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A Geissler tube is a precursor to modern gas discharge tubes, demonstrating the principles of electrical glow discharge, akin to contemporary neon lights, and central to the discovery of the electron. [1]: 67 This device was developed in 1857 by Heinrich Geissler, a German physicist and glassblower.
Therefore, as the ray reflects first from side x then side y and finally from side z the ray direction goes from [a, b, c] to [−a, b, c] to [−a, −b, c] to [−a, −b, −c] and it leaves the corner with all three components of its direction exactly reversed. Corner reflectors occur in two varieties.
A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. [ 1 ] [ 2 ] In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle.
A ray tracing diagram for a converging lens. A device that produces converging or diverging light rays due to refraction is known as a lens. Lenses are characterized by their focal length: a converging lens has positive focal length, while a diverging lens has negative focal length. Smaller focal length indicates that the lens has a stronger ...
The principal ray or chief ray (sometimes known as the b ray) in an optical system is the meridional ray that starts at an edge of an object and passes through the center of the aperture stop. [5] [8] [7] The distance between the chief ray (or an extension of it for a virtual image) and the optical axis at an image location defines the size of ...
Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays.The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances.
Simplified representation of an anode ray tube, showing the rays to the right of the perforated cathode Anode ray tube schematics. Goldstein used a gas-discharge tube which had a perforated cathode. When an electrical potential of several thousand volts is applied between the cathode and anode, faint luminous "rays" are seen extending from the ...
For a (reflecting) mirror, the real image is on the same side as the object while the virtual image is on the opposite side of, or "behind", the mirror. In diagrams of optical systems, virtual rays (forming virtual images) are conventionally represented by dotted lines, to contrast with the solid lines of real rays.