Sensitivities of reflectance of two-material non-polarizing all-dielectric beamsplitter coatings on variations of the angle of incidence, refractive indices and thickness of layers were studied. Taking into account sensitivities and optical specifications, tolerance requirements for these parameters were estimated. Three types of coatings, for 0,2, 0,32 and 0,5 nominal reflectance at 45° incidence in air, were taken into consideration. Coatings were designed on the basis of a buffer layer and internal antireflection.
Spectral properties of excitation and emission path of epifluorescence microscope at object and image planes has been determined and analyzed for two of filter sets. Attenuation of excitation path at object plane and attenuation of emission path at image plane were proved to be useful for this purpose. Calculations were carried out for epifluorescence filters made for FITC (fluorescein) type fluorophores (494ex/518em).
A direct measurement of reflectance spectrum of steeply curved surfaces on commercial spectrophotometer is almost impossible. This work describes the use of colorimetry to estimate the change of spectral reflectance of antireflection coating deposited on such surfaces. The investigations show that the color coordinates for daylight D65 of coatings may be uses for this purpose. The coating deposited on curved surface consists of layers of aluminum oxide, substance H4 highly refractive and magnesium fluoride. Color coordinates for normal CIE'31 observer and illuminant D65 was calculated for varying thickness of layers of the coating. Comparison of calculated on this way color coordinates and observed colors on surface show that method may be used to estimate the reflectance spectrum distribution on the lens surfaces.
Loci of the optical admittance of GRIN thin films are studied. We have investigated by means of the computer modeling, how the trajectory of the loci will change if the layer will have a different inhomogeneity coefficient. During the modeling we have employed a method of discretization of the GRIN layer by dividing the layer to sublayers which have equal thickness and constant refractive index. We have also examined how these loci will be affected by absorption in the layer, determined by different values of the extinction coefficient. Layers are assumed to be deposited on the bare glass substrate or substrate with a quarter- or eight-wave optical thickness layer. Results may be applied to the interpretation of the monitoring signals of the thin-film optical monitors.
Costich's concept of intersection admittance for s- and p-polarization components of reflectivity of symmetrical three-layer subsystems together with depolarization of the incident medium and the substrate is used to design nonpolarizing narrow band anti-reflection coating. First, incident medium with one layer sub-coating and the substrate with three-layer sub- coating which forms a nonpolarizing structure of defined depolarized effective admittances are discussed. Next, the group of three layers was found which operates as depolarized system with effective admittance which match effective admittances of incident medium and the substrates are discussed. Superimposing of all these subsystems arrive at the design of the seven layer narrow band nonpolarizing anti-reflection coating. Ohmer's algorithm in generalized form by Knittl and Houserkova was used for finding the structure of the matching subsystem. Results of calculations are shown in graphical forms using conjugate s- and p- admittance diagrams.
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