| 摘要 |
PROBLEM TO BE SOLVED: To enable an optical device to be used in a vacuum ultraviolet region of <=200 nm wavelength. SOLUTION: (a) A substrate composed of fluorite is used as a substrate 11. Thereon an i-line negative photoresist is coated using a resist coating device. Succeedingly a pattern of the first chromium mask 12 is reduced baked to it using an i-line stepper. Subsequently it is subjected to a specified resist developing treatment so as to form a resist pattern 13 corresponding to the mask 12. (b) A CaF2 film 14 is film formed on the substrate 11 and the resist pattern 13 using a vacuum deposition device. Subsequently the resist pattern 13 is removed and ashing is carried out. (c) A CaF2 pattern 15 is formed. (d) Then a diffraction optical element 18 having a four-step outermost ring band is prepared by similarly laminating more CaF2 films using the second and third chromium mask 16, 17. |
