A method for determining information about a transparent optical element including a lens portion and a plane parallel portion, the lens portion having at least one curved surface and the plane parallel portion having opposing first and second surfaces, includes: directing measurement light to the transparent optical element; detecting measurement light reflected from at least one location on the first surface of the plane parallel portion; detecting measurement light reflected from the second surface of the plane parallel portion at a location corresponding to the at least one location on the first surface; determining, based on the detected light, information about the plane parallel portion; and evaluating the transparent optical element based on the information about the plane parallel portion.