| CPC B24B 13/005 (2013.01) [B24B 9/146 (2013.01)] | 14 Claims |

|
1. An apparatus for attaching in a predetermined relative position a blocking device (13) and a semi-finished optical element (11) having a first face (14) to which the blocking device (13) is to be attached and having opposite to the first face (14) a second face (15) to be surfaced in a surfacing machine (10) configured for holding the semi-finished optical element (11) via the blocking device (13), said blocking device (13) comprising:
a mounting portion (20) provided for mounting the blocking device (13) on a corresponding mounting member (17) of said surfacing machine (10); and
a blocking portion (21) for blocking the semi-finished optical element (11), said blocking portion (21) comprising a support member configured for providing a rigid support to the semi-finished optical element (11), said support member including a support element (23) made of a shape-memory material having a rigid state below a predetermined temperature and a plastic state above said predetermined temperature, said support element (23) assuming in the absence of external forces a predetermined memory shape when heated above said predetermined temperature, said support member having a contact face onto which said first face (14) of said semi-finished optical element (11) is to be applied,
said apparatus (38) comprising a positioning system (45) configured to determine a current position of said semi-finished optical element (11) with respect to a reference frame (41) of said apparatus (38), and configured for positioning said semi-finished optical element (11) with respect to said reference frame (41) into said predetermined relative position,
said apparatus further comprising a heating device configured for heating the support element (23) of said blocking device (13) above said predetermined temperature, said heating device comprises an electromagnetic coil (37) coaxially aligned and surrounding the support element (23), wherein the electromagnetic coil (37) and support element (23) are on the same level, and said shape-memory material of said support element (23) of said blocking device (13) comprises ferromagnetic elements (27) such that said support element (23) is configured for being inductively heated by said electromagnetic coil (37) above said predetermined temperature.
|