In an optical disc apparatus reading and writing data with respect to an optical disc, a motor controller uses widest pattern signals outputted from an optical pickup for judging size of an optical disc mounted on a turn table and stop of rotation of the optical disc. An extra DAC element in addition to the DAC is used to function in place of a DAC element under calibration. The novel imaging probe is capable of detecting infected cells, as well tissue. The channel includes a recess between the tab and the lip.