bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionized-Cluster-Beam Deposition of Optical Interference Coatings
Authors: Takagi T. , Yamada I.
Published: February 2023

Ionized-Cluster-Beam (ICB) deposition has been applied to form metal, dielectric and compound films for optical coatings. In ICB deposition, it is possible to control the mechanical, crystallographic and optical properties of films by variation of the acceleration voltage and ion content in the total flux. Experimental results of film deposition by ICB show that optical properties can be improved through proper selection of acceleration voltage and ratio of ionization Applications such as high-reflectance mirrors, AR coatings and other optical devices have been demonstrated.
Process Control and Automation in the Deposition of Optical Coatings
Authors: Thoeni W. P.
Published: February 2023

Compared to the breathtaking evolution of new coating technologies in the semiconductor industry in the last few years, developments in the field of optical interference coatings have been extremely modest. Classical thermal evaporation methods are still by far the most widely used for the large scale production of optical coatings. "Automation: The Optical Coating Revolution", to quote a recent publication1, is just about now having its first impact in the industry. Apart from control of the layer thickness, any automatic system must cope with the control and reproducibility of an inherent nonideal film structure2,3.
A Survey of Optical Coating Automation
Authors: Willey R. R.
Published: February 2023

In the process of acquiring three new optical coating chambers, several United States and European manufacturers were surveyed with respect to the automation that could be demonstrated for optical coating processes. The findings of that survey show that several manufacturers have or are rapidly approaching automation which allows the production of high quality optical coatings without operator intervention after the process is developed and a specific run has been initiated.
Refinement of Thin-Film Coating Designs by Fabrication Simulation
Authors: Tepfenhart W. M. , Case W. E.
Published: February 2023

Direct optical monitoring is considered a reliable means of controlling layer thicknesses during multilayer thin-film depositions. However, accuracy depends on precise knowledge of optical constants for all materials used in a given coating under actual conditions of deposition1. This information is very difficult to obtain directly. In this paper, we describe an indirect method based on computer simulation of the monitoring process.
Coating Design Using Very Thin High and Low Index Layers
Authors: Southwell W. H.
Published: February 2023

Presented here is the concept of synthesizing interference coatings using many layers of 2 materials whose optical thicknesses are much less than a quarter wave, as opposed to the standard practice of using 2 or more materials for layers which are of the order of a. quarter wave in optical thickness.
Interference Coatings for Neutrons
Authors: Majkrzak C. F.
Published: February 2023

The principle interactions of slow neutrons with condensed matter are nuclear and magnetic. For the present purpose, the neutron-nucleus interaction can be regarded as an isotropic point interaction characterized by a coherent scattering length b, the magnitude of which varies non-monotonically with different nuclei. Because the neutron is a spin 1/2 particle and possesses a magnetic dipole moment of - 1.913 nuclear magnetons, it interacts with those atomic electrons which give rise to a magnetic moment. This interaction can also be characterized by a scattering length p, although an angular form factor must, in general, be included due to the relatively large spatial extent of the interaction region. However, for scattering at the small angles of interest here, this form factor can be taken to be unity.
Non-degrading Color Transparencies
Authors: Gibson U. J. , Macleod H. A. , Saxe S. G. , Van Milligen F.
Published: February 2023

The use of conventional color slides for continuous displays and archival storage is made less than ideal by the fading of the organic dyes with time. The fading problems are extremely severe in systems where high intensity projection systems are used on a continuous basis. Significant fading occurs in one to two hours of continuous showing; after eight hours the slides are severely bleached. The slide production technique that we describe will circumvent the inherent problems with dye based color systems by using thin film interference stacks to generate the colors.
2000-3000Å Ultraviolet Interference Filters
Authors: Fuchu Zhang , Ziyi Wang
Published: February 2023

Since the concept of potential transmission was presented first by Berning and Turner(1), a number of papers on the preparation and design of induced transmission(IT) filter have been published(2,3,4,5,6,7). IT filters 2200-2600Å was reported (5) and our work is a continuation of it. A design method for IT filters is described on the basis of the transmittance characteristics of Fabry-Perot(F.P.) filters. Measurements are provided for absorption coefficient of MgO. The results are given of 2000-3000Å UV interference filters with high transmittance, narrow HBW and deep blocking.
Hard Carbon Layers for Wear Protection and Antireflection Purposes of Infrared Devices
Authors: Enke Knut
Published: February 2023

Hard infrared transparent carbon layers are produced by means of a hydrocarbon e-low discharge /1/. Since it has become known that their refractive index can be matched to 2.0 /2/ they are very interesting antireflection single layer coatings for germanium and silicon. Their universal chemical resistance makes them suited for heavy duty environment.
Chemical bonding, physical properties and optical applications of hard carbon coatings
Authors: Dischler B. , Bubenzer A. , Koidl P. , Sah R.E.
Published: February 2023

Hard coatings of hydrogenated amorphous carbon (a-C:H) have several useful properties: optical transparency over a wide spectral range, chemical resistance against concentrated acids and bases, good electrical insulation and extreme hardness. These properties are closely related to the microstructure and type of bonding. For carbon the hybridisation of the electronic orbitals can be sp3 (diamond), sp2 (graphite) or sp1 (carbyne). We have studied the influence of the deposition parameters on the type of carbon bonding and on the optical properties.
Indium - Tin - Oxide Films for Optical Applications
Authors: Hamberg I. , Granqvist C.G.
Published: February 2023

