In-situ high-temperature Raman spectroscopy via remote fiber Raman probes

Abstract

The invention discloses an optical fiber sensor system for in-situ high-temperature Raman spectroscopy. The system comprises an excitation source, a spectrograph and a Raman probe. The Raman probe includes at least one optical fiber coupled to an excitation source and to a spectrometer. The at least one optical fiber transmits laser excitation from the excitation source to the sample and collects light scattered by the sample for analysis by the spectrometer. An outer lens arrangement positioned at a distal end of the at least one optical fiber of the Raman probe optically couples the at least one optical fiber to the sample and physically separates the at least one optical fiber from the sample during sampling. The spectrometer performs Raman spectroscopy of the sample based on the light collected by the at least one optical fiber.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 447,594, filed February 22, 2023, the entire disclosure of which is incorporated herein by reference.

[0003] Government Interest Statement

[0004] This invention was made with government support, including awards DE-EE0009392 and DE-EE0009119 from the Office of Advanced Manufacturing (AMO) of the Office of Energy Efficiency and Renewable Energy (EERE) of the U.S. Department of Energy. The government holds certain rights to this invention. Background Technology

[0005] When photons of light interact with molecules, most photons are affected by slight density fluctuations that alter their direction, resulting in Rayleigh scattering. However, a minority of photons also change their frequency through Raman scattering. The intensity of Raman-scattered light accounts for 10% of the total scattered light intensity. -6 Up to 10 -10 Raman scattering arises from the energy exchange between photons and molecules, which alters the photon's energy. These scattered photons enter different vibrational states specific to the chemical bonds and symmetries of the molecules. Therefore, Raman scattering is known as a fingerprinting technique for diagnosing chemical substances, providing a tool for chemical structure research and molecular structure identification. With the introduction of lasers, the high-power supply of high-quality, stable, and high-intensity monochromatic lasers has become available, providing a tremendous impetus for the study of Raman scattering and its applications under various conditions.

[0006] Raman spectroscopy has been applied in various fields, such as chemistry, physics, biology, and medicine. Even in civil engineering, Raman spectroscopy is used to detect the chemical properties of concrete materials during hydration or carbonation reactions. Furthermore, Raman spectroscopy is valuable for qualitative and highly quantitative analysis, as well as for determining molecular structures. While conventional benchtop Raman systems offer advantages in high precision and accuracy, their drawbacks are also apparent. First, the complex equipment is unsuitable for real-time online measurements. Second, benchtop Raman systems have specific requirements related to sample size. Therefore, special preparation is needed for large samples, and non-destructive measurements are not possible. However, online and real-time diagnostics for biochemical, medical, and materials science applications are essential for scientific research. Therefore, portable fiber optic Raman sensors are needed to allow for the real-time study of material properties.

[0007] Several fiber optic Raman sensor designs have been reported for various applications. The low collection efficiency of fiber optic Raman sensors has led to the development of tilted fiber confocal Raman probes. A spherical lens is coupled to the end of the fiber to focus the light into a tiny spot. By selecting appropriate fiber spherical lenses and the tilt angle of the collecting fiber, the design of the confocal Raman probe can be optimized to maximize superficial tissue Raman measurements of epithelial tissues. Fiber optic Raman probes have been widely used in biochemistry and medicine. However, the properties of fiber optic materials limit the expansion of fiber optic Raman probes in some materials science applications, such as in-situ high-temperature studies. New materials have been developed through high-temperature heat treatment, and understanding how chemical composition changes in real time during high-temperature reactions could be a transformative breakthrough in materials science research. Early studies reported in-situ Raman spectra of silica glass ranging from room temperature to glass transition to 1950 K for supercooled liquids. These studies used novel wire-loop heating techniques to heat samples to high temperatures. However, the diameter of the micro-heating coils, only 0.5 mm to 0.8 mm, significantly limited the size of the experimental samples. Furthermore, the use of a benchtop Raman system to collect Raman spectra limits its applicability in other applications.

[0008] Researchers have proposed applying Raman spectroscopy to extreme high temperatures to study the chemical properties of molten materials. Preliminary studies using high-temperature Raman spectroscopy were conducted using a small electric heating device and a benchtop Raman system. Results showed a correlation between high-temperature Raman spectra and the chemical structure in the liquid, which aids in understanding the chemical properties of molten samples. However, the small electric heating device uses a heating wire ring with a diameter of 0.5mm-0.8mm to fix the glass sample, which greatly limits the volume and size of the sample being tested. Furthermore, the lack of portability of the benchtop Raman system also limits the application of high-temperature Raman technology in practical industrial and production applications.

[0009] A probe is needed that can be positioned near the high-temperature molten material, away from the Raman spectrometer. Summary of the Invention

[0010] This disclosure relates to an in-situ high-temperature fiber optic Raman probe that allows for the study of the structure of glass and slag samples at temperatures up to 1400°C. A custom-designed external telescope is integrated into the portable fiber optic Raman probe to extend the optical working distance, allowing the probe to operate in high-temperature environments. Furthermore, this disclosure includes a deconvolution algorithm configured to identify peaks in the spectrum, which can then be correlated with the molecular structure of the components in each sample. This flexible and reliable high-temperature Raman measurement method holds great potential for a wide range of applications, such as materials development, compositional and structural monitoring during high-temperature processing, chemical identification, and processing monitoring in industrial production.

[0011] In one aspect, a fiber optic sensor system for in-situ high-temperature Raman spectroscopy is disclosed. The system includes an excitation source, a spectrometer, and a Raman probe. The Raman probe includes at least one optical fiber coupled to the excitation source and the spectrometer. This at least one optical fiber transmits laser excitation from the excitation source to the sample and collects light scattered by the sample for analysis by the spectrometer. An external lens arrangement is positioned at the distal end of the at least one optical fiber of the Raman probe, optically coupling the at least one optical fiber to the sample and physically separating the at least one optical fiber from the sample during sampling. The spectrometer performs Raman spectroscopy on the sample based on the light collected by the at least one optical fiber.

[0012] Other objects and features of this disclosure are partly obvious and partly stated herein. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an optical fiber Raman probe with an external telescope according to an embodiment.

[0014] Figure 2 According to the embodiments, including Figure 1 A schematic diagram of an in-situ high-temperature fiber Raman system for a Raman probe.

[0015] Figure 3 Examples of Raman spectra of electric arc furnace slag samples according to embodiments are shown at room temperature and at a temperature of 1400°C.

[0016] Figure 4A and Figure 4B The embodiments are illustrated respectively. Figure 3 Examples of deconvolution results for the Raman spectra of the samples at room temperature and at 1400℃.

[0017] Figure 5 Examples of Raman spectra of the protective slag according to the embodiments are shown at room temperature, at 800°C and at 1400°C.

