The resist development method of the present invention includes a step of applying a resist film to a wafer substrate, a step of exposing the resist film in a prescribed pattern, a step of removing the exposed part of the resist film with an alkaline liquid, and a step of cleaning the patterned resist film with ozone water. The method comprises the steps of measuring the current of one of the parallel capacitor branches, and determining from the measured current the magnitude of the inverter current. The supplemental optical signal is then selected by a wavelength-division multiplexer, converted to an electrical signal and used for powering respective components of the optoelectronic probe.