fixed mirror
91Navigation — This article is about determination of position and direction on or above the surface of the earth. For other uses, see Navigation (disambiguation). Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. Navigation is the… …
92Laser engraving — is the practice of using lasers to engrave or mark an object. The technique can be very technical and complex, and often a computer system is used to drive the movements of the laser head. Despite this complexity, very precise and clean… …
93Rear-projection television — Rear projection is a type of large screen television display technology. Most very large screen TVs (to 100 inches [254 cm] or more) use rear projection. A variation is a video projector, using similar technology, which projects onto a… …
94heliostat — heliostatic, adj. /hee lee euh stat /, n. an instrument consisting of a mirror moved by clockwork, for reflecting the sun s rays in a fixed direction. [1740 50; < NL heliostata. See HELIO , STAT] * * * ▪ instrument instrument used in solar… …
95Symmetry group — Not to be confused with Symmetric group. This article is about the abstract algebraic structures. For other meanings, see Symmetry group (disambiguation). A tetrahedron can be placed in 12 distinct positions by rotation alone. These are… …
96Astrophotography — An image of Orion s Belt composited from digitized black and white photographic plates recorded through red and blue astronomical filters, with a computer synthesized green channel. The plates were taken using the Samuel Oschin Telescope between… …
97Orbifold — This terminology should not be blamed on me. It was obtained by a democratic process in my course of 1976 77. An orbifold is something with many folds; unfortunately, the word “manifold” already has a different definition. I tried “foldamani”,… …
98Differential amplifier — symbol The inverting and non inverting inputs are distinguished by − and + symbols (respectively) placed in the amplifier triangle. Vs+ and Vs− are the power supply voltages; they are often omitted from the diagram for simplicity, but of course… …
99Operation Frequent Wind — Part of the Fall of Saigon, Vietnam War …
100TalkTalk — For other uses, see Talk Talk (disambiguation). TalkTalk Telecom Group PLC Type Public limited company Traded as LSE:  …
