Physics Commons^™

Total Refraction At Oblique Incidence By A Transparent Bilayer Coating On A High-Index Transparent Or Absorbing Substrate, R. M.A. Azzam, Karim Javily

Electrical Engineering Faculty Publications

Transparent bilayer coatings that produce total refraction (TR) of obliquely incident monochromatic light into an underlying substrate are considered. When the substrate is transparent, it is shown that TR takes place without any accompanying change of polarization. Totally refracting bilayers are realizable in the IR where high-refractive-index substrates are available. This is illustrated by a BaF₂–ZnSe bilayer on a Ge substrate at a 10.6-μm (CO₂-laser) wavelength and 45° angle of incidence. Limited changes of the angle of incidence, wavelength, and refractive indices and thicknesses of the two films of the bilayer are introduced, and their effects …

Investigation Of Electronic Holography Using Spice Computer Simulation Experiments, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

Using SPICE experiments, it has been possible to verify most of the important aspects of electronic holography. The generation and properties of dynamic echoes under different types of nonlinearities have been extensively tested, and some new information has been garnered in the process. The case of pulse and generalized memory echoes has also been tested, and the results have been fairly satisfactory. Most of all, the simplicity with which the intriguing concept of memory echoes has translated into the circuit implementation on SPICE, and the closeness of the results to predicted behavior have been somewhat of a pleasant surprise.

Since …

27th Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 27th annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, July 14-18, 1985.

Measuring R And D Productivity, Richard A. Pappas, Donald S. Remer

All HMC Faculty Publications and Research

Measuring the productivity of an R&D organization is extremely tricky. Productivity is usually defined as a ratio of an output, like number of cars produced on an assembly line, to an input, like the wages paid the workers. While R&D may have a measurable input, the output is often intangible and difficult to quantify. This is further complicated because the return from an R&D department may not be realized for one or two decades,which means the time lag is much higher than in factory measurements. Furthermore, many researchers believe that this kind of measurement may be counterproductive,since the mere act …

Constraint On The Optical Constants Of A Film-Substrate System For Operation As An External-Reflection Retarder At A Given Angle Of Incidence, R. M.A. Azzam, Bruce E. Perilloux

Electrical Engineering Faculty Publications

Given a transparent film of refractive index n₁ on an absorbing substrate of complex refractive indexn₂-jk₂, we examine the constraint on n₁, n₂, and k₂ such that the film-substrate system acts as an external-reflection retarder of specified retardance Δ at a specified angle of incidence φ. The constraint, which takes the form ƒ(n₁,n₂,k₂;φ,Δ) = 0, is portrayed graphically by equi-n₁ contours in the n₂,k₂ plane at φ = 45, 70° and for Δ …

Explicit Equations For The Polarizing Angles Of A High-Reflectance Substrate Coated By A Transparent Thin Film, R. M.A. Azzam

Electrical Engineering Faculty Publications

Simple explicit equations are derived that determine the angles of incidence at which the parallel and perpendicular polarization components of light are extinguished on reflection from a transparent film coating a high-reflectance (metallic) substrate. The polarizing angles obtained from our approximate expressions are in excellent agreement with those determined by iterative numerical solution of the exact nonlinear equations that govern such angles. For the approximation to be valid, the intensity reflectance of the film-substrate interface, evaluated at the critical angle of the film-ambient interface, must exceed 0.5.

Antireflecting And Polarizing Transparent Bilayer Coatings On Absorbing Substrates At Oblique Incidence, R. M.A. Azzam, Karim Javily

Electrical Engineering Faculty Publications

The condition of zero reflection of p- and s-polarized light by a transparent bilayer on an absorbing substrate is derived in the form |g_ν(ø,N_i)| ≤ 1, where g_ν is a function of the angle of incidence ø, the refractive indices N_i(i = 0,1,2,3) of the system, and the polarization state ν (= p or s). As an application, the air-Si₃N₄-SiO₂-Si system is considered at two laser wavelengths λ = 6328 and 3250 Å. The thicknesses of the two films of the bilayer and the …

Single-Layer Antireflection Coatings On Absorbing Substrates For The Parallel And Perpendicular Polarizations At Oblique Incidence, R. M.A. Azzam

Electrical Engineering Faculty Publications

Explicit equations are derived that determine the refractive index of a single layer that suppresses the reflection of p- or s-polarized light from the planar interface between a transparent and an absorbing medium at any given angle of incidence. The required layer thickness and the system reflectance for the orthogonal unextinguished polarization also follow explicitly. This generalizes earlier work that was limited to normal incidence or to oblique incidence at dielectric—dielectric interfaces. Specific examples are given of p- and s-antireflection layers on Si and Al substrates at λ = 6328 Å at various angles of incidence.

Extinction Of The P And S Polarizations Of A Wave On Reflection At The Same Angle From A Transparent Film On An Absorbing Substrate: Applications To Parallel-Mirror Crossed Polarizers And A Novel Integrated Polarimeter, R. M.A. Azzam

Electrical Engineering Faculty Publications

The p- and s-polarized components of light can be suppressed on reflection at the same angle of incidence from an absorbing substrate coated by a transparent thin film if the wave is refracted in the film at 45° and the constraint Re[(ε₂ - α)/(l -α)]^1/2 = α + | ε₂ - α| is satisfied, where 2α and ε₂ are the ratios of dielectric constants of the film and substrate, respectively, to that of the ambient. For high-reflectance metal substrates (|ε₂| » 1), α≈ 1, the ratio of film to ambient refractive index …

Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Thermal Stress Analysis, A. Ballantyne, H.A. Hyman, Clive L. Dym, R.C. Southworth

All HMC Faculty Publications and Research

This paper examines the effects of thermal loading and time history upon the thermal stresses developed in lithographic mask structures as would be expected under irradiation by intense soft x rays. The objective of this work was to examine the phenomenology of the interaction and to evaluate the limits placed upon mask dosage. The mechanics of mask failure are examined in terms of single pulse and cumulative, or fatigue, effects. A number of prototypical mask structures are investigated, which show that the application of intense pulsed sources to x‐ray lithography does not reduce the potential utility of the techique. However, …

Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Dynamic Response, Clive L. Dym, A. Ballantyne

All HMC Faculty Publications and Research

This paper addresses the issue of the dynamic response of thin lithographic mask structures to thermally induced stress fields. In particular, the impact of repetitively pulsed x‐ray sources are examined: the short duration (1–100 nsec) pulses induce large step changes in mask temperatures, which can, in turn, induce a dynamic response. The impact of conductive cooling of the mask is to reduce the repetitively pulsed problem to a series of isolated nearly identical thermal impulses of duration approximately equal to the cooling time. The importance of self‐weight and prestress is examined, and an analysis of the nonlinear dynamic response to …