RESUMO
A broadband transmission filter from 400 to 1100 nm was selected for the manufacturing problem contest. The purpose of the contest is to test the state of the art of current optical thin film manufacturing capabilities. A total of 37 people from 15 teams participated in the contest and submitted 17 samples. Diverse approaches were taken by participants to tackle the problem. A range of different solutions was obtained where the number of layers varied from 22 to 608, and the total layer thickness ranged from 1.859 to 23.099 µm. Two independent laboratories performed sample evaluation measurements. Three teams shared the best result with the lowest average measured merit function.
RESUMO
Thin films of high reflecting metal, such as Ag, have a high reflectance in the long-wavelength region. When they are combined with dielectric layers, it is possible, through thin film interference effects, to induce transmission in certain shorter wavelength regions. Thus, they are useful components for the design of long-wavelength cutoff filters with a broad rejection region. In this paper, metal/dielectric multilayer designs based on this principle are numerically investigated. Three designs with different cutoff wavelengths and with very broad transmission regions in the visible or near-IR spectral ranges are presented. An excellent rejection on the long-wavelength side extends beyond 20 µm. Experimental results for one of the designs produced in our magnetron sputtering system are given.
RESUMO
Our first attempts at the fabrication of long-wavelength infrared cut-off filters with extended transmission and rejection regions that are based on the use of the critical angle, the dispersion of refractive indices, and on thin-film interference were not very successful. The design of the filter consisted of layers placed at the interface between two high-index prisms. Using the available deposition equipment, the layers produced were porous and very rough. The pores adsorbed water vapor, which resulted in absorption. The roughness made the process of optical contacting very difficult. In this paper we describe the adjustments in the design and deposition processes that allowed us to obtain filters with a better and more stable performance.
RESUMO
For the 2010 Manufacturing Problem, the participants were required to produce a filter that had normal incidence transmittances of 0.001, 0.01, 0.1, and 0.96, respectively, in four separate 60 nm wide bands in the 400 to 700 nm wavelength region. The problem is not unlike those that need to be routinely solved in the telecommunication industry. Nine groups submitted a total of 11 different filters for the contest. The number of layers in the filters received ranged from 28 to 678, and the total metric thicknesses varied between 4,038 and 22,513 nm. The transmittances of the filters were measured at two independent laboratories. Some of the performances were quite close to the specifications.
RESUMO
The use of solid frustrated total internal reflection (FTIR) layers to control the polarization effects in optical coatings usually results in large substrate sizes and complicated designs. To overcome this problem, it is proposed to incorporate an air FTIR layer into the multilayer thin film coatings. The low refractive index of air not only helps to reduce the substrate sizes, but also simplifies coating designs or improves the performance. The principle and layer structures of the proposed multilayers are described. Examples of polarizing- and non-polarizing beam-splitters for the infrared spectral region are given. Some practical manufacturing issues are also discussed.
Assuntos
Lentes , Manufaturas , Membranas Artificiais , Refratometria/instrumentação , Ar , Desenho de Equipamento , Análise de Falha de Equipamento , Integração de SistemasRESUMO
The Fourier transform thin film synthesis method often results in solutions that call for indices that lie outside the range of values of the available materials. To make the resulting refractive index profiles always realizable in our meta-mode sputtering machine, a modified Fourier transform synthesis method is proposed with which the reflectance spectra can be accurately synthesized with controllable and predictable refractive index profiles. In our procedure, an optimal phase function is explored to yield acceptable refractive index profiles. Then the overall thickness is estimated using the Parseval theorem. Finally, several errors inherent to the Fourier transform method, including the imprecision of the spectral function, the truncation of the film and the apodization of the refractive index profiles, are compensated by successive corrections to the magnitude of the spectral function. An explicit iterative formula based on the derivative of the magnitude function is proposed for the compensation of the spectral mismatches. We show with a number of examples that, with the proposed method, it is possible to synthesize gradient-index optical filters with almost any desired spectral performance using experimentally realizable refractive indices.
Assuntos
Astrologia , História do Século XV , História do Século XVI , Magia , Filosofia Médica , Europa (Continente) , VitalismoRESUMO
Chuck Carniglia was an industrial scientist, an educator, and a friend to all he met. He had an important impact on the optical thin-film community. This article highlights his career and accomplishments.