Indium-Tin-Oxide (ITO) films exhibit a combination of useful properties. The most important of these are high transmittance at short wavelengths (visible light), high reflectance at long wavelengths (thermal infrared radiation), low electrical resistance, strong adherence to glass and other substrates, and good chemical inertness. As a consequence, ITO films are presently being used on a large and increasing scale. The optical and electrical properties of the ITO films are often a limiting factor for device performance etc., and it is therefore not surprising that ITO - and similar materials - have been extensively studied in many laboratories throughout the world during recent years.1-3 The main purpose of this paper is to discuss the current experimental and theoretical status for optimized ITO films. Detailed reports on this work are given elsewhere.4-8
Electrically Conductive and Heat Reflecting TiO2/Ag/TiO2 Coatings
Authors: Kattelus H. , Koskiahde E.
Published: February 2023

Visually transparent, but infrared reflecting and electrically conductive coatings are usually made of highly doped tin oxide or indium-tin oxide /1/. However, multilayer structures using induced transmission of a thin metal film /2/ offer several advantages compared to the single layer oxide coatings. For applications as optically transparent heat mirrors or electrically conductive electrodes relatively thin layers are required. This results in faster deposition cycles, lower material cost, less variation in interference colours and less severe step coverage problems. For coatings incorporating a metal film a higher NIR reflectivity can be achieved as well. In this study we report on optical and electrical properties of TiO2/Ag/TiO2 multilayer coatings.
Design of the Wide Band Dichroic Filter for Transmitting Visible and Reflecting Infrared Bands
Authors: Hengyi Li , Qiongrui Li
Published: February 2023

The beem-splitting technique of the visible and infrared band is an important method of multispectral scan in remote sensing technology. Using optical film technique is a simple and efficient method to make the beamsplitting. In this paper a wide-beam dichroic filter for transmitting visible and reflecting infrared bands is described, which is designed on the basis of the metal films with properties of both high reflection for infrared and induced transmission for visible bands. The combined thin film stack designed is a dieletric-metal-dielectric thin film system. Experimental results are presented: the transmittance of the dichroic filter in the visible region is 80-88 %, while it's reflectance in the intermediate and far infrared region is 90 %.
Light Scattering from Optical Coatings
Authors: Lissberger P. H.
Published: February 2023

In view of persistent difficulties in relating observations of radiation scattered from optical coatings to predictions of relevant physical models embodying measurable parameters of the interfacial roughnesses, there have recently been re-appraisals,1,2 of these models. In particular, the limitations of diffraction theory have been re-emphasised in relation to the evaluation of total integrated scatter (TIS)3,4 attributable to rough layer boundaries.
Characterization of Optical Surfaces by Measurement of Scattering Distribution
Authors: Roche P. , Pelletier E.
Published: February 2023

The micropolish of optical surfaces of good quality can be characterized by measurement of the distribution of scattered light. Very often the surface defects are not isotropic but display preferred orientations that are translated into an anisotropy of the scattered light distribution. The total amount of light scattered by very high quality surfaces, coated or uncoated, scarcely exceeds a few hundred parts per million. The precise measurement of the distribution of the scattered light is always a task requiring great care and attention to detail.
The Relationships of a Material's Properties to the Onset of Laser Induced Damage in Thin Film Coatings
Authors: Lange M. R. , McIver J. K. , Guenther Arthur H.
Published: February 2023

The sensitivity of the pulsed laser induced damage threshold of optical thin films to the thermal and optical properties of the film, substrate and included materials are studied within the context of inclusion-dominated damage models. Two models are considered. In one, a spherical inclusion is embedded in an infinite host. The absorption cross-section for the incident laser radiation is calculated using Mie scattering theory. A diagram of the model including all of the relevant paramters is shown in Fig. 1.
The Influence of Substrate Preparation on Optical Coatings
Authors: Karow Hank H.
Published: February 2023

It is still quite common for optical fabrication and optical coating to exist as equal but separate entities in many optical companies. Even in vertically integrated production facilities we find only minimal overlap in their respective activities. But between the fabrication of an optic and its subsequent coating there are a number of critical preparation steps that can determine the quality of the finished product.
AR coating design: An efficient coating for germanium in the 7.5-12.5μm region
Authors: Lubezky I. , Szafranek I.
Published: February 2023

Germanium is the most important raw material used in the fabrication of optical elements for the second atmospheric window in the infra red. Due to its high index of refraction germanium requires AR coating for the relevant wavelengths. Current applications in numerous devices limit the average maximum reflectance to 0.3% in the 8.0-11.5μm region and to a maximum of 1.0% (or less), in the peripheral regions down to 7.5μm and up to 12.5μm. A number of commercial coating companies offer such a product, without revealing the coating design(1). A few publications describe AR coatings for Ge in this region, but with inferior performances(2-3).
General Synthesis with Layers of Equal Optical Thickness
Authors: Thelen Alfred
Published: February 2023

