TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Holst, Gerhard A1 - Franke, Robert T1 - An Approach of Identifying Polymers With Fluorescence Lifetime Imaging T2 - 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) N2 - Nowadays, fluorescence lifetime measurements and the method of fluorescence lifetime imaging are already state of the art in biomedical research. Also first investigations show that polymers could be identified due to their endogenous fluorescent lifetime. Thus an approach of identifying polymers with fluorescence lifetime imaging is done in this contribution. Therefore, four different polymers are examined and evaluated with statistical methods in order to determine their specific fluorescence lifetimes. KW - polymer KW - fluorescence Y1 - 2019 SP - 186 EP - 189 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Laforsch, Christian T1 - Investigation of the Impact of CaCO3 Concentrations on the Fluorescence Lifetime of Polypropylene T2 - 2022 Conference on Lasers and Electro-Optics (CLEO) N2 - The impact of fillers on the fluorescence lifetime of polymers is still unknown. Investigating polypropylene containing different CaCO 3 concentrations using FD-FLIM show an exponential increase in fluorescence lifetime proportional to the CaCO 3 density in polypropylene. KW - Fluorescence KW - Lasers and electrooptics KW - Plastics KW - Electrooptical waveguides Y1 - 2022 SP - 1 EP - 2 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Holst, Gerhard A1 - Versen, Martin T1 - A novel approach to optically distinguish plastics based on fluorescence lifetime measurements T2 - 2020 IEEE Sensors Applications Symposium (SAS) N2 - In medical and biological research, fluorescence lifetime measurements and fluorescence lifetime imaging is already a part of the standardized analysis procedures. As first investigations have shown, polymers can be identified using fluorescence lifetime imaging and an evaluation algorithm. Thus, this contribution pursues a novel approach for the direct differentiation of four polymers with fluorescence lifetime imaging. Therefore, the evaluation algorithm is extended to compare several fluorescence lifetime images to prove that a distinction is possible. Y1 - 2020 U6 - https://doi.org/10.1109/SAS48726.2020.9220084 SP - 1 EP - 6 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Laforsch, Christian T1 - Non-destructive evaluation of treated polyethylene terephthalate films by fluorescence lifetime imaging T2 - 2021 IEEE Sensors Applications Symposium (SAS) N2 - The fluorescence decay time allows to identify and distinguish polymers from each other. Three differently treated biaxially-oriented polyethylene terephthalate films are examined with two excitation wavelengths of 445 and 488nm. The fluorescence decay time is dependent of the treatment method of the films and is a means for identification. KW - polymer KW - polymer identification KW - fluorescence lifetime imaging KW - fluorescence KW - FD-FLIM Y1 - 2021 U6 - https://doi.org/10.1109/SAS51076.2021.9530008 SP - 1 EP - 5 ER - TY - CHAP A1 - Bernöcker, Anton A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin T1 - Entwicklung eines neuronalen Netzwerks als Basis zur automatisierten Holzartenerkennung T2 - Tagungsband AALE 2022, 18. AALE-Konferenz. Pforzheim, 09.03.-11.03.2022 N2 - Holz ist ein vielseitig einsetzbarer nachwachsender Rohstoff. Neben seinem wirtschaftlichen Nutzen ist er für den Erhalt des Klimas unersetzlich. Eine sortenreine Sortierung für die Weiterverarbeitung von Altholz spielt für einen ressourcenschonenden Umgang eine wichtige Rolle. Um das Potenzial eines neuronalen Netzwerks basierend auf Messdaten der bildgebenden Fluoreszenzabklingzeitmessung für die Altholzsortierung aufzuzeigen, wurden zwei unterschiedliche Klassifikationsansätze auf Basis der Programmiersprache Python gewählt. Die Ergebnisse zeigen, dass die bildbasierte Klassifizierung der Holzart mit einer Genauigkeit von 47,36 % noch ausbaufähig ist. Eine datenbasierte Klassifizierung der Holzart mit einer Identifikationsgenauigkeit von 98,28 % ist