of the multiple measurement points receives a corresponding excitation laser pulse train from the multiple excitation laser pulse trains; - Multiple Raman scattered light pulses are received from the sample by a collecting optical component; - Multiple Raman scattered light pulse trains are received from the collecting optical components by an optical fiber array block, which includes multiple pulse emission points; - Multiple Raman scattered light pulses are emitted toward the spectrometer from multiple pulse emission points in a spatially offset manner; and - During predetermined time intervals, multiple Raman scattered light pulse trains are captured from the spectrometer by the detector; -This method also includes delaying one of the following: - Multiple excitation laser pulse trains to be received at multiple measurement points on the sample are delayed via an excitation optics component, wherein each of the multiple excitation laser pulse trains is delayed for a predetermined time period, so that the multiple excitation laser pulse trains are incident on the sample at predetermined time intervals, or - A collection optical component delays multiple Raman scattered light pulse trains to be emitted by multiple pulse emission points of the fiber array block, wherein each of the multiple Raman scattered light pulse trains is delayed for a predetermined time period, so that the multiple Raman scattered light pulse trains are captured by the detector at predetermined time intervals.

[0008] In another aspect, embodiments of this disclosure provide a system for measuring Raman scattered light from a sample, the system comprising: - A pulsed laser source used to emit excitation laser pulse trains; - A beam splitter, used to divide an excitation laser pulse train into multiple excitation laser pulse trains; - An excitation optical component for receiving multiple excitation laser pulse trains and directing the multiple excitation laser pulse trains to multiple measurement points in a sample, wherein each of the multiple measurement points receives a corresponding excitation laser pulse train from the multiple excitation laser pulse trains; -Collecting optical components for receiving multiple Raman scattered light pulse trains from the sample; - An optical fiber array block for receiving multiple Raman scattered light pulse trains from a collection optics component, wherein the optical fiber array block includes multiple pulse emission points; - A spectrometer for receiving multiple Raman scattered light pulses emitted from multiple pulse emission points in a spatially offset manner; and - A detector for capturing multiple Raman scattered light pulses from a spectrometer during predetermined time intervals; -In this configuration, one of the excitation optical component and the collection optical component is configured as follows: - The multiple excitation laser pulse trains to be received at multiple measurement points are delayed for a predetermined time period for each of the multiple excitation laser pulse trains, so that the multiple excitation laser pulse trains are incident on the sample at predetermined time intervals, or - The Raman scattered light pulse trains to be emitted by multiple pulse emission points are delayed for a predetermined time period for each of the multiple Raman scattered light pulse trains, so that the multiple Raman scattered light pulse trains are captured by the detector at predetermined time intervals.

[0009] The embodiments of this disclosure substantially eliminate or at least partially solve the aforementioned problems in the prior art, and realize multi-point time-gated Raman spectroscopy without using conventional optomechanical multiplexers. Aspects of multi-point time-gated Raman spectroscopy are achieved by using excitation optics and collection optics configured to respectively delay multiple excitation laser pulse trains to be incident on multiple measurement points of the sample or multiple Raman scattered light pulse trains to be emitted by multiple pulse emission points of an fiber array. Furthermore, the multiple pulse emission points of the fiber array emit multiple Raman scattered light pulse trains toward the spectrometer in a spatially offset manner, and the spectrometer guides the multiple Raman scattered light pulse trains to be captured by a detector at predetermined time intervals. Additional aspects, advantages, features, and examples of this disclosure will become apparent from the accompanying drawings and the detailed description of illustrative embodiments as interpreted in conjunction with the appended claims.

[0010] It should be understood that the features of this disclosure are readily combined in various combinations without departing from the scope of this disclosure as defined by the appended claims. Attached Figure Description

[0011] The above-described invention and the following detailed description of illustrative embodiments will be better understood when read in conjunction with the accompanying drawings. Exemplary constructions of this disclosure are shown in the drawings for illustrative purposes. However, this disclosure is not limited to the specific methods and means disclosed herein. Furthermore, those skilled in the art will understand that the drawings are not drawn to scale. Where possible, the same elements are indicated by the same reference numerals.

[0012] Embodiments of this disclosure will now be described by way of example only with reference to the following figures, in which: Figure 1 This is a block diagram of a system for measuring Raman scattered light from a sample according to an embodiment of the present disclosure; Figure 2 According to embodiments of this disclosure Figure 1 A schematic diagram of a system having excitation optics configured to delay multiple excitation laser pulse trains for a predetermined time period; Figure 3 According to another embodiment of this disclosure Figure 1 A schematic diagram of a system having a collection optics configured to delay multiple Raman scattered light pulse trains for a predetermined time period; Figure 4 According to embodiments of this disclosure Figure 2 and Figure 3 A schematic diagram of system elements used to depict the capture of multiple Raman scattered light pulse trains; Figure 5 According to embodiments of this disclosure Figure 2 and 3 A schematic diagram of the system elements used to depict the synchronous activation of the detector for capturing multiple Raman scattered light pulse trains; Figure 6 According to embodiments of this disclosure Figure 2 and Figure 3 An exemplary perspective view of the fiber optic array block of the system; and Figure 7 This is a flowchart listing the steps involved in a method for measuring Raman scattered light from a sample according to embodiments of the present disclosure.

[0013] In the accompanying drawings, underlined reference numerals are used to indicate items that are above or adjacent to the underlined reference numeral. Ununderlined reference numerals refer to items identified by lines linking the ununderlined reference numeral to the item. When an accompanying drawing is ununderlined and accompanied by an associated arrow, the ununderlined reference numeral is used to identify the general item that the arrow points to. Detailed Implementation

[0014] The following detailed description illustrates embodiments of the present disclosure and ways in which these embodiments may be implemented. While some modes of implementing the present disclosure have been disclosed, those skilled in the art will recognize that other embodiments for implementing or practicing the present disclosure are also possible.

