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Polymers for Optics
Published in Solomon Musikant, Optical Materials, 2020
Epoxies and methacrylates are widely used for adhesives with index refraction varying from 1.47 to 1.61. Initially, Canada balsam (n = 1.52, νd = 42) was used as a cement but was supplanted due to its temperature and humidity sensitivity. Canada balsam is made from the sap of the North American balsam fir. It is a turpentine consisting of essential oils and resins and is soluble in xylol. Polyester styrene was introduced about 1950, and today a variety of adhesives are available which are servicable between −85 and +180°F without failure.
Optical Materials for Ultraviolet, Visible, and Infrared
Published in Moriaki Wakaki, Optical Materials and Applications, 2017
Arai Toshihiro, Wakaki Moriaki
Several kinds of typical polarizing prisms are shown in Figures 2.16a, 2.16b, 2.16c, 2.16d, 2.16e, and 2.16f. Prisms (a) and (b) are made by two pieces of calcite stuck together with Canada balsam. The refractive index of Canada balsam is 1.55, which has an intermediate value between the refractive indices of ordinary ray, 1.66, and extraordinary ray, 1.47, in calcite. Therefore, ordinary ray reflects totally upon the Canada balsam layer between two pieces of calcite, and extraordinary ray passes through the Canada balsam layer. Prisms (c) and (d) have similar structures to (a) and (b), but they have an air gap instead of a Canada balsam layer. Therefore, these prisms can be used in a wider wavelength region. Prisms (e) and (f) also have similar structures, but the arrangement of the optical axes of two pieces of calcite differs from the above prisms. The optical axes of two pieces of Calcite cross perpendicularly to each other. Furthermore, the two pieces of uniaxial crystals are stuck by vacuum compression. A calcite prism can be used in the range between 300 nm and 2.2 μm, a quartz prism can be used in the range of 190 to 400 nm, and a MgF2 prism can be used within a 130 to 200 nm range. Furthermore, there are two different types of polarizing beam splitters. The structures and the directions of separated beams are shown in Figures 2.17a and 2.17b. As shown in Figure 2.17a, two orthogonal prisms are stuck with sloping surfaces that are coated multiply with dielectric materials. The optical beam enters on the boundary of the multilayer with nearly Brewster angle. Therefore, p-polarized light passes the boundary without reflection, but s-polarized light reflects many times by many boundaries of the multilayer, and the reflectivity reaches over 98%. Figure 2.17b is called a Savart plate. The light beam enters along the diagonal direction to the optical axis. Therefore, one polarized beam propagates along the incident beam direction, and other one refracts on the incident plane and propagates along an oblique direction to the incident beam direction after coming out from the other surface.
Effect of different forms of carbon on the reduction behaviour of iron ore-carbonaceous material composite pellets in multi-layer bed rotary hearth furnace (RHF)
Published in Canadian Metallurgical Quarterly, 2021
Shailesh Priyadarshi, Srinibash Mishra, Binay Kumar, Gour Gopal Roy
Phase and microstructural characterisation of the reduced pellets were done using XRD and SEM/EDS (energy-dispersive X-ray spectroscopy). The metallographic samples of the reduced pellets were prepared by dipping the pellets in liquid resin, Canada balsam, at 100°C and then subsequently cooling. Canada balsam penetrates the pellet’s pores and anchors the particles on solidification, resulting in more integrity of particles facilitating smooth polishing during sample preparation. Canada balsam is a resin with a refractive index identical to that of glass, such that it does not appear in the microstructural analysis. The equilibrium phase constituents in the microstructure were also estimated using Factsage thermodynamic software.