Over 30 years ago, Pohlack1 proposed a method of synthesis based on polynomial curve fitting. After proving that 1/T (or R/T) of a sequence of layers with equal optical thickness had to be a polynomial of the type P=A0cos2mφ +A1cos2m−2φ+A2cos2m−4 φ +. . . , with φ =(πλ)/(2λ0) and m= total number of layers, he proceeded to calculate the coefficients of the polynomial as a function of the refractive indices of the individual layers. Equating these equations with the desired coefficients, he could arrive at a system of equations of sufficient number to calculate the refractive indices. Although the theory had a large impact on the theoretical understanding of multilayer interference coatings, the equations were too complex to be of much practical value.
Merit Functions for More Effective Thin Film Calculations
Authors: Dobrowolski J.A. , Ho F.C. , Delkind A. , Koss V.A.
Published: February 2023

At times multilayer coatings are required with properties that are a complicated function of the spectral transmittance or reflectance curve. We have modified our thin film synthesis program FILTER1to accept merit functions of the following type: where and In the above
GiT, Giare the target and calculated quantities that are equal to or are functions of up to 3 different integrals Ijof the form and δGiare the acceptable tolerances on
GiT. Wiis a weight factor provided in the input.
Design and Optimization of Optical Coatings by Simulated Annealing
Authors: Tirri B. , Danek J. , Turner A. , Zwieg D.
Published: February 2023

Simulated Annealing is a statistical optimization method for finding the global minimum of a multivariable function. Design examples which demonstrate the discriminatory nature of this approach will be shown.
Spectral Characteristics of an Optical Filter Due to Changes at the Air/Film Interface
Authors: Johnson Walter E. , Davison Joseph E.
Published: February 2023

Both calculations and experiments show dramatic spectra changes occur to an interference filter as a function of removing fractional film thicknesses at the air/film interface.
Applications of equivalent layers in multilayer design
Authors: Baumeister Philip
Published: February 2023

The original publication1 on equivalent layers lists a design of a wide bandpass and a two-layer antireflection coating AR. This paper surveys of some of the more recent uses of equivalent layers in multilayer design. An equivalent layer consists of a symmetrical group of nonabsorbing films. If the symbols A, B, C, and D each represent a nonabsorbing layer, then equivalent layers are represented by groups containing an odd number of layers, such as ABA, ABCBA, ABCDCBA, and so on.
Optical Constants of be Mirrors
Authors: Garcia Marie
Published: February 2023

Very little information is available concerning the optical constants of polished bare beryllium mirrors especially for beryllium produced by hot-isostatic pressing (HIP) and vacuum hot-pressing (VHP) material manufacturing techniques. The optical constants would be useful in thin-film coating designs for Be mirrors.
Automated Rugate Deposition Control through Multiple Monitoring Techniques
Authors: Lazo-Wasem J.E. , LaFleur L.D. , Grosso R. P. , Dunn D. E.
Published: February 2023

A design for automation of the coating deposition process for the manufacture of rugate filters is presented. Three monitoring techniques, photometry, interferometry, and ellipsometry, are being evaluated for use in the deposition control loop. A design for each is summarized. The system design for process control, sensor fusion, and long-term analysis is outlined. The task objective is to provide a cost-effective, accurate, reproducible, and time-efficient method of producing rugate filters.
The Antiscattering of Multilayer Antireflection Coatings
Authors: Lee Cheng-Chung , Yeh Pei-Hung
Published: February 2023

It is possible to have antiscattering coatings if the air-film interface roughness correlates with the film-substrate interface roughness.
Simultaneous Determination of Refractive Index, Its Dispersion and Depth Profile of Magnesium Oxide Thin Film by Spectroscopic Ellipsometry
Authors: Vedam K. , Kim S.Y.
Published: February 2023

One of the major problems that has been plaguing the optical and materials engineers in the effective utilization of thin films in a variety of optical devices, is that even the basic data on the true refractive index, and its dispersion of many materials have not yet been determined since they are not available in bulk form and in thin film form they are inhomogeneous with consequent irreproducible results. Borgogno et al. [1] have recently developed a method of determining the complex refractive index, the thickness and the magnitude of film inhomogeneity from an analysis of normal incidence spectral reflectance and transmittance results with the assumption that the refractive index of the film decreases (or increases) linearly with thickness due to inhomogeneity. Such an assumption is however seldom valid.
Deposition of Optical Coatings by Molecular Beam Techniques and Their Characterisation
Authors: Lewis K L , Muirhead I T , Pitt A M , Cullis A G , Chew N G , Miller A , Wyatt-Davies T J
Published: February 2023

Significant improvements can be made in the fabrication of optical thin film structures by using molecular beam and ultrahigh vacuum techniques. These lead to the achievement of more stable films and multilayer coatings, with improved morphology, density and resistance to laser induced damage. The microstructure of the film can be controlled to a high degree by using quasi-superlattice techniques, which also provide a means of refractive index synthesis. This can be applied to simple graded structures or to complex periodic gradings as required for Bragg-like structures. Etalon filters fabricated using the technique have been used for optical bistability experiments and have exhibited stable operation for periods of many hours, under continuous cycling.
Intermittent Ion Assisted Deposition of Silica and Titania
Authors: Kaspar M. , Pfefferkorn R.
Published: February 2023

