Temperature Measurement Applications Research Articles

Thermistors and stacked thermopile on III-nitride LED wafer and their application for on-chip temperature measurement

Temperature measurement of devices in working state is of critical importance. In this work, GaN-based thermistors and a thermopile are monolithically integrated with a III-nitride blue light-emitting diode (LED) for the on-chip temperature measurement of the LED. The thermistor is based on the temperature-dependent resistance, and the stacked thermopile is based on the Seebeck effect. The measured results indicate that both thermistors and the thermopile can monitor the temperature of the LED sensitively. Due to the advantages of higher sensitivity and easier signal processing, the thermopile is more suitable for real-time monitoring.

On the intrusiveness of phosphor thermometry for metal surface temperature measurements in reciprocating engines: an experimental and heat conduction modeling study

Abstract Lifetime-based phosphor thermometry has been applied in a wide variety of surface temperature measurement applications due to its relative ease of implementation and robustness to background interference when compared to other optical temperature measurement methods. It is often assumed that the technique is minimally intrusive if the thickness of the applied phosphor coating is < 20 µm. To evaluate this assumption, high-speed phosphor surface temperature and thermocouple measurements were performed on 4140 steel substrates installed in the cylinder head of an optically-accessible internal-combustion engine for four operating conditions. For phosphor thermometry measurements, four substrates were studied, each coated with a phosphor layer of different thickness ranging between 6 µm and 47 µm. The phosphor thermometry measured temperature swings during combustion were shown to be heavily impacted by the presence of the phosphor coatings, increasing by roughly a factor of 2 - 2.5 when increasing the thickness from 6 µm to 30 µm. A technique was implemented which utilizes the temperature data in combination with a heat conduction model to provide estimates of the temperature swing and heat transfer flux in the absence of the phosphor coating. It was shown that even the 6 µm phosphor coating could lead to an order of magnitude increase in the temperature swing relative to the uncoated 4140 steel substrate. Despite the intrusiveness of phosphor thermometry for the surface temperature measurements, reasonable agreement was demonstrated between heat flux estimates determined with the heat transfer modeling technique and those deduced from temperature-swing measurements using two different high-speed thermocouples. The results indicate that phosphor surface thermometry can be a reliable surface temperature and heat flux diagnostic for transient high heat flux environments, as long as proper care is taken to account for the impact of the phosphor layer on the measurement.

Implementation of Linear Regression Method for Calibration and Temperature Measurement on PT100 Temperature Sensor

The PT100 temperature sensor, a type RTD (resistance temperature detector), is widely employed in industries, particularly for steam boiler temperature regulation. Precise temperature measurement is vital for operational efficiency and safety maintenance. Utilizing linear regression for calibrating and measuring temperature with the PT100 sensor integrated with Arduino Uno and LCD I2C is proposed to enhance accuracy. Testing involved assembling the PT100 sensor with Arduino Uno and LCD I2C. Test data were employed for linear regression to derive the calibration equation. Measurements were conducted by comparing PT100 sensor readings with a digital thermometer across a temperature range of 30ºC to 75ºC at 5ºC intervals, with each temperature point tested five times. Results exhibit good accuracy in temperature measurement with the PT100 sensor, featuring low error and percentage error. The standard deviation indicates consistent measurement. Integration of the PT100 temperature sensor with Arduino Uno and LCD I2C, coupled with linear regression for calibration, yields a precise temperature measurement system. Testing against a digital thermometer demonstrates highly accurate outcomes. This developed system finds application in high-precision temperature measurement for steam boiler operations.

Strong red upconversion luminescence of Yb3+/Er3+ co-doped Sc6WO12 phosphor for optical thermometry

Herein, a strong red upconversion phosphor of Yb3+/Er3+ co-doped Sc6WO12 was prepared by employing an equivalent substitution approach. When irradiated by 980 nm near-infrared laser, the phosphor emits strong 660 nm red light. The main excitation mechanism for its red upconversion luminescence emission is the energy transfer process, through which the Er3+ ions is promoted from the 4I13/2 energy level to the 4F9/2 energy level. In addition, it is noteworthy that the multimode upconversion luminescence phosphor exhibits three different trends upon temperature change, and its upconversion emission integral intensity ratio exhibits a linear relationship with temperature in the range of 298 K–623 K. This special property makes the phosphor promising for applications in optical temperature measurement.

