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| Author | Neroev, V. V.; Iomdina, E. N.; Khandzhyan, A. T.; Khodzhabekyan, N. V.; Sengaeva, M. D.; Ivanova, A. V.; Seliverstov, S. V.; Teplyakova, K. O.; Goltsman, G. N. | ||||
| Title | Experimental study of the effect of corneal hydration and its biomechanical properties on the results of photorefractive keratectomy | Type | Journal Article | ||
| Year | 2021 | Publication | Vestn. Oftalmol. | Abbreviated Journal | Vestn. Oftalmol. |
| Volume | 137 | Issue | 3 | Pages | 68-75 |
| Keywords | THz scanning, cornea, photorefractive keratectomy, medicine | ||||
| Abstract | Water content in the cornea may affect the outcome of its excimer laser ablation, especially in presbyopic patients with myopic refraction. This hypothesis can be tested by scanning the cornea in the terahertz (THz) range to determine its hydration level. Purpose: To study the effect of hydration of the cornea determined by non-contact THz scanning and its biomechanical parameters on the results of photorefractive keratectomy (PRK) in an experiment. Material and methods: PRK was performed using the Nidek EC-5000 QUEST excimer laser on 8 rabbit eyes. Corneal hydration was evaluated by determining the reflection coefficient (RC) in the THz electromagnetic radiation range before PRK, after 3-5 days, and after 1, 2, 3, and 4 months. Clinical examination included autorefractometry, assessment of corneal thickness and other anatomical and optical parameters of the anterior eye segment (Galilei G6, Ziemer Ophthalmic Systems AG 6.0.2, Switzerland), measurement of corneal hysteresis (CH) and corneal resistance factor (CRF) using the Ocular Response Analyzer (ORA; Reichert, USA), as well as tear production (Schirmer test). Results: The initial water content in the cornea has a significant effect on the thickness of the removed layer, i.e. on the PRK effect, with correlation coefficient of Rs= -0.976 (p<0.01). The correlation between CH and the ablation depth is less pronounced (Rs=0.643), and CRF had no correlation with it (Rs= -0.089). Biomechanical indicators of the cornea depend on its hydration: changes in CH and CRF after excimer laser ablation qualitatively coincide with changes in RC, the correlation coefficient between RC and the initial value of CH is R= -0.619 (moderate negative correlation). Conclusion: THz scanning is an effective non-contact technology for monitoring corneal hydration level. The mismatch of the hypoeffect of keratorefractive excimer laser intervention planned for patients with presbyopia with the actual outcome can be caused by individual decrease in the initial water content in the cornea. |
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| Language | Russian | Summary Language | Original Title | ||
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ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1794 | |||
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| Author | Moshkova, M. A.; Morozov, P. V.; Antipov, A. V.; Vakhtomin, Y. B.; Smirnov, K. V. | ||||
| Title | High-efficiency multi-element superconducting single-photon detector | Type | Conference Article | ||
| Year | 2021 | Publication | Proc. SPIE | Abbreviated Journal | Proc. SPIE |
| Volume | 11771 | Issue | Pages | 2-8 | |
| Keywords | PNR SSPD, large active area, detection efficiency | ||||
| Abstract | We present the result of the creation and investigation of the multi-element superconducting single photon detectors, which can recognize the number of photons (up to six) in a short pulse of the radiation at telecommunication wavelengths range. The best receivers coupled with single-mode fiber have the system quantum efficiency of ⁓85%. The receivers have a 100 ps time resolution and a few nanoseconds dead time that allows them to operate at megahertz counting rate. Implementation of the multi-element architecture for creation of the superconducting single photon detectors with increased sensitive area allows to create the high efficiency receivers coupled with multi-mode fibers and with preserving of the all advantages of superconducting photon counters. | ||||
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| Publisher | SPIE | Place of Publication | Editor | Prochazka, I.; Štefaňák, M.; Sobolewski, R.; Gábris, A. | |
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| Area | Expedition | Conference | Quantum Optics and Photon Counting | ||
| Notes | Approved | no | |||
| Call Number | Serial | 1795 | |||
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| Author | Shcherbatenko, M.; Elezov, M.; Manova, N.; Sedykh, K.; Korneev, A.; Korneeva, Y.; Dryazgov, M.; Simonov, N.; Feimov, A.; Goltsman, G.; Sych, D. | ||||
| Title | Single-pixel camera with a large-area microstrip superconducting single photon detector on a multimode fiber | Type | Journal Article | ||
| Year | 2021 | Publication | Appl. Phys. Lett. | Abbreviated Journal | Appl. Phys. Lett. |
| Volume | 118 | Issue | 18 | Pages | 181103 |
| Keywords | NbN SSPD, SNSPD | ||||
