Radiation-curable ink is used to form an image on a moving substrate. In one embodiment, a data processing system includes a processing system, a cellular telephone transceiver, and a port which is configured to provide, as an output from the handheld data processing system, data representing movie video images. 5% photoinitiator, 1-2% filler, 0. Therefore, compact optical scanning device, in which the deterioration of the optical performance in the oblique incident system can be suppressed and a generation of a refractive index gradient during lens manufacturing can be also suppressed, and image forming apparatus using the optical scanning device can be provided.