[0018] Figure 6A and Figure 6B The embodiments are illustrated respectively. Figure 5 Examples of deconvolution results of the protective slag at room temperature and at 1400℃ in Raman spectra.

[0019] Figure 7 Examples of Raman spectra of bioglass according to embodiments at room temperature, at 100°C, at 700°C, and at 1300°C.

[0020] Figure 8A and Figure 8B The embodiments are illustrated respectively. Figure 7Examples of deconvolution results for the Raman spectra of bioglass at room temperature and at 1300 °C.

[0021] Figure 9 According to another embodiment, it includes Figure 1 A schematic diagram of an in-situ high-temperature fiber Raman system for a Raman probe.

[0022] Figure 10 The diagram shows the height from 400cm. -1 Up to 1200cm -1 The example Raman spectra show the Raman regions of four synthetic flux samples at a temperature of 1400 °C.

[0023] Figures 11A to 11D The diagram shows... Figure 10 The fluxes synthesized at 1400℃ for samples 1 to 4 were from 850 cm⁻¹ -1 Up to 1100cm -1 Example deconvolution Raman spectra of the Q region.

[0024] Figures 12A to 1 2D illustration from Figure 10 The Q-region peak area ratios of samples 1 to 4 show an example correlation with flux chemical composition and basicity acquisition.

[0025] Figure 13 The illustration shows example Raman spectra of industrial sample A under different temperature conditions according to an embodiment.

[0026] Figures 14A to 14C The illustration shows industrial flux samples A to C at 1350°C according to the embodiment, at a temperature ranging from 850 cm⁻¹. -1 Up to 1100cm -1 Example deconvolution Raman spectra of the Q region.

[0027] Figure 15 The illustration shows the example Q region relative Raman peak area ratio compared to the viscosity value of an industrial sample, according to an embodiment.

[0028] In all the accompanying drawings, the corresponding reference numerals indicate the corresponding parts. Detailed Implementation

[0029] According to embodiments of this disclosure, a fiber optic Raman probe is configured for high-temperature Raman spectroscopy to perform in-situ high-temperature Raman analysis. A custom-designed external telescope is embedded at the end of the Raman probe, extending the probe's working distance from, for example, 0.8 cm to 3 cm, thus protecting the probe from the high-temperature environment (e.g., 1400 °C) used for in-situ studies. A deconvolution algorithm is applied to analyze and deconvolve the Raman spectra to identify unique chemical bonds contributing to the total Raman spectral response.

[0030] Now for reference Figure 1The fiber optic Raman probe 101 has a main optical body 103 and an extended tip 107 that maintains the final focusing lens 109. The probe 101 is coupled to the excitation source via two optical fibers 111 and 113 (see...). Figure 2 ) and spectrometer (see Figure 2 This allows for remote measurement of samples. In one embodiment, such as... Figure 1 As shown, the probe 101 employs an excitation fiber 111 with a core diameter of 105 μm and a collection fiber 113 with a core diameter of 100 μm. It should be understood that within the scope of this disclosure, the Raman probe 101 may include multiple collection fibers 113.

[0031] Within the main optical body 103 of the fiber Raman probe 101, micro-optical components transmit laser excitation to the sample via fiber 111 and collect scattered light via fiber 113, resulting in a compact probe optically coupled to the laser source and spectrometer. The effective use of one or more filters, such as a bandpass filter 117, a dichroic filter 119, and an edge filter (not shown), separates the excitation and scattered light, achieving a 180° sampling geometry. Due to the overlap between the excitation and collection cones, the backscattering collection geometry allows for easy sample alignment and provides optimal throughput. Another advantage of using a second fiber 113 for signal collection is the removal of inelastic background signals from the excitation fiber 111 itself. Based on the lens design of the Raman probe in the illustrated embodiment, the default working distance is, for example, 8 mm. Furthermore, the laser spot size can vary based on the transmission properties of the sample under test. For example, when the sample-to-probe distance is approximately 8 mm, the minimum spot size used is approximately 100 μm. Each fiber 111, 113 is provided within a protective polyurethane sheath 123. The Raman probe 101 has an outer sheath 125 formed of metal (e.g., 316 stainless steel) that provides a maximum temperature threshold of 650°C for high-temperature use.

[0032] Common glass materials, slag, and flux are processed at temperatures reaching 1300°C to 1400°C. Therefore, the Raman probe 101 employs an external telescope 129 to extend its working distance by isolating the probe 101 from the heated environment. The external telescope 129, protected by a stainless steel sheath 125 (operating up to 900°C), is custom-designed to extend the Raman probe 101's ability to be used at even higher temperatures. Figure 1As shown, the excitation light can be focused to, for example, 0.8 cm after passing through lens 109 (e.g., a sapphire lens). In an alternative embodiment, the external telescope 129 includes two additional optical lenses 133 that first collimate and then focus the light, increasing the focusing distance of the optical path to, for example, 3 cm without energy loss. The increased working distance of the Raman probe 101 provided by the external telescope 129 allows for experiments at higher temperatures.

[0033] exist Figure 2 In the high-temperature fiber Raman system 201 shown, the excitation source 203 and the spectrometer 205 are connected to each end of the Raman probe 101 via optical fibers 111 and 113, respectively. In one embodiment, the excitation source 203 includes a 532 nm laser (green laser) configured to provide optimal Raman performance for the test sample, and the spectrometer 205 includes a QE-Pro spectrometer for collecting samples with a diameter of 3 cm⁻¹. -1 Raman spectra with high spectral resolution. The induction coil furnace 207 is used to provide continuous high-temperature heating.

[0034] Further references are as follows Figure 2 As shown, the fiber optic Raman probe 101 is mounted on the support 209 at an appropriate probe working distance. A type K thermocouple 213 is fixed near the Raman probe 101 to monitor the temperature around it in real time. After repeated experiments, the temperature in the probe area at a controlled distance of 3 cm from the sample was approximately 150 °C. Furthermore, a data logger 215 was used to sample and record real-time temperature data. According to embodiments of this disclosure, two types of graphite crucibles can be used for high-temperature experiments. The bottom crucible 217 is surrounded by aluminosilicate refractory material and fixed in the induction coil 207. The working crucible or insert crucible 219 is embedded in the bottom crucible 217 as a container for heating the sample. A type S thermocouple 223, mounted in direct contact with the working crucible 219, is used to control the sample temperature. After repeated experimental measurements, it was found that the heating system was consistently able to heat the sample to 1400 °C for 10 to 15 minutes. Therefore, real-time high-temperature Raman spectra can be repeatedly acquired under the same temperature conditions to improve experimental accuracy.

