Measurement of optical penetration depth and refractive index of human tissue

Experimental techniques for measurement of optical penetration depth and refractive index of humantissue are presented, respectively. Optical penetration depth can be obtained from the measurement ofthe relative fluence-depth distribution inside the target tissue. The depth of normal and carcinomatoushuman lung tissues irradiated with the wavelengths of 406.7, 632.8 and 674.4 nm in vitro are respectivelydetermined.In addition,a novel simple method based on total internal reflection for measuring therefractive index of biotissue in vivo is developed,and the refractive indices of skin from people of differentage, sex and skin color are measured.Their refractive indices are almost same and the average is 1.533.     

Effect of temperature on refractive index match of laser glass edge cladding

An Nd：glass disc requires an edge cladding to absorb the amplified spontaneous emission. The absorption is determined by reflections （R） from disc edges. R is primarily induced by the refractive index （n） mismatch. Thus, the temperature at the cladding interface increases due to absorption, and leads to the variation of n. In order to investigate the effect of temperature on the refractive index match, temperature coefficients （dn/dT） of the laser glass, adhesive polymer, and cladding glass are measured. The effect of temperature on the refractive index match is discussed. Results show that the indices match below 40 ℃.     

Measurement of the magnetic field-dependent refractive index of magnetic fluids in bulk

An optical alignment-free and highly accurate method is employed to measure the magnetic field-dependent refractive index of magnetic fluid(MF)in bulk.The measured refractive index decreases significantly with the increasing magnetic strength and then tends to saturate in the high intensity range.By applying a tunable magnetic field ranging between 0 and 1661 Oe,the maximum shift of the refractive index of MF in bulk is found to be 0.0231.     

Study of refractive index and thickness of TiO2／ormosil planar waveguide

Hybrid titania/ormosil waveguide films have been prepared by sol-gel method at low thermal treatment temperature of 150℃. The influence of processing parameters including the molar ratios of Ti(OBu)_{4}/glycidoxypropyltrimethoxysilane (GLYMO) and H_{2}O/Ti(OBu)_{4} (expressed as R), especially aging of sol, on the refractive index and thickness of film was investigated. The optical properties of films were measured with Scanning Electron Microscope and m-line spectroscopy. The results indicate that the film thickness increases with the aging time of sol, but the variation of refractive index as a function of aging time of sol depends on the relative ratio of GLYMO to Ti-alkoxide. The relation between film thickness and corresponding sol viscosity is linear as the volume of GLYMO is 80% within the range of measured data.     

Determination of the effective refractive index of porous silicon/polymer composite films

Porous silicon, whose refractive index varies according toits porosity, is a good candidate for use in optical inter-connect technology. Moreover, optical devices based onporous silicon, such as light-emitting diodes, photodetec-tors, and photomodulators, have already been realized.The open porous structure and the very large specificsurface area of porous silicon are strong motivations fortrying to introduce different kinds of materials inside thepores. The resulting composite structures can …     

Optical–digital joint design of refractive telescope using chromatic priors

The conventional optical system design employs combinations of different lenses to combat aberrations, which usually leads to considerable volume and weight. In this Letter, a tailored design scheme that exploits state-ofthe-art digital aberration correction algorithms in addition to traditional optics design is investigated. In particular, the proposed method is applied to the design of refractive telescopes by shifting the burden of correcting chromatic aberrations to software. By enforcing cross-channel information transfer in a post-processing step, the uncorrected chromatic aberrations are well-mitigated. Accordingly, a telescope of F-8, 1400 mm focal length,and 0.14° field of view is designed with only two lens elements. The image quality of the designed telescope is evaluated by comparing it to the equivalent designs with multiple lenses in a traditional optical design manner,which validates the effectiveness of our design scheme.     

Research on refractive index of optical cement used in Glan-Thompson prisms

The influence of the refractive index n2 of optical cement on the structure angle, field angle, and transmission of Glan-Thompson prism has been studied in detail. The results show that the structure angle will increase with the decrease of n2 under the condition of the largest field angle. Thus, the ratio of length to width (L/A) of the prism will decrease, which means more materials can be saved. When the value of L/A is 3.0 or 2.5 in the routine design, the field angle will firstly increase and then decrease with the increment of n2. Two routine designs with the n2 values of 1.47 and 1.45 have the optimal field angle. In addition, n2 also has great influence on light intensity transmittance of the prism. Considering all these factors, it will be the best choice with L/A = 2.5 and n2 = 1.45-1.46.     

Nonlinear refractive index of multicomponent glasses designed for fabrication of photonic crystal fibers

The second order nonlinear refractive index n ₂ of various multicomponent glasses was measured at the wavelength of 1240 nm close to the 1.3-μm fiber transmission window. With the refractive index covering the range from 1.45 to 2.3, a comparatively broad range of n ₂ with values from 1.1×10^?20 m²/W for boro-silicate based glass NC21 to 4.3×10^?19 m²/W for lead–bismuth-gallate based glass PBG08 was measured using the Z-scan method. Considering the broad infrared transmission range of multicomponent glasses, these materials pose a great potential for future applications as photonic crystal fiber sources of infrared supercontinuum.     

Accurate measurement of the main refractive indices and thermo-optical coefficients of the calcite crystal

The main refractive indices of calcite crystal are measured by the means of auto-collimation,and the thermo-optical coefficients are calculated.The coefficient expression of SeUmeier equation is obtained by solving Sellmeier equation strictly and the refractive indices of different wavelengths are calculated,which accord with experimental results very well.The measured main refractive indices of calcite at 488-nm wavelength are identical with the values obtained by Sellmeier equation.     