[0015] In one aspect, embodiments of this disclosure provide a method for measuring Raman scattered light from a sample, the method comprising: -Emit excitation laser pulse trains from a pulsed laser source; - The excitation laser pulse train is divided into multiple excitation laser pulse trains by a beam splitter; - Multiple excitation laser pulse trains are received by an excitation optics component so that the multiple excitation laser pulse trains are directed to multiple measurement points in the sample, wherein each of the multiple measurement points receives a corresponding excitation laser pulse train from the multiple excitation laser pulse trains; - Multiple Raman scattered light pulses are received from the sample by a collecting optical component; - Multiple Raman scattered light pulse trains are received from the collecting optical components by an optical fiber array block, which includes multiple pulse emission points; - Multiple Raman scattered light pulses are emitted toward the spectrometer from multiple pulse emission points in a spatially offset manner; and - During predetermined time intervals, multiple Raman scattered light pulse trains are captured from the spectrometer by the detector; -This method also includes delaying one of the following: - Multiple excitation laser pulse trains to be received at multiple measurement points on the sample are delayed via an excitation optics component, wherein each of the multiple excitation laser pulse trains is delayed for a predetermined time period, so that the multiple excitation laser pulse trains are incident on the sample at predetermined time intervals, or - A collection optical component delays multiple Raman scattered light pulse trains to be emitted by multiple pulse emission points of the fiber array block, wherein each of the multiple Raman scattered light pulse trains is delayed for a predetermined time period, so that the multiple Raman scattered light pulse trains are captured by the detector at predetermined time intervals.

[0016] In another aspect, embodiments of this disclosure provide a system for measuring Raman scattered light from a sample, the system comprising: - A pulsed laser source used to emit excitation laser pulse trains; - A beam splitter, used to divide an excitation laser pulse train into multiple excitation laser pulse trains; - An excitation optical component for receiving multiple excitation laser pulse trains and directing the multiple excitation laser pulse trains to multiple measurement points in a sample, wherein each of the multiple measurement points receives a corresponding excitation laser pulse train from the multiple excitation laser pulse trains; -Collecting optical components for receiving multiple Raman scattered light pulse trains from the sample; - An optical fiber array block for receiving multiple Raman scattered light pulse trains from a collection optics component, wherein the optical fiber array block includes multiple pulse emission points; - A spectrometer for receiving multiple Raman scattered light pulses emitted from multiple pulse emission points in a spatially offset manner; and - A detector for capturing multiple Raman scattered light pulses from a spectrometer during predetermined time intervals; -In this configuration, one of the excitation optical component and the collection optical component is configured as follows: - The multiple excitation laser pulse trains to be received at multiple measurement points are delayed for a predetermined time period for each of the multiple excitation laser pulse trains, so that the multiple excitation laser pulse trains are incident on the sample at predetermined time intervals, or - The Raman scattered light pulse trains to be emitted by multiple pulse emission points are delayed for a predetermined time period for each of the multiple Raman scattered light pulse trains, so that the multiple Raman scattered light pulse trains are captured by the detector at predetermined time intervals.

[0017] This disclosure provides a method and system for measuring Raman scattered light from a sample. Specifically, the method and system of this disclosure implement multi-point time-gated Raman spectroscopy. Typically, the method and system of this disclosure eliminate the need for conventional optomechanical multiplexers used in multi-point time-gated Raman spectroscopy. Multi-point time-gated Raman spectroscopy is achieved by using excitation optics and collection optics configured to delay one of the following for a predetermined time period: the incident excitation laser pulse train onto the sample and the capture of the Raman scattered light pulse train by a detector. The absence of an optomechanical multiplexer avoids the potential loss of transmission characteristics due to wear and tear of such an optomechanical multiplexer. The method and system of this disclosure enable the convenient use of imaging sensors (such as conventional CMOS SPADs) for multi-point time-gated Raman spectroscopy, i.e., sensing Raman scattered light pulses typically generated in the picosecond range. Furthermore, the size of such imaging sensors can be narrower (or smaller) compared to the size of standard conventional imaging sensors used to perform multi-point time-gated Raman spectroscopy.

[0018] Throughout this disclosure, the term "sample" refers to a material that emits optical radiation (including, but not limited to, Raman scattering) when irradiated with light (such as a laser). In fact, all samples can emit Raman scattering when irradiated with light, for example, when the sample contains molecules and / or crystal structures with vibrational energy levels. Samples can include, for example, organic and / or biological materials. Furthermore, samples can include, for example, gases, solids, and / or liquids. Samples can be contained, for example, in a sample cell. For example, organic molecules containing conjugated aromatic rings can emit light through fluorescence and Raman scattering.

[0019] Raman scattering typically includes two types of radiation: Stokes Raman scattering and anti-Stokes Raman scattering. Stokes Raman scattering is an inelastic scattering process in which photons of the illuminating light (such as lasers) can lose energy to changes in the vibrational and / or rotational states of the sample; that is, the difference between the energy of the incident photon and the corresponding scattered photon is positive. Anti-Stokes Raman scattering is an inelastic scattering process in which the scattered photons can gain energy from changes in the vibrational states of the sample; that is, the difference between the energy of the incident photon and the corresponding scattered photon is negative. The Raman spectra of a sample can, for example, provide information about the sample's molecular composition. This information can be used, for example, for qualitative chemical analysis of the sample, for quantitative chemical analysis of the sample, and / or for analyzing the sample's crystal structure. Furthermore, this information can be used to control industrial processes.

[0020] This method involves emitting an excitation laser pulse train from a pulsed laser source. The term "excitation laser pulse train" refers to a series of laser pulses generated by a pulsed laser source. This method utilizes a strong monochromatic light source (such as a laser source) to generate the excitation laser pulse train. The pulsed laser source is used to emit light pulses, preferably in the ultraviolet, visible, or near-infrared region of the electromagnetic spectrum. Examples of pulsed laser sources include diode lasers, solid-state lasers, etc. Alternatively, the pulsed laser source can be a Q-switched laser capable of emitting short pulses of light.

[0021] The method also includes dividing the excitation laser pulse train into multiple excitation laser pulse trains using a beam splitter. In the example, the beam splitter can be a 1×3 beam splitter, a 1×4 beam splitter, a 1×8 beam splitter, a 1×24 beam splitter, or a 1×64 beam splitter, etc., as needed. The 1×3 or 1×4 beam splitter configuration can be a structure used to separate the excitation laser pulse train into three or four excitation laser pulse trains respectively.

