Abstract: A photolithographic process includes providing a layer of photoresistive material on a target substrate. Radiation is transmitted to the photoresistive material through a layer of absorbing material that absorbs the radiation with a transmittance proportional to the thickness of the absorbing material. A surface relief structure is formed in the absorbing material, so that the photoresistive material is only partially exposed in a pattern corresponding to the surface relief structure. Thus, when the photoresistive material is developed, it has a surface relief structure corresponding to the surface relief structure in the absorbing material. Etching the developed photoresistive material and target substrate then forms a surface relief structure in the target substrate that corresponds to the surface relief structure in the developed photoresistive material.
Type:
Grant
Filed:
September 16, 1999
Date of Patent:
September 2, 2003
Assignee:
MEMS Optical LLC
Inventors:
David R. Brown, Barry S. McCoy, Gerald Tuck, Miles Scott, Bruce Peters
Abstract: A multi-aperture irradiation profile shaping system is presented that uses at least one arrangement of at least three apertures associated with a plurality of optical elements, wherein at least one optical element has positive optical power and another one element has negative optical power. The system may be implemented with the apertures in one, two, or three dimensions. The system yields a predetermined arbitrary irradiation profile on a target. The shape of the apertures may be any one of square, rectangular, and hexagonal. The shape of the apertures may also be asymmetric so that a rotation of the aperture shape by 180 degrees around an axis perpendicular to the surface of the aperture yields an inverted aperture shape. The system may be implemented with apertures having symmetric and asymmetric shapes that allow nearly 100% fill factor.