| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element having an antireflection structure by a rugged pattern which can prevent abrupt appearance of diffraction waves in the first or higher orders and which can be easily manufactured at a low cost. SOLUTION: The optical element has an antireflection structure which prevents reflection of light at the critical wavelength or longer. The antireflection structure comprises a rugged pattern formed on the entrance face. The pitch of the rugged pattern is determined at random so as to reduce the diffracted light in the first or higher orders to substantially zero in the entrance side and in the exit side for the light at the critical wavelength or longer. |