[0022] The method also includes receiving multiple excitation laser pulse trains by an excitation optics component. According to an embodiment, the excitation optics component may be a fiber optic splitter (PLC splitter or fused fiber splitter). In another embodiment, free space may be used instead of the excitation optics component. Essentially, the excitation optics component can be configured to act as an optical delay element to delay the multiple excitation laser pulse trains in the optical paths of the multiple excitation laser pulse trains so that the multiple excitation laser pulse trains are directed to the sample. For each optical path, a predefined time delay may exist, which differs from the time delays of the other optical paths.

[0023] In one embodiment, the excitation optics comprises multiple optical fibers. The optical fibers are thin, flexible bundles of transparent material capable of transmitting multiple laser pulse trains therethrough. The optical fibers may include a core surrounded by a cladding having a low refractive index. Furthermore, the optical fibers are configured to efficiently transmit multiple excitation laser pulse trains through them with low attenuation and low dispersion.

[0024] In one embodiment, each of the plurality of optical fibers is configured, for example, to have a length difference relative to the other optical fibers, to cause a time delay for a predetermined time period. For example, a predetermined length difference may exist between the optical fibers that excite the optical components and / or between the optical fibers that collect the optical components. In an example, the length difference is in the range of 1 meter to 100 meters. Optionally, the length difference is in the range of 1 meter, 10 meters, 20 meters, 30 meters, 40 meters, 50 meters, 60 meters, 70 meters, 80 meters, or 90 meters to 10 meters, 20 meters, 30 meters, 40 meters, 50 meters, 60 meters, 70 meters, 80 meters, 90 meters, or 100 meters. In an example, the length difference may result in a time delay for a predetermined time period in the range of 5 nanoseconds to 500 nanoseconds. Optionally, the interval of the predetermined time period may be in the range of 5, 10, 50, 100, 200, 300, or 400 to 10, 50, 100, 200, 300, 400, or 500.

[0025] The method further includes directing a plurality of excitation laser pulse trains to a plurality of measurement points in the sample via excitation optics. Each of the plurality of measurement points receives one excitation laser pulse train from the plurality of excitation laser pulse trains. The term "multiple measurement points" refers to a physical point used for measurement of the plurality of excitation laser pulse trains. Simply put, multiple measurement points are the number of physical points present in the sample on which multiple excitation laser pulse trains are received. Furthermore, each of the plurality of measurement points receives one excitation laser pulse train from the plurality of excitation laser pulse trains. It should be understood that the number of multiple measurement points will be based on the number of multiple excitation laser pulse trains generated by the beam splitter from the emitted laser pulse train. For example, if the beam splitter splits the excitation laser pulse train into 3, 4, 16, 32, or 64 excitation laser pulse trains, then 3, 4, 16, 32, or 64 measurement points are formed at the sample accordingly. Therefore, it will be apparent to those skilled in the art that the number of measurement points in the sample is related to the "multi-point" aspect of multi-point time-gated Raman spectroscopy.

[0026] According to an embodiment, when multiple excitation laser pulse trains are directed to a sample, multiple Raman scattered light pulse trains will be scattered from the sample. For example, irradiating the sample with a series of excitation laser pulse trains, each pulse train will cause some light to be absorbed and scattered by the sample. This will result in the generation of multiple Raman scattered light pulse trains from the sample. As described above, the multiple excitation laser pulse trains will arrive at or be incident on multiple measurement points in the sample with a predetermined time delay, and correspondingly, multiple Raman scattered light pulse trains will be generated with a predetermined time delay.

[0027] The method also includes receiving multiple Raman scattered light pulse trains from a sample via a collection optics component. According to an embodiment, the excitation optics component comprises multiple optical fibers. Each of the multiple optical fibers of the collection optics component can be configured to have a length difference relative to the other optical fibers in the collection optics component to cause a time delay for a predetermined time period. In an example, the length difference is in the range of 1 meter to 100 meters. Optionally, the length difference is in the range of 1 meter, 10 meters, 20 meters, 30 meters, 40 meters, 50 meters, 60 meters, 70 meters, 80 meters, or 90 meters to 10 meters, 20 meters, 30 meters, 40 meters, 50 meters, 60 meters, 70 meters, 80 meters, 90 meters, or 100 meters. In an example, the length difference can result in a time delay for a predetermined time period in the range of 5 nanoseconds to 500 nanoseconds. Optionally, the reserved time period is within the range of 5, 10, 50, 100, 200, 300 or 400 to 10, 50, 100, 200, 300, 400 or 500.

[0028] The method further includes receiving multiple Raman scattered light pulse trains from a collecting optics component by an optical fiber array block, the optical fiber array block including multiple pulse emission points. Each of the multiple pulse emission points is configured to emit a Raman scattered light pulse train toward the spectrometer. The method also includes emitting multiple Raman scattered light pulse trains toward the spectrometer by the multiple pulse emission points in a spatially offset manner.

[0029] According to an embodiment, the term "multiple pulse emission points" refers to physical points used for measuring multiple Raman scattered light pulse trains. In other words, the multiple pulse emission points can be associated input slits or optical fibers present in an fiber array block, configured to emit multiple Raman scattered light pulse trains therethrough. For example, each of the multiple pulse emission points can be an input slit of the fiber array block or an end of an optical fiber that emits multiple Raman scattered light pulse trains through it. It should be understood that the number of multiple pulse emission points can be based on the number of multiple optical fibers present in the collecting optics. The multiple optical fibers of the collecting optics serve as optical channels for the multiple Raman scattered light pulse trains to pass through and be received by the fiber array block. Furthermore, the number of multiple optical fibers present in the collecting optics can be based on the number of measurement points associated with the sample, which in turn is based on the number of multiple optical fibers present in the excitation optics.