| Abstract | High sensitivity imaging at the level of single photons is an invaluable tool in many areas, ranging from microscopy to astronomy. However, development of single-photon sensitive detectors with high spatial resolution is very non-trivial. Here we employ the single-pixel imaging approach and demonstrate a proof-of-principle single-pixel single-photon imaging setup. We overcome the problem of low light gathering efficiency by developing a large-area microstrip superconducting single photon detector coupled to a multi-mode optical fiber interface. We show that the setup operates well in the visible and near infrared spectrum, and is able to capture images at the single-photon level. We thank Philipp Zolotov and Pavel Morozov for NbN film fabrication, ARC coating, and fiber coupling of the detector. We also thank Swabian Instruments GmbH and Dr. Helmut Fedder personally for the kindly provided experimental equipment (Time Tagger Ultra 8). The work in the part of SNSPD research and development was supported by the Russian Foundation for Basic Research Project No. 18-29-20100. The work in the part of the optical setup and imaging was supported by Russian Foundation for Basic Research Project No. 20-32-51004. |
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| ISSN |
0003-6951 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1770 | |||
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| Author | Morozov, P.; Lukina, M.; Shirmanova, M.; Divochiy, A.; Dudenkova, V.; Gol'tsman, G. N.; Becker, W.; Shcheslavskiy, V. I. | ||||
| Title | Singlet oxygen phosphorescence imaging by superconducting single-photon detector and time-correlated single-photon counting | Type | Journal Article | ||
| Year | 2021 | Publication | Opt. Lett. | Abbreviated Journal | Opt. Lett. |
| Volume | 46 | Issue | 6 | Pages | 1217-1220 |
| Keywords | SSPD, SNSPD, applications | ||||
| Abstract | This Letter presents, to the best of our knowledge, a novel optical configuration for direct time-resolved measurements of luminescence from singlet oxygen, both in solutions and from cultured cells on photodynamic therapy. The system is based on the superconducting single-photon detector, coupled to the confocal scanner that is modified for the near-infrared measurements. The recording of a phosphorescence signal from singlet oxygen at 1270 nm has been done using time-correlated single-photon counting. The performance of the system is verified by measuring phosphorescence from singlet oxygen generated by the photosensitizers commonly used in photodynamic therapy: methylene blue and chlorin e6. The described system can be easily upgraded to the configuration when both phosphorescence from singlet oxygen and fluorescence from the cells can be detected in the imaging mode. Thus, co-localization of the signal from singlet oxygen with the areas inside the cells can be done. | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN |
0146-9592 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:33720151 | Approved | no | ||
| Call Number | Serial | 1221 | |||
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| Author | Korneeva, Y. P.; Manova, N. N.; Dryazgov, M. A.; Simonov, N. O.; Zolotov, P. I.; Korneev, A. A. | ||||
| Title | Influence of sheet resistance and strip width on the detection efficiency saturation in micron-wide superconducting strips and large-area meanders | Type | Journal Article | ||
| Year | 2021 | Publication | Supercond. Sci. Technol. | Abbreviated Journal | Supercond. Sci. Technol. |
| Volume | 34 | Issue | 8 | Pages | 084001 |
| Keywords | NbN SSPD, SMSPD | ||||
| Abstract | We report our study of detection efficiency (DE) saturation in wavelength range 400 – 1550 nm for the NbN Superconducting Microstrip Single-Photon Detectors (SMSPD) featuring the strip width up to 3 μm. We observe an expected decrease of the $DE$ saturation plateau with the increase of photon wavelength and decrease of film sheet resistance. At 1.7 K temperature DE saturation can be clearly observed at 1550 nm wavelength in strip with the width up to 2 μm when sheet resistance of the film is above 630Ω/sq. In such strips the length of the saturation plateau almost does not depend on the strip width. We used these films to make meander-shaped detectors with the light sensitive area from 20×20μm2 to a circle 50 μm in diameter. In the latter case, the detector with the strip width of 0.49 μm demonstrates saturation of DE up to 1064 nm wavelength. Although DE at 1310 and 1550 nm is not saturated, it is as high as 60%. The response time is limited by the kinetic inductance and equals to 20 ns(by 1/e decay), timing jitter is 44 ps. When coupled to multi-mode fibre large-area meanders demonstrate significantly higher dark count rate which we attribute to thermal background photons, thus advanced filtering technique would be required for practical applications. | ||||
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| ISSN |
0953-2048 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1793 | |||
| Permanent link to this record | |||||