Concave/Convex Mirror Accessory Investigate the behavior of light being reflected off of a curved surface. This two-piece set includes a plastic, two-sided concave/convex mirror and a semicircular half-screen. The half-screen, which can be rotated, allows light to pass through on one side, and a real image formed from the concave mirror to be focused on the other. Both pieces are mounted in holders for easy placement on the Basic Optics Track.