[0035] It is well known that thermal radiation affects Raman scattering at high temperatures. The energy level of thermal radiation is closely related to temperature. Therefore, strong thermal radiation signals can significantly affect the Raman signal of a test sample. However, under the same temperature conditions, the energy level of thermal radiation can be considered the same. Therefore, if all Raman spectra are examined at the same temperature, the problem associated with the inherent temperature dependence of Raman scattering can be eliminated. Aspects of this disclosure include a background subtraction method for eliminating background thermal radiation signals. For example, in a high-temperature experiment, an empty furnace is first heated to 1400°C and held to ensure thermal stability. Then, an optical fiber Raman probe 101 is moved to the measurement area for background signal acquisition. Subsequently, the prepared sample is poured into a crucible for sintering and melting. Finally, when the sample is completely melted, a second Raman signal is acquired through probe 101. To improve the signal-to-noise ratio of the actual sample Raman signal, the acquisition integration time is set to, for example, 2 to 5 seconds. Multiple sets of Raman spectra (e.g., ten sets) are acquired for each temperature, and then the multiple sets of Raman spectra are averaged to further reduce noise interference and address uncertainties in signal acquisition.

[0036] Example 1:

[0037] For example, the first sample tested by the in-situ fiber Raman probe 101 was EAF slag produced during the electric arc furnace (EAF) steelmaking process. According to previous studies, the viscosity of this molten slag is similar to that at 800 cm⁻¹. -1 Up to 1050cm -1 The Raman signal in the Q region is strongly correlated. Therefore, the Raman spectrum of the Q region in EAF slag is studied in this example. Figure 3 As shown, the Raman spectra of the indicator samples successfully collected at room temperature and 1400℃ exhibit a strong carbonate peak (1083 cm⁻¹) before heating. -1 However, after the slag is heated to a liquid state (1400℃), the intensity of the carbonate Raman peak decreases due to the decomposition of carbonates in the high-temperature environment. The Raman signal spectrum in the Q region at room temperature changes significantly at high temperatures. Multiple compounds or molecular bonds with similar wavenumbers often lead to overlapping peaks in complex samples. Therefore, deconvolution methods are widely used in Raman spectroscopy for further chemical analysis over a wide range of Raman spectra.

[0038] In one embodiment, a deconvolution algorithm with a Gaussian function for curve fitting is applied. Figure 4A The deconvolution results of the Raman spectra of EAF slag at room temperature are shown, and Figure 4B The deconvolution results of the Raman spectra of EAF slag at high temperatures are shown. Based on the Raman spectral data summarized in previous experiments, the Q-region signal is deconvolved to Q... 0 (Si2O4)4- Q 1 (Si2O7) 6- Q 2 (SiO3) 2- And Q 3 (Si2O5) 2- .

[0039] Referring further to Example 1, by comparing the deconvolution results of EAF slag samples at two temperatures, a rightward shift of the Raman signal in the Q region was observed after heating. The following findings were obtained after comparing the Raman deconvolution data at room temperature and high temperature: First, no Q region signal was found in the room temperature deconvolution Raman results. 3 Peak. This is because the high Fe2O3 content (26wt%) and high alkalinity (Cao / SiO2 = 2) in the slag provide a sufficient amount of free oxygen ions to convert Q. 3 Decompose into Q 2 Q 1 and Q 0 However, when the sample was heated to a molten state at 1400°C, a small Q was observed. 3 Peak. Secondly, Q was observed after heat treatment. 2 The addition of a key is based on all other Q keys. n The reduction in bond density comes at the cost of a cyclic silicate crystalline phase. Previous studies of quenched and cooled samples have confirmed this conclusion.

[0040] Example 2:

[0041] The second sample tested by the in-situ fiber Raman probe 101 was a mold flux, a Ca-Si-Al-fluorine oxide glass used to control heat transfer and lubricate molds in continuous casting processes. Figure 5 As shown, Raman spectra were collected under three different temperature conditions. In addition to the Q-region Raman signal, a signal was also observed at 520 cm⁻¹. -1 Up to 540cm -1 645cm -1 Two more prominent Raman peaks were found at 520 cm⁻¹, representing Al-O-Al and Si-O vibrational bonds. Based on the high melting points of alumina and silicon, at 520 cm⁻¹... -1 Up to 540cm -1 645cm -1 The peak at 800 cm⁻¹ was very stable, and no significant change with increasing temperature was observed. However, from 800 cm⁻¹... -1 up to 1100cm -1 The Q-zone Raman spectrum shows a significant change with temperature, representing three states of the protective slag: solid, crystalline, and liquid or molten.

[0042] Next, deconvolution analysis was performed on the Raman data of room temperature protective slag and high temperature protective slag, such as... Figure 6A and Figure 6B As shown. For the two Raman spectra, there are four separate Raman peaks Q. 0 Q 1 Q 2 and Q 3 Successfully resolved. The most prominent Q in the Raman spectrum. 0 The peak indicates the presence of a large amount of silicate monomers in the sample at room temperature. Upon heating, a large number of monomers recombine with oxygen to form chains and sheets, i.e., Q. 2 and Q 3 Then, Q 0 The Raman peak was significantly weakened, and Q was found in the Raman spectrum at 1400℃. 2 The dominant Raman peak indicates that the molten flux sample contains silicate chains. Furthermore, the increased degree of polymerization is associated with higher melting temperature and higher mechanical strength. Previous studies have found that Q... 3 / Q 2 The ratio is a good indicator of the degree of polymerization. After analyzing the data from this preliminary study, Q... 3 / Q 2 The ratio decreases as temperature increases, consistent with previous studies.

[0043] Example 3:

[0044] The third sample studied using the in-situ fiber Raman probe 101 was bioactive glass (45S5), which is used as an implantable device in the human body to repair and replace diseased or damaged bone. Figure 7 As shown, four Raman spectra were successfully observed at room temperature, 100°C, 700°C, and 1300°C. Room temperature Raman spectra were first acquired before heating the sample. Then, the sample was heated to 1300°C to melt, and Raman spectra were acquired. The furnace temperature was then adjusted to 700°C and maintained at this temperature. Once the temperature stabilized, Raman spectra at 700°C were acquired. Finally, the temperature was lowered to 100°C, and Raman spectra were acquired. This heating scheme was used to mitigate the influence of metastable crystals on the relative analysis. The room temperature Raman spectra showed two main bands: 620 cm⁻¹. -1 PO bending strip, 800cm -1 Up to 1100cm -1 The range is in the Q region. However, high-temperature Raman spectra at 100℃, 700℃, and 1300℃ show that after heating, the value at 620 cm⁻¹ is [missing information]. -1 The PO bending band disappears at this location. Conversely, at 585cm... -1 A new Raman peak was discovered, which may represent v4PO4 containing contributions from acid phosphate (HPO4) and octacalcium phosphate (OCP). 3-Furthermore, the Raman signal in the Q region varies considerably at different temperatures.

