With the increasing importance of advanced imaging systems in aerospace and defense applications, a group of U.S. optical engineers and other scientists who manufacture, test, and use infrared materials have formed a working group to update standards for measuring optical material properties in the IR.
SPIE helped form the group at SPIE Defense, Security, and Sensing in April, and the group met again in August at SPIE Optics + Photonics to discuss the need for adopting standards and updating decades-old data so that future systems can be designed more cost-effectively and with improved quality control. The trend toward multispectral imaging systems for defense and security applications has made the need for updated standards especially acute.
The goals of the unofficially named Infrared Materials Standards Working Group include developing standard sampling and test protocols for measuring materials in the 0.7- to 20-micron wavelength region.
“The properties of interest encompass all optical, mechanical, thermal, and thermo-optical characteristics,” says SPIE Senior Member David Aikens, executive director of the Optics and Electro-Optics Standards Council (OEOSC) and president of Savvy Optics. Aikens has chaired the meetings with SPIE member Gary Wiese from Lockheed Martin.
OEOSC will work with the American National Standards Institute (ANSI) to publish standards developed by the working group.
Inside and outside the IR
The group’s initial focus will be on optical and thermo-optical properties used for the design of IR imaging systems, such as index of refraction, dn/dT, dispersion, attenuation coefficient, inhomogeneity, and inclusions, Wiese says. “Since some materials that transmit in the IR are also used at wavelengths outside the IR range, the group may also develop standards at wavelengths beyond the IR,” he says.
Because there is industry-wide consensus that updating the current IR optical materials data is essential, the group has sought and received the involvement of the U.S. National Institute of Standards and Technology (NIST).
“Variance in material properties and a lack of standards affects organizations from NASA and Lockheed Martin all the way to small businesses supplying materials, lenses, and coatings,” according to a letter signed by SPIE Executive Director Eugene Arthurs and 50 industry members who attended the April meeting.
Without accurate data on IR materials properties, engineers compensate by overdesigning systems, Arthurs said. Also defects at the component blank level are often not detected until after production costs have been incurred for component fabrication, coating, and subassembly of the imaging systems.
Representatives from NIST labs reported at the August meeting that the agency intends to upgrade its existing optical properties measurement capability to support this effort but that additional funding will be required to conduct all the measurements the working group requires.
Challenges for IR standards group include funding
Wiese said that major hurdles remain, especially in funding, and that participation by all interested organizations is encouraged.
Companies represented in the working group include material suppliers, system developers, instrument designers, measurement labs, and optical design software developers.
Group members are gathering information on the work to be done and are expected to hold another meeting at SPIE Photonics West in February 2013 and/or SPIE Defense, Security, and Sensing in April 2013.
For more information visit spie.org/irstandards or contact Wiese at firstname.lastname@example.org
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