Patent ID: 8128240

Claim:
An optical unit comprising: a frame; an optical member disposed on the frame, the optical member having a rectangular plate-shape having a width, a height, and a thickness; and a pair of mount portions formed in the frame, each of the mount portions holding a side of the optical member in a width direction, wherein each of the mount portions includes an insertion slot into which an end of the optical member in the width direction at an end of the optical member in a height direction is inserted in the height direction, wherein the insertion slot includes an opening and a bottom facing each other in a depth direction of the insertion slot, wherein the insertion slot is formed between a first wall and a second wall of the frame, the first and second walls facing each other, wherein the first wall includes a thickness direction positioning surface that is in contact with one of the surfaces of the optical member in a thickness direction, the optical member being inserted into the insertion slot, so that the optical member is positioned in the thickness direction, wherein the second wall includes an inclined surface near the bottom of the insertion slot, the inclined surface being inclined such that the distance between the inclined surface and the thickness direction positioning surface decreases with decreasing distance from the bottom, and wherein the optical member is fixed to the frame using an adhesive applied between the frame and the optical member in a state in which the one of the surfaces of the optical member is pressed against the thickness direction positioning surface and an end of the optical member in the height direction on the other of the surfaces of the optical member in the thickness direction is pressed against the inclined surface.