Pub Date : 2022-11-10DOI: 10.3389/fphot.2022.1018773
Tatiane Moraes Veloso, A. de Souza da Fonseca, Gilson Costa dos Santos
Currently, light-emitting diodes (LEDs) are considered a substitute for low-power lasers in phototherapy protocols. LEDs enable photobiomodulation on biological tissues and are considered safe and economical. However, the molecular and metabolic mechanisms involved in LED-induced photobiomodulation are not yet fully understood. This review summarizes the metabolic mechanisms involved in LED-induced photobiomodulation in biological tissues under different irradiation parameters and conditions. Studies on LED-induced metabolism photobiomodulation were accessed using scientific article databases, whose findings were summarized in terms of molecular and cellular mechanisms. Data from the accessed studies suggested that the molecular mechanism of LED-induced photobiomodulation involves photoacceptors, such as cytochrome C oxidase, membrane ion channels, mitochondrial modulation, and the production of ROS.
{"title":"Effects of light-emitting diodes on cell biology","authors":"Tatiane Moraes Veloso, A. de Souza da Fonseca, Gilson Costa dos Santos","doi":"10.3389/fphot.2022.1018773","DOIUrl":"https://doi.org/10.3389/fphot.2022.1018773","url":null,"abstract":"Currently, light-emitting diodes (LEDs) are considered a substitute for low-power lasers in phototherapy protocols. LEDs enable photobiomodulation on biological tissues and are considered safe and economical. However, the molecular and metabolic mechanisms involved in LED-induced photobiomodulation are not yet fully understood. This review summarizes the metabolic mechanisms involved in LED-induced photobiomodulation in biological tissues under different irradiation parameters and conditions. Studies on LED-induced metabolism photobiomodulation were accessed using scientific article databases, whose findings were summarized in terms of molecular and cellular mechanisms. Data from the accessed studies suggested that the molecular mechanism of LED-induced photobiomodulation involves photoacceptors, such as cytochrome C oxidase, membrane ion channels, mitochondrial modulation, and the production of ROS.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42336391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-09DOI: 10.3389/fphot.2022.1032776
Silvère Ségaud, L. Baratelli, E. Felli, E. Bannone, L. Cinelli, M. R. Rodríguez-Luna, Nariaki Okamoto, D. Keller, M. de Mathelin, S. Lecler, Michele Diana, S. Gioux
Despite recent technological progress in surgical guidance, current intraoperative assessment of tissue that should be removed (e.g., cancer) or avoided (e.g., nerves) is still performed subjectively. Optical imaging is a non-contact, non-invasive modality that has the potential to provide feedback regarding the condition of living tissues by imaging either an exogenously administered contrast agent or endogenous constituents such as hemoglobin, water, and lipids. As such, optical imaging is an attractive modality to provide physiologically and structurally relevant information for decision-making in real-time during surgery. The Trident imaging platform has been designed for real-time surgical guidance using state-of-the-art optical imaging. This platform is capable of dual exogenous and endogenous imaging owing to a unique filter and source combination, allowing to take advantage of both imaging modalities. This platform makes use of a real-time and quantitative imaging method working in the spatial frequency domain, called Single Snapshot imaging of Optical Properties (SSOP). The Trident imaging platform is designed to comply with all relevant standards for clinical use. In this manuscript, we first introduce the rationale for developing the Trident imaging platform. We then describe fluorescence and endogenous imaging modalities where we present the details of the design, assess the performance of the platform on the bench. Finally, we perform the validation of the platform during an in vivo preclinical experiment. Altogether, this work lays the foundation for translating state-of-the-art optical imaging technology to the clinic.