[0030] In one embodiment, the method includes arranging a plurality of pulse emission points of an optical fiber array block in a spatially offset manner by a predetermined distance. Essentially, each of the plurality of pulse emission points is spaced apart from each other such that a pulse emission point is spaced apart from its adjacent pulse emission point by a predetermined distance. In other words, the optical fiber array block can be a block having multiple optical fibers, each fiber having a uniform length. For example, the optical fibers can be arranged side-by-side, stacked on top of each other to form a matrix (a two-dimensional grid of points). As described above, the multiple optical fibers are arranged in a spatially offset manner to form a matrix, and each of the multiple optical fibers is spaced apart from its adjacent optical fibers by a predetermined distance.

[0031] According to an embodiment, the predetermined distance is in the range of 10 micrometers to 1000 micrometers. Optionally, the predetermined distance is in the range of 10 micrometers, 100 micrometers, 200 micrometers, 300 micrometers, 400 micrometers, 500 micrometers, 600 micrometers, 700 micrometers, 800 micrometers, or 900 micrometers to 100 micrometers, 200 micrometers, 300 micrometers, 400 micrometers, 500 micrometers, 600 micrometers, 700 micrometers, 800 micrometers, 900 micrometers, or 1000 micrometers. In the example, sufficiently precise placement of the optical fiber can be achieved by using a 2D matrix fiber array based on a precision-machined glass substrate. Furthermore, a V-groove-based fiber array can be used to stack the optical fibers. It should be understood that the output portion of the optical fiber of the fiber array block, which emits multiple Raman scattered light pulse trains passing through it, can define multiple pulse emission points for the fiber array block. Therefore, the multiple pulse emission points depend on the number of optical fibers present in the fiber array block.

[0032] In embodiments, rows or columns of a matrix of multiple optical fibers can define a single pulse emission point. For example, if a fiber array block comprises 12 optical fibers, it can form a 3x4 matrix, and each row or column (each with 4 fibers) can define a single pulse emission point. Thus, a fiber array block can include a total of 3 distinct pulse emission points. Collecting or grouping fibers in this way allows for the collection of more light while simultaneously emitting Raman scattered light pulse trains within it. Alternatively, a fiber array block with 12 optical fibers can be considered to have 12 distinct pulse emission points (which can correspond to 12 different measurement points in a sample). Furthermore, all fibers in the fiber array block can have the same length or different lengths.

[0033] Based on the above description, it should be understood that the excitation optics and / or collection optics can have multiple optical fibers, each of which can be configured to have a length difference relative to the other fibers to cause a predetermined time delay for each of the multiple optical pulse trains. Utilizing this time delay, the detector's capture of the Raman scattered light pulse train is delayed in a predetermined manner. In other words, delaying multiple Raman scattered light pulse trains in their optical path by multiple predetermined time delays results in the capture of collected signal pulses at the detector at different times.

[0034] The method also includes capturing multiple Raman scattered light pulse trains from the spectrometer at predetermined time intervals using a detector.

[0035] According to an embodiment, the detector may be a complementary metal-oxide-semiconductor (CMOS). Specifically, the detector may include a CMOS single-photon avalanche diode (SPAD), which will be explained in more detail below.

[0036] The method also includes one of the following: - Multiple excitation laser pulse trains to be received at multiple measurement points on the sample are delayed via excitation optics, wherein each of the multiple excitation laser pulse trains is delayed for a predetermined time period, so that the multiple excitation laser pulse trains are incident on the sample at predetermined time intervals, or - A plurality of Raman scattered light pulse trains to be emitted by a plurality of pulse emission points of an optical fiber array block are delayed by a collection optical component, wherein each of the plurality of Raman scattered light pulse trains is delayed for a predetermined time period, so that the plurality of Raman scattered light pulse trains are captured by a detector at intervals of the predetermined time period.

[0037] In embodiments, the method further includes capturing multiple Raman scattered light pulse trains from a spectrometer through a predefined region of the detector. According to embodiments, the “predefined region” of the detector is a region of the detector defined by physical measurement points of the detector. Obviously, the size of the predefined region of the detector can be increased or decreased based on the number of physical measurement points. In this disclosure, a smaller number of physical measurement points will define the predefined region of the detector, which can be effectively used to perform multi-point time-gated Raman spectroscopy. Typically, multiple Raman scattered light pulse trains departing from multiple pulse emission points of an fiber array block are received by a spectrometer, which focuses the multiple Raman scattered light pulse trains toward the detector. Furthermore, the delay caused by the multiple pulse emission points when guiding the multiple Raman scattered light pulse trains to the spectrometer allows the same portion of the detector (or a predetermined region of the detector) to receive or capture the multiple Raman scattered light pulse trains guided to the detector. This makes it possible to effectively use the detector to perform multi-point time-gated Raman spectroscopy. In short, according to this disclosure, the detector can be made of a smaller number of photoelectric sensors (such as CMOS SPADs), which can be conveniently used for multi-point time-gated Raman spectroscopy.

[0038] According to an embodiment, the method further includes guiding the multiple Raman scattered light pulse trains to a spectrometer before they are captured by a detector. The spectrometer is configured to: - Collimate the multiple Raman scattered light pulse trains received from the multiple pulse emission points. -Dispersion of multiple collimated Raman scattered light pulse trains, and - Focus the dispersed Raman light pulse trains so that they are directed to the detector.

[0039] Clearly, the aspects of collimating, dispersing, and focusing multiple Raman light pulse trains are associated with a typical spectrometer. For example, a spectrometer may include: a collimating lens for collimating multiple Raman scattered light pulse trains exiting multiple pulse emission points; a diffraction grating for dispersing the multiple collimated Raman scattered light pulse trains; and a focusing lens for focusing the dispersed multiple Raman light pulse trains for capture by a detector. In this example, the spectrometer may be based on a volumetric holographic grating. Furthermore, it is evident that the spectrometer is positioned in front of the detector to input the Raman scattered light pulse trains into the detector. Additionally, an fiber optic array block may be positioned before the spectrometer, which is positioned before the detector.

