Refractive index is an important optical constant that characterizes the interaction between light and specimen. A difference in refractive index between specimen and immersion medium introduces the imaging aberration and leads to a problem that the direct thickness measurement of a specimen by optical microscopy is not accurate. However, this aberration correction still requires the exact information of the refractive index of specimen and immersion medium. Herein, we propose an imaging strategy to estimate the refractive index for an unknown specimen. A simplified diffraction model is generated to obtain the relationship between axial scaling factor and refractive index. Then regular fluorescence microscopy is performed to measure the actual axial scaling factors of specimens from mouse muscle and tumor xenograft. Referring to our theoretical plot of axial scaling factor versus refractive index, the refractive index of tissue specimen is determined. For example, we obtain a mean refractive index (n) value of 1.36 for normal muscle tissues, and 1.41 for tumor xenografts. We demonstrate that this diffraction model-based estimation method is an alternative to the current techniques, improving the accurate measurement for refractive index of tissue specimen. The simple instrument requirement with an easy specimen preparation for this estimation method of refractive index may increase the image quality on tissue specimens with less aberration.
{"title":"Method for the refractive index of various tissues based on fluorescence microscopy","authors":"Xiaoming Fan, Lele Tao, Xiaoyu Zhou, Xiao He, Yu Zhang, Haixin Huang, Jiale Yang, Simei Wang, Zhihui Ma, Thomas Gensch, Ruimin Huang","doi":"10.1364/optcon.492897","DOIUrl":"https://doi.org/10.1364/optcon.492897","url":null,"abstract":"Refractive index is an important optical constant that characterizes the interaction between light and specimen. A difference in refractive index between specimen and immersion medium introduces the imaging aberration and leads to a problem that the direct thickness measurement of a specimen by optical microscopy is not accurate. However, this aberration correction still requires the exact information of the refractive index of specimen and immersion medium. Herein, we propose an imaging strategy to estimate the refractive index for an unknown specimen. A simplified diffraction model is generated to obtain the relationship between axial scaling factor and refractive index. Then regular fluorescence microscopy is performed to measure the actual axial scaling factors of specimens from mouse muscle and tumor xenograft. Referring to our theoretical plot of axial scaling factor versus refractive index, the refractive index of tissue specimen is determined. For example, we obtain a mean refractive index (n) value of 1.36 for normal muscle tissues, and 1.41 for tumor xenografts. We demonstrate that this diffraction model-based estimation method is an alternative to the current techniques, improving the accurate measurement for refractive index of tissue specimen. The simple instrument requirement with an easy specimen preparation for this estimation method of refractive index may increase the image quality on tissue specimens with less aberration.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135922451","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}
In a total internal reflection fluorescence microscope, there is a 3D anisotropy in intensity of the excitation light. Using a mirror in a prism-based total internal reflection fluorescence microscope, we propose a very low-cost method to decrease the anisotropic property of the excitation light. Theoretically, we obtained the electric field of the transmitted light inside the sample as a function of the rotational angle of the mirror, polarization degree of the incident beam, and the refractive indices of the prism, immersion oil, cover glass, and sample. By using the refractive indices that are commercially available, proper practical combinations of the angle of mirror and polarization degree of the incident light are suggested to provide a merely 2D isotropic excitation light at the sample plane of a total internal reflection fluorescence microscope.
{"title":"A mirror-based 2D isotropic illumination in total internal reflection fluorescence microscopy","authors":"Sarina Yaghoubi, B. Sajad, S. Tavaddod","doi":"10.1364/optcon.491682","DOIUrl":"https://doi.org/10.1364/optcon.491682","url":null,"abstract":"In a total internal reflection fluorescence microscope, there is a 3D anisotropy in intensity of the excitation light. Using a mirror in a prism-based total internal reflection fluorescence microscope, we propose a very low-cost method to decrease the anisotropic property of the excitation light. Theoretically, we obtained the electric field of the transmitted light inside the sample as a function of the rotational angle of the mirror, polarization degree of the incident beam, and the refractive indices of the prism, immersion oil, cover glass, and sample. By using the refractive indices that are commercially available, proper practical combinations of the angle of mirror and polarization degree of the incident light are suggested to provide a merely 2D isotropic excitation light at the sample plane of a total internal reflection fluorescence microscope.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48215470","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}
Optical detectors are essential for gas detection using optical technology. This study introduces an armchair graphene nanoribbon (AGNR) molecular optical gas detector with two conjugated molecular elements and a non-conjugated interface for gas detection using optical technology. The detector absorbs light and generates peaks in the current-voltage curve that correspond to gas concentration and the Raman frequency spectrum. The detector exhibits negative resistances controlled by input light frequency, suitable for high-frequency oscillators. Multiple gases can be simultaneously identified and monitored using the detector. The detector was analyzed using the non-equilibrium Green function method and offers high-speed, accurate selectivity, precise gas detection, and reproducibility with multiple electrical outputs.
