scholarly journals Quantitative interferometric measurements of the refractive index and its applications

2021 ◽  
Author(s):  
Mohammed Yahya
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Human Blood ◽  
Medical Science ◽  
Medical Diagnostics ◽  
Blood Analysis ◽  
Optical Systems ◽  
Refractive Indices ◽  
Contact Method

Optical interferometry is a non-contact method used for the imaging and measurement of the optical properties of small or large objects with nanoscale accuracy. Interferometers are essential optical systems in engineering and medical science and are generally used to measure refractive index changes, cell pathology and shape irregularities. The ability to provide quantitative, non-invasive measurements makes interferometers suitable candidates for the study of living cells in vivo and in vitro applications. In this study, a simple interferometric system capable of providing precise measurements of the refractive indices of transparent and semi-transparent mediums was designed and developed based on the Mach-Zehnder arrangement. During the development phase, the system was used to take precise measurements of the contrast factors of the three hydrocarbon components 1,2,3,4-Tetrtahydronaphtalenene (THN), Isobutylbenzen (IBB), and Dodecane (nC12), prepared in the laboratory. The results were also compared with the corresponding results obtained using the Abbemat refractometer. The results were in agreement with those obtained from both techniques as well as the results obtained from the literature, confirming the accuracy of the measurements obtained with the new system with deviations of ± 2.50×10-3. Blood analysis is a routine procedure used in medical diagnostics to confirm a patient’s condition. Measuring the optical properties of blood is difficult due to the non-homogenous nature of the blood itself. In addition, there is a lot of variation in the refractive indices reported in the literature. These are the reasons that motivated this research to develop an empirical model that can be used to predict the refractive index of human blood as a function of concentration, temperature and wavelength. The experimental measurements were conducted on mimicking phantom, that shows better stability compared to human blood, using the Abbemat Refractometer. The values obtained using the model was in substantial agreement with those obtained experimentally with standard deviations of ± 2.33×10-3. Once the accuracy of the interferometric system was confirmed, the system was used to study the refractive index and morphology of human red blood cells. The results of the analysis confirmed the system’s ability to determine refractive index and/or blood hematocrit values with appropriate clinical accuracy.

scholarly journals Quantitative interferometric measurements of the refractive index and its applications

2021 ◽  
Author(s):  
Mohammed Yahya
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Human Blood ◽  
Medical Science ◽  
Medical Diagnostics ◽  
Blood Analysis ◽  
Optical Systems ◽  
Refractive Indices ◽  
Contact Method

Optical interferometry is a non-contact method used for the imaging and measurement of the optical properties of small or large objects with nanoscale accuracy. Interferometers are essential optical systems in engineering and medical science and are generally used to measure refractive index changes, cell pathology and shape irregularities. The ability to provide quantitative, non-invasive measurements makes interferometers suitable candidates for the study of living cells in vivo and in vitro applications. In this study, a simple interferometric system capable of providing precise measurements of the refractive indices of transparent and semi-transparent mediums was designed and developed based on the Mach-Zehnder arrangement. During the development phase, the system was used to take precise measurements of the contrast factors of the three hydrocarbon components 1,2,3,4-Tetrtahydronaphtalenene (THN), Isobutylbenzen (IBB), and Dodecane (nC12), prepared in the laboratory. The results were also compared with the corresponding results obtained using the Abbemat refractometer. The results were in agreement with those obtained from both techniques as well as the results obtained from the literature, confirming the accuracy of the measurements obtained with the new system with deviations of ± 2.50×10-3. Blood analysis is a routine procedure used in medical diagnostics to confirm a patient’s condition. Measuring the optical properties of blood is difficult due to the non-homogenous nature of the blood itself. In addition, there is a lot of variation in the refractive indices reported in the literature. These are the reasons that motivated this research to develop an empirical model that can be used to predict the refractive index of human blood as a function of concentration, temperature and wavelength. The experimental measurements were conducted on mimicking phantom, that shows better stability compared to human blood, using the Abbemat Refractometer. The values obtained using the model was in substantial agreement with those obtained experimentally with standard deviations of ± 2.33×10-3. Once the accuracy of the interferometric system was confirmed, the system was used to study the refractive index and morphology of human red blood cells. The results of the analysis confirmed the system’s ability to determine refractive index and/or blood hematocrit values with appropriate clinical accuracy.