[0040] In embodiments, the method further includes synchronizing the activation of the detectors based on predetermined time intervals. As used herein, the term "synchronization" refers to determining the time intervals for turning the detectors on and off to measure multiple Raman scattered light pulse trains. Typically, multi-point time-gated Raman spectroscopy techniques associated with this disclosure employ time-resolved detectors (such as CMOS SPAD sensor elements) configured to remain in an "on" state for a short duration to measure Raman scattered light falling upon them, while they are configured to remain in an "off" state for a longer duration during which fluorescence or other non-Raman optical emission is primarily observed. Notably, emission via fluorescence is typically a long-lived process compared to Raman radiation emission. Therefore, the "on" state associated with the sensor element ideally equals the time width of the laser pulse (e.g., 1 nanosecond to 5 nanoseconds (ns), further divided into 32 time slots) during which Raman radiation is observed. This device employing time-gated Raman spectroscopy eliminates some of the fluorescence effects (particularly the tail of fluorescence). Simply put, the detector is turned on at a point in time after a predetermined time interval (i.e., the delay in arrival at the detector caused by the excitation or collection optics of the Raman scattered light pulse train). In an embodiment, the controller implements the synchronous activation of the detector.

[0041] According to an embodiment, the method further includes calibrating a signal measured by a predefined region of the detector, which corresponds to a plurality of Raman scattered light pulse trains captured from the spectrometer. As used herein, the term "calibrate" for a signal measured by the detector refers to correcting or adjusting the peak value of a measured signal (spectral intensity of the Raman spectrum) that has been offset by a small distance in the spectral direction on the detector. This small distance (or offset) between measured signals in the spectral direction of the detector is caused by a predetermined distance between the fibers of the fiber array block. Therefore, calibrating the signal allows for adjusting or correcting the measured signals to ensure they are accurate and correctly positioned in the spectral direction of the detector (or within the predefined region of the detector). In an example, this can be done by comparing the measured signal to a known reference signal and adjusting the measured signal to correct any offset in the peak value of the measured signal intensity (e.g., by adjusting the wavelength axis of the Raman spectrum). This is done to improve the precision and accuracy of measurements performed by a predetermined region of the detector.

[0042] Optionally, in this disclosure, the activation of the detector is synchronized based on a control signal; that is, the detector is switched on between spectral intensity distribution periods. Furthermore, the spectral intensity distribution period is based on a predetermined time delay (for multiple excitation laser pulse trains incident on or captured from the sample). Importantly, the predetermined time period is in the range of 5 nanoseconds to 500 nanoseconds, which allows imaging sensors such as CMOS SPAD imaging matrices to efficiently perform time-gated Raman spectroscopy measurements.

[0043] Furthermore, the method also includes the synchronous activation of the pulsed laser source based on a predetermined time period. Simply put, the pulsed laser source is only subsequently activated when the detector measures the excitation laser pulse train emitted by the pulsed laser source and the detector is ready to measure the subsequent excitation laser pulse train to be emitted by the pulsed laser source. Clearly, the activation of the pulsed laser source is correspondingly related to a predetermined time period delay caused in the excitation or collection optics.

[0044] This disclosure also relates to the system described above. Various embodiments and variations of the methods disclosed above are applicable to the system with necessary modifications.

[0045] Optionally, the system further includes a controller operatively coupled to the pulsed laser source and the detector, wherein the controller is operable to synchronize the activation of the detector based on a predetermined time interval.

[0046] Optionally, the system may also include a spectrometer, i.e., a combination of at least a collimating lens, a diffraction grating, and a focusing lens.

[0047] Optionally, the system may include a data processing unit for processing measurements obtained from sensor elements. The device may include a memory for storing output values ​​determined from the measurements. The output values ​​may specify the time-resolved spectrum of the sample measurement. The data processing unit may be configured to determine a time delay and operate a pulsed laser source and detector based on the time delay.

[0048] Optionally, the system may include a memory for storing operating parameters. For example, operating parameters may include time delays and data associated with those time delays, spectral data, etc.

[0049] Optionally, the system may include a user interface for providing information to a user and / or for receiving user input from the user. The user interface may include, for example, a display, a touchscreen, and / or a keyboard. For example, the user interface may be configured to graphically display the measured time-resolved spectrum. For example, the user interface may be configured to display a graph representing the measured time-resolved spectrum, such as a histogram.

[0050] Optionally, the system may include a communication unit for sending and / or receiving data. The communication unit may be configured to communicate with a local area network, the Internet, and / or a mobile communication network. The system may also be configured to perform data processing in a distributed manner (e.g., by using an Internet server).

[0051] Detailed description of the attached figures refer to Figure 1A block diagram of a system 100 for measuring Raman scattered light from a sample 102 according to an embodiment of the present disclosure is shown. System 100 includes a pulsed laser source 104, a beam splitter 106, an excitation optics component 108, a collection optics component 110, a fiber array block 112, a spectrometer 114, and a detector 116. System 100 also includes a controller 120 operatively coupled to the pulsed laser source 104 and the detector 116. Figure 1 Multiple excitation laser pulse trains 122 guided to sample 102 by excitation optics 108, and multiple Raman scattered light pulse trains 124 received from sample 102 by collection optics 110 are also depicted.

[0052] In operation, a laser pulse train from pulsed laser source 104 is output to beam splitter 106, which splits the excitation laser pulse train into multiple excitation laser pulse trains. After the beam splitter, the multiple excitation laser pulse trains are guided by excitation optics 108 to sample 102, directing them to multiple measurement points within sample 102, each of which receives a corresponding excitation laser pulse train from the multiple excitation laser pulse trains. Laser pulse trains reflecting from the sample surface, including Raman scattered light, are guided to collection optics 110, where the multiple Raman scattered light pulse trains return towards fiber array block 112, and are then transmitted via fiber array block 112 to detector 116 coupled to spectrometer 114.

[0053] Figure 2 yes Figure 1 A schematic diagram of the system. In Figure 2 In this design, the excitation optics 108 includes multiple optical fibers 202, 204, and 206, each configured to be associated with the sample 102. More specifically, a first end of fiber 202 is connected to a beam splitter 106, and a second end is connected to a measurement point 212. Similarly, a first end of fiber 204 is connected to the beam splitter 106, and a second end is connected to a measurement point 214. Likewise, a first end of fiber 206 is connected to the beam splitter 106, and a second end is connected to a measurement point 216.

