Multibeam optical system incorporating a microlens array

Parallel recording using a multibeam laser diode array is effective for recording at a high data transfer rate. Focused spot interval equal to the track pitch is realized effectively in an optical disk drive by tilting the spots away from the track direction. However, this method is not applicable in an optical tape recording system using a rotating optical head. We studied theoretically and experimentally a new multibeam optical system incorporating a microlens array to realize a narrow spot interval. The beams that pass through the microlens can be treated as Gaussian beams. The introduction of the microlens array realized a small spot interval of 4 mu m at a transmittance of 40%. This value is larger than that without the microlens array by a factor of about 20.