A writable optical disc has an information writing track, and a guiding track for introducing a laser beam to the information writing track. The housing and the cleaning head are designed such that the user can easily and comfortably apply a downward force to the cleaning head. A step-down circuit couples to the plug for receiving AC power and outputting a supply voltage. Also, the present invention enables the formation of waveform patterns on the surface of the fluid without mechanical contact with the surface of the fluid so there is little restriction in the waveform pattern size, and the production cost of the waveform pattern is reduced.