[0054] refer to Figure 2 Each of optical fibers 202, 204, and 206 is configured to have a length difference relative to the other optical fibers 202, 204, and 206 in the excitation optics, so as to cause a time delay of a predetermined period when directing multiple excitation laser pulse trains to measurement points 212, 214, and 216. Figure 2 In this text, the length difference is indicated by loops arranged in the optical fiber. For example, as shown, fiber 204 has two loops, while fiber 202 has no loops. In this text, the number of loops indicates that fiber 204 is longer than fiber 202. Fiber 206 has four loops, therefore fiber 206 is longer than fiber 204.

[0055] The impact of length variations in optical fibers is further illustrated by diagrams. Figure 2 The right side shows three graphs illustrating the pulse amplitude as a function of time. The top graph (represented as Excitation 1) depicts the excitation laser pulse train leading to measurement point 212, the middle graph (represented as Excitation 2) depicts the excitation laser pulse train leading to measurement point 214, and the bottom graph (represented as Excitation 3) depicts the excitation laser pulse train leading to measurement point 216. Due to the length differences of fibers 202, 204, and 206, Raman scattering occurs at different times at measurement points 212, 214, and 216. In the top graph, the excitation laser pulse is on the left side of the graph. In the middle graph, the excitation laser pulse is delayed relative to the top and shifted to the right along the time axis, and in the bottom graph, the excitation laser pulse is further delayed relative to the top and shifted further to the right. The collected laser pulse is detected with the same relative time delay as the excitation laser pulse when reflected from the measurement point of the sample.

[0056] Figure 2 A collecting optical component 110 is further depicted having multiple optical fibers 222, 224, and 226, each fiber having a uniform length. Here, the lengths of the optical fibers 222, 224, and 226 can, for example, be equal. Furthermore, the optical fibers 222, 224, and 226 do not necessarily need to have the same length. Figure 2 An optical fiber array block 112 is depicted having multiple pulse emission points 232, 234, 236 associated with multiple optical fibers 222, 224, 226. More specifically, optical fiber 222 has a first end arranged to connect to pulse emission point 232 and a second end connected to measurement point 212. Furthermore, optical fiber 224 has a first end arranged to connect to pulse emission point 234 and a second end connected to measurement point 214. Additionally, optical fiber 226 has a first end arranged to connect to pulse emission point 236 and a second end connected to measurement point 216.

[0057] Figure 2 The spectrometer 114, controller 120, pulsed laser source 104, and spectrometer 106 associated with detector 116 are also depicted. The controller can be used to synchronize time-gated detectors, such as SPAD matrices, to activate the detector between each measurement pulse and capture the collected signal from each measurement point separately.

[0058] Figure 3 According to another embodiment of this disclosure Figure 1 A schematic diagram of the system. In Figure 3In this design, the excitation optics 108 includes multiple optical fibers 302, 304, and 306, each fiber associated with the sample 102. More specifically, fiber 302 has a first end connected to a beam splitter 106 and a second end connected to a measurement point 212 on the sample 102. Fiber 304 has a first end connected to the beam splitter 106 and a second end connected to a measurement point 214. Furthermore, fiber 306 has a first end connected to the beam splitter 106 and a second end connected to a measurement point 216.

[0059] Figure 3 A collecting optics component 110 with multiple optical fibers 322, 324, and 326 is also depicted. In the collecting optics component 110, optical fiber 322 has a first end connected to pulse emission point 232 and a second end connected to measurement point 212. Optical fiber 324 has a first end connected to pulse emission point 234 and a second end connected to measurement point 214. Furthermore, optical fiber 326 has a first end connected to pulse emission point 236 and a second end connected to measurement point 216. Each of the multiple optical fibers 322, 324, and 326 is configured to have a length difference relative to the other optical fibers 322, 324, and 326 in the collecting optics component, so as to cause a time delay of a predetermined time period when multiple Raman scattered laser pulse trains are received from sample 102. The length difference is illustrated by loops arranged in the optical fiber. The more loops an optical fiber has, the longer the optical fiber is. Here, optical fiber 324 has three loops, optical fiber 326 has four loops, while optical fiber 322 has no loops. Therefore, fiber 324 is longer than fiber 322, and fiber 326 is longer than fiber 324. The longer fibers 322, 324, and 326 are, the longer the time delay of the light pulse traveling from one end of the fiber to the other. When Raman scattered laser pulse trains are emitted toward the spectrometer 114 from multiple pulse emission points 232, 234, and 236 of the fiber array block 112, the time delay caused by fibers 322, 324, and 326 also causes the same time delay.

[0060] Figure 3 The detector 116, controller 120, pulsed laser source 104, and beam splitter 106 are also depicted.

