Large-area Reflective Infrared Filters for Millimeter/sub-mm Telescopes
  Ground-based millimeter and sub-millimeter telescopes are attempting to image the sky with ever-larger cryogenically-cooled bolometer arrays, but face challenges in mitigating the infrared loading accompanying large apertures. Absorptive infrared filters supported by mechanical coolers scale insufficiently with aperture size. Reflective metal-mesh filters placed behind the telescope window provide a scalable solution in principle, but have been limited by photolithography constraints to diameters under 300 mm. We present laser etching as an alternate technique to photolithography for fabrication of large-area reflective filters, and show results from lab tests of 500 mm-diameter filters. Filters with up to 700 mm diameter can be fabricated using laser etching with existing capability. 
Z. Ahmed, J.A. Grayson, K.L. Thompson, C. L. Kuo, G. Brooks, T.   Pothoven
astro-ph.IM