In a filing before the U.S. Patent and Trademark Office, the Boeing Company has disclosed a post-processing method for dielectric combiner elements that may reduce the cost of grading dual combiner sets by 90 percent compared to currently produced dielectric types.

One problem encountered with nongraded dual combiner sets is an optical defect that appears which appears when viewing the overlap region between the two elements: a dark band that can be mistaken for an artificial horizon becomes visible. In addition, the displayed data in the overlap region appears brighter, producing objectionable nonuniformity in both the transmitted and received images.

In the past these problems have been solved by grading the overlap zones on each of the elements during coating of the substrates. But these methods are relatively expensive and require considerable skill, experience, and capital investment.

Boeing's method is a post-processing etching performed on nongraded coated combiner elements. The coating has been applied to test articles of various substrates and has produced uniformly high-quality results, including predictable grading results and integrity of the nonetched coating.

The grading coating is best applied to dielectric combiner elements. where it can be used to reduce cost significantly. The process can be applied equally well to high-value coated optics, where a grading is required. It may be useful on large coated optics or structures with an optical component such as canopies, windows, and mirrors.

The Boeing Company is currently developing business relationships with companies interested in applying Boeing technologies to their products. If actively interested, please contact

Dennis Donahue, Marketing Manager, Licensing;
MC 306-1285,
PO Box 516,
St. Louis, MO 63166;
(314) 234-7093; f
ax (314) 232-4313;