The improvement of the optical and mechanical properties of optical thin films towards more bulk like behaviour achieved by ion assisted deposition is well established1-5. In principle it should be possible to mount a ion gun in a conventional evaporation chamber in order to take advantage of the IAD process. But there are some questions to be answered regarding the effective area which can be treated by the ion beam of a commercially available ion gun.
Effect of IAD on Trnsition Properties of Vanadium Dioxide Thin Films
Authors: Liying Han , Jiancun Gao
Published: February 2023

Optical properties of vanadium dioxide thin films show a hysteretic behavior which was well known as the results of phase transition from semiconducting to metal and corresponding transition of structure from monoclinic to tetragonal. The characteristic curves of IR transmission as a function of temperature of vanadium dioxide thin films are double valued over a finite temperature range, i,e as hysteresis loops. Shape of hysteresis loop depends upon the crystalization, the grain size, the packing density and the stress of the thin film, however all these factors of microstructure of thin film correlate with the deposition conditions. Effect of low energy argon ion bombardment on optical properties of predeposited vanadium dioxide films were investigated by F. Cardillo Case. (1)
Ion Beam Sputtered Magnesium Fluoride
Authors: Allen Thomas H. , Lehan John , McIntyre L. C.
Published: February 2023

We will report on the composition, optical and mechanical properties of ion beam sputter deposited films of magnesium fluoride. Sputtered films were found to be more fluorine deficient and absorptive than thermally deposited films. Both of these film properties increased with increasing atomic weight of the sputter ion. Depositing films in the presence of a fluorine-containing gas (CF4) reinstated the fluorine and decreased the oxygen content of the film. Film composition and density were determined using Rutherford backscattering spectroscopy. The refractive index, stress, and microstructure of the films will also be discussed.
Ultra-Low Loss Optical Interference Coating by Ion Beam Sputtering
Authors: Wei David T.
Published: February 2023

In scientific and industrial applications, ultra-low loss optical coatings are desirable. From its outset in the mid-1970's by Wei et al,1 ion beam sputtered interference coating (IBIC) has shown (a) two orders of magnitude over conventional fabrication methods in the reduction of scattering and absorption losses, and (b) high bonding strength and resistance against abrasion. This method for coating was first developed for ring laser gyro, where IBIC mirrors made the gyro a practical reality. The success in that area should stimulate IBIC applications in various spectral regions and power levels.
Improved Oxide Coatings by Reactive Ion Plating Deposition
Authors: Guenther Karl H.
Published: February 2023

The metal of the desired oxide thin film is molten in an electron beam evaporator (6-10 kW power) at below 10−6 mbar. After admitting the reactive gas (O2) into the coating chamber, a low-voltage, high-current (50-80 V, 40-100 A) plasma arc burns into the melt which acts as the anode for the arc.1 A hot hollow-cathode source mounted at the lower viewport of a standard 32″ box-coater delivers the arc at an Argon pressure of about 1 mbar. A 1 mm diameter orifice serves as differential pressure stage.
Verification of Momentum Transfer as the Dominant Densifying Mechanism in Ion-assisted Deposition
Authors: Targove James D. , Lingg Linda J. , Macleod H. Angus
Published: February 2023

Ion-assisted deposition (IAD), the bombardment of thermally evaporated thin films by low-energy ions during growth, has been used very successfully to density thermally evaporated coatings.1 However, the physical mechanism involved in this densification Is still unclear. The only theoretical attempt to explain this densification is that of Müller.2,3 He first investigated the effect on film densification of thermal spikes,2 ion-induced localized annealing events for which the relevant ion parameter is the ion energy. The conclusion was that these annealing events do not significantly density the films under typical IAD conditions. A collisional cascade model3 then showed that film densification can be caused by the recoil implantation of near-surface atoms, a momentum dependent process. We therefore decided to perform an experiment that would differentiate between energy and momentum effects in the IAD process.
Ion-Assisted Deposition of Thermally Evaporated Ag Films
Authors: Hwangbo C.K. , Lingg L.J. , Lehan J.P. , Jacobson M.R. , Macleod H.A. , Makhous J.L. , Kim S.Y.
Published: February 2023

Correlation of film properties and microstructure with ion beam parameters in ion-assisted deposition (IAD) provides insights for improving IAD thin films. It is well-known that the ion beam energy and ion flux are two main parameters which alter the microstructure of thin films and their optical properties. Parmigiani et al.1 related the normalized energy, defined as the energy delivered by the bombarding ions per arriving metal atom, to microstructural changes of Ag films in a dual ion-beam sputtering system.
Stability of Dielectric Multilayer Coatings Produced by Different Coating Technologies
Authors: Herrmann R. , Goetzelmann R. , Schneider R.
Published: February 2023

