Structure for attaching a lens to prevent distortion from changes in the ambient conditions

摘要

Fitting holes are formed on a line of extension or a substantially vertical bisector in an arranging direction of a pair of lenses of a plastic plate formed integrally with at least the pair of lenses. Correspondingly, bosses are formed protruding from a base body using an adherable material so that a height thereof is larger than a sum of a thickness of the plastic plate and a thickness of a stop plate. Even after attaching the stop plate and the plastic plate to the base body, the bosses are protrudable from the plastic plate. Thus, the plastic plate and the stop plate are fixed in a sandwiched state between the base body and an adhesive agent. The plastic lens having a poor adhesion with the adhesive agent can be surely fixed without increasing the number of parts, and an instability of a positional accuracy due to environmental changes is obviated.