Optical properties of a liquid crystal with small ordinary and extraordinary refractive indices and small optical anisotropy

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
J. Kędzierski ◽  
K. Garbat ◽  
Z. Raszewski ◽  
M. Kojdecki ◽  
K. Kowiorski ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Optical Anisotropy ◽  
Order Parameter ◽  
Orientational Order ◽  
Refractive Indices ◽  
Orientational Order Parameter ◽  
Unknown Density ◽  
Abbe Refractometer

AbstractOptical properties of a nematic liquid crystal with small refractive index and small birefringence were studied. The ordinary and extraordinary refractive indices and birefringence were measured as functions of temperature by using an Abbe refractometer and wedge nematic cells. From values of these indices the nematic orientational order parameter was calculated by using several methods and corresponding mathematical models. Kuczyński et al. method was found to be suitable for determining the order parameter also for materials featuring small ordinary refractive index, with unknown density.

The use of a slit in determining refractive indices with the microscope

1917 ◽  
Vol 18 (84) ◽  
pp. 130-132
Author(s):  
John William Evans
Keyword(s):  
Crystal Structure ◽  
Refractive Index ◽  
Optical Properties ◽  
Critical Angle ◽  
Total Reflection ◽  
Index Of Refraction ◽  
Refractive Indices ◽  
Object Image ◽  
Ordinary Object

Certain optical properties of crystals, and more particularly the refractive index, may be determined either in the directions-image, often referred to as the 'image in convergent light', or in the ordinary object-image in which the object itself is seen. In the former case, in which the index of refraction is 'usually determined by means of the critical angle of total-reflection, every point in the image corresponds to a single direction of propagation of the wave-front through the crystal-structure and to the two corresponding directions of vibration. One of these can, however, be eliminated by the insertion of a nicol in an approximate position, and thus all ambiguity in the determination of the refractive index is removed.

Optical Properties of AlGaAsSb, AlGalnP, AlGaInAs, and GaInAsP for Optoelectronic Applications

1999 ◽  
Vol 579 ◽  
Author(s):  
M. Linnik ◽  
A. Christou
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Interband Transition ◽  
Theoretical Data ◽  
Quaternary Alloy ◽  
Refractive Indices ◽  
Incident Wavelength ◽  
Semiconductor Alloy ◽  
Transparent Region ◽  
Semi Empirical

ABSTRACTThe authors present calculations of quaternary III–V semiconductor alloy optical properties and the comparison of the theoretical data with available experimental results for AlGaAsSb, AlGaInP, AlGaInAs, and GaInAsP alloys. The investigation includes material's energy bandgap and refractive index calculations as a function of the incident wavelength in the transparent region, as well as the composition of the alloy. Optimization of the quaternary alloy refractive indices was obtained from a semi-empirical dielectric function calculations based on the interband transition contributions.

Optical Properties of Low Dielectric Constant Polyimides and Effects of Orientation

1993 ◽  
Vol 323 ◽  
Author(s):  
David C. Rich ◽  
Peggy Cebe ◽  
Anne K. St. Clair
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Fluorine Content ◽  
Polymer Chains ◽  
Low Dielectric Constant ◽  
Refractive Indices ◽  
Electronic Polarizability ◽  
Low Dielectric ◽  
Preferential Alignment

AbstractControl of the refractive index in low dielectric constant polyimides through modification of chemistry and structure was investigated. The optical refractive indices of several low dielectric constant polyimides were measured, and the effects of orientation on optical anisotropy were determined. Refractive index in these polyimides was found to decrease with increasing fluorine content due primarily to the low electronic polarizability of the fluorine-carbon bonds. In zone drawn polyimides, refractive index was found to increase substantially in the direction of the draw, but decrease substantially normal to the draw direction. This was explained in terms of the preferential alignment of the polymer chains.

scholarly journals Remote sensing of soot carbon – Part 1: Distinguishing different absorbing aerosol species

2015 ◽  
Vol 15 (9) ◽  
pp. 13607-13656 ◽  
Author(s):  
G. L. Schuster ◽  
O. Dubovik ◽  
A. Arola
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Iron Oxide ◽  
South America ◽  
Biomass Burning ◽  
Southern Africa ◽  
Refractive Indices ◽  
Carbonaceous Aerosols ◽  
Fine Mode ◽  
Soot Carbon