[0045] Referring further to Example 3, to further understand the relationship between chemical bonds and the Raman spectra of bioglass, the Raman spectra at room temperature and high temperature were deconvolved, applying peaks identified from earlier studies of bioglass. Deconvolving was performed on the seven main Raman peaks, and as shown... Figure 8A and Figure 8B The properties used for peak fitting shown are considered as follows: at 864 cm⁻¹ -1 Q at the location 0 ; at 906cm -1 Q at the location 1 ; at 944cm -1 Q at the location 2 At 974cm -1 POP expansion at 1008cm -1 The stretching of P2O5 plate-like units OPO at the location; the asymmetric stretching of bridging oxygen in all Q types; and at 1086 cm⁻¹ -1 Q at the location 3 Symmetric scaling. The room-temperature Raman results obtained by deconvolution were also compared with previous results and showed good agreement.

[0046] Advantageously, the fiber optic Raman probe 101 has been proven capable of performing real-time in-situ high-temperature Raman spectroscopy. The external telescope 129 increases the working distance of the fiber optic Raman probe 101, allowing for real-time Raman analysis of large samples at high temperatures. The extended working distance successfully demonstrates the fiber optic Raman probe 101's capability for high-temperature environmental measurements and long-term detection. Aspects of this disclosure can serve as a roadmap for studying material properties under high-temperature conditions, potentially facilitating the use of high-temperature fiber optic Raman spectroscopy in metal processing, steelmaking, and other high-temperature-related material research. In another embodiment, aspects of this disclosure provide an in-situ high-temperature fiber optic Raman sensor for the analysis of protective slag in steel manufacturing applications.

[0047] The ability to remotely control the composition of molten flux through in-situ chemical fingerprinting using real-time Raman signal analysis significantly impacts continuous casting in the steel industry. Continuous casting in steel production utilizes specially developed fluoride glass (mold flux) to lubricate the mold and control the solidification of the steel within it. The composition of the flux influences properties including basicity, viscosity, and crystallization rate, all of which affect the stability of the casting process and the quality of the solidified steel. However, the interaction between the mold flux and the steel during the casting process causes variations in the mold flux's chemical properties that must be considered in its design. Currently, the chemical composition of the mold flux must be determined by extracting samples from the mold during casting and then processing these samples offline to estimate the working chemical composition, and thus, the expected properties of the mold flux.

[0048] Raman spectroscopy offers an alternative method for performing flux analysis, with the potential to perform online measurements during the casting process. Raman spectroscopy uniquely identifies specific molecules in a glassy flux by revealing peaks that act as fingerprints of the vibrational modes of molecules within the flux. The intensity of specific peaks in the Raman spectrum can be correlated with the chemical composition of the melt, as well as related properties such as basicity and viscosity.

[0049] Figure 9 The illustration depicts a high-temperature fiber Raman system 901 according to an alternative embodiment configured to study the chemistry of protective slag in a high-temperature environment. The probe system 901 includes a probe 101. In one embodiment, the main optical body 103 of the probe 101 includes a removable extension (e.g., 25 cm in length) to further protect the probe from harsh environments. In this embodiment, the probe 101 has a 0.9 cm diameter tip suitable for testing in the confined spaces and harsh environments associated with steel manufacturing. Within the Raman probe 101, a 105 μm excitation fiber 111 and a 100 μm collection fiber 113 are included for photoexcitation and collection, respectively. Filters such as long-pass and band-pass filters (e.g., centered at 532 nm) are mounted inside the probe body to block laser reflections and eliminate inelastic background signals generated from the fiber. A concave sapphire window is employed at the tip of the extended probe to provide a 7.5 mm working distance for the Raman probe. All fiber optic subunits are enclosed in a 316 stainless steel outer protective sleeve 125, which can withstand a maximum operating temperature of 650°C. For example... Figure 9 In the fiber Raman system shown, the excitation source 203 includes a 532 nm laser (green laser) and the spectrometer 205 includes spectrometers for measuring wavelengths at 3 cm⁻¹. -1 The QE-Pro spectrometer records Raman spectra with high spectral resolution.

[0050] exist Figure 9In this embodiment, induction furnace 207 provides heating for the high-temperature Raman experiment. As shown, two thermocouples 213 (e.g., type K and type S) are mounted to monitor the temperature of the crucible 219 containing the molten flux. The type K thermocouple is aligned with the tip of the Raman probe 101 to monitor the ambient temperature, ensuring that the probe does not overheat. Real-time temperature data is collected via thermocouple data logger 215. The type S thermocouple is positioned in direct contact with the graphite crucible 219 containing the molten flux sample to monitor the flux temperature. The crucible 219 is, for example, approximately 10 mm in diameter and 20 mm deep, and the flux sample typically forms spheres with a diameter of 10 mm upon melting. Using this heating system, the synthetic protective slag sample is melted and heated to 1400 °C, and high-temperature Raman spectra are acquired in real time.

[0051] Considering the potential influence of natural light on Raman signals, high-temperature Raman signal acquisition was performed under darkroom conditions to improve the signal-to-noise ratio. Furthermore, thermal radiation generated at high temperatures is a significant component of the Raman signal. Therefore, a background subtraction method was applied to remove the thermal radiation signal, minimizing its interference with the natural Raman spectrum of the flux sample. First, the furnace was heated to 1400°C. Then, the Raman probe 101 was moved above a graphite crucible 219 to collect the background light signal in a high-temperature environment. After acquiring the background spectrum, a protective slag material was added to the graphite crucible 219 and completely melted at 1400°C, and Raman spectra were collected again. The background subtraction method effectively subtracts the thermal radiation signal characteristics from the acquired spectra, leaving only the actual Raman signal from the sample. The Raman signal integration time was set from, for example, 2 to 5 seconds for data acquisition. Multiple spectra (e.g., five) were collected for each measurement condition, and the multiple spectra were averaged to reduce measurement uncertainty.

[0052] Example 4:

[0053] Four flux samples with different compositions were prepared. The melt structures of samples 1 to 4 were then analyzed by Raman spectroscopy. Figure 10 Real-time Raman spectroscopy results at 1400℃ are shown. (At 480 cm⁻¹) -1 -560cm -1 590cm -1 -740cm -1 The Raman peaks at 800 cm⁻¹ correspond to the bending vibrations of Al-O-Al and Si-O-Si, respectively. -1 -1200cm -1 The Raman shift at that point is related to the stretching of the Q(Si) bond. For example... Figure 10 The Raman spectra shown indicate that the peak in the Q region at 1400℃ varies with the chemical composition of the protective slag. Furthermore, at 480 cm⁻¹... -1 -560cm -1The characteristic peaks of Al-O-Al bonds at 590 cm⁻¹ and at 590 cm⁻¹ -1 -740cm -1 The bending vibration characteristic peaks of the region did not show significant shifts or compositional changes in the Si-O-Si region. However, a preliminary comparison of the silica peak intensities of sample 1 and sample 4 showed that sample S4 had a higher silica peak intensity at 640 cm⁻¹. -1 The characteristic peak of silica at this location is weaker than that of the S1 sample, indicating a decrease in SiO2 content.

