The invention in one form is directed to an ignition terminal for coupling an internal combustion engine coil-on-plug ignition coil assembly with a spark plug. The reflector comprises a reflective material for receiving solar radiation and directing the received solar radiation to an absorber. A recess is provided in the area of the overlap in at least the one partial joint surface, a coating is kept in the recess. At least one of a polishing endpoint or an adjustment for a polishing rate is determined based on at least one normalized predetermined spectrum from the sequence of normalized spectra. The optical amplification section includes an optical fiber amplifier and is optically connected to the laser light generation section to amplify the pulsed light.