Light guide member and light guide member manufacturing method

A manufacturing method for a light guide member, the light guide member comprising:

• first and second ends, the first end being one end, in a length direction, of the light guide member elongated in one direction, the second end being an opposite end of the light guide member from the first end, a light entrance surface being provided on at least one of the first and second ends;
• a reflective surface that is provided along the length direction of the light guide member and configured to reflect light from the light entrance surface;
• and
• a light exit surface that is provided along the length direction of the light guide member and allows the light reflected in the reflective surface to exit from, wherein
• the reflective surface comprises at least one diffusion groove array including diffusion grooves that are arranged in the reflective surface in the length direction of the light guide member and configured to diffuse the light from the light entrance surface, the diffusion groove array comprising, as the diffusion grooves, at least two inspection grooves and a non-inspection diffusion groove, the two inspection grooves being spaced in the length direction of the light guide member, the non-inspection diffusion groove being between the two inspection grooves, and
• the manufacturing method for the light guide member comprising:
• forming the diffusion grooves by grooving work onto the reflective surface of the light guide member;
• and
• dividing an intermediate part, in a length direction, of each of the two inspection grooves by an ungrooved portion to which the grooving work is not applied, thereby forming the two inspection grooves;
• stopping or decreasing laser output while the two inspection grooves are formed by the laser radiation, thereby providing the ungrooved portions, wherein
• the grooving work includes laser radiation onto the reflective surface,
• the reflective surface comprises groove formation regions arranged in the length direction of the light guide member, and
• the reflective surface comprises, as said at least one diffusion groove array, diffusion groove arrays arranged in the length direction of the light guide member;
• and wherein
• the manufacturing method for the light guide member further comprises:
• applying the grooving work to the groove formation regions based on respective prepared patterns for the groove formation regions, thereby forming the diffusion groove arrays in the groove formation regions one by one.