{"title":"Trident: A dual oxygenation and fluorescence imaging platform for real-time and quantitative surgical guidance","authors":"Silvère Ségaud, L. Baratelli, E. Felli, E. Bannone, L. Cinelli, M. R. Rodríguez-Luna, Nariaki Okamoto, D. Keller, M. de Mathelin, S. Lecler, Michele Diana, S. Gioux","doi":"10.3389/fphot.2022.1032776","DOIUrl":"https://doi.org/10.3389/fphot.2022.1032776","url":null,"abstract":"Despite recent technological progress in surgical guidance, current intraoperative assessment of tissue that should be removed (e.g., cancer) or avoided (e.g., nerves) is still performed subjectively. Optical imaging is a non-contact, non-invasive modality that has the potential to provide feedback regarding the condition of living tissues by imaging either an exogenously administered contrast agent or endogenous constituents such as hemoglobin, water, and lipids. As such, optical imaging is an attractive modality to provide physiologically and structurally relevant information for decision-making in real-time during surgery. The Trident imaging platform has been designed for real-time surgical guidance using state-of-the-art optical imaging. This platform is capable of dual exogenous and endogenous imaging owing to a unique filter and source combination, allowing to take advantage of both imaging modalities. This platform makes use of a real-time and quantitative imaging method working in the spatial frequency domain, called Single Snapshot imaging of Optical Properties (SSOP). The Trident imaging platform is designed to comply with all relevant standards for clinical use. In this manuscript, we first introduce the rationale for developing the Trident imaging platform. We then describe fluorescence and endogenous imaging modalities where we present the details of the design, assess the performance of the platform on the bench. Finally, we perform the validation of the platform during an in vivo preclinical experiment. Altogether, this work lays the foundation for translating state-of-the-art optical imaging technology to the clinic.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91194469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-31DOI: 10.3389/fphot.2022.1037473
J. Martins, A. Skripka, C. Brites, A. Benayas, R. Ferreira, F. Vetrone, L. Carlos
Luminescence thermometry is a spectroscopic technique for remote temperature detection based on the thermal dependence of the luminescence of phosphors, presenting numerous applications ranging from biosciences to engineering. In this work, we use the Er3+ emission of the NaGdF4/NaGdF4:Yb3+,Er3+/NaGdF4 upconverting nanoparticles upon 980 nm laser excitation to determine simultaneously the absolute temperature and the excitation power density. The Er3+ 2H11/2→4I15/2 and 4S3/2→4I15/2 emission bands, which are commonly used for thermometric purposes, overlap with the 2H9/2 →4I13/2 emission band, which can lead to erroneous temperature readout. Applying the concept of luminescent primary thermometry to resolve the overlapping Er3+ transitions, a dual nanosensor synchronously measuring the temperature and the delivered laser pump power is successfully realized holding promising applications in laser-supported thermal therapies.
{"title":"Upconverting nanoparticles as primary thermometers and power sensors","authors":"J. Martins, A. Skripka, C. Brites, A. Benayas, R. Ferreira, F. Vetrone, L. Carlos","doi":"10.3389/fphot.2022.1037473","DOIUrl":"https://doi.org/10.3389/fphot.2022.1037473","url":null,"abstract":"Luminescence thermometry is a spectroscopic technique for remote temperature detection based on the thermal dependence of the luminescence of phosphors, presenting numerous applications ranging from biosciences to engineering. In this work, we use the Er3+ emission of the NaGdF4/NaGdF4:Yb3+,Er3+/NaGdF4 upconverting nanoparticles upon 980 nm laser excitation to determine simultaneously the absolute temperature and the excitation power density. The Er3+ 2H11/2→4I15/2 and 4S3/2→4I15/2 emission bands, which are commonly used for thermometric purposes, overlap with the 2H9/2 →4I13/2 emission band, which can lead to erroneous temperature readout. Applying the concept of luminescent primary thermometry to resolve the overlapping Er3+ transitions, a dual nanosensor synchronously measuring the temperature and the delivered laser pump power is successfully realized holding promising applications in laser-supported thermal therapies.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47684378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-20DOI: 10.3389/fphot.2022.891565
U. Aeberhard, A. Schiller, Y. Masson, Simon Zeder, B. Blülle, B. Ruhstaller
This paper reports on the analysis and optimization of high-efficiency organic tandem solar cells via full opto-electronic device simulation on continuum level and using a hopping model for the explicit description of the charge recombination junction. Inclusion of the electrical sub-cell interconnection allows for a rigorous assessment of the impact of the internal charge distribution and associated built-in fields as well as quasi-Fermi level profiles on the measured device characteristics. It enables the direct evaluation of the external quantum efficiency in a simulation that follows closely the measurement protocol, and sheds light on complications related to the dependence of the band profile on the illumination conditions. The study also points at fingerprints of insufficient junction quality in the electrical characteristics of the tandem device. After studying the impact of key electrical parameters such as, carrier mobility, lifetime and interface hopping rate, onto the device characteristics, the latter are optimized not only optically, but also electronically, adding in both cases an increasing number of layers to the parameters of the global optimization procedure. An improvement of 2% absolute power conversion efficiency by using the full opto-electronic optimization as compared to optical optimization only is found.
