Filters for astronomical imaging have typically admitted more or less uniformly all of the light between two wavelength extremes. However, there are instances where more complex transmission functions are highly desirable. One such case is in the near-infrared, where terrestrial atmospheric emission arising from the molecule OH occurs in narrow bands. Here, the background for imaging with a broadband filter could be reduced by a factor of two if the molecular lines could be selectively blocked. Until recently, custom "tuning" of filters was not possible. However, it is now not only practical but also a compelling technique for improving the speed of near-IR surveys. Compared to other methods of enhancing efficiency, there is every reason to believe that such innovative imaging filters should also be inexpensive.
Dr. James Rhoads of the Arizona State University proposes to carry out the development of custom infrared imaging filters, working with commercial vendors in their design and characterization for a variety of applications in astronomy. Among the research areas that will see a qualitative benefit are a) finding the earliest galaxies and quasars, b) discovering high-redshift supernovae and characterizing dark energy, and c) identifying the lowest-mass brown dwarfs through the development of a special filter tuned to its unique near-IR spectrum. The PI will oversee the design, construction, and evaluation of these filters, and in addition provide functioning optics for use by the public on instruments operated at the National Optical Astronomy Observatories. Furthermore, the filter prescriptions will be publicized for duplication by the entire observational astronomy community. Funding for this work is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.
