| 摘要 |
PROBLEM TO BE SOLVED: To effectively suppress the oscillation of the loci of a beam at an exposure point by setting the diameters at the cross-sections of the cylindrical bodies disposed in an optical path nearly the same as or slightly larger than the light beam diameter over the entire part in a longitudinal direction from an incident side to an exit side. SOLUTION: The laser beam 1a is emitted via an exit port from an exposure laser 1. The laser beam 1a passes various kinds of optical elements 2a to 2h, a modulator 3, etc., and finally focuses via an objective lens 5 on an exposure master disk 6 coated with a photoresist. A suitable number of the special cylindrical bodies 4a to 4g for preventing the fluctuation in the laser beam are arranged on the optical path of the laser beam 1a. The inside volume of the cylindrical bodies 4a to 4g is reduced to the required smallest possible extent for the purpose of suppressing the convection of the internal air. Both apertures of the cylindrical bodies 4a to 4g are closed by transparent materials mounted with antireflection films on an incident side. When the cylindrical bodies 4a to 4g are used, a density change of the air hardly occurs and, therefore, refractive indices are stable. |
