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Development and Fabrication of High-Precision Dichroic Filters, 18-9332

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Principal Investigator
James H. Arps

Inclusive Dates: 06/27/02 - 10/27/02

Background - High-performance multilayer coatings are increasingly required in a number of leading edge technologies. Optical coatings have been utilized for filters, mirrors, anti-reflection, and polarization control for decades. Therefore, a great deal of technological information exists to provide a basis from which to work. Despite the large volume of knowledge, there are still key areas to be examined if the state of the art is to improve. Many of the problems for optical coatings lie in the area of film structure. The coating design needed for this dichroic filter is both long and sensitive to error. Therefore, an improved monitoring method must be engineered to match SwRI's chamber characteristics to achieve the filter requirements.

Approach - An experienced optical thin film scientist was brought in as a consultant to avoid reinvention of the wheel. With his assistance, the necessary modification and improvements to the vacuum chamber were made to enable the preparation of the necessary optical coating. Also a state-of-the-art design with an improved monitoring method was implemented to make manufacture of this complex design possible. Several test runs were made to establish good uniformity, repeatable optical parameters, and reliable machine performance. Concurrently, efforts were made to establish a good diagnostic capability at SwRI to allow for the necessary metrology. Finally, test runs of the actual coating were produced and evaluated.

Accomplishments - At project end, a reliable optical coater was online. This system has the capability to produce a range of sophisticated optical coatings as is, and, with slight modifications, can produce a whole new genre of optical coatings. A highly complex, state-of-the-art dichotic filter design was manufactured successfully and has contributed to the generation of several near-term significant opportunities to support other SwRI activities and for aerospace and defense industry clients.

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