{"title":"Analysis and Optimization of Organic Tandem Solar Cells by Full Opto-Electronic Simulation","authors":"U. Aeberhard, A. Schiller, Y. Masson, Simon Zeder, B. Blülle, B. Ruhstaller","doi":"10.3389/fphot.2022.891565","DOIUrl":"https://doi.org/10.3389/fphot.2022.891565","url":null,"abstract":"This paper reports on the analysis and optimization of high-efficiency organic tandem solar cells via full opto-electronic device simulation on continuum level and using a hopping model for the explicit description of the charge recombination junction. Inclusion of the electrical sub-cell interconnection allows for a rigorous assessment of the impact of the internal charge distribution and associated built-in fields as well as quasi-Fermi level profiles on the measured device characteristics. It enables the direct evaluation of the external quantum efficiency in a simulation that follows closely the measurement protocol, and sheds light on complications related to the dependence of the band profile on the illumination conditions. The study also points at fingerprints of insufficient junction quality in the electrical characteristics of the tandem device. After studying the impact of key electrical parameters such as, carrier mobility, lifetime and interface hopping rate, onto the device characteristics, the latter are optimized not only optically, but also electronically, adding in both cases an increasing number of layers to the parameters of the global optimization procedure. An improvement of 2% absolute power conversion efficiency by using the full opto-electronic optimization as compared to optical optimization only is found.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44958848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-18DOI: 10.3389/fphot.2023.1066993
Zifu Wang, Liyang Luo, Di Xia, Siqi Lu, Guosheng Lin, Shecheng Gao, Zhaohui Li, Bin Zhang
Octave-spanning Kerr combs bridging the spectral windows of the near-infrared region (NIR) and the mid-infrared (MIR) region are expected in a number of applications, including high-capacity coherent optical communications, and gas molecular absorption footprints. Here, we propose novel concentric dual-ring microresonators (DRMs) for advanced dispersion engineering to tailor the comb spectral profile. The dispersion can be flexibly engineered not only by the cross-section of the DRMs, but also by the gap between concentric dual-ring microresonators, which provides a new path to geometrically control the spectral profile of the soliton Kerr combs. An octave-spanning Kerr soliton microcomb with multi-dispersive waves has been achieved numerically covering from the telecommunication band (1224 nm) to the mid-infrared band region (2913 nm) with a −40 dB bandwidth of 1265 nm. Our results are promising to fully understand the nonlinear dynamics in hybrid modes in DRMs, which helps control broadband comb formation.