dagegen vielversprechend. KW - FD-FLIM KW - Fluoreszenz KW - Fluoreszenzabklingzeit KW - Holzart KW - Neuronales Netz KW - Klassifizierung Y1 - 2022 U6 - https://doi.org/https://doi.org/10.33968/2022.11 SP - 115 EP - 124 ER - TY - CHAP A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin T1 - Frequency-domain fluorescence lifetime imaging as method to analyze wood structures T2 - 2022 Conference on Lasers and Electro-Optics (CLEO) Y1 - 2022 SP - 1 EP - 2 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin ED - Bauer, Benedict ED - Wittenberg, Carsten T1 - Bestimmung einer Quanteneffizienz für das automatisierte Sortieren von Kunststoffen durch Fluoreszenz T2 - AALE 2019 - Autonome und intelligente Systeme in der Automatisierungstechnik 16. Fachkonferenz KW - Quanteneffizienz KW - Fluoreszenz Y1 - 2019 SN - 978-3-8007-4860-0 SP - 179 EP - 187 PB - VDE Verlag CY - Berlin ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Holst, G. A1 - Versen, Martin T1 - A novel approach to optically distinguish plastics based on fluorescence lifetime measurements T2 - 2020 IEEE Sensors Applications Symposium (SAS), Kuala Lumpur, Malaysia KW - fluorescence Y1 - 2020 SP - 1 EP - 6 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Langhals, H. T1 - A method for sorting of plastics with an apparatus specific quantum efficiency approach T2 - 2019 IEEE Sensors Applications Symposium (SAS) N2 - Today, the automatic separation of polymers from each other in an industrial scale is an unsolved problem. In laboratory environments, two methods are known whereby plastic is sorted either by color or by fluorescence decay time measurements that require fast synchronization and thus expensive equipment. A simple and pragmatic process is proposed to separate plastics from each other: all fluorescent photons are counted in relation to the absorbed photons. A theoretical model and an experimental setup are built in order to determine an apparatus specific quantum efficiency. KW - polymer KW - plastic sorting KW - fluorescence KW - quantum efficiency Y1 - 2019 UR - https://ieeexplore.ieee.org/document/8706034 ER - TY - CHAP A1 - Maniyattu, Georgekutty Jose A1 - Geegy, Eldho A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Laforsch, Christian T1 - Development of a neural network to identify plastics using Fluorescence Lifetime Imaging Microscopy T2 - 2022 IEEE Sensors Applications Symposium (SAS) N2 - Plastics have become a major part of human’s daily life. An uncontrolled usage of plastic leads to an accumulation in the environment posing a threat to flora and fauna, if not recycled correctly. The correct sorting and recycling of the most commonly available plastic types and an identification of plastic in the environment are important. Fluorescence lifetime imaging microscopy shows a high potential in sorting and identifying plastic types. A data-based and an image-based classification are investigated using python programming language to demonstrate the potential of a neural network based on fluorescence lifetime images to identify plastic types. The results indicate that the data-based classification has a higher identification accuracy compared to the image-based classification. KW - fluorescence lifetime imaging KW - FLIM KW - neural networks KW - plastic identification Y1 - 2022 U6 - https://doi.org/10.1109/SAS54819.2022.9881372 SP - 1 EP - 6 ER - TY - JOUR A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Laforsch, Christian T1 - An algorithmic method for the identification of wood species and the classification of post-consumer wood using fluorescence lifetime imaging microscopy JF - Journal of Sensors and Sensor Systems N2 - In this contribution the frequency domain fluorescence lifetime imaging microscopy (FD-FLIM) technique is evaluated for post-consumer wood sorting. The fluorescence characteristics of several wood samples were determined, whereby two excitation wavelengths (405 and 488 nm) were used. The measured data were processed using algorithmic methods to identify the wood species and post-consumer wood category. With the