Light guide plate and surface light source using same

摘要

An exemplary light guide plate ( 500 ) includes: a light incident portion ( 51 ) for receiving a light; a light reflecting portion ( 52 ) for reflecting the light input through the light incident portion; and a light emitting portion ( 53 ) opposite to the light reflecting portion, for outputting the reflected light. The light incident portion includes a first diffractive optical element ( 512 ) located thereat. The first diffractive optical element includes a plurality of protrusions ( 512 a) each having a curved surface, with the protrusions being arranged symmetrically opposite to each other across a central axis of symmetry of the first diffractive optical element. The light emitting portion may include a second diffractive optical element ( 532 ) located thereat. The second diffractive optical element includes a plurality of elongate protrusions, with the protrusions being arranged symmetrically opposite to each other across a central axis of symmetry of the second diffractive optical element.