tutorial

tutorialVariations in materials and physical parameters yield optical coatingsthat can act as high reflectors, antireflectors, and optical filters.By Ranko Galeb, VLOCptical thin films have become an inte-gral part of almost all the opticalcomponents and systems manufacturedtoday. Their primary function is to gov-ern the spectral composition and theintensity of the light transmitted or reflectances of 90% to 98%.reflected by the optical system. Properly applied to variousoptical surfaces in a given system, optical coatings can greatly coating designenhance image quality and provide a convenient method to Without getting into deep analysis of design methods of opticalspectrally manipulate light. thin films, let us point out that the main building blocks inLight behaves according to the laws of electromagnetic designing optical coatings are quarter-wave optical thicknesswaves. Thus, the interaction of light with the media that it trav- (QWOT) layers of different materials. The QWOT materialsels through or is reflected from is directly related to its wave of high, medium, and low refractive index are usually denotednature and manifests as the phenomena of interference and as H, M, and L, respectively. If there are two QWOT layers ofpolarization. Whenever light interacts with a thin-film struc- the same material next to each other, they form a half-waveture, interference occurs. The degree of polarization imparted optical thickness (HWOT) layer. If only a ...