High-efficiency, multilevel, diffractive optical elements
AssigneeMassachusetts Institute of Technology
InventorsGary J. Swanson, Wilfrid B. Veldkamp
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Abstract
A high-efficiency, diffractive optical element having at least one surface including multilevel steps, the steps determined by calculating equiphase boundaries utilizing a disclosed equation and algorithm. The optical element can be adapted to correct for chromatic and/or spherical aberration, and can be used in UV lithographic apparatus.
Claims10
High-efficiency, diffractive optical element having at least one surface including multilevel steps, the steps determined by calculating equiphase boundaries utilizing the equation ##EQU6## where x and y denote coordinates on the optical element, .lambda. denotes wavelength, and a.sub.nm represents a series of optimized coefficients, and the algorithm
- ______________________________________ Equiphase Boundaries Level #N (l = 0, .+-.1, .+-.2, . . .) Phase Etch Depth .theta. ______________________________________ 1 .phi.(x, y) = (l + 1).pi. .pi. ##STR14## ##STR15## 3 ##STR16## ##STR17## 4 ##STR18## ##STR19## ______________________________________
In UV lithographic apparatus, an optical system including at least one optical element, one surface of said optical element including a multilevel step pattern adapted for aberration correction.
UV lithographic exposure system comprising:
- a source of UV radiation;
- and
- an optics column for generating an optical beam or image, the optics column including at least one optical element, one surface of which includes a multilevel step pattern adapted for aberration correction.
Dependencies are inferred from the claim text.