An insulating cover for a portable toilet as used on construction sites and for outdoor events is described. At least one end of the narrow groove is a terminal end. Two of the row of plates adjacent to each other are connected by a connecting member having first and second ends. This can securely prevent the particles from attaching to the semiconductor chips 25 obtained by cutting the object 1. According to this apparatus, since the dispensable charges are previously removed from the electric charges generated by the photoelectric converter by the charge discarding portion, it is possible to improve SN ratio and accurately determine the spatial information.