{"title":"Modeling and simulation of molecular armchair graphene nanoribbons as a gas detector","authors":"Alireza Tashakori, A. Rostami, M. M. Karkhanehchi","doi":"10.1364/optcon.486370","DOIUrl":"https://doi.org/10.1364/optcon.486370","url":null,"abstract":"Optical detectors are essential for gas detection using optical technology. This study introduces an armchair graphene nanoribbon (AGNR) molecular optical gas detector with two conjugated molecular elements and a non-conjugated interface for gas detection using optical technology. The detector absorbs light and generates peaks in the current-voltage curve that correspond to gas concentration and the Raman frequency spectrum. The detector exhibits negative resistances controlled by input light frequency, suitable for high-frequency oscillators. Multiple gases can be simultaneously identified and monitored using the detector. The detector was analyzed using the non-equilibrium Green function method and offers high-speed, accurate selectivity, precise gas detection, and reproducibility with multiple electrical outputs.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47266378","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}
We investigated the stability and mutual coherence of a Raman microcomb in a silica microrod resonator by monitoring the output power and longitudinal mode spacings. The results indicate that we can obtain a stable Raman comb formation without the need for four-wave mixing processes. The use of a Raman comb will open the possibility of simplifying the setup because it will relax the phase matching condition usually required for microresonator frequency comb generation. Although there are some restrictions in regard to using a Raman comb for applications due to the coexistence of the comb components in different mode families, a proof-of-concept demonstration shows that it is sufficiently stable and robust for applications such as optical communications.
{"title":"Stability and mutual coherence of Raman combs in high-Q silica microresonators","authors":"Shuto Sugawara, S. Fujii, S. Kawanishi, T. Tanabe","doi":"10.1364/optcon.493749","DOIUrl":"https://doi.org/10.1364/optcon.493749","url":null,"abstract":"We investigated the stability and mutual coherence of a Raman microcomb in a silica microrod resonator by monitoring the output power and longitudinal mode spacings. The results indicate that we can obtain a stable Raman comb formation without the need for four-wave mixing processes. The use of a Raman comb will open the possibility of simplifying the setup because it will relax the phase matching condition usually required for microresonator frequency comb generation. Although there are some restrictions in regard to using a Raman comb for applications due to the coexistence of the comb components in different mode families, a proof-of-concept demonstration shows that it is sufficiently stable and robust for applications such as optical communications.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49367726","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}
The spin and orbital angular momentum of photons can perturb during propagation in few mode optical fiber, and hence, in the receiver, perturbations must be adjusted. For polarization adjustment, polarization controllers have been developed previously. In this paper, we show that in the presence of external effects such as tension and tortion, the entanglement between the different degrees of freedom of a photon does not change. A device for simultaneous adjustment of polarization and spatial distribution in few mode fiber is proposed. In addition to modification, this device can also be used to produce different modes in fiber.
{"title":"All-fiber spatial profile and polarization controller","authors":"F. Ghorbani, F. Farman, A. Bahrampour","doi":"10.1364/optcon.476392","DOIUrl":"https://doi.org/10.1364/optcon.476392","url":null,"abstract":"The spin and orbital angular momentum of photons can perturb during propagation in few mode optical fiber, and hence, in the receiver, perturbations must be adjusted. For polarization adjustment, polarization controllers have been developed previously. In this paper, we show that in the presence of external effects such as tension and tortion, the entanglement between the different degrees of freedom of a photon does not change. A device for simultaneous adjustment of polarization and spatial distribution in few mode fiber is proposed. In addition to modification, this device can also be used to produce different modes in fiber.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41622534","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}
Typical waveplates are limited to specific frequencies. We propose a general design of a series of THz achromatic quarter-wave plates that work for different frequency range. The simplified formulas and the basic parameters that are used to calculate the thicknesses and rotating angles with the possibility of choosing the frequency range are provided. The main feature of the design is that the number of the x-cut quartz plates is equal to the frequency expansion factor (f max /f min ) of the resulting waveplate, and by altering the thicknesses of quartz plates following a specific pattern only, the frequency range of the waveplate can be shifted. Two achromatic waveplates working in the frequency range of 0.2-0.6 THz and 0.2-1.2 THz were manufactured for testing. The measurement result demonstrates the reliability of the proposed design.