Temperature-Dependent Photoluminescence from Well-Resolved Excited State Structures in Rare-Earth-Based Double Perovskites.

Lead-free halide double perovskites (DPs) have become a research hotspot in the field of photoelectrons due to their unique optical properties and flexible compositional tuning. However, the reports on the optical properties of DPs primarily concentrate on the room temperature state and only exhibit single emission band. Here, we synthesized Cs2NaYCl6:Sb3+, Dy3+ DPs by a solvothermal method to realize white light emission with photoluminescence (PL) quantum yield as high as 70.7%. The energy-transfer process from self-trapped excitons (STEs) to Dy3+ ions was revealed by optical characterization and theoretical simulation calculations. Interestingly, we observed the double-emission from low-energy STE emission of Sb3+ ions and Dy3+ emission at low temperatures, and the double-emission is consistent with the asymmetric doublet feature of the 3P1 → 1S0 transition split into two minima. The PL spectra further showed that the fluorescence intensity ratios of Dy3+ ions at 580 and 680 nm were strongly temperature-dependent, and the relative sensitivity is up to 1.79% K-1 at 360 K. Moreover, the near-infrared and radiation luminescence properties indicated that the Cs2NaYCl6:Sb3+, Dy3+ DPs also have good prospects for night vision and radiation detection, as well as the great potential for applications in solid-state illumination and optical temperature measurement.

Charge compensation improves energy transfer to realize anti-thermal-quenching and enhances the CaMoO4: Sm3+ phosphors optical temperature measurement sensitivity base on the FIR model

Luminescent materials are the main focus of non-contact thermometers due to their high detection sensitivity, non-invasiveness, quick reaction, exceptional stability. It is still difficult to design high sensitivity optical temperature sensors using fluorescence intensity ratio technology. This article increases fluorescence intensity ratio value and obtains high sensitivity temperature sensitive phosphors by utilizing the anti-thermal-quenching effect of rare earth luminous centers. Sm3+ and alkali metal co-doped CaMoO4 phosphors have been prepared by high-temperature solid-state method. Rietveld refinement results showed that the co-doping of Sm3+ and K+ can significantly improve the energy transfer from the host to Sm3+ and significantly increase the luminous intensity of Sm3+. We found that co-doping of Sm3+ and K+ not only effectively enhanced the luminescence intensity, but also regulated the lifetime of this phosphors. When K+ is introduced into the CaMoO4: 0.02Sm3+, the τ value decreased from 4.12 to 3.54 ms, which proves to be effective in light-emitting diode. The optical temperature measurement of CaMoO4: 0.001Sm3+, 0.001 K+ was studied using fluorescence intensity ratio technology. The maximum SaMAX and SrMAX values are 0.27 K−1 at 483 K and 2.25 % K−1 at 363 K, respectively. Moreover, the CaMoO4: 0.02Sm3+, 0.02 K+ also has a certain absorption capacity in visible optical drive, which proved by ultraviolet visible diffused reflectance spectra. The electronic density of states of phosphors are drawn via first-principles to understand the effect of Sm3+ and alkali metals co-doped on luminescence. The above results demonstrate that the Sm3+ and K+ co-doping CaMoO4 might be an attractive material for the application of temperature measurement and light-emitting diode.

Upconversion fluorescent Sr9In(PO4)7:Yb3+, Er3+ phosphors with applications in temperature measurement and anti-counterfeiting

In this work, Yb3+ and Er3+-co-doped Sr9In(PO4)7 upconversion fluorescent materials with dual functionality were synthesized though simple high-temperature solid state method. Based on International Commission on Illumination (CIE) color coordinates, the calculation of color purity at different temperatures demonstrates the attainment of highly pure green luminescence (color purity >90 %) for the synthesized materials. The analysis of activation energy proves that synthesized materials are stable. Utilizing the fluorescence intensity ratio (FIR) of the thermally coupled energy levels (2H11/2, 4S3/2) as a metric for optical sensing performance, absolute sensitivity and relative sensitivity are determined, and their maximum values are 0.44 % and 1.13 %, respectively. Inspired by the variation in CIE coordinates with temperature, thermally responsive two-dimensional barcode image was developed, demonstrating the practical application of Sr9In(PO4)7:Yb/Er materials in the field of information security and anti-counterfeiting.

