摘要 |
Attention is paid to the shifting of a focal point depth due to an interference between some light penetrating even a light shielding film, that is, a light shielding film having a nonzero transmittance, and light passing through an opening. Study has been made about how both the transmittance of the light shielding film and the phase difference between the light penetrating the light shielding film and light passing through a light transmitting medium the same in thickness as the light shielding film vary, arriving at a conclusion that the broadest focal point tolerance can be obtained if a phase difference of substantially nx pi (n: an positive integer) exists between light penetrating the light shielding film and light passing through the light transmitting medium. |