[0054] Identifying the correlation between Raman spectroscopy and chemical composition demonstrates the relationship between Raman spectroscopy and flux properties. To more accurately quantify the obtained Raman spectra, typical deconvolution methods were performed on the peaks in the alumina and silica regions using software such as Origin. A Gaussian function was applied to curve fitting of the deconvolution algorithm. Based on previous research, peaks at 480 cm⁻¹ were analyzed. -1 -560cm -1 The interval and 590cm -1 -740cm -1 Deconvolution is performed within the interval 520cm. -1 The peak at 640cm -1 The peak at a certain point was identified as the central peak after deconvolution. Comparing the cumulative fitted peak in the figure with the original spectral data, an overall fit of more than 96% of the R-squared value was achieved, thus resolving the uncertainty of deconvolution.

[0055] Referring again to Example 4, the main components of the synthesized protective slag are SiO2, CaO, and Al2O3. Al2O3 was fixed at 4.69 wt% in all four samples; therefore, any structural variations are strongly influenced by the CaO / Al2O3 ratio or the SiO2 / Al2O3 ratio. Quantitative comparison of the absolute peak intensities using Raman spectra for different samples is challenging. For example, unavoidable temperature fluctuations at high temperatures directly affect the background light in the Raman spectrum, and thus affect the peak intensities. However, the energy from the background light will uniformly affect the entire Raman spectrum. Therefore, considering the intensity ratios of characteristic peaks in the Raman spectra of the same sample should provide a means for quantification. The analysis of high-temperature Raman data then involves collecting data representing peaks at 520 cm⁻¹. -1 Al-O-Al at 640cm -1 The original and deconvolutioned Raman peaks of Si-O-Si were determined to establish a relative Raman ratio that could be compared with the chemical content ratio. The relative Raman peak ratio of SiO2 / Al2O3 content was compared with the SiO2 / Al2O3 content ratio.

[0056] For both the raw peak data and the peak data extracted after deconvolution, the relative Raman peak intensity ratio was compared with the SiO2 / Al2O3 chemical content ratio. Sample S1 had the highest SiO2 content and the lowest CaO content. Conversely, sample S4 had the lowest SiO2 content and the highest CaO content. Sample S1, containing the highest SiO2, had the highest SiO2 / Al2O3 content ratio and the highest Raman peak intensity ratio. Sample S4 had the lowest SiO2 content, corresponding to the lowest SiO2 / Al2O3 content ratio and the lowest Raman peak intensity ratio. In both datasets, the relative Raman peak intensity ratio of SiO2 / Al2O3 was positively correlated with the SiO2 / Al2O3 chemical content ratio. Furthermore, both datasets yielded fit R-squared values ​​higher than 92%. Next, the Raman peak intensity ratio was analyzed using the CaO / Al2O3 chemical content ratio. Sample S4 contains the highest amount of CaO and the lowest amount of SiO2, and has the highest CaO / Al2O3 content ratio, but it has the lowest SiO2 / Al2O3 Raman peak intensity ratio among all four flux samples.

[0057] In Example 4, the relative Raman peak intensity ratio of SiO2 / Al2O3 increases with increasing SiO2 / Al2O3 content. However, the CaO / Al2O3 content ratio decreases, indicating that the Raman spectra of silica and alumina from the self-flux sample will be affected by the degree of polymerization of the silicate and calcium oxide networks. Furthermore, based on the high R-squared value, the fiber Raman system and deconvolution algorithm can be trusted for further data analysis. This data analysis shows that the correlation of material components can be obtained using the deconvolution algorithm and the intensity ratio of Raman characteristic peaks. The study of the viscosity properties of the protective slag material can be further analyzed and correlated using the deconvolution algorithm.

[0058] Based on previous studies of fluxing agents, Raman spectra often contain overlapping peaks. Deconvolution analysis of Raman spectra is necessary for qualitative and quantitative descriptions of different structural units. It is assumed that the Raman curves follow a Gaussian function and are fitted only in regions where prominent shoulders or peaks are observed or rigorously demonstrated by previous studies. After deconvolution analysis, the Raman spectrum can reflect all possible structures represented by peaks located at different positions. Furthermore, silicates are considered to play a key role in the degree of polymerization of the melt because the SiO2 content is relatively high compared to other components in the molten flux sample. The mole fraction of silica is further obtained through deconvolution of Raman spectra.

[0059] For Example 4, the deconvolution result of the Raman spectrum obtained by Gaussian fitting for each of the four samples in Example 4 is as follows: Figures 11A to 11D As shown. At 850cm -1 -1100cm -1 In the Raman displacement region, Qi The (Si) stretching band is deconvoluted into four typical peaks. They are located at 850 cm⁻¹. -1 -895cm -1 (Q 0 ), 905cm -1 -925cm -1 (Q 1 ), 945cm -1 -985cm -1 (Q 2 ) and 1015cm -1 -1100cm -1 (Q 3 These peaks correspond to [SiO4]Q. 0 stretching vibration, [Si2O7]Q 1 stretching vibration, [SiO3]Q 2 stretching vibration and [Si2O5]Q 3 The stretching vibration. In Figures 11A to 11D The details of the identified peaks are given. The cumulative peak fitting was generated by summing four deconvolutioned Raman peaks. The R-squared value was calculated by comparing the original Raman data and the cumulative peak fitting. R-squared values ​​above 99.6% resolved any uncertainties in the deconvolution process. Compared with existing literature, Q can be determined for flux samples at 1400 °C. 0 The (monomer) peak shows a slight rightward shift, and the Q3 (lamellae) peak shows a slight leftward shift. This shift can be explained by the fact that, compared to the results of rapidly quenched samples, the monomer and lamellar contents are slightly reduced at high temperatures, as given in the literature. This finding also demonstrates that the flux samples exhibit Raman signals at high temperatures that are significantly different from those of the quenched flux samples with the cooling rate used in this study. Therefore, it further proves that the inherent physical properties of the quenched flux samples are altered due to the cooling treatment. Thus, studying Raman signals to understand property changes at high temperatures is highly significant.

