A lens barrel includes a driven ring, a follower provided on the driven ring, a rotational transfer ring including a circumferential groove having no axial-direction component and a rotational transfer groove including an axial-direction component, a guide ring, and a cam groove formed on the guide ring for guiding the driven ring via the follower. The ends of the plate are provided with at least one hole enabling an attachment screw to pass therethrough, and the central portion of which has an opening defined by two opposite sides. The process is conducted in the presence of an effective amount of at least one catalyst C, comprising a carbene. In accordance with specific embodiments of the present invention, the desired burst width is three-fourths of a data track wide. Optionally, game indicia are randomly assigned to game matrix locations lacking a match. An extendable shield having a plurality of windows disposed along a length of the shield may be disposed about a line source so that the windows form an array of point sources when the source and the shield are extended.