An enhanced laser beam deflection measurement system for refractive index gradient and diffusivity

Abstract To measure refractive index at a particular altitude in a solution with vertical refractive index gradient, a transparent wedge-shaped container was constructed altogether with the development of mathematical formula derived from the Snell’s law. The refractive index of the solution can be calculated by measuring the angles of incoming and outgoing laser beams relative to respective normal line. By varying height of the laser beam, the refractive index as a function of height of a sugar solution was obtained. This technique is applied to investigate Fata Morgana which is a kind of superior mirage resulting from bending of light in a medium with density gradient.

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Tomographic reconstruction of refractive index fields based on laser beam deflection measurement

Optics Communications ◽

10.1016/j.optcom.2021.126951 ◽

2021 ◽

Vol 492 ◽

pp. 126951

Author(s):

Linyang Wei ◽

Hong Qi ◽

Guojun Li ◽

Shi-Ting Ruan ◽

Hongru Li

Keyword(s):

Refractive Index ◽

Laser Beam ◽

Tomographic Reconstruction ◽

Beam Deflection ◽

Deflection Measurement

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A Refractive INdex Gradient (RING) diagnostic for transient discharges or expansions of vapor or plasmas

IEEE Transactions on Plasma Science ◽

10.1109/27.108417 ◽

1991 ◽

Vol 19 (5) ◽

pp. 800-813 ◽

Cited By ~ 19

Author(s):

M.E. Cuneo ◽

T.R. Lockner ◽

G.C. Tisone

Keyword(s):

Refractive Index ◽

Refractive Index Gradient ◽

Index Gradient

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The Reflection of Waves at a Discontinuity in Refractive Index Gradient

Journal of Mathematics and Physics ◽

10.1002/sapm1966451162 ◽

1966 ◽

Vol 45 (1-4) ◽

pp. 162-168 ◽

Cited By ~ 2

Author(s):

R. Burman

Keyword(s):

Refractive Index ◽

Refractive Index Gradient ◽

Index Gradient ◽

Reflection Of Waves

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Comparisons between high-resolution profiles of squared refractive index gradient <i>M</i><sup>2</sup> measured by the Middle and Upper Atmosphere Radar and unmanned aerial vehicles (UAVs) during the Shigaraki UAV-Radar Experiment 2015 campaign

Annales Geophysicae ◽

10.5194/angeo-35-423-2017 ◽

2017 ◽

Vol 35 (3) ◽

pp. 423-441 ◽

Cited By ~ 5

Author(s):

Hubert Luce ◽

Lakshmi Kantha ◽

Hiroyuki Hashiguchi ◽

Dale Lawrence ◽

Masanori Yabuki ◽

...

Keyword(s):

Refractive Index ◽

Convective Cloud ◽

Upper Atmosphere ◽

Refractive Index Gradient ◽

Very High Frequency ◽

Range Resolution ◽

Mu Radar ◽

Radar Echo ◽

Index Gradient ◽

Complex Features

Abstract. New comparisons between the square of the generalized potential refractive index gradient M2, estimated from the very high-frequency (VHF) Middle and Upper Atmosphere (MU) Radar, located at Shigaraki, Japan, and unmanned aerial vehicle (UAV) measurements are presented. These comparisons were performed at unprecedented temporal and range resolutions (1–4 min and ∼  20 m, respectively) in the altitude range ∼  1.27–4.5 km from simultaneous and nearly collocated measurements made during the ShUREX (Shigaraki UAV-Radar Experiment) 2015 campaign. Seven consecutive UAV flights made during daytime on 7 June 2015 were used for this purpose. The MU Radar was operated in range imaging mode for improving the range resolution at vertical incidence (typically a few tens of meters). The proportionality of the radar echo power to M2 is reported for the first time at such high time and range resolutions for stratified conditions for which Fresnel scatter or a reflection mechanism is expected. In more complex features obtained for a range of turbulent layers generated by shear instabilities or associated with convective cloud cells, M2 estimated from UAV data does not reproduce observed radar echo power profiles. Proposed interpretations of this discrepancy are presented.

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Label-Free Digital Holo-tomographic Microscopy Reveals Virus-Induced Cytopathic Effects in Live Cells

mSphere ◽

10.1128/mspheredirect.00599-18 ◽

2018 ◽

Vol 3 (6) ◽

Cited By ~ 5

Author(s):

Artur Yakimovich ◽

Robert Witte ◽

Vardan Andriasyan ◽

Fanny Georgi ◽

Urs F. Greber

Keyword(s):

Refractive Index ◽

Vaccinia Virus ◽

Virus Type ◽

Live Cells ◽

Refractive Index Gradient ◽

Label Free ◽

Virus Infections ◽

Cytopathic Effects ◽

Infected Cells ◽

Index Gradient

ABSTRACTCytopathic effects (CPEs) are a hallmark of infections. CPEs are difficult to observe due to phototoxicity from classical light microscopy. We report distinct patterns of virus infections in live cells using digital holo-tomographic microscopy (DHTM). DHTM is label-free and records the phase shift of low-energy light passing through the specimen on a transparent surface with minimal perturbation. DHTM measures the refractive index (RI) and computes the refractive index gradient (RIG), unveiling optical heterogeneity in cells. We find that vaccinia virus (VACV), herpes simplex virus (HSV), and rhinovirus (RV) infections progressively and distinctly increased RIG. VACV infection, but not HSV and RV infections, induced oscillations of cell volume, while all three viruses altered cytoplasmic membrane dynamics and induced apoptotic features akin to those caused by the chemical compound staurosporine. In sum, we introduce DHTM for quantitative label-free microscopy in infection research and uncover virus type-specific changes and CPE in living cells with minimal interference.IMPORTANCEThis study introduces label-free digital holo-tomographic microscopy (DHTM) and refractive index gradient (RIG) measurements of live, virus-infected cells. We use DHTM to describe virus type-specific cytopathic effects, including cyclic volume changes of vaccinia virus infections, and cytoplasmic condensations in herpesvirus and rhinovirus infections, distinct from apoptotic cells. This work shows for the first time that DHTM is suitable to observe virus-infected cells and distinguishes virus type-specific signatures under noninvasive conditions. It provides a basis for future studies, where correlative fluorescence microscopy of cell and virus structures annotate distinct RIG values derived from DHTM.

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