A method is provided for processing a lead frame. The printing unit selects, during printing on a recording medium, whether printing information or a background is rendered with first dots having a size set in advance or rendered with second dots larger than the first dots and prints the printing information or the background. The secondary sealing portion is formed of a bead and a foamed coating layer coated on one side or both sides of the bead to cover at least a portion of the bead in a belt shape. By providing a tapering in a direction in a direction at least substantially parallel to the first optical axis, any inaccuracies primarily affects the non-critical positioning in the direction along the optical axis, whereas the critical positioning transverse to the optical axis merely depends on the symmetry of alignment features.