A safety spinning top is formed by stamping on a rigid and flexible round card to produce two diametrically opposite strips that could be upward bent at inner ends and then engaged with each other to provide a revolving shaft, and a conic member located between and perpendicular to the two strips and adapted to downward bent to provide a supporting and revolving center below the round card. The photon beam assists emission of electrons from the source surface due to a photo effect. The hanger device includes a support plate of which an upper end comes into contact with an inner circumference of the magnetic recording medium and a liquid-cutting plate which extends from a lower end of the support plate and is distant by a space along the inner circumference of the magnetic recording medium from the inner circumference of the magnetic recording medium. A thermal process is performed so that a decrosslinking reaction is generated in the ARC layer on the exposure portions.