Generalized Brewster-angle conditions for quarter-wave multilayers at non-normal incidence*

1974 ◽  
Vol 64 (5) ◽  
pp. 647 ◽  
Author(s):  
H. F. Mahlein
Keyword(s):  
Normal Incidence ◽  
Brewster Angle ◽  
Quarter Wave

Reflection refractometry for nearly normal incidence and at the Brewster angle

2012 ◽  
Vol 79 (1) ◽  
pp. 148-156 ◽  
Author(s):  
E. A. Tikhonov ◽  
V. A. Ivashkin ◽  
A. K. Ljamec
Keyword(s):  
Normal Incidence ◽  
Brewster Angle

MODELING MULTILAYER ANTIREFLECTION COATING SYSTEMS BASED ONLiNbO3

2010 ◽  
Vol 24 (11) ◽  
pp. 1145-1150 ◽  
Author(s):  
FILIZ KARAOMERLIOGLU
Keyword(s):  
High Performance ◽  
Optoelectronic Devices ◽  
Normal Incidence ◽  
Ferroelectric Material ◽  
Antireflection Coating ◽  
Electromagnetic Spectrum ◽  
Antireflection Coatings ◽  
Different Types ◽  
Quarter Wave ◽  
Ar Coating

Antireflection coatings have had the greatest impact on optics. The antireflection (AR) coating is the critically important technology in obtaining high performance of optoelectronic devices. In the present paper, characteristics of the ferroelectric based multilayered antireflection coating systems are investigated. Multilayer antireflection coatings consisting of insulator thin films have been modeled in the region between the 400 nm and 800 nm visible bands of electromagnetic spectrum to reduce reflectance from ferroelectric based substrate.In this type of antireflection coating we can regulate the optical properties of a system by external electric (or thermal field) and design a broadband low reflection coating system for optoelectronic devices. In order to design and simulate the normal incidence wideband visible multilayer AR coatings, we have developed a Fortran software program based upon Fresnell equations. Different types of layers which are two-different materials like ZnSe and ZrO2for even-folded multilayer (two-, four-, six-, eight-, ten-, and twelve-layer) antireflection coatings are used. Ferroelectric material, LiNbO3is used as the substrate. The optical thicknesses of each layer are equal to a quarter-wave thick at a certain wavelength.

Absorption loss influence on optical characteristics of multilayer distributed Bragg reflector: wavelength-scale analysis by the method of single expression

2010 ◽  
Vol 18 (4) ◽  
Author(s):  
H.V. Baghdasaryan ◽  
T.M. Knyazyan ◽  
T.H. Baghdasaryan ◽  
B. Witzigmann ◽  
F. Roemer
Keyword(s):  
Power Flow ◽  
Normal Incidence ◽  
Bragg Reflector ◽  
Flow Density ◽  
Problem Solution ◽  
Absorption Loss ◽  
Distributed Bragg Reflector ◽  
Method Of Single Expression ◽  
Quarter Wave ◽  
Wavelength Scale

AbstractElectrodynamical model of a classical distributed Bragg reflector (DBR) consisting of alternating quarter-wave layers of high and low permittivity is considered at the plane wave normal incidence. Reflective characteristics of DBR possessing absorption loss in constituting layers are analysed via correct wavelength-scale boundary problem solution by the method of single expression (MSE). Analysis of optical field and power flow density distributions within the lossy DBR structures explained the peculiarities of their reflective characteristics. Optimal configurations of lossless and lossy DBRs are revealed. Specific DBR structures possessing full transparency at definite number of layers are also analysed.

Free Space Microwave Characterization of Silicon Wafers for Microelectronic Applications

2005 ◽  
Vol 2 (2) ◽  
pp. 35
Author(s):  
Zaiki Awang ◽  
Deepak Kumar Ghodgaonkar ◽  
Noor Hasimah Baba
Keyword(s):  
Complex Permittivity ◽  
Free Space ◽  
Normal Incidence ◽  
Silicon Wafers ◽  
Reflection And Transmission Coefficients ◽  
Frequency Range ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Quarter Wave ◽  
Mode Transitions

A contactless and non-destructive microwave method has been developed to characterize silicon semiconductor wafers from reflection and transmission measurements made at normal incidence using MNDT. The measurement system consists of a pair of spot-focusing horn lens antenna, mode transitions, coaxial cables and a vector network analyzer (VNA). In this method, the free-space reflection and transmission coefficients, S11 and S21 are measured for silicon wafers sandwiched between two Teflon plates of 5mm thickness which act as a quarter-wave transformer at mid-band. The actual reflection and transmission coefficients, S11 and S21 of the silicon wafers are then calculated from the measured S11 and S21 using ABCD matrix transformation in which the complex permittivity and thickness of the Teflon plates are known. From the complex permittivity, the resistivity and conductivity can be obtained. Results for p-type and n-type doped silicon wafers are reported in the frequency range of 11 – 12.5 GHz. The dielectric constant of silicon wafer obtained by this method agrees well with that measured in the same frequency range by other conventional methods.

Analysis of Contrast Reversal in SEM Images

1972 ◽  
Vol 30 ◽  
pp. 398-399
Author(s):  
M. D. Coutts ◽  
E. R. Levin
Keyword(s):  
Incident Beam ◽  
Normal Incidence ◽  
Beam Current ◽  
Secondary Emission ◽  
Image Contrast ◽  
Sem Images ◽  
Secondary Electrons ◽  
Image Position

On tilting samples in an SEM, the image contrast between two elements, x and y often decreases to zero at θε, which we call the no-contrast angle. At angles above θε the contrast is reversed, θ being the angle between the specimen normal and the incident beam. The available contrast between two elements, x and y, in the SEM can be defined as,(1)where ix and iy are the total number of reflected and secondary electrons, leaving x and y respectively. It can easily be shown that for the element x,(2)where ib is the beam current, isp the specimen absorbed current, δo the secondary emission at normal incidence, k is a constant, and m the reflected electron coefficient.

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