[0061] refer to Figure 4 The following illustrates embodiments according to the present disclosure. Figure 2 and Figure 3A schematic diagram of system elements for capturing multiple Raman scattered light pulse trains in system 100. Typically, the system elements involve a spectrometer 114 having a collimating lens 402, a diffraction grating 404, and a focusing lens 406. As shown, the collimating lens 402 is configured to collimate multiple Raman scattered light pulse trains 410 exiting multiple pulse emission points 232, 234, 236 of the fiber array block 112. Subsequently, the diffraction grating 404 is configured to disperse the collimated multiple Raman scattered light pulse trains 412, and finally, the focusing lens 406 is configured to focus the dispersed multiple Raman light pulse trains 414 so that they are captured by the detector 116. As shown, the fiber array block 112 includes 12 optical fibers in a matrix 3*4 configuration, where each column (with 4 fibers) defines pulse emission points 232, 234, 236. As described above, the excitation optics 108 ( Figure 2 The optical fibers 202, 204, 206 or the collecting optical component 110 shown in the figure Figure 3 Fibers 322, 324, and 326 (as shown in the diagram) are configured to cause a time delay for a predetermined period. Therefore, multiple Raman scattered light pulse trains 410 departing from pulse emission points 232, 234, and 236 are delayed when captured by detector 116. It should be understood that... Figure 4 Only the light emitted from one fiber corresponding to pulse emission points 232, 234, and 236 is depicted. In addition, this group of four fibers (belonging to a column of fiber array block 112), each defining pulse emission points 232, 234, and 236 respectively, can cause more light to be collected. Figure 4A graph 450 depicting the spectral intensity distribution of Raman scattered light based on multiple dispersed Raman light pulse trains 414 (corresponding to multiple Raman scattered light pulse trains 124 or measurement signals) captured by detector 116 is also shown. Graph 450 depicts the time and amplitude distribution of spectral intensity along the X and Y axes, respectively. Graph 450 also depicts intervals of predetermined time periods, such as time period T1 (i.e., a 40 ns delay) and time period T2 (i.e., a 50 ns delay), to delay the multiple Raman scattered light pulse trains so that they can be captured by detector 116. The spectral intensity distributions corresponding to the measurement signals of the multiple dispersed Raman light pulse trains 414 are shown with different line types (i.e., dotted lines, dashed lines, and center lines). Graph 450 also depicts the spectral intensity distribution corresponding to multiple Raman scattered light pulse trains emitted from pulse emission points 232, 234, and 236 and measured by detector 116 at different time points (i.e., with a predetermined time delay caused by excitation optics 108 or collection optics 110). Clearly, the spatial offset between pulse emission points 232, 234, and 236 will cause a shift in the multiple Raman scattered light pulse trains 410 leaving fiber array block 112, which in turn causes a shift in the multiple dispersed Raman light pulse trains 414 leaving focusing lens 406 and falling into different positions on detector 116. Detector 116 can be designed such that different wavelength components are incident on specific regions of detector 116. Therefore, channels within detector 116 are calibrated to capture the spatial distribution of different wavelengths. Calibration will involve mapping the spatial positions of the channels to the corresponding wavelengths of interest, ensuring accurate wavelength assignment for each detected signal. Thus, by acquiring spectra at different positions on detector 116, it is possible to examine how spectral characteristics vary on the sample. For example, by obtaining spectra at different spatial coordinates, we can analyze the molecular composition at different locations in a sample.

[0062] refer to Figure 5 The following illustrates embodiments according to the present disclosure. Figure 2 and Figure 3 The system 100 is used to depict detectors (such as those used to capture multiple Raman scattered light pulse trains) for capturing multiple Raman scattered light pulse trains. Figure 1 A schematic diagram of the synchronously activated system elements of the detector 116. Typically, Figure 5A controller 120 is shown, operable to synchronize the operation of detector 116 with respect to a Raman scattered light pulse train. Specifically, controller 120 is operable to synchronize the operation of detector 116 based on the arrival of the Raman scattered light pulse train at detector 116, i.e., when detector 116 should be turned on and for how long. As shown, multiple Raman scattered light pulse trains corresponding to pulse measurement points 232, 234, and 236 are about to arrive at detector 116 at 10 ns, 50 ns, and 100 ns, respectively. Therefore, controller 120 is operable to synchronize the operation of detector 116 based on the control signal shown in graph 502. Graph 502 depicts the synchronization control signal that detector 116 will use based on its operation (turning on and off). Specifically, the synchronization control signal in graph 502 indicates time points along the time axis: 10 ns, 50 ns, and 100 ns. At these time points, detector 116 will be turned on based on the synchronous arrival of the Raman scattered light pulse train at 10 ns, 50 ns, and 100 ns. Graph 502 also depicts the duration (e.g., 5 ns) for which detector 116 will be turned on at different time points (i.e., 10 ns, 50 ns, and 100 ns) when the Raman scattered light pulse train arrives at detector 116.

[0063] Now for reference Figure 6 The following illustrates embodiments according to the present disclosure. Figure 2 and Figure 3 An exemplary perspective view of a system's fiber optic array block (such as fiber optic array block 112) is shown. As illustrated, fiber optic array block 112 includes a plurality of optical fibers 602 configured to receive and transmit a plurality of Raman scattered light pulse trains therethrough. It should be understood that the plurality of optical fibers 602 constitute Figure 2 and Figure 3 The fiber array block 112 shown has pulse emission points 232, 234, and 236. Multiple optical fibers 602 are shown arranged in a 9 × 9 matrix. Furthermore, the multiple optical fibers 602 are shown arranged between a pair of plates 604. Additionally, each of the multiple optical fibers 602 (forming pulse emission points 232, 234, and 236) is shown spaced from the adjacent optical fiber by a predetermined distance D.

[0064] refer to Figure 7This diagram illustrates a flowchart of the steps involved in a method 700 for measuring Raman scattered light from a sample, according to an embodiment of the present disclosure. At step 702, an excitation laser pulse train is emitted from a pulsed laser source. At step 704, the excitation laser pulse train is split into multiple excitation laser pulse trains by a beam splitter. At step 706, the multiple excitation laser pulse trains are received by an excitation optics component for guiding the multiple excitation laser pulse trains to multiple measurement points in the sample, wherein each of the multiple measurement points receives one excitation laser pulse train from the multiple excitation laser pulse trains. At step 708, the multiple Raman scattered light pulse trains are received from the sample by a collection optics component. At step 710, the multiple Raman scattered light pulse trains are received from the collection optics component by an fiber array block, the fiber array block including multiple pulse emission points. At step 712, the multiple Raman scattered light pulse trains are emitted towards a spectrometer from the multiple pulse emission points in a spatially offset manner. At step 714, the multiple Raman scattered light pulse trains are captured from the spectrometer by a detector at predetermined time intervals. The method further includes delaying one of the following: delaying multiple excitation laser pulse trains to be received at multiple measurement points on the sample via an excitation optics component, wherein each of the multiple excitation laser pulse trains is delayed for a predetermined time period so that the excitation laser pulse trains are incident on the sample at predetermined time intervals; or delaying multiple Raman scattered light pulse trains to be emitted from multiple pulse emission points of the fiber array block via a collection optics component, wherein each of the multiple Raman scattered light pulse trains is delayed for a predetermined time period so that the multiple Raman scattered light pulse trains are captured by the detector at predetermined time intervals.