Er3+/Yb3+ ions doped chiral inorganic nanostructured BiOCl phosphor as a novel temperature sensing material

AbstractInorganic chiral materials have attracted increasing attention due to their application prospects. In this work, we synthesized the chiral nanostructured bismuth oxychloride co‐doped with Er3+/Yb3+ phosphor (D‐BYEP) by hydrothermal growth with a subsequent air‐annealing strategy using chiral sugar alcohols as the chiral inducer. The D‐BYEP emitted bright red light under the excitation of 980 nm near‐infrared laser. The temperature sensing behavior was evaluated by employing the thermally coupled (TCLs) or non‐thermally coupled (NTCLs) levels of Er3+. The maximum relative sensitivities (SR) obtained are 0.84% K−1 and 1.30% K−1 (298 K), respectively. The results show that the D‐BYEP may be ideal candidates for optical temperature sensors. We anticipate that this new type of inorganic chiral phosphor may have a range of applications in temperature measurement of light sources.

Optical thermometry and multi-mode anti-counterfeiting based on Bi3+/Ln3+ and Ln3+ doped Ca2ScSbO6 phosphors

A series of novel Bi3+/Ln3+-activated Ca2ScSbO6 (CSSO) phosphors were synthesized by solid-state method and their luminescent behaviors were investigated in detail. Under the 302 nm excitation, the CSSO:Bi3+ shows remarkable near-ultraviolet photoluminescence with a peak emission at 365 nm. Eu3+-activated CSSO phosphor possesses high efficiency and no obvious reduction of emission intensity even after replacing Sc with Eu completely, which indicates a low-concentration quenching effect. In addition, its emission intensity at 423 K (I423K) still maintains 88 % compared with that of at room temperature (I298K), indicating good thermostability. In contrast, the CSSO:Bi3+ phosphor exhibits a significant reduction in emission intensity, maintaining only 49 % of its luminescence at 423 K (I423K/I298K). By codoping Bi3+ and Ln3+ (Ln = Eu, Tb, Dy, Sm), the energy transfer was observed from the Bi3+ to Ln3+ ions, endowing the CSSO:Bi3+, Ln3+ phosphors with tunable multicolor emissions. Leveraging the differing thermostabilities of the emission spectra for Bi3+ and Ln3+ ions, we designed and assessed a range of sensitive optical thermometers. Among these, the CSSO:Bi3+, Eu3+ phosphors exhibited the best performance, boasting maximum absolute and relative sensitivities of 9.96 % K−1 and 2.002 % K−1, respectively. Additionally, we displayed the multi-mode anti-counterfeiting function of synthesized phosphors, and a multi-color switching system was designed with the advantages of direct visualization and easy identification of encrypted information. These results indicate that Bi3+ and Ln3+ coactivated CSSO phosphor has the potential application for non-contact temperature measurement and anti-counterfeiting.

High-accuracy high temperature measurement based on forward Brillouin scattering of polyimide-coated optical fiber

In this paper, a novel method for high-accuracy high temperature measurement is proposed, which is based on forward Brillouin scattering (FBS) of double-coated optical fiber with polyimide outer coating. The temperature variation changes the acoustic properties of polyimide-coated fiber that is suitable for high temperature measurement in the range of 120 ∼ 220 ℃. An interesting feature is that different radial acoustic modes have different frequency responses in the polyimide-coated fiber. Another interesting phenomenon is that the temperature linearly depends on the frequency shift of FBS spectrum with high sensitivity from 120 ℃ to 220 ℃. By using one acoustic mode with a high frequency shift-temperature sensitivity, we propose a novel high temperature measurement method based on FBS with high measurement accuracy. The experimental result shows that the low temperature measurement uncertainty of 0.02 ℃ can be achieved. The proposed method is expected to be used for high-accuracy temperature measurement applications within a temperature range of 100 ∼ 200 ℃, such as underground oil layer detection, power plant monitoring and high-power electrical systems monitoring.

