Abstract: A hologram optical system includes a stem, a laser diode fixed to the stem, and a focusing error detector fixed to the stem. The focusing error detector is divided into a first region and a second region by at least one straight dividing line. The hologram optical system further includes a cap mounted on the stem so as to surround the laser diode and the focusing error detector, and a hologram mounted on the cap so as to make given positional relationship with the laser diode and the focusing error detector. When the dividing line of the focusing error detector has a positive gradient, the hologram has a distribution of interference fringes such that the product of a change rate of an X-directional component of the pitch of the interference fringes and a change rate of a Y-directional component of the pitch of the interference fringes is negative.

Abstract: Various kinds of data such as destination addresses, messages to be transmitted are registered beforehand while they are made to correspond to respective abbrebiated dialing numbers or one-touch dial numbers. The invoice format into which the data will be written is stored in a storage unit. At the time of the transmission, the invoice format is read out by inputting the abbreviated dialing number or the one-touch dial key, and the data are written into the pertinent address in the format.