An optical head and a disk unit are provided, in which the height and the weight of the optical head are reduced to enable a disk unit of small size and high recording density. A liquid thermal diffusion andor electric field separation is used to produce the fractions. The data flow management device includes a plurality of buffers outputting data flows received from the sources; and a transmitting unit transmitting the data flows output from the buffers to the destinations. One or more signage member may be stored behind the displayed signage member. A first value near a median of the selected first values is selected as a first optimum value for setting the first phase delay value.