[0060] In CaO-Al2O3-SiO2-based protective slags, SiO2 is the primary network forming agent because alumina is a conditional glass-forming agent (it does not form glass in the absence of other network forming agents) and considering the low fixed alumina content. In the silica network, four oxygen anions surround the center of each silicon cation, and Si-O-Si bonds connect all the tetrahedral SiO4 groups. 4- Complex. When Na from Na₂O or CaO + ions or Ca 2+In the presence of ions, some Si-O-Si bonds will break. Therefore, when the melt has a high CaO / SiO2 ratio, as in sample 4, many network disruptors in the melt are used to break Si-O-Si bonds; however, they can also promote [AlO4] formation. 5- The formation of this indicates that when the CaO content is high, the Q region in the Raman spectrum is most affected by the breaking of Si-O-Si bonds. Therefore, based on previous studies, Q... 3 / Q 2 The ratio of Q can potentially be used as a polymerization index to quantify the effect of silicate structure on melt viscosity. Furthermore, Q... 0 (Monomer) has been studied as a factor influencing the properties of protective slag materials. Therefore, the deconvolutioned Q 3 / Q 2 Raman peak coefficient and Q 3 / Q 0 The Raman peak coefficients were studied and correlated with CaO (wt%), SiO2 (wt%), and basicity value. The main components of the synthetic flux samples used in this study were SiO2, CaO, and Al2O3. The Al2O3 content of all four samples was fixed at 4.69%. Therefore, the flux structure is strongly influenced by the CaO / Al2O3 ratio or the SiO2 / Al2O3 ratio.

[0061] See further example 4, Q 3 / Q 2 ratio and Q 3 / Q 0 The ratio increases as the CaO content decreases. On the other hand, as the SiO2 content increases, the degree of polymerization of the silicate network increases, which corresponds to Q... 3 / Q 2 ratio and Q 3 / Q 0 The ratio increases. Finally, Q 3 / Q 2 ratio and Q 3 / Q 0 The ratio is related to the alkalinity ratio of the four protective slag components. Q 3 / Q 2 Scale factor and Q 3 / Q 0 The scaling factors all decrease linearly with increasing alkalinity ratio, where Q 3 / Q 0 A 99.5% linear correlation was observed. The relative peak ratio based on the Q-region peaks can be considered a well-correlated indicator of alkalinity because significant differences in intensity are always present. However, peak area ratio (molar fraction) is more robust than peak intensity and has been widely used in previous studies.

[0062] The combined area of ​​each deconvolution peak is Q. i Semi-quantitative assessment of the quantity of units. Q increases with decreasing SiO2 content. 0 The content of (monomer) gradually increases, and Q 3 The content of (flaky) gradually decreases. To more effectively compare the correlation, Q will also be used. 3 / Q 2 peak area and Q 3 / Q 0 The peak area is compared with the chemical composition and viscosity of the flux, such as... Figure 12A and Figure 12B As shown. Figure 12A and Figure 12B The graphs show the relative peak area ratios of the Q region compared to SiO2 (wt%) and compared to CaO (wt%). 3 / Q 2 Peak area ratio and Q 3 / Q 0 The peak area ratio is linearly and positively correlated with the SiO2 content. As the SiO2 content increases, Q... 3 / Q 2 Peak area ratio and Q 3 / Q 0 The peak area ratio also increased, and the fitted R-squared coefficient was greater than 96%. Conversely, the CaO content was related to Q. 3 / Q 2 Peak area ratio and Q 3 / Q 0 The peak area ratio is negatively correlated. With increasing SiO2 content, Q... 3 / Q 2 Peak area ratio and Q 3 / Q 0 The peak area ratio is reduced. Finally, Q... 3 / Q 2 Peak area ratio and Q 3 / Q 0 The peak area ratio was compared with the sample alkalinity value, such as... Figure 12C As shown. Q 3 / Q 2 Peak area ratio and Q 3 / Q 0 The peak area ratio was negatively correlated with the sample viscosity, exhibiting high R-squared values ​​of 94% and 95%, respectively. Available analytical data indicate that both peak intensity ratio and peak area ratio showed good correlations with the composition and properties of the flux sample. Furthermore, by comparing the results, the data showed that the peak area ratio provided a higher degree of correlation than the peak intensity ratio for predicting flux chemistry and viscosity. Previous researchers have noted that Q... 3 / Q2 The area ratio was used to estimate the flux viscosity, which is consistent with the results of this study. Furthermore, Q was determined. 3 / Q 0 The area ratio can be considered a fundamental parameter that correlates the properties of protective slag with the measured Raman spectra.

[0063] Example 5:

[0064] Following the observation of the relationship between Raman spectroscopy and the chemical composition of synthetic fluxes, in-situ fiber Raman spectroscopy analysis was applied to more complex commercial flux samples. Five samples with different chemical compositions were tested. Based on previous analysis, the Si-O-Si stretching band directly affects the viscosity value. Therefore, flux samples with reported viscosity values ​​of 2.8, 6.6, 1.5, 1, and 1.5 at 1300 °C were tested.

[0065] To clearly understand the influence of different temperature conditions on the Q-region Raman spectra of industrial flux samples, real-time Raman spectra of sample A were acquired from room temperature to 1350℃, and the results were included in... Figure 13 In the middle, it can be observed that these Raman spectra show significant differences with temperature. At 475 cm⁻¹ -1 and 1125cm -1 The Raman spectral range between these two points consists of two significant regions, namely 500 cm⁻¹ and 500 cm⁻¹. -1 -700cm -1 and 800cm -1 -1100cm -1 .

[0066] For example 5, at 500cm -1 -700cm -1 In the Raman region, at 540cm -1 The peak at 640cm -1 The peaks at these locations correspond to the bending vibrations of Al-O-Al and Si-O-Si bonds, respectively. Compared to the synthetic flux sample, the alumina peak in the industrial sample exhibits a larger peak from 520 cm⁻¹ due to the higher CaO / SiO₂ ratio. -1 Slightly shifted to 540cm -1 This causes more network breakage (non-bridging oxygen) in the Si-O-Si bonds and simultaneously promotes [AlO4] formation. 5- The formation of [something] occurs at 500cm. -1 -700cm -1 The Raman spectra of the alumina and silica regions were once again stable, showing no significant changes at high temperatures. The most significant change occurred at 800 cm⁻¹ with increasing temperature. -1 -1100cm -1The first change occurs between room temperature and 800 °C, when the sample is completely solid and contains microcrystals. Between 800 °C and 1000 °C, the flux sample remains solid but above the crystallization initiation temperature, and there is no significant change in the Q region. In the range between 1200 °C and flux melting, the Q region exhibits a second significant change due to the breaking of Si-O stretching bonds. At 1350 °C, the sample is completely in the liquid phase, and Raman spectra show additional changes in the Q region directly affected by temperature increases. Monitoring these temperature-dependent changes can provide insights into the viscosity-temperature dependence of industrial flux samples.