{"title":"Engineered octave frequency comb in integrated chalcogenide dual-ring microresonators","authors":"Zifu Wang, Liyang Luo, Di Xia, Siqi Lu, Guosheng Lin, Shecheng Gao, Zhaohui Li, Bin Zhang","doi":"10.3389/fphot.2023.1066993","DOIUrl":"https://doi.org/10.3389/fphot.2023.1066993","url":null,"abstract":"Octave-spanning Kerr combs bridging the spectral windows of the near-infrared region (NIR) and the mid-infrared (MIR) region are expected in a number of applications, including high-capacity coherent optical communications, and gas molecular absorption footprints. Here, we propose novel concentric dual-ring microresonators (DRMs) for advanced dispersion engineering to tailor the comb spectral profile. The dispersion can be flexibly engineered not only by the cross-section of the DRMs, but also by the gap between concentric dual-ring microresonators, which provides a new path to geometrically control the spectral profile of the soliton Kerr combs. An octave-spanning Kerr soliton microcomb with multi-dispersive waves has been achieved numerically covering from the telecommunication band (1224 nm) to the mid-infrared band region (2913 nm) with a −40 dB bandwidth of 1265 nm. Our results are promising to fully understand the nonlinear dynamics in hybrid modes in DRMs, which helps control broadband comb formation.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48977646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-14DOI: 10.3389/fphot.2022.1015661
J. Ku, C. Pasarikovski, Y. Dobashi, J. Ramjist, S. Priola, V. Yang
Cerebral aneurysms are an abnormal ballooning of blood vessels which have the potential to rupture and cause hemorrhagic stroke. The diagnosis, treatment, and monitoring of cerebral aneurysms is highly dependant on high resolution imaging. As an imaging modality capable of cross-sectional resolution down to 10 μm, intraluminal optical coherence tomography (OCT) has great potential in improving care for cerebral aneurysms. The ability to assess the blood vessel microanatomy in vivo may be able to predict aneurysm growth and rupture. During treatment, intraluminal OCT may aid in assessment of treatment efficacy and complication avoidance, such as via visualization of in-stent thrombosis, stent wall apposition, and the fate of covered branch vessels. This technology can also be used in post-treatment monitoring, to assess for aneurysmal remnants or for endothelialisation and healing over the diseased segments. The goal of this clinically focused narrative review is to provide an overview of the previous applications of intraluminal OCT in cerebral aneurysms and future prospects of applying this technology to improve care in patients with cerebral aneurysms, including a specific neurovascular OCT catheter, doppler OCT for high resolution blood flow assessment, and further research endeavors.
{"title":"Review of intraluminal optical coherence tomography imaging for cerebral aneurysms","authors":"J. Ku, C. Pasarikovski, Y. Dobashi, J. Ramjist, S. Priola, V. Yang","doi":"10.3389/fphot.2022.1015661","DOIUrl":"https://doi.org/10.3389/fphot.2022.1015661","url":null,"abstract":"Cerebral aneurysms are an abnormal ballooning of blood vessels which have the potential to rupture and cause hemorrhagic stroke. The diagnosis, treatment, and monitoring of cerebral aneurysms is highly dependant on high resolution imaging. As an imaging modality capable of cross-sectional resolution down to 10 μm, intraluminal optical coherence tomography (OCT) has great potential in improving care for cerebral aneurysms. The ability to assess the blood vessel microanatomy in vivo may be able to predict aneurysm growth and rupture. During treatment, intraluminal OCT may aid in assessment of treatment efficacy and complication avoidance, such as via visualization of in-stent thrombosis, stent wall apposition, and the fate of covered branch vessels. This technology can also be used in post-treatment monitoring, to assess for aneurysmal remnants or for endothelialisation and healing over the diseased segments. The goal of this clinically focused narrative review is to provide an overview of the previous applications of intraluminal OCT in cerebral aneurysms and future prospects of applying this technology to improve care in patients with cerebral aneurysms, including a specific neurovascular OCT catheter, doppler OCT for high resolution blood flow assessment, and further research endeavors.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42549251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-29DOI: 10.3389/fphot.2022.977343
A. Aceves, A. Copeland
The effective engineering of linear and nonlinear optical properties in photonic media has led to new advances in the theory and applications of spatio-temporal light–matter interactions. In some instances, research has been motivated by phenomena in a quantum mechanical framework; two notable examples being Anderson localization and parity–time symmetry. Herein, we present theoretical and numerical results on light propagation in the presence of fractional diffraction and classical dispersion, highlighting the role mixed functionality has on stability, spatio-temporal localization, and possible collapse events.