Abstract. We describe a method of using the aerosol robotic network (AERONET) size distributions and complex refractive indices to retrieve the relative proportion of carbonaceous aerosols and iron oxide minerals. We assume that soot carbon has a spectrally flat refractive index, and that enhanced imaginary indices at the 440 nm wavelength are caused by brown carbon or hematite. Carbonaceous aerosols can be separated from dust in imaginary refractive index space because 95% of biomass burning aerosols have imaginary indices greater than 0.0042 at the 675–1020 nm wavelengths, and 95% of dust has imaginary refractive indices of less than 0.0042 at those wavelengths. However, mixtures of these two types of particles can not be unambiguously partitioned on the basis of optical properties alone, so we also separate these particles by size. Regional and seasonal results are consistent with expectations. Monthly climatologies of fine mode soot carbon are less than 1.0% by volume for West Africa and the Middle East, but the southern Africa and South America biomass burning sites have peak values of 3.0 and 1.7%. Monthly-averaged fine mode brown carbon volume fractions have a peak value of 5.8% for West Africa, 2.1% for the Middle East, 3.7% for southern Africa, and 5.7% for South America. Monthly climatologies of iron oxide volume fractions show little seasonal variability, and range from about 1.1 to 1.7% for coarse mode aerosols in all four study regions. Finally, our sensitivity study indicates that the soot carbon retrieval is not sensitive to the component refractive indices or densities assumed for carbonaceous and iron oxide aerosols, and differs by only 15.4% when these parameters are altered from our chosen baseline values. The associated soot carbon absorption aerosol optical depth (AAOD) does not vary at all when these parameters are altered, however, because the retrieval is constrained by the AERONET optical properties.

scholarly journals Group Refractive Index of Nanocrystalline Yttria-Stabilized Zirconia Transparent Cranial Implants

2021 ◽  
Vol 9 ◽  
Author(s):  
David L. Halaney ◽  
Nitesh Katta ◽  
Hamidreza Fallah ◽  
Guillermo Aguilar ◽  
Thomas E. Milner
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Spectral Range ◽  
Laser Speckle ◽  
Yttria Stabilized Zirconia ◽  
Optical Systems ◽  
Stabilized Zirconia ◽  
Swept Source ◽  
Group Refractive Index ◽  
Cranial Implants

Transparent “Window to the Brain” (WttB) cranial implants made from a biocompatible ceramic, nanocrystalline Yttria-Stabilized Zirconia (nc-YSZ), were recently reported. These reports demonstrated chronic brain imaging across the implants in mice using optical coherence tomography (OCT) and laser speckle imaging. However, optical properties of these transparent cranial implants are neither completely characterized nor completely understood. In this study, we measure optical properties of the implant using a swept source OCT system with a spectral range of 136 nm centered at 1,300 nm to characterize the group refractive index of the nc-YSZ window, over a narrow range of temperatures at which the implant may be used during imaging or therapy (20–43°C). Group refractive index was found to be 2.1–2.2 for OCT imaging over this temperature range. Chromatic dispersion for this spectral range was observed to vary over the sample, sometimes flipping signs between normal and anomalous dispersion. These properties of nc-YSZ should be considered when designing optical systems and procedures that propagate light through the window, and when interpreting OCT brain images acquired across the window.

scholarly journals Determining the infrared radiative effects of Saharan dust: a radiative transfer modelling study based on vertically resolved measurements at Lampedusa

2017 ◽  
Author(s):  
Daniela Meloni ◽  
Alcide di Sarra ◽  
Gérard Brogniez ◽  
Cyrielle Denjean ◽  
Lorenzo De Silvestri ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Size Distribution ◽  
Radiative Forcing ◽  
Refractive Indices ◽  
Radiative Effects ◽  
Brightness Temperatures ◽  
Dust Size Distribution ◽  
Aerosol Properties