[0067] High-temperature Raman spectra of five industrial flux samples were successfully collected at 1350℃, and these five spectra showed strong correlations in the Al-O-Al bond region, the bending vibrations of Si-O-Si, and the Q region (Q...). i The samples exhibited significant Raman peaks, consistent with previous results from synthetic flux samples. Since samples D and E contained viscosity values ​​very similar to sample C, three industrial flux samples from A to C were selected to investigate the relationship between Raman spectra and chemical composition. Figures 14A to 14C As shown in the diagram. Four separate Qs. i The peaks are deconvolved from the original Raman spectra. R-squared values ​​greater than 98.7% indicate the cumulative fit matching coefficients of the deconvolution process, providing additional confidence in the method.

[0068] According to Example 5 Figures 14A to 14C The deconvolution results show no significant shift in the Q region of the spectrum. However, based on the study of the synthetic flux samples detailed in the previous paragraph, Q... 3 / Q 2 Raman peak intensity ratio and Q 3 / Q 0 The Raman peak intensity ratio was used to study the correlation between Raman spectra and viscosity. 3 / Q 2 Fitted curve and Q 3 / Q 0 The fitted curves all showed a linear negative correlation with the viscosity of the industrial flux samples, which matches the results for the synthetic flux. 3 / Q 2 The ratio showed a correlation of 97.1 with viscosity.

[0069] Based on the data analysis results of the synthetic flux samples detailed in the preceding paragraphs, the area fraction of each individual Raman peak in the Q region was calculated. As the viscosity of the industrial flux samples decreased, Q... 0 (monomer) mole fraction and Q 1 The mole fraction of (dimer) decreases, and Q 3The molar fraction of (flaky) increased. This conclusion is also consistent with previous results from studies on control samples. Finally, Q... 3 / Q 2 area ratio and Q 3 / Q 0 The area ratio was compared with the viscosity of the industrial flux sample, such as... Figure 15 As shown in the image. Q was found. 3 / Q 2 The curve function and Q 3 / Q 0 The curve function shows a negative correlation with the viscosity of industrial flux samples, consistent with results from synthetic flux samples. The accuracy of the linear correlation between the two parameters is close to 90%.

[0070] Advantageously, this disclosure provides real-time analysis of fluxing agents using an in-situ fiber optic Raman sensor, which can be performed directly at a high temperature of 1400°C. Raman spectroscopy uniquely identifies specific molecules by detecting vibrational bands at high resolution, providing in-depth understanding of molecular structure. It enables direct online processing of flux samples to determine chemical composition and other properties. The advantages of using fiber optic Raman spectroscopy at high temperatures to evaluate the structure and chemical composition of fluxing agents are demonstrated. Furthermore, Raman spectroscopy results show that a range of chemical substances can be successfully captured using an in-situ fiber optic Raman sensor at 1400°C. Experimental results also show differences between the Raman spectra of the fluxing agent in the high-temperature molten state and those of previously reported rapidly quenched samples. By deconvolving the high-temperature Raman spectra, Q can be determined. 3 / Q 2 Ratio (flaky / chain) and Q 3 / Q 0 The (flaky / monomer) ratio can be used to evaluate the chemical composition and physical properties of protective slag. Furthermore, the relationship between the viscosity, chemical composition, and Raman peak area ratio of protective slag samples was identified, demonstrating the potential of online protective slag analysis.

[0071] According to one embodiment of this disclosure, a method for in-situ and real-time analysis of the composition of a protective slag during continuous steel casting includes the steps of: a) introducing a portable fiber optic Raman sensor into a molten flux environment at a temperature of 1400°C during the continuous casting process; b) performing high-temperature Raman spectroscopy measurements of the molten flux using the fiber optic Raman sensor; c) detecting component-dependent Raman signal shifts in the high-temperature environment; d) correlating the intensity of specific peaks in the Raman spectrum with the chemical composition, basicity, and viscosity of the molten flux; and e) providing real-time information on the molecular structure and composition of the protective slag during continuous casting operations.

[0072] According to another embodiment of this disclosure, a remote fiber Raman sensor system for real-time measurement of materials at high temperatures includes: a) a high-temperature resistant fiber optic probe designed for in-situ placement in a molten flux environment; b) a Raman spectroscopy unit integrated into the fiber optic probe, capable of recording Raman spectra at 1400°C; c) a high-temperature Raman system configured for online flux analysis, demonstrating good potential for real-time assessment of protective slag composition; d) a deconvolution algorithm suitable for accurate analysis of the raw Raman spectra; and e) carefully selected Raman peak intensities and Raman peak areas for establishing ratios related to chemical composition and physical material properties.

[0073] According to another embodiment of this disclosure, a system for in-situ chemical fingerprint analysis of molten flux components in the steel industry using remote fiber Raman technology includes: a) a high-temperature fiber Raman sensor system capable of being remotely placed in a molten flux environment; b) a real-time Raman signal analysis module configured to remotely control the molten flux components via chemical fingerprint analysis; c) the ability to influence online slag and flux component analysis during continuous casting in the steel industry; d) the observed correlations between the structure and thermophysical properties (including basicity, viscosity, and density) of silicate melts; and e) the system demonstrating applicability to both synthetic flux samples and complex industrial flux samples.

[0074] When describing elements of this disclosure or embodiments thereof, the articles “a,” “an,” “the,” and “the” are intended to refer to one or more elements. The terms “comprising,” “including,” and “having” are intended to be open-ended and mean that additional elements may be present in addition to those listed.

[0075] Not all illustrated or described components are necessary. Furthermore, some implementations and embodiments may include additional components. Changes in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additionally, different or fewer components may be provided, and components may be combined. Alternatively or additionally, a component may be implemented by several components.

[0076] The foregoing description illustrates various aspects of the invention by way of example, not limitation. This description enables those skilled in the art to make and use aspects of the invention, and describes several embodiments, modifications, variations, substitutions, and uses of aspects of the invention, including modes currently believed to be the best mode for carrying out aspects of the invention. Furthermore, it should be understood that aspects of the invention are not limited to the details of the construction and arrangement of the components described in the following description or illustrated in the accompanying drawings. Aspects of the invention can be other embodiments and can be practiced or performed in various ways. Moreover, it will be understood that the wording and terminology used herein are for descriptive purposes and should not be considered restrictive.

[0077] Modifications and variations are apparent without departing from the scope of the invention as defined in the appended claims. Since various changes can be made to the above constructions and methods without departing from the scope of the invention, everything contained in the above description and shown in the accompanying drawings should be interpreted as illustrative rather than restrictive.