Order-disorder phase transitions significantly improving the upconversion luminescence intensity of BiTa7O19:Er3+/Yb3+

BiTa7O19 (BTO) has two lattice structure, P–6C2 (188) ordered phase and P63/mcm (193) disordered phase. Ordered and disordered BTO:Er3+/Yb3+ upconversion phosphors (UCPs) were obtained by solid sintering with different temperatures. The lattice structure of all the samples was investigated by XRD, SEM and Raman spectroscopy, and upconversion luminescence (UCL) spectra were tested by spectrometers. The green integral UCL intensity of the disordered BTO:Er3+/Yb3+ UCP is 60.76 times than that of the ordered sample. By comparing Er3+/Yb3+ co-doped and Er3+ single-doped UCPs with different structures, it is found that the disordered structure enhances the energy transfer from Yb3+ to Er3+, which may be caused by the disordered structure reducing the distance between Yb3+ and Er3+. The absolute temperature sensitivity of the sample with the highest UCL intensity is 0.01005 K-1 at 352 K. All results suggest that the disordered structure of BTO host can greatly improve green UCL intensity and the disordered BTO:Er3+/Yb3+ UCPs are suitable for the application of optical temperature measurement.

InAsSb Photodiode Fibre Optic Thermometry for High-Speed, near-Ambient Temperature Measurements

Infrared radiation thermometers (IRTs) overcome many of the limitations of thermocouples, particularly responsiveness and calibration drift. The main challenge with radiation thermometry is the fast and reliable measurement of temperatures close to room temperature. A new IRT which is sensitive to wavelengths between 3 μm and 11 μm was developed and tested in a laboratory setting. It is based on an uncooled indium arsenide antimony (InAsSb) photodiode, a transimpedance amplifier, and a silver halogenide fibre optic cable transmissive in the mid- to long-wave infrared region. The prototype IRT was capable of measuring temperatures between 35 °C and 100 °C at an integration time of 5 ms and a temperature range between 40 °C and 100 °C at an integration time of 1 ms, with a root mean square (RMS) noise level of less than 0.5 °C. The thermometer was calibrated against Planck’s law using a five-point calibration, leading to a measurement uncertainty within ±1.5 °C over the aforementioned temperature range. The thermometer was tested against a thermocouple during drilling operations of polyether ether ketone (PEEK) plastic to measure the temperature of the drill bit during the material removal process. Future versions of the thermometer are intended to be used as a thermocouple replacement in high-speed, near-ambient temperature measurement applications, such as electric motor condition monitoring; battery protection; and machining of polymers and composite materials, such as carbon-fibre-reinforced plastic (CFRP).

Enhanced anti-aging behaviors in cubic phase CeO2 induced BaSnO3 thermosensitive ceramics

The anti-aging ability is an important index to measure the temperature measurement application of thermosensitive materials. Herein, the BaSnO3 + xCeO2 (x = 0 %, 2 %, 4 %, 7 %) ceramics were synthesized via mixing BaSnO3 with CeO2. By combining with CeO2, some Ce4+ replaces Sn4+ to improve the phase structure stability, which improves the high-temperature stability of the thermosensitive ceramic, reducing the aging coefficient from 50 % to 2.5 %. Meanwhile, the resistivity decreases with the increase of CeO2 composition, which can be attributed to the increase of Ce3+ content, resulting in the increase of the number of small polaron. With the increase of x content, thematerial constant B500/850, activation energy Ea and resistivity ρ500 of the ceramic decrease. The B values and Ea values of the thermistors are in the range of 12341–17155 K and 1.06–1.48 eV, respectively. These results indicate that BaSnO3 + xCeO2 composites are potential candidates in high temperature NTC thermistor devices.