Multilayer dielectric filters exhibit a more or less strong shift of their spectral properties when subjected to environmental changes such as changing humidity or temperature. The shift depends on the type of coating materials used and their internal structure. The structure is influenced by the process technology applied for the production of the filters.
Transparent Conducting Indium-Doped ZnO Films by D.C. Reactive S-Gun Magnetron Sputtering*
Authors: Zhi-Zheng Ye , Jin-Fa Tang
Published: February 2023

Transparent conducting coatings have found major applications in a number of electronic and opto-electronic devices. Among many transparent conducting coatings indium oxide films doped with tin (ITO) prepared by a number of deposition techniques have shown excellent performances in optical transparency and electrical conductivity. However, many efforts have been made to develop transparent conducting ZnO films since ZnO is a less expensive coating material than ITO. Zinc oxide thin films are transparent due to a wide band gap of about 3.2 ev, and exhibit conductivity due to a large free carrier concentration created by oxygen deficiency or intentional doping.
Film Microstructure and its Effects on Optical Coatings
Authors: Hodgkinson Ian
Published: February 2023

This paper reviews the development of thin film models as they apply to microstructure in vapor deposited thin films and the various effects that are induced in the film properties. In general the microstructure is anisotropic and so are the film properties.
Microstructure Effects on Light Propagation in ZnS Waveguides
Authors: Himel M. D. , Ruffner J. A. , Gibson U. J.
Published: February 2023

We report a waveguide method for measuring attenuation in thin films. Effects of O2 and H2O partial pressures on ZnS film losses have been investigated.
WDM: From Interference Filters to Integrated Optics
Authors: Mahlein H.F.
Published: February 2023

If the wavelength-division multiplexing (WDM) technique is used for optical communications with glass fibers, then wavelength-selective devices are in general required. Their function is to spatially combine or separate, at the route ends, the wavelength channels simultaneously transmitted unidirectionally or bidirectionally along a single glass fiber. Micro-optical WDM devices with interference filters have proved effective in initial experimental WDM fiber-optic links. Increasing use of WDM, which is of great interest for subscriber lines, in particular in its bidirectional form, would therefore lead us to expect an additional boost for the interference filter market. However, it should be noted that a series of other micro-optical WDM devices /1,2/ have been tested, to some extent as rivals to interference filter devices, and integrated-optical WDM devices /3/ will also be available in the future. Due to the good properties of standard single-mode fibers in the wavelength regions around 1.3 µm and 1.55 µm, the development of WDM devices is being concentrated on these wavelength regions. The parameters important for the application of these devices are insertion loss a, far-end crosstalk attenuation af (for unidirectional operation) and near-end crosstalk attenuation an (for bidirectional operation). Typical values are a = 1 dB, af = 20 dB and an > 40 dB.
In-Situ Ellipsometric Monitoring and Modelling of the Growth and Synthesis of Thin Films
Authors: Netterfield R.P. , Martin P.J. , Müller K.-H. , Sainty W.G. , Pacey C.G. , Filipczuk S.W.
Published: February 2023

In-situ ellipsometry is a powerful technique for monitoring the optical properties of thin films as a function of their thickness. Some results of measurements obtained during the growth of evaporated and ion-assisted films and during their ion-etching will be interpreted in terms of recently developed computer models.
Measurement of the Thermal Conductivity of Dielectric Thin Solid Films with a Thermal Comparator
Authors: Amsden C. A. , Gilman S. E. , Jacobs S. D. , Torok J. S.
Published: February 2023

In 1984 Decker, et al.1 reported the measurement of thermal conductivity for freestanding thin films of SiO2 and Al2O3. Values were found to be one or two orders of magnitude lower than those for the corresponding bulk materials. The authors attributed this difference to the unique microstructure of dielectric thin films, which, along with defects and impurities, would be expected to reduce the phonon mean free path, and thus conductivity. Work by others has recently reinforced these findings for other dielectric coatings.2
A Study of H2O and D2O Contamination Using Laser-Induced Desorption in an Automated System
Authors: Franck J. B. , Macleod H. A.
Published: February 2023

Previous work1,2 has shown that laser-induced desorption (LID) can prove useful for the determination of surface contamination. Because of the nature of small spot sampling, however, it proved rather difficult to gather statistically significant data. Now that automation of LID has been accomplished, a detailed study of CaF2 is in progress. As in the referenced work, the samples will be irradiated with the focused beam from an HF/DF laser inside an ultrahigh vacuum chamber. The molecules desorbed from the sample surface are largely contained in a glass envelope that surrounds the ionizer of a quadrupole mass analyzer. For this study, water will be the contaminant monitored on etched, bulk CaF2. Heavy water from bulk alkali halides as well as from thin CaF2 films also will be studied in an attempt to determine the mechanism associated with the LID process.
Optical Monitoring Scheme for Narrow Bandpass Filters
Authors: Willey Ronald R.
Published: February 2023