[0065] Modifications to the embodiments of the present disclosure described above are possible without departing from the scope defined by the appended claims. Expressions such as “comprising,” “including,” “containing,” “having,” and “are” used to describe and claim this disclosure are intended to be interpreted in a non-exclusive manner, allowing for the presence of items, components, or elements not explicitly described. References to the singular should also be interpreted to refer to the plural.

Claims

1. A method for measuring Raman scattered light from a sample (102), the method comprising: -Emit an excitation laser pulse train from the pulsed laser source (104); - The excitation laser pulse train is divided into multiple excitation laser pulse trains (122) by a beam splitter (106); - The plurality of excitation laser pulse trains are received by the excitation optics (108) so that the plurality of excitation laser pulse trains are directed to a plurality of measurement points (212, 214, 216) in the sample, wherein each of the plurality of measurement points receives a corresponding excitation laser pulse train from the plurality of excitation laser pulse trains; - A plurality of Raman scattered light pulse trains (124) are received from the sample by the collecting optical component (110); - The plurality of Raman scattered light pulse trains are received from the collecting optical component by the fiber array block (112), the fiber array block including a plurality of pulse emission points (232, 234, 236). - The plurality of Raman scattered light pulse trains are emitted toward the spectrometer (114) in a spatially offset manner from the plurality of pulse emission points; and - During the interval of a predetermined time period (T1, T2), the detector (116) captures the plurality of Raman scattered light pulses from the spectrometer; -The method further includes delaying one of the following: - The excitation optics delay the plurality of excitation laser pulse trains to be received at the plurality of measurement points on the sample, wherein each of the plurality of excitation laser pulse trains is delayed for a predetermined time period, so that the plurality of excitation laser pulse trains are incident on the sample at intervals of the predetermined time period, or - The collection optics delay the plurality of Raman scattered light pulses to be emitted by the plurality of pulse emission points of the fiber array block, wherein each of the plurality of Raman scattered light pulses is delayed for a predetermined time period, so that the plurality of Raman scattered light pulses are captured by the detector at intervals of the predetermined time period.

2. The method according to claim 1 further includes arranging the plurality of pulse emission points (232, 234, 236) of the fiber array block (112) in a manner offset by a predetermined distance (D) in space.

3. The method according to claim 2, further comprising capturing the plurality of Raman scattered light pulse trains from the spectrometer (114) through a predetermined region of the detector (116).

4. The method of claim 3 further includes calibrating a signal measured by a predetermined region of the detector (116), the signal corresponding to the plurality of Raman scattered light pulse trains captured from the spectrometer (114).

5. The method according to any one of the preceding claims, wherein, The interval between the predetermined time periods (T1, T2) is in the range of 5 nanoseconds to 500 nanoseconds.

6. The method according to any one of the preceding claims, wherein, The spectrometer (114) is configured as follows: - The multiple Raman scattered light pulse trains (410) received from the multiple pulse emission points (232, 234, 236) are collimated. -Dispersion of multiple collimated Raman scattered light pulse trains (412), and - The dispersed multiple Raman light pulse trains (414) are focused so that the dispersed multiple Raman light pulse trains are directed to the detector (116).

7. The method according to any one of the preceding claims further includes synchronizing the activation of the detector (116) based on the interval of the predetermined time period (T1, T2).

8. A system (100) for measuring Raman scattered light from a sample (102), the system comprising: - A pulsed laser source (104) is used to emit an excitation laser pulse train; - A beam splitter (106) is used to divide the excitation laser pulse train into multiple excitation laser pulse trains (122). - An excitation optical component (108) is used to receive the plurality of excitation laser pulse trains and guide the plurality of excitation laser pulse trains to a plurality of measurement points (212, 214, 216) in the sample, wherein each of the plurality of measurement points receives a corresponding excitation laser pulse train from the plurality of excitation laser pulse trains; -Collection optical component (110) for receiving multiple Raman scattered light pulse trains (124) from the sample. - Fiber optic array block (112) for receiving the plurality of Raman scattered light pulse trains from the collecting optical component, wherein the fiber optic array block includes a plurality of pulse emission points (232, 234, 236). - A spectrometer (114) for receiving the plurality of Raman scattered light pulse trains emitted by the plurality of pulse emission points in a spatially offset manner; and - Detector (116) for capturing the plurality of Raman scattered light pulse trains from the spectrometer during intervals of predetermined time periods (T1, T2); - Wherein, one of the excitation optical component and the collection optical component is configured as follows: - The plurality of excitation laser pulse trains to be received at the plurality of measurement points are delayed for a predetermined time period for each of the plurality of excitation laser pulse trains, so that the plurality of excitation laser pulse trains are incident on the sample at intervals of the predetermined time period, or - The Raman scattered light pulse trains to be emitted by the plurality of pulse emission points are delayed for a predetermined time period for each of the plurality of Raman scattered light pulse trains, so that the plurality of Raman scattered light pulse trains are captured by the detector at intervals of the predetermined time period.

9. The system according to claim 8, wherein, Each of the excitation optics (108) and the collection optics (110) includes multiple optical fibers (202-206, 222-226 or 302-306, 322-326), and each of the multiple optical fibers of one of the excitation optics and the collection optics is configured to have a length difference to cause a time delay of the predetermined time period.

10. The system according to claim 9, wherein, The length difference is in the range of 1 meter to 100 meters.

11. The system according to claim 8, wherein, The plurality of pulse emission points (232, 234, 236) of the fiber array block (112) are arranged in a spatially offset manner to form an array, and each of the plurality of pulse emission points is spaced apart from the adjacent pulse emission point by a predetermined distance (D).

12. The system according to claim 11, wherein, The predetermined distance (D) is in the range of 10 micrometers to 1000 micrometers.

13. The system according to any one of claims 8 to 12, further comprising a controller (120) operatively coupled to the pulsed laser source (104) and the detector (116), wherein, The controller is operable to synchronize the activation of the detector based on the interval of the predetermined time period.

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