A state-of-the-art review on laser-induced fluorescence (LIF) method with application in temperature measurement

Laser-induced fluorescence (LIF) is a robust and vigorous method for non-intrusive measurement of temperature, pressure, concentration, and pH in fluids. The application of LIF for measurement is also extendable to solid and gaseous environments. In this method, the fluorescent molecules are transferred to a higher energy state by absorbing the energy of a laser beam and subsequently undergo spontaneous emission of light in the form of fluorescence during the transition to the ground. The emitted fluorescence is commonly captured using a setup consisting of a solvent, fluorescent material, detecting cameras, lenses, and filters, which enables the determination of the thermophysical parameters of the measuring environment using pertinent mathematical formulae. This method can be used for precise measurements in a wide range of engineering and medical applications. Despite the numerous studies on the utilization of LIF for measurement, there is not a comprehensive review paper with a focus on various types of LIF techniques and their applications in temperature measurement. This paper seeks to address this gap by fully discussing these approaches, demonstrating temperature measurements in different environments and circumstances, and outlining their benefits and drawbacks. Accordingly, one-dye one-color, two-dye two-color, one-dye two-color, one-dye three-color, two-dye three-color, volumetric LIF, and encapsulation techniques are fully discussed as the main LIF approaches and their applications for the temperature measurement in fluid flows, droplets, microfluidics, and gas environments.

A simplified model for minor and major loop magnetic hysteresis and its application for inference of temperature in induction heated particle beds

In this work, a LangArc model is presented that successfully fits both major and minor hysteresis loops of a bed of magnetic particles in real time using instruments that detect changes in the magnetic field strength, such as in-situ pick-up coils. A novel temperature measurement application is demonstrated based on a real-time characterisation of a magnetic material, in this case magnetite, as a function of temperature. Magnetic hysteresis can be used to provide useful induction heating in a packed bed of magnetic materials. This can be used for general heating and to provide energy to chemical reactions in chemical processes. Accurate temperature measurement of magnetic particles under induction heating is a well-known challenge: conventional techniques give a single-point measurement, and are subject to inaccuracy due to self-heating of the instrument tip. Thermal lag can be problematic given the rapid heating rates that are characteristic of induction heating. The LangArc inferred temperature measurement technique is shown to detect heating rates in excess of 30 °C·s−1, under which circumstances an in-bed thermocouple was shown to lag by as much as 180 °C. This new method has significant importance for temperature measurement in applications involving the induction heating of magnetic materials as it avoids the location of an instrument inside the magnetic particle bed and is highly responsive under rapid heating where other techniques can give misleading results.

High-sensitivity fiber optic temperature sensor based on CTFBG-FPI and Vernier effect.

A novel high-sensitivity temperature sensor based on a chirped thin-core fiber Bragg grating Fabry-Perot interferometer (CTFBG-FPI) and the Vernier effect is proposed and demonstrated. With femtosecond laser direct writing technology, two CTFBG-FPIs with different interferometric cavity lengths are inscribed inside a thin-core fiber to form a Vernier effect system. The two FPIs consist of two pairs of CTFBGs with a full width at half maximum (FWHM) of 66.5 nm staggered in parallel. The interferometric cavity lengths of the two FPIs were designed to be 2 mm and 1.98 mm as the reference arm and sensing arm of the sensor, respectively. The temperature sensitivity of this sensor was measured to be -1.084 nm/°C in a range of 40-90°C. This sensor is expected to play a crucial role in precision temperature measurement applications.

Efficient upconversion and downshifting luminescence of CaIn2O4: Yb3+/Tm3+/RE3+ (RE=Er/Ho) phosphor: Temperature sensing performance in the visible and near-infrared range

In this paper, the upconversion(UC) and downshifting(DS) luminescence and thermal sensing performances of the CaIn2O4: RE3+/Tm3+/Yb3+(RE=Er, Ho) phosphors are investigated in detail. The bright UC emission bands from 450 to 900 nm and the DS luminescence bands from 1000 to 1700 nm are obtained under 980 nm excitation. The typical near infrared(NIR) emisson band(∼1550 nm) of Er3+ ions and the NIR emission band(∼1200 nm) of Ho3+ ions are gained. The temperature sensing features of CaIn2O4: RE3+/Tm3+/Yb3+ (RE=Er, Ho) phosphors are investigated with the luminescence intensity ratio (LIR) technique. The results indicate that the maximum relative sensitivity (SRmax) of CaIn2O4: Er3+/Tm3+/Yb3+ sample reaches 1.576% K-1 at 313 K, and the SRmax of CaIn2O4: Ho3+/Tm3+/Yb3+ sample reaches 0.797% K-1 at 353 K in UC range. In addition, the higher temperature measuring sensitivities have been obtained in NIR-II region with the DS luminescence of CaIn2O4: RE3+/Tm3+/Yb3+ phosphors. The above results indicate that the CaIn2O4: RE3+/Tm3+/Yb3+ phosphors show bright emission bands in visible and NIR-II, and higher sensitivity for temperature measurement. The CaIn2O4: RE3+/Tm3+/Yb3+ phosphors present great application in optical temperature measurement.