We were presented with the problem of producing a series of narrow bandbass filters in the 8 to 12 micrometer spectral band of high durability with 1.0% tolerances on the edges and bandwidths. After some design study, it was decided to use germanium (Ge) and thorium fluoride (ThF2) as the coating materials and germanium for the substrates. The available coating chamber was equiped with an optical monitor using a photomultiplier whose response was adequate to 1064 nanometers (nm) but not at much longer wavelengths. Germanium films absorb significantly at 1064nm but it is practical to deposit 15 or more quarter waves (QWOT,s) before the optical monitor signal becomes too attenuated to make reasonable layer terminations. Figure 1 shows a typical example of the monitor signal in reflection for a series of ThF4 and Ge layers. This structure could not be monitored directly in transmittance because the monitoring signal would be too severely attenuated after the first or second Ge layer. However, the whole layer system can be monitored directly in reflection if certain design conditions are satisfied. There is also some flexibility benefit to reflection monitoring in this case where each thick Ge layer masks the reflection characteristics of the underlying layers. Each low index layer has somewhat of a fresh start on the monitor. This approach cannot take advantage of error compensation features as described by Macleod and Pelletier(1) and Zhao(2), but the fact that the layers are being monitored at 1/10th the passband wavelength gives enough sensitivity for good spectral control.
The Fabrication of Rugate Filters Using the Digital Technique
Authors: Hall R.L. , Southwell W.H. , Gunning W.J.
Published: February 2023

This paper will discuss the fabrication of rugate filters using the thin layer equivalence or digital technique. This technique uses very thin high- and low-index layers to generate an effective index profile.
Si(1-x)Nx Near Infrared Rugate Filter Fabrication by Ion Beam Assisted Deposition
Authors: Donovan E.P. , Van Vechten D. , Kahn A. , Carosella C.A. , Hubler G.K.
Published: February 2023

Infrared rugate filters were fabricated under computer control by nitrogen beam-assisted silicon e-beam evaporation. Refractive index, composition, deposition parameters, and thermal treatments were correlated.
A Study of Random Errors in Rugate Filters
Authors: Davison Joseph E. , Johnson Walter E.
Published: February 2023

Reflectance spectra for rugate filters having refractive index profiles containing random errors were calculated and compared to the spectrum of the ideal filter.
Design of Rugate Reflectors for P-polarization at Non-normal Incidence
Authors: Bloom Arnold L.
Published: February 2023

I am working with a computer program that models inhomogeneous layers as a series of up to 100 homogeneous steps per layer. With this program I have examined the behavior of reflectors containing graduated layers of various types such as straight-line ramps in log (index) and rugates. A rugate layer is defined for this purpose by an index, n, and a quarter wave optical thickness, x, such that where nmax is assumed to be the maximum n(x) at x = 1/σ. It is known that reflectors made up entirely of rugate layers should have a high reflectance at the design wavenumber σ and very little reflectance at 2σ, 3σ or any other integer multiple of σ. Such behavior is not obtained if n varies linearly, or log (n) varies linearly, or the sin2 curve is in n itself rather than log (n). In all such cases reflectance bands will appear at odd harmonics, even harmonics or both.
Determination of the refractive index and thickness of a thin film embedded into a given stratified medium
Authors: Chabrier G. , Goudonnet J.P. , Vernier P.
Published: February 2023

A thin film embedded into a known stratified medium can be characterized by non destructive optical measurements. Transmittance and reflectance can be easily measured with s and p polarizations and several incidence angles. Light can enter into the medium through a prism or a cylinder in order to extend the usable incidence angles and fulfil attenuated total reflection (ATR) conditions.
Spectroscopic Ellipsometric Characterization of TiO2/Ag/TiO2 Optical Coatings
Authors: Memarzadeh K. , Woollam J. A. , Belkind A.
Published: February 2023

Optical constants (3000-800Å) and layer thicknesses in a three-layer glass/TiO2/Ag/TiO2 structure were determined using variable angle of incidence spectroscopic ellipsometry (VASE). Spectral characteristics due to plasmon effects were observed in n and k spectra for the thin silver layers.
Optical Characterization of a Silver Film in Presence of a Dielectric Layer Using the ATR Technique
Authors: Regalado L.E. , Cruz-Encinas I.
Published: February 2023

Some methods for optical characterization of metals or absorbing films use dielectric overcoatings on the sample1. However, a possible transition layer is not taken into account and it may cause changes in the actual optical constants to be determined.
Studies on Optical Properties of Extremely Thin Films Using ATR Techniques
Authors: Jing-Jiang Xu , Jin-Fa Tang
Published: February 2023

The optical properties of extremely thin films have been of considerable interest for years. Below a certain critical thickness, thin films consist of isolated islands. Their optical constants and properties depend on the shapes of the islands and their seperation, the substrate, the deposition conditions etc. The film optical properties therefore reflect the successive stages of film growth.
Determination of The Optical Constants and Thickness of Thin Films by Measurement of Surface Plasmon Resonances
Authors: Zhang F. S. , Macleod H. A. , Jacobson M. R.
Published: February 2023

Surface plasmon resonances in metallic and dielectric thin films can be measured to determine their optical constants and thicknesses. Some optical constants and thicknesses for Ag, Al, Cu, Ta2O5, ZrO2, and SiO2 films are presented.
The Theoretical Models of the Relationship Between N and P for the Thin Films
Authors: Wang Xue-Ren , Zhou Jiu-Lin
Published: February 2023

