A disk drive is disclosed which generates a pole tip protrusion measurement by performing a write operation to heat the transducer while measuring a fly height of the transducer. The power delivery system includes a power transmitting unit having a power source operable to source alternating current power and a sending resonant coupling component operable to couple the alternating current power to a coil for wireless power transmission by a non-radiated magnetic field at a target resonant frequency. The translucent substrate has a rear surface and a first light shielding portion on a periphery of the rear surface.