A method comprises disposing a photosensitive film layer on a surface of a substrate layer and placing a variable neutral density (ND) filter such that a surface of the variable ND filter faces an exposure region of the photosensitive film layer. The variable ND filter is a thin film that has an attenuation profile that modulates transmittance of light passing through the variable ND filter to the exposure region to cancel out an uneven power distribution in an intermediate interference exposure pattern at the exposure region of the photosensitive film layer. The method further comprises arranging one or more laser generators such that at least two generated beams of light from the one or more laser generators intersect with each other and form the intermediate interference exposure pattern that is modulated by the variable ND filter to form a target interference exposure pattern at the exposure region.