A diamond film is deposited in the thickness of 20 m on a silicon wafer 0. Both the architecture of the cutaway and the cross sections of the lens cell implicate an arcuate curve with an opening oriented a smooth plane. A first operation causes the status signal generating portions SL and DL to selectively generate a status signal and a second operation causes the position calculating portion to selectively process the status signals generated by the status signal generating portions SL and DL. The housing includes a coupling portion for removably securing the housing to the interactive user terminal.