A scanning device producing a first and a second scanning spot which move in different directions and an apparatus containing that device which uses the first spot for reading and/or recording and the second spot to monitor such reading and/or recording

A read and/or record apparatus for reading and/or recording information from and/or in tracks of a scanning surface of a record carrier, the apparatus comprising:

• a scanning device including:
• beam generating means for generating a first scanning beam for scanning the scanning surface to read and/or recording information from and/or in the tracks of the scanning surface and a second scanning beam for scanning the scanning surface to provide information for use in monitoring the reading and/or recording, the first scanning beam and the second scanning beam forming a first scanning spot and a second scanning spot, respectively, on the scanning surface;
• and
• scanning spot movement means for causing the first scanning spot and the second scanning spot to scan the scanning surface synchronously along a first scanning path and a second scanning path, respectively, which are non-parallel so that the second scanning spot moves relative to the first scanning spot in a direction transverse to the direction of the first scanning spot and the position of the second scanning spot with respect to the position of the first scanning spot is related to the position of the first scanning spot on the first scanning path, the tracks have a track direction substantially corresponding to the direction of the first scanning path;
• detection means for converting radiation emanating from the second scanning spot into a corresponding detection signal;
• and
• derivation means for deriving a position measurement signal indicative of deviation of track pitch of the tracks on the basis of a deviation in a relationship between the detection signal and a reference signal indicative of the position of the first scanning spot on the first scanning path.

A read and/or record apparatus for reading and/or recording information from and/or in tracks of a scanning surface of a record carrier, the apparatus comprising:

• a scanning device including:
• beam generating means for generating a first scanning beam for scanning the scanning surface to read and/or record information from and/or in the tracks of the scanning surface, and a second scanning beam and a third scanning beam for scanning the scanning surface to provide information for use in monitoring the reading and/or recording, the first scanning beam, the second scanning beam and the third scanning beam forming a first scanning spot, a second scanning spot and a third scanning spot, respectively, on the scanning surface;
• and
• scanning spot movement means for causing the first scanning spot, the second scanning spot and the third scanning spot to scan the scanning surface synchronously along a first scanning path, a second scanning path and a third scanning path, respectively, in which the first scanning path is non-parallel to the second scanning path and the third scanning path so that the second scanning spot and the third scanning spot each moves relative to the first scanning spot in a direction transverse to the direction of the first scanning spot and the position of each of the second scanning spot and the third scanning spot with respect to the position of the first scanning spot is related to the position of the first scanning spot on the first scanning path, the tracks have a track direction substantially corresponding to the direction of the first scanning path;
• first detection means for converting radiation emanating from the second scanning spot into a corresponding first detection signal;
• second detection means for converting radiation emanating from the third scanning spot into a corresponding second detection signal;
• and
• derivation means for deriving a position measurement signal indicative of deviation of track pitch of the tracks on the basis of a deviation of the first detection signal and/or the second detection signal.

A read and/or record apparatus for reading and/or recording information from and/or in tracks of a scanning surface of a record carrier, the apparatus comprising:

• a scanning device including
• beam generating means for generating a first scanning beam for scanning the scanning surface to read and/or record information from and/or in the tracks of the scanning surface, and a second scanning beam and a third scanning beam for scanning the scanning surface to provide information for use in monitoring the reading and/or recording, the first scanning beam, the second scanning beam and the third scanning beam forming a first scanning spot, a second scanning spot and a third scanning spot, respectively, on the scanning surface;
• and
• scanning spot movement means for causing the first scanning spot, the second scanning spot and the third scanning spot to scan the scanning surface synchronously along a first scanning path, a second scanning path and a third scanning path, respectively, in which the first scanning path is non-parallel to the second scanning path and the third scanning path so that the second scanning spot and the third scanning spot each moves relative to the first scanning spot in a direction transverse to the direction of the first scanning spot and the position of each of the second scanning spot and the third scanning spot with respect to the position of the first scanning spot is related to the position of the first scanning spot on the first scanning path, the tracks have a track direction substantially corresponding to the direction of the first scanning path;
• first detection means for converting radiation emanating from the second scanning spot into a corresponding first detection signal;
• second detection means for converting radiation emanating from the third scanning spot into a corresponding second detection signal;
• and
• derivation means for deriving from the first detection signal and the second detection signal an inclination measurement signal indicative of the angle between the track direction and the first scanning path on the basis of a combination of a first deviation and a second deviation, the first derivation being a deviation in a relationship between the first detection signal and a reference signal indicative of the position of the first scanning spot on the first scanning path, and the second derivation being a deviation in a relationship between the second detection signal and the reference signal.