Patent ID: 8467042

Claim:
A lens shape measuring apparatus for measuring a shape of an edge surface of an edged spectacle lens, the measuring apparatus comprising: a lens holding mechanism section that holds the edged spectacle lens with a holding axis from a side of a lens surface, the edge surface extending in a different direction than the side of the lens surface; a first laser displacement meter that is fixed at a position separated from an axis line implicit of the holding axis by a predetermined distance in a radial direction of the edged spectacle lens, and has a light projecting section that projects a laser beam and a light receiving section that receives the laser beam, wherein the light projecting section and the light receiving section are installed to be aligned in a direction perpendicular to the axis line of the holding axis, the first laser displacement meter measures displacement of the edge surface of the edged spectacle lens by irradiating the edge surface of the edged spectacle lens with the laser beam from the light projecting section, and receiving a reflected light thereof by the light receiving section; a holding position changing section that changes a position of the edged spectacle lens with respect to the first laser displacement meter that is expressed by a position in a direction of the axis line of the holding axis and a position around the axis line of the holding axis; a holding position control section that sequentially changes the position of the edged spectacle lens, in accordance with a previously defined rule, by controlling the holding position changing section; a lens shape obtaining section that obtains the shape of the edge surface of the edged spectacle lens by obtaining a distance between the edge surface of the edged spectacle lens and the axis line of the holding axis, based on a distance between the axis line of the holding axis and the first laser displacement meter, and measurement output of the first laser displacement meter for each position of the edged spectacle lens to be changed by the holding position control section; and a second laser displacement meter which is installed at a position separated from the axis of the holding axis by a predetermined distance in the radial direction of the edged spectacle lens so that alight projecting section for projecting a laser beam and a light receiving section for receiving a laser beam are aligned in one of (1) a plane containing the axis line of the holding axis and (2) a plane in parallel with the axis line of the holding axis, wherein if it is determined that a measured value acquired by the first laser displacement meter is not a proper value, the measured value acquired by the first laser displacement meter is complemented with a measured value acquired by the second laser displacement meter at a same measurement position with the first laser displacement meter.