Patent ID: 7499147

Claim:
A generation method of a light intensity distribution, comprising: passing a light beam through a first light modulation element and a second light modulation element which are arranged to be apart from each other by a distance D and face each other in parallel to optically modulate the light beam that enters the light modulation elements, thereby generating a light intensity distribution on a focusing plane of an image forming optical system located on an optical axis of the second light modulation element, the focusing plane being positioned on a surface to be treated at a substrate, wherein the first light modulation element has a pattern formed by repeating a basic unit having a pitch P, and wherein the distance D satisfies the following condition: D≈P 2 (2 +n 1)/2λ where λ is a wavelength of the light beam, and n is an integer equal to or above 0 (0, 1, 2, 3. . . ).