Patent ID: 6379017
Filing Date: 2002-04-30
Classification: G02B,G02F

Abstract:
An illuminating system for illuminating an object by overhead light irradiation, said illuminating system comprising:a light source; and a light guide member, wherein a plurality of grooves are provided on a top face of said light guide member at specified intervals and in a direction parallel to a longitudinal direction of said light source; wherein each of said plurality of grooves provided on the top face of said light guide member is a V-shaped groove having a first slope of the groove located on a side closer to said light source and a second slope of the groove located on a side farther from said light source, and wherein an angle &thgr;2 formed by the second slope and a bottom face of said light guide member satisfies a condition of &thgr;2&lE;(1/2)sinâˆ’1(1/n), wherein n is a refractive index of said light guide member; wherein flat portions constituting a part of the top face of said light guide member are arranged in between adjacent ones of said plurality of the grooves; and wherein the object is disposed on a side of the bottom face of said light guide member and is observable from the top face side of said light guide member.