[0078] In view of the above, it can be seen that several advantages of the present invention have been achieved, and other favorable results have been obtained.

[0079] The abstract and summary are provided to help the reader quickly ascertain the nature of the technical disclosure. They are submitted on the understanding that they will not be used to interpret or limit the scope or meaning of the claims. The summary is provided to introduce selected concepts in a simplified form, which will be further described in the detailed description. The summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the claimed subject matter.

Claims

1. A fiber optic sensor system for in-situ high-temperature Raman spectroscopy, the system comprising: Excitation source; Spectrometer; A Raman probe configured for in-situ placement in a molten flux environment, the Raman probe comprising at least one optical fiber coupled to the excitation source and to the spectrometer, the at least one optical fiber transmitting laser excitation from the excitation source to the sample and collecting light scattered by the sample for analysis by the spectrometer; as well as An external lens arrangement is positioned at the distal end of at least one optical fiber of the Raman probe, the external lens arrangement optically couples the at least one optical fiber to the sample and physically separates the at least one optical fiber from the sample during sampling; The spectrometer is configured to perform Raman spectroscopy on the sample based on light collected by the at least one optical fiber.

2. The fiber optic sensor system as described in claim 1, further comprising: The processor is coupled to the spectrometer; as well as A memory storage device coupled to the processor, the memory storage device storing instructions that, when executed by the processor, configure the processor to: Receive the Raman spectrum of the sample from the spectrometer; Deconvolve the peaks from the Raman spectrum; and The components of the sample are identified as functions of the deconvolutioned peaks.

3. The fiber optic sensor system as described in claim 2, wherein, The memory storage device stores instructions, which, when executed by the processor, further configure the processor to select Raman peak intensity and / or Raman peak area to establish ratios related to one or more of the chemical composition and physical material properties.

4. The fiber optic sensor system as described in claim 2 or claim 3, wherein, The memory storage device stores instructions, which, when executed by the processor, further configure the processor to perform chemical fingerprint analysis of the molten flux components.

5. The fiber optic sensor system as described in any of the preceding claims, wherein, The memory storage device stores instructions that, when executed by the processor, also configure the processor to identify correlations observed between the structure and thermophysical properties of the examined silicate melt, including one or more of basicity, viscosity, and density.

6. The fiber optic sensor system as described in any of the preceding claims further includes an induction coil system for heating the sample.

7. The fiber optic sensor system as claimed in any of the preceding claims further includes a protective sleeve on the at least one fiber optic cable, the protective sleeve being configured to withstand high temperatures.

8. The fiber optic sensor system as described in claim 7, wherein, The protective sleeve is made of polyurethane.

9. The fiber optic sensor system as claimed in any of the preceding claims further includes an external protective sheath on the Raman probe, the external protective sheath being configured to withstand high temperatures.

10. The fiber optic sensor system as described in claim 9, wherein, The outer protective sleeve is made of stainless steel.

11. The fiber optic sensor system as described in any of the preceding claims, wherein, The Raman probe comprises at least one optical fiber, including an excitation fiber and a collection fiber.

12. The fiber optic sensor system as described in claim 11, wherein, The excitation source generates a laser signal, and the excitation fiber transmits the laser signal into the sample.

13. The fiber optic sensor system as claimed in any of the preceding claims further includes one or more filters for separating laser excitation from the collected light scattered by the sample.

14. A Raman probe for in-situ high-temperature Raman spectroscopy, the probe comprising: The probe body houses an excitation fiber and a collection fiber, the excitation fiber being coupled to an excitation source and configured to transmit laser excitation from the excitation source to the sample at its distal end, and the collection fiber being coupled to a spectrometer and configured to collect light scattered by the sample at its distal end for analysis by the spectrometer. An external lens arrangement is provided, positioned at the distal ends of the excitation fiber and the collection fiber, which optically couples the excitation fiber and the collection fiber to the sample and physically separates the excitation fiber and the collection fiber from the sample during sampling. as well as The external protective sleeve on the probe body and the external lens arrangement is configured to withstand high temperatures.

15. The Raman probe of claim 14, further comprising protective sleeves on the excitation fiber and the collection fiber, the protective sleeves being configured to withstand high temperatures.

16. The Raman probe of claim 15, wherein, The protective sleeve is made of polyurethane.

17. The Raman probe according to any one of claims 14 to 16, wherein, The outer protective sleeve is made of stainless steel.

18. The Raman probe according to any one of claims 14 to 17, wherein, The excitation source generates a laser signal, and the excitation fiber transmits the laser signal into the sample.

19. The Raman probe of any one of claims 14 to 18, further comprising one or more filters, said one or more filters being housed in the probe body for separating laser excitation from light collected and scattered by said sample.

20. A method for in-situ and real-time analysis using high-temperature Raman spectroscopy, the method comprising: A portable fiber Raman sensor was introduced into a high-temperature environment during the continuous casting process; The fiber optic Raman sensor is used to perform high-temperature Raman spectroscopy measurements on the molten flux under the high-temperature environment to obtain the Raman spectrum of the molten flux; In response to the Raman spectroscopy measurement, a component-dependent Raman signal shift in the Raman spectrum is detected in the high-temperature environment; The intensity of a specific peak in the component-dependent Raman signal shift is correlated with at least one property of the molten flux; as well as The real-time changes in at least one property of the molten flux are identified based on the associated intensity.

21. The method of claim 20, wherein, The Raman sensor includes a probe body housing an excitation fiber and a collection fiber, the excitation fiber being coupled to an excitation source and configured to transmit laser excitation from the excitation source to a sample at its distal end, and the collection fiber being coupled to a spectrometer and configured to collect light scattered by the sample at its distal end for analysis by the spectrometer.

22. The method of claim 20 or claim 21, wherein, At least one property of the molten flux includes at least one of chemical composition, basicity, and viscosity.

23. The method according to any one of claims 20 to 22, wherein, Performing high-temperature Raman spectroscopy measurements on molten flux includes: Receive the Raman spectrum of the molten flux from the spectrometer; Deconvolve the peaks from the Raman spectrum; and The composition of the molten flux is identified as a function of the deconvolutioned peaks.

24. The method according to any one of claims 20 to 23, wherein, The associated intensity of a specific peak involves selecting Raman peak intensity and / or Raman peak area to establish a ratio associated with one or more of the chemical composition and physical material properties.

25. The method of any one of claims 20 to 24, further comprising performing chemical fingerprint analysis of the melt flux components based on the associated intensity.

26. The method of any one of claims 20 to 25, further comprising identifying an observed correlation between the structure and thermophysical properties of the molten flux based on the associated intensity, the properties including one or more of basicity, viscosity, and density.

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