Recently measurements of refractive index of the thin films as a function of packing density have been made at the CSIRO Division of Applied Physics on Ce02 and Zr02 films produced by ion-assisted deposition. We used the Stoner model to fit the experimental data for Ce02 and Zr02 films. Ce02 films should be considered as absorbing moisture even under vacuum. Zr02 films, are more complicated, with three regions of packing density each with appropriate column and void characteristics.
Spectrophotometer Design for the Characterization of Interference Coatings
Authors: LaDelfe Peter C. , Stahl D. B.
Published: February 2023

Commercially available spectrophotometers, designed to obtain spectra for chemical analysis, are commonly used to characterize optical components with interference coatings. In this application, they exhibit several shortcomings: the sample compartments do not accomodate large components, particularly at off-normal incidence; beam deviation introduces error in off-normal transmittance measurements; rigid beam geometry makes reflectance measurements at arbitrary angles of incidence difficult; reflectance measurements must be referenced to a standard; reflectance measurements at normal incidence are not possible; and the beam’s conic angle in the sample chamber introduces error in off-normal measurements and in the measurement of narrow bandpass filters. Previous attempts to alleviate these shortcomings1,2 have resulted in instruments which are mechanically complex, fail to address all the problems stated above, or are sensitive to the optical alignment.
Progress toward objective measurement of surface damage
Authors: Baker L R
Published: February 2023

The characterisation and measurement of surface damage such as digs and scratches concerns all manufacturers and users of optical quality surfaces. Modern methods of surface inspection, with atomic sized resolution, reveal that all real surfaces are less than perfect. But since most are fit for their intended purpose it is clearly necessary to define acceptable damage thresholds related to different situations whether these are cosmetic or functional in nature. This requirement leads to the need for a sensitive and objective means for measurement with traceability to national standards.
Optical Scatter Characteristics of Multilayer Dielectric Mirrors
Authors: Watkins Steve E. , Black J. Paul , Pond B.J.
Published: February 2023

Optical scatter characteristics were measured for high-reflectance (HR) dielectric thin films and polished fused-silica (FS) substrates. The measurements show lower scatter for thin films deposited on superpolished substrates than for identical films on conventionally polished substrates, and less scatter for uncoated superpolished surfaces than for conventionally polished surfaces. Scatter was also greatly affected by the design, the materials, the deposition process, and the process used to clean the substrates. The scatter characteristics were not improved by CO2 laser cleaning1 of the substrate prior to film deposition. Measurements were made at the design wavelengths of the thin films (i.e., 633 and 1320 nm) and consisted of bidirectional reflectance distribution function (BRDF) angle scans and spatial mappings.2
Observation of Rayleigh Scattering from Multilayer Dielectric Thin Films
Authors: Carniglia C.K. , Pond B.J. , Black J. Paul , Watkins Steve E.
Published: February 2023

This paper reports the direct observation of secondary scattering resulting from guided scattered light within a multilayer coating. In other words, the distribution and level of the light scattered by the coating is such that a significant fraction of this light is scattered into guided modes of the film. Because such guided light is trapped within the coating, it propagates within the coating until it is either absorbed or scattered a second time. The secondary scatter is observed at a significant distance from the point of incidence of the initial beam of light. Although we believe that the dramatic nature of the observations presented here results from a unique combination of experimental factors, this effect may be present in a variety of practical thin-film coatings. Perhaps even more interesting is the clear evidence that the secondary scatter observed demonstrates clearly that the primary scattered light is distributed in a dipole radiation pattern, corresponding to Rayleigh scattering from subwavelength-sized scatter sites.
Correlation Between Substrate Preparation Technique and Scatter Observed from Optical Coatings
Authors: Hickman K. C. , Wingler R. , Williams F. L. , Sobczak C. E. , Carniglia C. K. , Kranenberg C. F. , Jungling K. , McNeil J. R. , Black J. P.
Published: February 2023

Scatter from coated optical components results from the substrate surface as well as from the coating itself. In many cases the coating is the dominant source of scatter. This paper investigates the effects of substrate preparation on the scatter observed from the coated surface. The results demonstrate that the substrate preparation technique affects the level of the observed scatter and that the substrates with lowest scatter do not necessarily result in the coatings with the lowest scatter
A multiwavelength angle-resolved scatterometer or how to extend the optical window
Authors: Amra C. , Roche P. , Torriccini D.
Published: February 2023

Light scattering constitutes a powerful tool to characterize surface roughness at the scale of optical frequencies. Many results have been published [1] and show that the measured roughness spectrum is an intrinsic property of the surfaces. This valids both the accuracy of the scatterometer and the validity of the electromagnetic theory.
Ultra-Microhardness Testing and Mechanical Properties of Ceramic Optical Thin Films
Authors: Bangert H. , Wagendristel A. , Guenther K. H.
Published: February 2023

We evaluated ion plated and, for comparison, electron beam evaporated thin films with an ultra-microhardness tester used with an optical microscope. Implementations of the instrument for use inside a scanning electron microscope1,2,3 and with a high resolution optical microscope4 have been described in sufficient detail elsewhere. Figure 1 shows typical indentations made with a Vickers diamond in a rather thick ion plated single layer of TiO2 in comparison with an indentation obtained in an electron beam evaporated film of the same material and similar thickness. The ultra-microhardness values resulting from the measurement of the imprint diagonal differ whether the indentations are observed and measured with an optical microscope or with a scanning electron microscope.
Research on adhesion of thin films on plastins substrates
Authors: Lee Cheng-chung , Wei Chaur-Tsang , Lee Chii-hua
Published: February 2023