RESUMO
Measurements are described on the experimental filters submitted to the Third Optical Thin Film Manufacturing Problem in which the object was to produce multilayers with a measured colorimetric performance that is as close as possible to that specified. The perceived colors of the coating, when illuminated with randomly polarized light incident at 7 degrees by a source representing average daylight with a correlated color temperature of approximately 6500 K, were to be yellow and blue, respectively, in light reflected from its two surfaces, and the color was to appear white when viewed in transmission mode. Eleven teams from 7 different countries submitted a total of 18 samples.
RESUMO
We deal with optimal two-material antireflection (AR) coatings for the visible and adjacent spectral regions. It has been shown before that, for a given set of input parameters (refractive indices of the substrate, ambient medium and high- and low-index coating materials, and for a given spectral width of the AR coating), such designs consist of one or more clusters of layers of approximately constant optical thickness and number of layers. We show that, through the analysis of many different optimal coatings, it is possible to derive two parameters for a simple empirical expression that relates the residual average reflectance in the AR region to the number of clusters. These parameters are given for all possible combinations of relative spectral bandwidth equal to 2, 3, and 4; low-index to ambient-medium index ratio equal to 1.38 and 1.45; and high-to-low index ratio equal to 1.4, 1.5, and 1.7. The agreement between the numerically and the empirically calculated values of residual average reflectance is excellent. From the information presented the optical thin-film designer can quickly calculate the required number of layers and the overall optical thickness of an AR coating having the desired achievable residual average reflectance.
RESUMO
Alfred Thelen has made many very important contributions to the field of optical thin films. To honor him on the occasion of his 75th birthday, I prepared a bibliography of his many contributions for the ninth Topical Meeting on Optical Interference Coatings. Here an updated list of Alfred Thelen's books, chapters, papers, conference reports, and patents is presented.
RESUMO
Philip Baumeister pioneered the design of optical thin films by computer methods. He has published many important papers on various aspects of optical coatings, and he initiated the Optical Society of America's Topical Meetings on Optical Interference Coatings. Most important, during his time at the University of Rochester and thereafter, he trained and mentored generations of researchers and engineers in the theory and practice of thin-film interference coatings. Originally, a talk was prepared to celebrate his 75th birthday at the ninth Topical Meeting on Optical Interference Coatings. Because of his untimely demise on 22 October 2003, it was presented at the conference to honor his memory. This is a written version of the tribute that contains a comprehensive list of Philip Baumeister's various publications.
RESUMO
Results are presented for the second Optical Society of America's Optical Interference Coatings Manufacturing Problem. The participants were asked to produce multilayer coatings which, in the 450-650 nm spectral region and for light incident at 60 degrees, would have transmittances of 0.7 and 0.3 for p- and s-polarized light, respectively. Three different teams each submitted four solutions. Three different deposition processes were used to produce these coatings. The smallest average departure from the target transmission values was 0.79%. A number of interesting conclusions can be drawn from this exercise.
RESUMO
The equipment and methods used to produce wide-angle antireflection coatings based on Reststrahlen materials are described. The optical constants of the coating materials used in the construction of the multilayers were determined by spectrophotometric ellipsometry and are compared with the literature values. The measured performance of an experimentally produced antireflection coating is compared with the expected calculated performance. The reflectance is low over a wide range of angles, but only in the narrow-wavelength region at which the refractive index of the Reststrahlen material is close to unity.
RESUMO
A fast automatic synthesis program based on interference minus filters is described. It yields the parameters of a number of individual filters that together match any desired spectral transmittance curve, providing that the spectral range over which the latter is defined is not excessive. It is shown that in practice many of these components can be combined without significantly affecting the performance. When used alone, the program may yield solutions consisting of a large number of layers. It is demonstrated that far fewer layers are needed if intermediate solutions obtained with this program are refined using other automatic synthesis programs. The program is illustrated by a number of rather difficult hypothetical problems.
RESUMO
It is shown that sufficient progress in the design and manufacture of thin film interference filters has been made to consider the construction of filters with the rather complicated spectral characteristics necessary for the adjustment of the spectral response and spectral power distributions. By way of example, the calculated and experimental performance of filters for changing the color temperature of a light source and for duplicating the color mixture functions of the CIE standard observer are given. Other examples discussed are filters for obtaining a uniform spectral response of optical systems consisting of a light source and a monochromator, with or without a detector.
RESUMO
Some organizational aspects of the Second OSA Topical Meeting on Optical Interference Coatings held in June 1980 at Oakland, Calif., are briefly described.