{"title":"General approach of terahertz achromatic quarter-wave plate composed of stacked quartz plates","authors":"Tianmiao Zhang, G. Kropotov, M. Khodzitsky","doi":"10.1364/optcon.494818","DOIUrl":"https://doi.org/10.1364/optcon.494818","url":null,"abstract":"Typical waveplates are limited to specific frequencies. We propose a general design of a series of THz achromatic quarter-wave plates that work for different frequency range. The simplified formulas and the basic parameters that are used to calculate the thicknesses and rotating angles with the possibility of choosing the frequency range are provided. The main feature of the design is that the number of the x-cut quartz plates is equal to the frequency expansion factor (f\u0000 max\u0000 /f\u0000 min\u0000 ) of the resulting waveplate, and by altering the thicknesses of quartz plates following a specific pattern only, the frequency range of the waveplate can be shifted. Two achromatic waveplates working in the frequency range of 0.2-0.6 THz and 0.2-1.2 THz were manufactured for testing. The measurement result demonstrates the reliability of the proposed design.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43461228","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}
A method to treat the internal boundary condition in an optical diffusion calculation is proposed and is compared with the conventional methods. One of the existing internal boundary conditions is Haskel's method, which uses the effective reflection coefficient for partial currents. However, Haskel's method ignores incoming partial currents from the adjacent mesh in its derivation. As a result, the accuracy at the internal boundary is lower. This paper proposes a method to improve the accuracy by iteratively updating the effective reflection coefficient for partial current. The proposed method was applied to the benchmark calculations on a one-dimensional slab geometry and its accuracy was confirmed by comparing it with the reference solution obtained by the Monte Carlo code MCML, along with the previously proposed Haskel's method and Aronson's method. As a result, it was confirmed that the proposed method is more accurate than Haskel's method at the internal boundary and gives the same result as Aronson's method. The convergence of the effective reflection coefficient using iterative calculations in the proposed method was good.
{"title":"Comparison of internal boundary conditions for optical diffusion calculations considering reflection and refraction","authors":"Toranosuke Amano, Tomohiro Endo, Akio Yamamoto","doi":"10.1364/optcon.492445","DOIUrl":"https://doi.org/10.1364/optcon.492445","url":null,"abstract":"A method to treat the internal boundary condition in an optical diffusion calculation is proposed and is compared with the conventional methods. One of the existing internal boundary conditions is Haskel's method, which uses the effective reflection coefficient for partial currents. However, Haskel's method ignores incoming partial currents from the adjacent mesh in its derivation. As a result, the accuracy at the internal boundary is lower. This paper proposes a method to improve the accuracy by iteratively updating the effective reflection coefficient for partial current. The proposed method was applied to the benchmark calculations on a one-dimensional slab geometry and its accuracy was confirmed by comparing it with the reference solution obtained by the Monte Carlo code MCML, along with the previously proposed Haskel's method and Aronson's method. As a result, it was confirmed that the proposed method is more accurate than Haskel's method at the internal boundary and gives the same result as Aronson's method. The convergence of the effective reflection coefficient using iterative calculations in the proposed method was good.","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47975389","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}
D. Tafone, Luke McEvoy, Y. Sua, Patrick Rehain, Yuping Huang
{"title":"Surface Material Recognition through MachineLearning using Time of Flight Lidar","authors":"D. Tafone, Luke McEvoy, Y. Sua, Patrick Rehain, Yuping Huang","doi":"10.1364/optcon.492258","DOIUrl":"https://doi.org/10.1364/optcon.492258","url":null,"abstract":"","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42138774","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}
John Munga, Chi-Shin Yang, M. Rab, T. Shahbazyan, M. Durach, M. Noginov, N. Noginova
{"title":"Highly luminescent ultra-thin films with rare earth for plasmonic applications","authors":"John Munga, Chi-Shin Yang, M. Rab, T. Shahbazyan, M. Durach, M. Noginov, N. Noginova","doi":"10.1364/optcon.489698","DOIUrl":"https://doi.org/10.1364/optcon.489698","url":null,"abstract":"","PeriodicalId":74366,"journal":{"name":"Optics continuum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46006999","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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