Abstract: A light adjustment device includes a panel unit including a plurality of light adjustment panels stacked in a first direction, each light adjustment panel including a first substrate and a second substrate, the first substrate including a first terminal, the second substrate overlapping the first substrate and including a second terminal, and a metal film provided at a side part of the panel unit and extending in the first direction.

Abstract: A light receiving holder includes an abutting portion and a welded portion and the welded portion includes a ring-shaped projection which extends from the welded portion and whose cross-section is smaller as it is closer to the tip of the projection. A cap of a casing constituting a light receiving unit is received in a through-hole of the light receiving holder. The projection is brought into contact with a flange of the casing. Current is supplied between a lower electrode and an upper electrode to resistance-weld the projection to the flange. At this time, an angle is provided between a facing face of the lower electrode and a facing face of the upper electrode so that the light receiving holder is welded to the light receiving unit while an angle of the light receiving unit relative to the light receiving holder is adjusted.