Abstract: A disc comprising a substrate layer which comprises a support plate and a registration layer connected to the support plate. A protective plate is situated at the side of the registration layer remote from the support plate, which protective plate can be detachably fastened to the substrate layer. The support plate is disc-shaped and is provided with at least one raised edge extending upwards from a circumferential edge, by means of which the protective plate can be detachably fastened.

Abstract: An optical scanning device for scanning an information layer of an optical record carrier and including a rotary aim (2; 102; 202; 302; 402; 502) which is arranged to swing about a rotation axis (CR) to alter an angular position of the rotary arm about the rotation axis; a detector arrangement (10) arranged separate from the rotary arm (2; 102; 202; 302; 402; 502) for detecting a radiation beam spot, the radiation beam spot (40; 140; 240; 340; 440; 540) having an angular disposition; a first reflective surface (4; 104; 204; 304; 404; 504) attached to the rotary arm (2; 102; 202; 302; 402; 502); a second reflective surface (6; 106; 206; 306; 406; 506) attached to the rotary arm (2; 102; 302; 402; 502); a first light path (LP 1; LP 1 O 1; LP201; LP301; LP401; LP501) running from a location on the record carrier to said first reflective surface; a second light path (LP2; LP102; LP202; LP302; LP402; LP502) running from said first reflective surface to said second reflective surface; a third light path (LP3; LP103