Plastics become an importance optical components because of several advantages like, light in weight, can be injected for mass production, and cheaper in cost as compared with glass.
Design approach for multi-line narrowband-pass filters
Authors: Southwell William H.
Published: February 2023

The simplest narrowband-pass filter is a thin-film Fabry-Perot cavity consisting of a quarterwave stack with a central layer being a multiple halfwave, as shown in Fig.1. Such cavities can have a series of pass bands if the reflectance bands are broad enough and the spacer layer is thick enough. Such pass bands are uniformly spaced in wavenumber. The need sometimes arises for a multi-line narrowband-pass filter in which the wavelengths of the pass bands are not uniformly spaced.
Design of Fully Shaped Graded Reflectance Mirrors With Phase Control
Authors: Verly P.G. , Duplain G.
Published: February 2023

Dielectric graded reflectance mirrors (GRMs) with a gaussian or supergaussian radial variation of the reflectance are known to reduce significantly the detrimental effects of hard edge diffraction in unstable laser resonators. Different types of GRMs consisting of a single graded thickness layer incorporated in a conventional multilayer system have been demonstrated. Such mirrors are beginning to be offered, in moderate reflectances, by major manufacturers for use in high gain lasers.
Multilayer dielectric mirrors with minimal dispersion of differential phase shift upon reflection
Authors: Abelès Florin , Baumeister Philip
Published: February 2023

Lasers and liquid crystal displays often require coatings that reflect the incident radiant flux with minimal change in its state of polarization. The differential phase shift upon reflection of such a coating should be zero. Since there is always a possibility of drift of the wavelength centering of the stack during fabrication, the dispersion of the differential phase shift upon reflection should also be minimal.
Dielectric Wide-Band Nonpolarizing Prism Beam Splitter
Authors: Yongchang Lin , Shaoji Jiang , Weiqiang Lu
Published: February 2023

It is difficult to attain a nonpolarizing assembly of optical thin films because the optical admittance of layer for S polarizing component of light waves is not equal to that for P polarizing component when the waves are obliquely incident upon the surface of the layer. The dependence of the admittances on the refraction angle of the waves inside the layer is as fellows: where n1 is the refraction index of the layer, and θ1, the refraction angle.
Design of Filters for Two Widely Separated Spectral Regions
Authors: Li Li , Dobrowolski J. A.
Published: February 2023

In a previous paper1 a systematic method was described for the design of antireflection coatings which act simultaneously in two widely separated spectral regions. Examples were given of antireflection coatings that were effective in the visible and in the infrared for a number of different substrate materials.
Design of Optical Multilayer Systems Desensitized With Respect to Construction Parameter Errors
Authors: Ho F. C. , Dobrowolski J. A.
Published: February 2023

Uncertainties in the optical constants and finite errors in the thicknesses of the layers due to shortcomings of the deposition and monitoring processes lead to a divergence between the expected and measured performances of optical multi-layer coatings. One way to reduce the effect of errors is to use a continuous evaluation and reoptimization process for the control of the deposition process.1,2 Another is to find designs whose performances are less sensitive to the experimental errors.3,4 The performances of de-sensitized multilayer systems are invariably worse than those of the optimum solutions. However, the chances of satisfactory deposition runs with such systems are significantly increased.
A Recursive Formulation of the Stability of Optical Interference Coatings
Authors: García-Llamas R. , Leyva-Lucero M. , Regalado L.E.
Published: February 2023

The knowledge of variations in the reflectance in terms of the optical thickness in an all-dielectric multilayer coating simplifies the design and fabrication of a given optical device using thin film techniques. This variation has been defined as stability /1/ and has been demostrated to be inversely proportional to the partial derivative of the reflectance with respect to the phase change (∂R/∂ψ) or when this quantity vanishes, it is inversely proportional to the second derivative (∂2R/∂ψ2), following a second order development.
The influence of Variation of Electrophysical Parameters and the Small Losses in the Layers of Superfine Stratified Periodic Structures on Their Optical Properties
Authors: Kozar A. V. , Putrina E. V.
Published: February 2023

The article deals with the problems of synthesis and analysis of optical and structural properties of superfine stratified periodic structures (1-3). On the basis of the development of the general theory of their synthesis, an analytical and numerical investigation is carried out of the influence of variation in layers' thicknesses and refraction indecies in such class of structures on their optical characteristics and properties.
Fundamental Properties Of Superfine Stratified Periodic Structures
Authors: Kozar A. V.
Published: February 2023

The general analysis of the propagation of electromagnetic waves through multilayer periodic structures has been carried out by the auther. The analysis of the results obtained reveales, that along with traditional quarter wave-length (or multiplied of) layers, other structures can be constructed. The algorithm of their synthesis is based on the absolute minimization of the layers' optical thickness. This minimization is carried out relatively to the alterating of the phase of wave which is reflected from the whole structure.