SURFACE LIGHT SOURCE DEVICE LIGHT GUIDE ELEMENT USED FOR SURFACE LIGHT SOURCE DEVICE AND METHOD FOR PRODUCING LIGHT GUIDE ELEMENT

摘要

A light guide 24 having a light incident surface, a light exit surface 242, and a back surface 243 located on the opposite side of the light exit surface 242. A foaming surface layer 244 is formed on at least a part of at least one of the light exit surface 242 and the back surface 243. The foaming surface layer 244 includes bubbles and also has a light exit surface 242 or a back surface 243 have a concave shape in cross section including the direction of the normal line. The light guide 24 is formed by forming the foamed surface layer 244 by performing infrared laser etching on at least a part of at least one main surface of a plate-like light guide material made of an acrylic resin plate produced by a continuous plate making method .