Luminescence and temperature‐sensing properties of Y4GeO8:Bi3+,Eu3+ phosphor

AbstractIn this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid‐state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from 3P1 → 1S0 transition of Bi3+ ions and characteristic emission peaks from 4f–4f transition of Eu3+ ions. Outstanding temperature‐sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (Sr) can attain 1.51% K−1 (λex = 290 nm). With temperature raising (303–513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (λex = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high‐temperature safety marker.

Anti-thermal quenching behavior of Sm3+ doped SrMoO4 phosphor for new application in temperature sensing

SrMoO4: Sm3+ orange red-emitting phosphors for novel application in temperature measurement were prepared by solid-phase synthesis method. SrMoO4: Sm3+ phosphor with scheelite structure was assigned to tetragonal system and I41/a space group. Sm3+ ions could occupy Sr2+ lattice sites of SrMoO4. SrMoO4: Sm3+ consisted of irregular microparticle with well-crystallized pomegranate seed-like morphology and Sm3+ ions can be evenly distributed in the SrMoO4 matrix. The band gap value of SrMoO4: 1.0%Sm3+ (∼4.228 eV) is less than that of SrMoO4 (∼4.267 eV), which is due to generation of defective energy levels in band gap. The appropriate quenching concentration of Sm3+ was 1.0%, the critical distance is ∼25.57 Å and θ is 7.1, close to 8, which was attributed to dipole−quadrupole interaction type of electric multipolar interaction. SrMoO4:1.0%Sm3+ had excellent thermal stability of the PL peak at 598 nm and 644 nm and anti-thermal quenching property of the PL peak at 530 nm and 563 nm. The activation energy based on the intensity of the PL peak at 598 nm is 0.318 eV. The new dual-model thermometry strategy base on exponential function and modified Boltzmann population distribution would be proposed. SrMoO4:Sm3+ phosphor had the absolute sensitivities of 0.108 K−1 based on exponential function and the relative sensitivities of 0.601% K−1 based on modified Boltzmann population distribution. The excellent anti-thermal quenching and good thermal stability of SrMoO4: Sm3+ phosphors indicate that it has a potential for applications as pc-WLEDs and optical thermometry.

Simultaneous application of soot and temperature measurements in a pressurized turbulent flame by laser-induced incandescence and coherent anti-Stokes Raman scattering for particle sizing

Simultaneous application of multi-channel laser-induced incandescence (LII) and shifted vibrational coherent anti-Stokes Raman scattering (SV-CARS) to study sooting flames is demonstrated for the first time. The potential of this diagnostics combination is evaluated on the basis of characterization of soot particles and correlation of soot presence with temperature. For that purpose, a sooting swirl flame operated at three bars has been employed with ethylene as fuel. The novel combination of CARS and time-resolved LII (TiRe LII) enables the estimation of particle size and correlation of this quantity with local gas temperature; simultaneously acquired 2D LII images provide information on the soot distribution in the ambience of the measurement volume which is used by CARS and TiRe LII. Even if the used LII model is approximative in some respect, the detected LII decay times indicate very small particle size throughout the flame relative to an atmospheric laminar diffusion flame which was used for comparison. In most instances, soot presence relates to local gas temperatures in a range between 1600 and 2400 K. Rare soot events at cooler temperatures occur near the nozzle exit and are attributed to transported soot. Comparison of the peak soot temperatures during the LII process shows a significant decrease in the turbulent pressurized flame relative to the laminar atmospheric reference flame. This is attributed to a less-efficient LII heat-up process at turbulent pressurized conditions due to beam steering. The background blackbody temperature, which can be derived by evaluating the signal captured in the different color channels of the LII system towards the end of the LII process, has been identified to be mostly controlled by hotter soot filaments between the laser plane and the detector. Thus, the LII signal tail is not a good measure of the local gas temperature in the measurement volume for this type of configuration.