Error scrutiny of measuring coefficients of refractive indices and Soret coefficients using Mach–Zehnder interferometer

No matter how vigilantly an experiment is performed, errors always there inside the experimental results. Since the results of laser based optical experiments are somewhat loftier in precision, commonly, sources of errors are mistreated. However, ample error scrutiny is vital in quantifying of physical parameters of liquids such as Soret and diffusion coefficients. There are two types of experimental errors, explicitly, systematic error and random error. Systematic error is associated to the apparatus and cannot be enhanced by recurrent experiments. Frequent systematic errors in Mach–Zehnder Interferometer (MZI) techniques originate from stability of laser wavelength, resolution of the electronics component etcetera. Random error is interrelated to the variation in the equivalent measurements of repeating experiment. Resolution of electronic components likewise constructs random errors by providing diverse values in the recurring experiment. Foremost, random error of MZI is caused by the environmental circumstances such as nonconformity of background light, air temperature, and air humidity. In this current amendment, a meticulous error analysis has been accomplished for evaluating thermodiffusion or Soret coefficients of hydrocarbon binary mixtures. Based on our knowledge, such a completed error scrutiny for measuring Soret coefficients using MZI does not yet exist in the literature. Study reveals that the utmost error of measuring Soret coefficient using MZI is less than 0.22%.     

Application of the probability theory in predicting 3D focusing behaviors of compound X-ray refractive lenses

X-rays promise a high resolving power due to the veryshort wavelength. Therefore, people have been trying todevelop X-ray optical devices for focusing X-ray beam toa small spot to perform X-ray analysis techniques. In1996, Snigirev et al.[1] proposed and demonstrated thatX-ray refractive focusing could be accomplished with acompound X-ray refractive lens (CRL). And then manypublications on the further researches appeared[2-8]. Thetheoretical results on the focusing performances in the fo-c…     

Nonlinear refractive index of RECOB (RE = Gd and La) crystals

The Z-scan technique is employed to obtain the nonlinear refractive index (n ₂) of the Ca₄REO(BO₃)₃ (RECOB, where RE = Gd and La) single crystals using 30 fs laser pulses centered at 780 nm for the two orthogonal orientations determined by the optical axes (X and Z) relative to the direction of propagation of the laser beam (k//Y// crystallographic b-axis). The large values of n ₂ indicate that both GdCOB and LaCOB are potential hosts for Yb:RECOB lasers operating in the Kerr-lens mode locking (KLM) regime.     

The refractive index dispersion of Hg1−xCdxTe by infrared spectroscopic ellipsometry

The refractive indices of Hg_1−xCd_xTe (x=0.276, 0.309, and 0.378) bulk samples in the region below, in, and above the fundamental band gap have been measured by infrared spectroscopic ellipsometry at room temperature. A refractive index peak, in which the corresponding energy equals approximately the band gap energy, is observed for each refractive index spectrum with different compositions. Above the band gap, the refractive index drops quickly near the gap, then decreases slowly as photon energy increases. The refractive index n above the band gap is found to follow the Sellmeier dispersion relationship n²(λ)=A+B/λ²+C/λ⁴+D/λ⁶ as a function of the wavelength of light λ.     

Measurements of refractive index profiles of proton－exchanged LiNbO_3 waveguidesusing TE－TM mode conversion

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Asymptotic behavior of the Schrödinger–Debye system with refractive index of quadratic wave amplitude

We obtain local well-posedness for the one-dimensional Schrödinger–Debye interactions in nonlinear optics in the spaces \(L^2\times L^p,\; 1\le p < \infty \). When \(p=1\) we show that the local solutions extend globally. In the focusing regime, we consider a family of solutions \(\{(u_{\tau }, v_{\tau })\}_{\tau >0}\) in \( H^1\times H^1\) associated to an initial data family \(\{(u_{\tau _0},v_{\tau _0})\}_{\tau >0}\) uniformly bounded in \(H^1\times L^2\), where \(\tau \) is a small response time parameter. We prove that \(\left( u_{\tau }, v_{\tau }\right) \) converges to \(\left( u, -|u|^2\right) \) in the space \(L^{\infty }_{[0, T]}L^2_x\times L^1_{[0, T]}L^2_x\) whenever \(u_{\tau _0}\) converges to \(u_0\) in \(H^1\) as long as \(\tau \) tends to 0, where u is the solution of the one-dimensional cubic nonlinear Schrödinger equation with the initial data \(u_0\). The convergence of \(v_{\tau }\) for \(-|u|^2\) in the space \(L^{\infty }_{[0, T]}L^2_x\) is shown under compatibility conditions of the initial data. For non-compatible data, we prove convergence except for a corrector term which looks like an initial layer phenomenon.     

Effect of crystalline lens surfaces and refractive index on image quality by model simulation analysis

The surfaces and refractive index of crystalline lens play an important role in the optical performance of human eye.On the basis of two eye models,which are widely applied at present,the effect of lens surfaces and its refractive index distribution on optical imaging is analyzed with the optical design software ZEMAX (Zemax Development Co.,San Diego,USA).The result shows that good image quality can be provided by the aspheric lens surfaces or (and) the gradient-index (GRIN) distribution.It has great potential in the design of intraocular lens (IOL).The eye models with an intraocular implantation are presented.