An optical element disposed behind a main mirror and inclined relative to the optical axis is arranged at a position to correct aberration in the luminous flux generated by transmission through the main mirror. The program verification method includes applying a plurality of verification voltages, and determining whether programming of memory cells, having different target threshold voltage distributions, from among the plurality of memory cells is completed based on one of the plurality of verification voltages. After identifying the domain name of the Web page and comparing that domain name to domain names of host computers from which elements of Web page will be obtained, the process prevents unwanted transmission of data from the client computer to such host computers by processing requests for such elements through a cookie filter andor a URL filter. In a second state the source of energy is connected to the handpiece. is 55 mNm or more,the compressibility rate =P\xd7100where P represents a tapped bulk density of the particulate water absorbing agent and A represents a loose bulk density of the particulate water absorbing agent.