{"title":"Spatio-temporal dynamics in the mixed fractional nonlinear Schrödinger equation","authors":"A. Aceves, A. Copeland","doi":"10.3389/fphot.2022.977343","DOIUrl":"https://doi.org/10.3389/fphot.2022.977343","url":null,"abstract":"The effective engineering of linear and nonlinear optical properties in photonic media has led to new advances in the theory and applications of spatio-temporal light–matter interactions. In some instances, research has been motivated by phenomena in a quantum mechanical framework; two notable examples being Anderson localization and parity–time symmetry. Herein, we present theoretical and numerical results on light propagation in the presence of fractional diffraction and classical dispersion, highlighting the role mixed functionality has on stability, spatio-temporal localization, and possible collapse events.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49121252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-29DOI: 10.3389/fphot.2022.1010958
S. Zanella, E. Trave, E. Moretti, A. Talon, M. Back, L. Carlos, R. Ferreira, C. Brites
The design of molecular materials suitable for disparate fields could lead to new advances in engineering applications. In this work, a series of Ln3+-doped BiF3 sub-microparticles were synthesized through microwave-assisted synthesis. The effects of doping are evaluated from the structural and morphological viewpoint. In general, increasing the Ln3+ concentration the octahedral habitus is distorted to a spheric one, and some aggregates are visible without any differences in the crystalline phase. The optical response of the samples confirms that the BiF3 materials are suitable hosts for the luminescence of the tested trivalent lanthanide (Ln3+) ions (Ln = Eu, Tb, Tm, Ho, Er, Yb). A Yb3+/Er3+ co-doped sample is presented as an illustrative example of all-photonic molecular logic operations and primary luminescent thermometry.
{"title":"Designing Ln3+-doped BiF3 particles for luminescent primary thermometry and molecular logic","authors":"S. Zanella, E. Trave, E. Moretti, A. Talon, M. Back, L. Carlos, R. Ferreira, C. Brites","doi":"10.3389/fphot.2022.1010958","DOIUrl":"https://doi.org/10.3389/fphot.2022.1010958","url":null,"abstract":"The design of molecular materials suitable for disparate fields could lead to new advances in engineering applications. In this work, a series of Ln3+-doped BiF3 sub-microparticles were synthesized through microwave-assisted synthesis. The effects of doping are evaluated from the structural and morphological viewpoint. In general, increasing the Ln3+ concentration the octahedral habitus is distorted to a spheric one, and some aggregates are visible without any differences in the crystalline phase. The optical response of the samples confirms that the BiF3 materials are suitable hosts for the luminescence of the tested trivalent lanthanide (Ln3+) ions (Ln = Eu, Tb, Tm, Ho, Er, Yb). A Yb3+/Er3+ co-doped sample is presented as an illustrative example of all-photonic molecular logic operations and primary luminescent thermometry.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46158897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-26DOI: 10.3389/fphot.2022.964719
M. Witteveen, D. Faber, H. Sterenborg, T. Ruers, T. V. van Leeuwen, Anouk L. Post
For a long time, steady-state reflectance spectroscopy measurements have been performed so that diffusion theory could be used to extract tissue optical properties from the reflectance. The development of subdiffuse techniques, such as Single Fiber Reflectance Spectroscopy and subdiffuse SFDI, provides new opportunities for clinical applications since they have the key advantage that they are much more sensitive to the details of the tissue scattering phase function in comparison to diffuse techniques. Since the scattering phase function is related to the subcellular structure of tissue, subdiffuse measurements have the potential to provide a powerful contrast between healthy and diseased tissue. In the subdiffuse regime, the interrogated tissue volumes are much smaller than in the diffuse regime. Whether a measurement falls within the diffuse or subdiffuse regime depends on tissue optical properties and the distance between the source and detector fiber for fiber-optic techniques or the projected spatial frequency for hyperspectral imaging and SFDI. Thus, the distance between source and detector fibers or the projected spatial frequency has important implications for clinical applications of reflectance spectroscopy and should be carefully selected, since it influences which tissue optical properties the technique is sensitive to and the size of the tissue volume that is interrogated. In this paper, we will review the opportunities and pitfalls in steady-state reflectance spectroscopy in the subdiffuse and the diffuse regime. The discussed opportunities can guide the choice of either the diffuse or subdiffuse regime for a clinical application, and the discussed pitfalls can ensure these are avoided to enable the development of robust diagnostic algorithms. We will first discuss the relevant basics of light-tissue interaction. Next, we will review all the tissue scattering phase functions that have been measured and investigate which scattering phase function models are representative of tissue. Subsequently, we will discuss the sensitivity of diffuse and subdiffuse techniques to tissue optical properties and we will explore the difference in the interrogation depth probed by diffuse and subdiffuse techniques.
