Abstract: A reflector (15) for cooling or trapping atoms or molecules, the reflector (15) having a reflecting surface (17) forming a perimeter around and facing a central axis (33), the reflecting surface (17) extending along the axis (33), and converging from a first end of the reflector (15) towards a second end of the reflector (15), such that the reflecting surface (17) is arranged to reflect input laser light to form a cooling region (21), wherein an aperture (23) for providing a beam (27) of cooled atoms or molecules from the cooling region (21) is formed in the reflecting surface (17), the aperture (23) perpendicular to the central axis (33), such that the reflector (15) forms a truncated pyramid, and wherein the reflecting surface (17) is formed by three or more planar mirrors (39a-d) arranged around and at an angle to the central axis (33).