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A large number of Indian Standard (IS) codes are available that are meant for virtually every aspect of civil engineering one can think of. During one's professional life one normally uses only a handful of them depending on the nature of work they are involved in. Civil engineers engaged in construction activities of large projects usually have to refer to a good number of IS codes as such ...
The basic principles behind optical waveguides can be described using the concepts of geometrical or ray optics, as illustrated in the diagram. Light passing into a medium with higher refractive index bends toward the normal by the process of refraction (Figure a.). Take, for example, light passing from air into glass.
A telecentric lens is a special optical lens (often an objective lens or a camera lens) that has its entrance or exit pupil, or both, at infinity. The size of images produced by a telecentric lens is insensitive to either the distance between an object being imaged and the lens, or the distance between the image plane and the lens, or both, and ...
Cone of light behind an achromatic doublet objective lens (A) without (red) and with (green) a Barlow lens optical element (B). The Barlow lens, named after Peter Barlow, is a type of diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system.
The size of the finest detail that can be resolved (the resolution) is proportional to λ / 2NA , where λ is the wavelength of the light. A lens with a larger numerical aperture will be able to visualize finer details than a lens with a smaller numerical aperture. Assuming quality (diffraction-limited) optics, lenses with larger ...
A catadioptric optical system is one where refraction and reflection are combined in an optical system, usually via lenses and curved mirrors . Catadioptric combinations are used in focusing systems such as searchlights , headlamps , early lighthouse focusing systems, optical telescopes , microscopes , and telephoto lenses .
The cardinal points were all included in a single diagram as early as 1864 (Donders), with the object in air and the image in a different medium. Cardinal point diagram for an optical system with different media on each side. F for Focal point, P for Principal point, NP for Nodal Point, and efl for effective focal length. The chief ray is shown ...
The distance is not the same as from the object to the lenses. Real images may also be inspected by a second lens or lens system. This is the mechanism used by telescopes, binoculars and light microscopes. The objective lens gathers the light from the object and projects a real image within the structure of the optical instrument.