{"title":"Opportunities and pitfalls in (sub)diffuse reflectance spectroscopy","authors":"M. Witteveen, D. Faber, H. Sterenborg, T. Ruers, T. V. van Leeuwen, Anouk L. Post","doi":"10.3389/fphot.2022.964719","DOIUrl":"https://doi.org/10.3389/fphot.2022.964719","url":null,"abstract":"For a long time, steady-state reflectance spectroscopy measurements have been performed so that diffusion theory could be used to extract tissue optical properties from the reflectance. The development of subdiffuse techniques, such as Single Fiber Reflectance Spectroscopy and subdiffuse SFDI, provides new opportunities for clinical applications since they have the key advantage that they are much more sensitive to the details of the tissue scattering phase function in comparison to diffuse techniques. Since the scattering phase function is related to the subcellular structure of tissue, subdiffuse measurements have the potential to provide a powerful contrast between healthy and diseased tissue. In the subdiffuse regime, the interrogated tissue volumes are much smaller than in the diffuse regime. Whether a measurement falls within the diffuse or subdiffuse regime depends on tissue optical properties and the distance between the source and detector fiber for fiber-optic techniques or the projected spatial frequency for hyperspectral imaging and SFDI. Thus, the distance between source and detector fibers or the projected spatial frequency has important implications for clinical applications of reflectance spectroscopy and should be carefully selected, since it influences which tissue optical properties the technique is sensitive to and the size of the tissue volume that is interrogated. In this paper, we will review the opportunities and pitfalls in steady-state reflectance spectroscopy in the subdiffuse and the diffuse regime. The discussed opportunities can guide the choice of either the diffuse or subdiffuse regime for a clinical application, and the discussed pitfalls can ensure these are avoided to enable the development of robust diagnostic algorithms. We will first discuss the relevant basics of light-tissue interaction. Next, we will review all the tissue scattering phase functions that have been measured and investigate which scattering phase function models are representative of tissue. Subsequently, we will discuss the sensitivity of diffuse and subdiffuse techniques to tissue optical properties and we will explore the difference in the interrogation depth probed by diffuse and subdiffuse techniques.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49086955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-09DOI: 10.3389/fphot.2022.960142
Ting-Hang Pei, Kei-Hsiung Yang
The analytical distribution of the electric field in a micro-lens made of polymer-stabilized blue phase liquid crystals (PS-BPLCs) between two electrodes has been derived, and ray bending and focusing for the o (ordinary) and e (extraordinary) rays caused by the field-induced extended Kerr effect on the PS-BPLC have also been calculated. Those calculations show that the focal lengths of most o rays are longer than those of e rays. The o and e rays result in a focal length of 11.6 cm at a Kerr constant of 2.3768 nm/V2 close to the experimental data, and the calculated focal spot diameter is about 80.0 μm. If the Kerr constant is decreased to 2.14 nm/V2, we can obtain a focal length of 13.1 cm, the same as the experimental data. This reduction in the Kerr constant is reasonable because it is still within the experimental error. In summary, our calculations reveal an efficient and accurate way to discuss the focusing phenomena in the PS-BPLC micro-lens.
{"title":"Light-focusing phenomena of field-tuned micro-lens made of polymer-stabilized blue phase liquid crystals","authors":"Ting-Hang Pei, Kei-Hsiung Yang","doi":"10.3389/fphot.2022.960142","DOIUrl":"https://doi.org/10.3389/fphot.2022.960142","url":null,"abstract":"The analytical distribution of the electric field in a micro-lens made of polymer-stabilized blue phase liquid crystals (PS-BPLCs) between two electrodes has been derived, and ray bending and focusing for the o (ordinary) and e (extraordinary) rays caused by the field-induced extended Kerr effect on the PS-BPLC have also been calculated. Those calculations show that the focal lengths of most o rays are longer than those of e rays. The o and e rays result in a focal length of 11.6 cm at a Kerr constant of 2.3768 nm/V2 close to the experimental data, and the calculated focal spot diameter is about 80.0 μm. If the Kerr constant is decreased to 2.14 nm/V2, we can obtain a focal length of 13.1 cm, the same as the experimental data. This reduction in the Kerr constant is reasonable because it is still within the experimental error. In summary, our calculations reveal an efficient and accurate way to discuss the focusing phenomena in the PS-BPLC micro-lens.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45777855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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