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31077918-1319569
LED Lighting Fixtures PLD E 409 W 350
the angle at which a display can be viewed with acceptable visual performance.
Lenses are classified by the curvature of the two optical surfaces. A lens is biconvex (or double convex, or just convex) if both surfaces are convex. If both surfaces have the same radius of curvature, the lens is equiconvex. A lens with two concave surfaces is biconcave (or just concave).
the measure of the perceived power of light.