A photodiode has a carrier accumulation layer of a second conductivity type and a surface area of a first conductivity type deposited in order from an inside towards a surface of a first conductivity type well region. The IDT electrode includes first finger-electrodes, second finger-electrodes and strip-line electrodes. In another preferred embodiment, a third section is provided after the second section and the apparatus is in the form of a disk, preferably an optical disk, having a central axis, and wherein the first, second and third section are arranged in the disk as channels in a direction away from the central axis, respectively. The second beam has an edge for mounting a rotatable rod having a handle opposite a curved latch.