excitation wavelength of 405 nm, 16 out of 19 samples could be correctly assigned to the corresponding post-consumer wood category by means of the fluorescence lifetimes. Thus, the experimental results revealed the high potential of the FD-FLIM technique for automated post-consumer wood sorting. Y1 - 2022 U6 - https://doi.org/10.5194/jsss-11-129-2022 VL - 11 IS - 1 SP - 129 EP - 136 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Laforsch, Christian T1 - Optical identification of car tire particles on soil using fluorescence lifetime imaging microscopy T2 - Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES), Technical Digest Series (Optica Publishing Group, 2022) N2 - Tire wear is one of the major contributors of environmental pollution by microplastic. FD-FLIM in combination with an image processing algorithm are successfully applied to detect tyre wear on soil. KW - Diode lasers KW - Fluorescence lifetime imaging KW - Image processing KW - Image processing algorithms KW - Phase modulation KW - Phase shift Y1 - 2022 U6 - https://doi.org/10.1364/ES.2022.ETu3H.3 SP - ETu3H.3 ER - TY - JOUR A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin T1 - Analysis of the phase-dependent fluorescence decay time of treated wood using FD-FLIM JF - tm - Technisches Messen N2 - For sustainable handling of wood and high material utilization, post-consumer wood has to be sorted by post-consumer wood categories in Germany. The non-destructive FD-FLIM method could improve the wood recycling process by automatic classification of waste wood into post-consumer wood classes. Thus, the phase-dependent fluorescence decay time of treated wood is analysed in this study to obtain the impact of the treatment on the fluorescence decay time. It is shown that treated and untreated wood can be differentiated using the fluorescence decay time, although the state-of-the-art theoretical fluorescence decay time differs from the experimentally determined fluorescence decay time. N2 - Für einen nachhaltigen Umgang mit Holz und eine hohe stoffliche Verwertung muss Altholz in Deutschland nach Altholzklassen sortiert werden. Die zerstörungsfreie FD-FLIM-Methode könnte den Holzrecyclingprozess durch eine automatische Klassifizierung von Altholz in Altholzklassen verbessern. Daher wird in dieser Studie die phasenabhängige Fluoreszenzabklingzeit von behandeltem Holz analysiert, um den Einfluss der Behandlung auf die Fluoreszenzabklingzeit zu ermitteln. Es wird gezeigt, dass behandeltes und unbehandeltes Holz anhand der Fluoreszenzabklingzeit unterschieden werden kann, auch wenn die nach dem Stand der Forschung theoretische Fluoreszenzabklingzeit von der experimentell ermittelten Fluoreszenzabklingzeit abweicht. KW - fluorescence KW - decay time KW - FD-FLIM KW - lifetime KW - wood Y1 - 2023 U6 - https://doi.org/10.1515/teme-2022-0114 VL - 90 IS - 6 SP - 401 EP - 406 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Holst, Gerhard A1 - Versen, Martin A1 - Laforsch, Christian T1 - An optical method to differentiate wood from polymers using fluorescence lifetime imaging microscopy T2 - OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES) (2021), paper EW4G.6 N2 - In this contribution investigations with fluorescence lifetime imaging microscopy (FLIM) are made to optically distinguish polymers and wood. The results show that the distinction and identification is possible in a graphical and calculative way. Y1 - 2021 U6 - https://doi.org/10.1364/ES.2021.EW4G.6 SP - EW4G.6 ER - TY - CHAP A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Auer, Veronika A1 - Versen, Martin A1 - Laforsch, Christian T1 - An algorithmic method to identify multiple wood species in a single image by their specific fluorescence lifetimes T2 - OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP) (2021), paper CF2B.3 N2 - Fluorescence lifetime imaging microscopy (FLIM) combined with an image processing algorithm is successfully used for the optical identification and areal separation of three wood species of maple, larch and nut in a single taken image. Y1 - 2021 U6 - https://doi.org/10.1364/COSI.2021.CF2B.3 SP - CF2B.3 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Khan, Yamna A1 - Leiter, Nina A1 - Versen, Martin A1 - Löder, Martin A1 - Laforsch, Christian T1 - Combining BLOB-Detection and MLP to Detect and Identify Plastics in an Environmental Matrix T2 - 2023 IEEE Sensors Applications Symposium (SAS) N2 - Environmental pollution by plastics is an increasing problem. However, state-of-the-art methods have significant disadvantages in detecting and identifying plastics directly in an environmental matrix. In this study, we propose a blob detection algorithm in combination with a neural network for fast and automated identification of plastics and non-plastics in a single fluorescence lifetime image. Therefore an artificial environmental matrix is prepared that contains soil, grass, spruce and HDPE (high density polyethylene) particles. Several FD-FLIM (frequency domain fluorescence lifetime imaging microscopy) images are taken, and the detection algorithm and the neural network are applied. We successfully demonstrated the suitability of the thresholding algorithm and the binary classification of the HDPE particles directly in the environmental matrix. KW - Fluorescence KW - Plastics KW - FD-FLIM KW - Neural networks KW - MLP KW - blob detection KW - Classification algorithms KW - Dogs KW - fluorescence lifetime KW - plastics identification KW - Soil KW - Thresholding (Imaging) Y1 - 2023 U6 - https://doi.org/10.1109/SAS58821.2023.10254171 SP - 1 EP - 5 ER - TY - JOUR A1 - Maniyattu, Georgekutty Jose A1 - Geegy, Eldho A1 - Wohlschläger, Maximilian A1 - Leiter, Nina A1 - Versen, Martin A1 - Laforsch, Christian T1 - Multilayer Perceptron Development to Identify Plastics Using Fluorescence Lifetime Imaging Microscopy JF - EDFA Technical Articles N2 - Existing plastic analysis techniques such as Fourier transform infrared spectroscopy and Raman spectroscopy are problematic because samples must be anhydrous and identification can be hindered by additives. This article describes a new approach that has been successfully demonstrated in which plastics can be classified by neural networks that are trained, validated, and tested by frequency domain fluorescence lifetime imaging microscopy measurements. Y1 - 2023 U6 - https://doi.org/10.31399/asm.edfa.2023-3.p031 VL - 25 IS - 3 SP - 31 EP - 37 ER - TY - CHAP A1 - Schwarz, Jonas A1 - Wohlschläger, Maximilian A1 - Leiter, Nina A1 - Auer, Veronika A1 - Risse, Michael A1 - Versen, Martin T1 - Frequency Domain Fluorescence Lifetime Imaging Microscopy (FD-FLIM) analysis of Quercus robur samples for origin differentiation purposes T2 - Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES) N2 - Increasing demand for wood products requires methods to determine its harvest origin and ensure sustainable and legal sourcing. In 15 out of 21 cases, the origin of Quercus robur was differentiable in FD-FLIM studies. KW - Fluorescence lifetime imaging KW - Phase shift KW - Phase modulation KW - Laser sources KW - Bandpass filters KW - Frequency modulation Y1 - 2023 U6 - https://doi.org/10.1364/AIS.2023.JTu4A.10 ER - TY - JOUR A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Löder, Martin G. J. A1 - Laforsch, Christian T1 - Identification of different plastic types and natural materials from terrestrial environments using fluorescence lifetime imaging microscopy. JF - Analytical and Bioanalytical Chemistry N2 - Environmental pollution by plastics is a global issue of increasing concern. However, microplastic analysis in complex environmental matrices, such as soil samples, remains an analytical challenge. Destructive mass-based methods for microplastic analysis do not determine plastics’ shape and size, which are essential parameters for reliable ecological risk assessment. By contrast, nondestructive particle-based methods produce such data but require elaborate, time-consuming sample preparation. Thus, time-efficient and reliable methods for microplastic analysis are needed. The present study explored the potential of frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) for rapidly and reliably identifying as well as differentiating plastics and natural materials from terrestrial environments. We investigated the fluorescence spectra of ten natural materials from terrestrial environments, tire wear particles, and eleven different transparent plastic granulates <5 mm to determine the optimal excitation wavelength for identification and differentiation via FD-FLIM under laboratory conditions. Our comparison of different excitation wavelengths showed that 445 nm excitation exhibited the highest fluorescence intensities. 