Illumination optical system, exposure device using the illumination optical system, and exposure method
In an illumination optical system constituted to uniformize the intensity distribution of illumination light by use of an optical integrator, the overall length thereof is shortened. The illumination optical system includes: a light source including a laser irradiating illumination light on an illuminated body such as a two-dimensional SLM and an optical integrator; the optical integrator being placed between this light source and the illuminated body and uniformizes the intensity distribution of the illumination light by passing the light through minute cells. In this system, the size of the minute cell of the optical integrator (S 1= S 2 ) is 1.5 mm or less.
1. An illumination optical system, comprising:
a light source which irradiates illumination light on a spatial light modulator; and
an optical integrator which is placed between the light source and the spatial light modulator and uniformizes an intensity distribution of the illumination light by passing light through optical elements,
wherein diagonal lengths of the optical elements of the optical integrator are 4 mm or less, and
wherein the Etendue of the light source is not more than 1 mm 2 ·str (steradian).
2. The illumination optical system of claim 1 , wherein the spatial light modulator is a DMD.
3. An exposure device having a constitution in which illumination light emitted from the illumination optical system of claim 1 is modulated by the spatial light modulator based on a predetermined image signal and exposure of a photosensitive material is performed with an image formed by this modulated illumination light.
4. An exposure device having a constitution in which illumination light emitted from the illumination optical system of claim 2 is modulated by the spatial light modulator based on a predetermined image signal and exposure of a photosensitive material is performed with an image formed by this modulated illumination light.