Abstract: A method is provided of fabricating a reflective mirror having a reflective surface on which light is incident. This method includes: coating at least one of opposite faces of a plate-shaped etchable material made of a single crystal material, with a film-like etching mask; forming a mask pattern on at least one of opposite faces of the etching mask, the mask pattern having a planar shape to which a circle is more similar than a quadrangle; and wet-etching the etchable material. This method allows the reflective mirror to be fabricated so as to have a silhouette of a planar shape to which a circle is more similar than a quadrangle, when viewed in a direction normal to the reflective surface.

Abstract: A method is provided of fabricating a reflective mirror having a reflective surface on which light is incident. This method includes: coating at least one of opposite faces of a plate-shaped etchable material made of a single crystal material, with a film-like etching mask; forming a mask pattern on at least one of opposite faces of the etching mask, the mask pattern having a planar shape to which a circle is more similar than a quadrangle; and wet-etching the etchable material. This method allows the reflective mirror to be fabricated so as to have a silhouette of a planar shape to which a circle is more similar than a quadrangle, when viewed in a direction normal to the reflective surface.