445 nm excitation was also superior for identifying plastic types and distinguishing them from natural materials from terrestrial environments with a high probability using FD-FLIM. We could demonstrate that FD-FLIM analysis has the potential to contribute to a streamlined and time-efficient direct analysis of microplastic contamination. However, further investigations on size-, shape-, color-, and material-type detection limitations are necessary to evaluate if the direct identification of terrestrial environmental samples of relatively low complexity, such as a surface inspection soil, is possible. KW - FD-FLIM KW - Fluorescence lifetime KW - Microplastic contamination KW - Microplastic in soils KW - Plastic identification KW - Terrestrial pollution Y1 - 2024 U6 - https://doi.org/10.1007/s00216-024-05305-w ER - TY - JOUR A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Löder, Martin G. J. A1 - Laforsch, Christian T1 - A promising method for fast identification of microplastic particles in environmental samples: A pilot study using fluorescence lifetime imaging microscopy JF - Heliyon N2 - Microplastic pollution of the environment has been extensively studied, with recent studies focusing on the prevalence of microplastics in the environment and their effects on various organisms. Identification methods that simplify the extraction and analysis process to the point where the extraction can be omitted are being investigated, thus enabling the direct identification of microplastic particles. Currently, microplastic samples from environmental matrices can only be identified using time-consuming extraction, sample processing, and analytical methods. Various spectroscopic methods are currently employed, such as micro Fourier-transform infrared, attenuated total reflectance, and micro Raman spectroscopy. However, microplastics in environmental matrices cannot be directly identified using these spectroscopic methods. Investigations using frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) to identify and differentiate plastics from environmental materials have yielded promising results for directly identifying microplastics in an environmental matrix. Herein, two artificially prepared environmental matrices that included natural soil, grass, wood, and high-density polyethylene were investigated using FD-FLIM. Our first results showed that we successfully identified one plastic type in the two artificially prepared matrices using FD-FLIM. However, further research must be conducted to improve the FD-FLIM method and explore its limitations for directly identifying microplastics in environmental samples. KW - FD-FLIM KW - Fluorescence lifetime KW - Environmental science KW - Fluorescence microscopy KW - Material identification KW - Microplastics Y1 - 2024 U6 - https://doi.org/10.1016/j.heliyon.2024.e25133 VL - 10 IS - 3 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Khan, Yamna A1 - Leiter, Nina A1 - Versen, Martin A1 - Löder, Martin A1 - Laforsch, Christian T1 - Development of a BLOB-detection algorithm based on DoG to detect Plastic in an environmental matrix using FD-FLIM T2 - Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES) N2 - The direct identification of plastics in an environmental matrix is heavily researched. We successfully developed a BLOB-detection algorithm based on differences of Gaussians to identify HDPE particles in an artificial environmental matrix using FD-FLIM. KW - Diode lasers KW - Fluorescence lifetime imaging KW - Phase shift KW - Neural networks KW - Optical filters KW - Spatial resolution Y1 - 2023 U6 - https://doi.org/10.1364/ES.2023.EW4E.4 ER - TY - CHAP A1 - Bernöcker, Anton A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin T1 - Entwicklung eines neuronalen Netzwerks als Basis zur automatisierten Holzartenerkennung T2 - 18. AALE-Konferenz. Pforzheim, 09.03.