Optical apparatus

An optical device comprising:

• a light-emitting unit that emits light forward in a first direction;
• and
• a light-receiving unit arranged backward in the first direction relative to the light-emitting unit,
• wherein the light-emitting unit comprises a light-emitting-side through hole that causes light traveling backward in the first direction to pass through, and the light-receiving unit comprises a light-receiving element provided with a light receiver that receives light having passed through the light-emitting-side through hole,
• the light-emitting unit comprises:
• a light-emitting-side base member having a light-emitting-side obverse surface that faces forward in the first direction, a light-emitting-side reverse surface that faces backward in the first direction, and a light-emitting-side recess recessed from the light-emitting-side obverse surface, the light-emitting-side recess having a light-emitting-side recess bottom surface that is spaced apart from the light-emitting-side reverse surface and faces forward in the first direction;
• light-emitting-side wiring formed on the light-emitting-side base member;
• and
• a light-emitting element housed in the light-emitting-side recess,
• wherein the light-emitting-side through hole is connected to the light-emitting-side obverse surface and the light-emitting-side reverse surface,
• the light-emitting-side wiring has a light-emitting-side through portion that extends from the light-emitting-side recess bottom surface to the light-emitting-side reverse surface through a thickness of the light-emitting-side base member,
• the light-emitting-side wiring has a light-emitting-side reverse surface portion that is formed on the light-emitting-side reverse surface and electrically connected to the light-emitting-side through portion,
• the light-emitting-side through hole has a first opening formed in the light-emitting-side obverse surface and a second opening formed in the light-emitting-side reverse surface, and the light-emitting-side recess has a third opening formed in the light-emitting-side obverse surface, the first opening being smaller in area than the third opening as viewed in plan, and
• the light receiver of the light-receiving element is greater in area than the second opening of the light-emitting-side through hole.