High-efficiency, multilevel, diffractive optical elements

DETAILED DESCRIPTION What is claimed is: 1.
Method for making high-efficiency, multilevel, diffractive optical elements comprising: generating at least one binary amplitude mask including multilevel information, the mask being configured to provide 2.
sup.
N levels where N is the number of masks; and utilizing the masks' information for constructing 2.
sup.
N levels in the optical element, the depths of the levels being related by a fixed ratio.
2.
The method of claim 1 wherein the masks are made by lithographic pattern generators.
3.
The method of claim 1 including three masks and eight levels.
4.
The method of claim 1 wherein the binary amplitude masks are defined by calculating equiphase boundaries utilizing the equation ##EQU5## and the algorithm
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Equi-phase Phase
Boundaries Etch
Mask # N (l = 0, .
+-.
1, .
+-.
2, .
.
.
)
Depth .
theta.

______________________________________
1 .
phi.
(x,y) = (l + 1).
pi.

.
pi.

##STR5## .
pi.
/2
3
##STR6## .
pi.
/4
4
##STR7## .
pi.
/8
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5.
The method of claim 1 wherein the masks are made by electron beam pattern generators.
6.
The method of claim 1 wherein the optical element is a lens.
7.
The method of claim 1 wherein the optical element corrects for spherical aberration.
8.
The method of claim 1 wherein the optical element is corrected for chromatic aberration.
9.
Method for making high-efficiency multilevel diffractive optical elements comprising: making a master optical element according to the method of claim 1; and using the master optical element to emboss multiple replicated optical components.
10.
The method of claim 9 wherein the master optical element is copied in metal which is used for the embossing.
11.
Method for making a high efficiency, multi-level, diffractive optical element comprising: providing a substrate including at least two initial levels; generating at least one binary amplitude mask including multi-level information; and utilizing the mask to double the number of levels in the element