-11.03.2022 N2 - Holz ist ein vielseitig einsetzbarer nachwachsender Rohstoff. Neben seinem wirtschaftlichen Nutzen ist er für den Erhalt des Klimas unersetzlich. Eine sortenreine Sortierung für die Weiterverarbeitung von Altholz spielt für einen ressourcenschonenden Umgang eine wichtige Rolle. Um das Potenzial eines neuronalen Netzwerks basierend auf Messdaten der bildgebenden Fluoreszenzabklingzeitmessung für die Altholzsortierung aufzuzeigen, wurden zwei unterschiedliche Klassifikationsansätze auf Basis der Programmiersprache Python gewählt. Die Ergebnisse zeigen, dass die bildbasierte Klassifizierung der Holzart mit einer Genauigkeit von 47,36 % noch ausbaufähig ist. Eine datenbasierte Klassifizierung der Holzart mit einer Identifikationsgenauigkeit von 98,28 % ist dagegen vielversprechend. KW - FD-FLIM KW - Fluoreszenz KW - Fluoreszenzabklingzeit KW - Holzart KW - Neuronales Netz KW - Klassifizierung Y1 - 2022 U6 - https://doi.org/10.33968/2022.11 ER - TY - CHAP A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin T1 - Frequency-domain fluorescence lifetime imaging as method to analyze wood structures T2 - Conference on Lasers and Electro-Optics N2 - The analysis of wood structures using FD-FLIM seems promising for the identification of wood at 488 nm, as lignin has a high impact on the fluorescence lifetime. KW - Diode lasers KW - Fluorescence KW - Fluorescence lifetime imaging KW - Microscopy Y1 - 2022 U6 - https://doi.org/10.1364/CLEO_AT.2022.JW3A.19 SP - JW3A.19 ER - TY - CHAP A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Auer, Veronika A1 - Versen, Martin A1 - Laforsch, Christian T1 - An algorithmic method to identify multiple wood species in a single image by their specific fluorescence lifetimes T2 - OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP) N2 - Fluorescence lifetime imaging microscopy (FLIM) combined with an image processing algorithm is successfully used for the optical identification and areal separation of three wood species of maple, larch and nut in a single taken image. KW - Confocal laser scanning microscopy KW - Fluorescence lifetime imaging KW - Image processing KW - Image processing algorithms KW - Phase shift KW - Ultraviolet radiation Y1 - 2021 U6 - https://doi.org/10.1364/COSI.2021.CF2B.3 SP - CF2B.3 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Holst, Gerhard A1 - Versen, Martin A1 - Laforsch, Christian T1 - An optical method to differentiate wood from polymers using fluorescence lifetime imaging microscopy T2 - OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES) N2 - In this contribution investigations with fluorescence lifetime imaging microscopy (FLIM) are made to optically distinguish polymers and wood. The results show that the distinction and identification is possible in a graphical and calculative way. KW - Diode lasers KW - Fluorescence lifetime imaging KW - Image processing algorithms KW - Phase shift KW - Raman spectroscopy KW - Stray light Y1 - 2021 U6 - https://doi.org/10.1364/ES.2021.EW4G.6 SP - EW4G.6 ER - TY - CHAP A1 - Wohlschläger, Maximilian A1 - Versen, Martin A1 - Laforsch, Christian T1 - Investigation of the Impact of CaCO3 Concentrations on the Fluorescence Lifetime of Polypropylene T2 - Conference on Lasers and Electro-Optics N2 - The impact of fillers on the fluorescence lifetime of polymers is still unknown. Investigating polypropylene containing different CaCO3 concentrations using FD-FLIM show an exponential increase in fluorescence lifetime proportional to the CaCO3 density in polypropylene. KW - Diode lasers KW - Fluorescence KW - Fluorescence lifetime imaging KW - Fourier transforms KW - Phase shift KW - Stray light Y1 - 2022 U6 - https://doi.org/10.1364/CLEO_AT.2022.AM2M.2 SP - AM2M.2 ER -