An apparatus for processing long, continuous lengths of a flexible foil substrate in discrete defined lengths in order to form high resolution, two-dimensional patterns with a high level of positional accuracy on the substrate, said apparatus comprising: a. a cylindrical drum, rotatably mounted about an axis parallel to a first direction, being porous or having an array of holes over one or more areas of the surface of the drum so that a vacuum can be applied via said porous areas or holes to retain a defined length of the flexible substrate on part of the drum surface; b. a motor system for rotating the drum in one or both directions about said axis; c. a laser process unit mounted adjacent the drum for processing the length of substrate retained on the surface of the drum; d. a mechanism for accurately moving the laser process unit in said first direction over the surface of the substrate; e. a first reeler unit situated on one side of the drum for periodically dispensing a defined length of unprocessed flexible substrate from a first reel in a second direction that is perpendicular to the first direction to the drum for processing thereon; f. a first substrate length compensator unit located between the first reel and the drum for accommodating variations in length of substrate due to differential movement of the first reel and the drum; g. a second reeler unit situated on the other side of the drum for periodically rewinding a defined length of the flexible substrate onto a second reel in the second direction after processing; h. a second substrate length compensator unit located between the drum and the second reel for accommodating variations in the length of substrate due to differential movement of the drum and second reel; and i. a control system arranged to control:- i. periodic application of a vacuum to the drum surface to retain a defined length of substrate on part of the drum surface; ii. operation of the laser process unit; iii. movement of the laser process unit along the length of the drum in the first direction; iv. rotation of the drum over part of a full revolution in one or both directions; and v. periodic release of the vacuum from the drum surface and operation of the first and second reels to rewind a length of substrate containing a processed area and unwind a further defined length of unprocessed substrate from the first reel. a. a cylindrical drum, rotatably mounted about an axis parallel to a first direction, being porous or having an array of holes over one or more areas of the surface of the drum so that a vacuum can be applied via said porous areas or holes to retain a defined length of the flexible substrate on part of the drum surface; b. a motor system for rotating the drum in one or both directions about said axis; c. a laser process unit mounted adjacent the drum for processing the length of substrate retained on the surface of the drum; d. a mechanism for accurately moving the laser process unit in said first direction over the surface of the substrate; e. a first reeler unit situated on one side of the drum for periodically dispensing a defined length of unprocessed flexible substrate from a first reel in a second direction that is perpendicular to the first direction to the drum for processing thereon; f. a first substrate length compensator unit located between the first reel and the drum for accommodating variations in length of substrate due to differential movement of the first reel and the drum; g. a second reeler unit situated on the other side of the drum for periodically rewinding a defined length of the flexible substrate onto a second reel in the second direction after processing; h. a second substrate length compensator unit located between the drum and the second reel for accommodating variations in the length of substrate due to differential movement of the drum and second reel; and i. a control system arranged to control:- i. periodic application of a vacuum to the drum surface to retain a defined length of substrate on part of the drum surface; ii. operation of the laser process unit; iii. movement of the laser process unit along the length of the drum in the first direction; iv. rotation of the drum over part of a full revolution in one or both directions; and v. periodic release of the vacuum from the drum surface and operation of the first and second reels to rewind a length of substrate containing a processed area and unwind a further defined length of unprocessed substrate from the first reel. i. periodic application of a vacuum to the drum surface to retain a defined length of substrate on part of the drum surface; ii. operation of the laser process unit; iii. movement of the laser process unit along the length of the drum in the first direction; iv. rotation of the drum over part of a full revolution in one or both directions; and v. periodic release of the vacuum from the drum surface and operation of the first and second reels to rewind a length of substrate containing a processed area and unwind a further defined length of unprocessed substrate from the first reel.