Abstract. Detailed atmospheric and aerosol properties, and radiation measurements were carried out in summer 2013 during the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) campaign in the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx) experiment. This study focusses on the characterization of infrared (IR) optical properties and direct radiative effects of mineral dust, based on three vertical profiles of atmospheric and aerosol properties and IR broadband and narrowband radiation from airborne measurements, made in conjunction with radiosonde and ground-based observations at Lampedusa, in the central Mediterranean. Satellite IR spectra from IASI are also included in the analysis. The atmospheric and aerosol properties are used as input to a radiative transfer model, and various IR radiation parameters (upward and downward irradiance, nadir and zenith brightness temperature at different altitudes) are calculated and compared with observations. The model calculations are made for different sets of dust size distribution and refractive indices, derived from observations and from the literature. The main results of the analysis are that the IR dust radiative forcing is non negligible, and strongly depends on size distribution (SD) and refractive index (RI). When calculations are made using the in situ measured size distribution, it is possible to identify the refractive index that produces the best match with observed IR irradiances and brightness temperatures (BTs). The most appropriate refractive indices correspond to those determined from independent measurements of mineral dust aerosols from the source regions (Tunisia, Algeria, Morocco) of dust transported over Lampedusa, suggesting that differences in the source properties should be taken into account. With the in situ size distribution and the most appropriate refractive index the estimated dust IR radiative forcing efficiency is +23.7 W m-2 at the surface, -7.9 W m-2 within the atmosphere, and +15.8 W m-2 at the top of the atmosphere. The use of column integrated dust SD from AERONET may also produce a good agreement with measured irradiances and BTs, but with significantly different values of the RI. This implies large differences, up to a factor of 2.5 at surface, in the estimated dust radiative forcing, and in the IR heating rate. This study shows that spectrally resolved measurements of brightness temperatures are important to better constrain the dust IR optical properties, and to obtain a reliable estimate of its radiative effects. Efforts should be directed at obtaining an improved description of the dust size distribution, its vertical distribution, and at including regionally-resolved optical properties.

Ellipsometric Study of the Interface Between Silicon and Silica

1993 ◽  
Vol 318 ◽  
Author(s):  
R. H. Doremus ◽  
S. C. Kao
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Transition Layer ◽  
Interfacial Layer ◽  
Vitreous Silica ◽  
Refractive Indices ◽  
Bulk Silicon ◽  
Ellipsometric Study

ABSTRACTEllipsometric measurements of surfaces of oxidized silicon give information on the optical properties, structure and composition of the interface between the silicon and oxide. From such measurements in ambient liquids with different refractive indices, some close to that of the oxide, we conclude that there is an interfacial layer about one nm thick at all oxide thicknesses. This layer is either a transition layer of partially oxidized silicon or a layer of silicon of higher absorption than bulk silicon. The oxide has the refractive index of vitreous silica at all thicknesses.

scholarly journals Complex refractive indices in the ultraviolet and visible spectral region for highly absorbing non-spherical biomass burning aerosol

2020 ◽  
Author(s):  
Caroline C. Womack ◽  
Katherine M. Manfred ◽  
Nicholas L. Wagner ◽  
Gabriela Adler ◽  
Alessandro Franchin ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Black Carbon ◽  
Biomass Burning ◽  
Spectral Region ◽  
Mie Theory ◽  
Visible Spectral Region ◽  
Aerosol Size Distribution ◽  
Refractive Indices ◽  
Biomass Burning Aerosol

Abstract. Biomass burning aerosol is a major source of PM2.5, and significantly affects Earth's radiative budget. The magnitude of its radiative effect is poorly quantified due to uncertainty in the optical properties of aerosol formed from biomass burning. Using a broadband cavity enhanced spectrometer with a recently increased spectral range (360–720 nm) coupled to a size-selecting aerosol inlet, we retrieve complex refractive indices of aerosol throughout the near-ultraviolet and visible spectral region. We demonstrate refractive index retrievals for two standard aerosol samples: polystyrene latex spheres and ammonium sulfate. We then retrieve refractive indices for biomass burning aerosol from 13 controlled fires during the 2016 Missoula Fire Science Laboratory Study. We demonstrate that the technique is highly sensitive to the accuracy of the aerosol size distribution method, and find that while we can constrain the optical properties of brown carbon aerosol for many fires, fresh smoke dominated by fractal-like black carbon aerosol presents unique challenges and is not well-represented by Mie theory. For the 13 fires, we show that the accuracy of Mie theory retrievals decreases as the fraction of black carbon mass increases. At 475 nm, the average refractive index is (1.635 ± 0.056) + (0.06 ± 0.12)i.

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