Abstract: A battery includes a wound electrode assembly. The wound electrode assembly has a flat shape. The wound electrode assembly includes a first separator, a positive electrode plate, a second separator, and a negative electrode plate. The first separator, the positive electrode plate, the second separator, and the negative electrode plate are stacked in this order and then wound spirally. In a cross section perpendicular to a winding axis of the wound electrode assembly, the first separator has a first winding start edge inside an innermost circumference of the wound electrode assembly; the second separator has a second winding start edge inside the innermost circumference of the wound electrode assembly; the first winding start edge faces the second winding start edge with the winding axis interposed therebetween; and the first winding start edge is located apart from the second winding start edge.

Abstract: A light source device includes: a light source that outputs laser light; an optical fiber that includes: a proximal end on which the laser light is incident and a distal end portion including a distal end and a distal end surface at the distal end; a fixing member that fixes the optical fiber by surrounding an entire circumference of the distal end portion; and an optical component disposed at a position through which an extension line of the optical fiber at the distal end of the optical fiber passes.