Marker

A marker formed of an optically transparent material, the marker comprising:

• a first surface including a plurality of convex surfaces disposed along at least a first direction;
• and
• a second surface disposed opposite to the first surface in a front-rear direction of the marker, and configured to be projected on the plurality of convex surfaces as an optically detectable image,
• wherein the second surface includes a plurality of first regions and a plurality of second regions which are optically discriminable from each other,
• wherein an interval between vertices of the plurality of convex surfaces in the first direction is greater than a center-to-center distance between each of the plurality of first regions in the first direction,
• wherein the plurality of first regions are disposed at positions further from the plurality of convex surfaces than focal point positions of the plurality of convex surfaces, and
• wherein when parallel light is incident on each of the plurality of convex surfaces from outside along the front-rear direction, a width of a light flux formed at a height of each of the plurality of first regions by each of the plurality of convex surfaces in the first direction is equal to or smaller than a width of each of the plurality of first regions in the first direction.