From bernies at panix.com Sat Aug 2 17:21:31 2014 From: bernies at panix.com (bernieS) Date: Sat, 02 Aug 2014 17:21:31 -0400 Subject: [Laser] test - please disregard Message-ID: <20140802212137.89B672EFC1@mailbackend.panix.com> From GTBecker at RighTime.com Sat Aug 2 19:26:44 2014 From: GTBecker at RighTime.com (Tom Becker) Date: Sat, 02 Aug 2014 19:26:44 -0400 Subject: [Laser] Filter Material. In-Reply-To: <023801cfac8e$dbbbdf90$0954fb48@mainframe> References: <001901cf2aa4$5fe26770$1fa73650$@alum.mit.edu><201402170859.s1H8xifY029502@c.mail.sonic.net> <3F35EC2B-5B18-46EE-9D44-12D9EFDF7F9B@oh.rr.com> <023801cfac8e$dbbbdf90$0954fb48@mainframe> Message-ID: <53DD73B4.4060209@RighTime.com> I was ready to suggest that you use a pair of Rosco (or similar) gels - a pair of specific products yield a pretty-dark short-IR filter - but reconsidered. If you need a filter for a motion detector you probably need one for longwave IR - or, more likely, a lens. The detectors I have use lenses to illuminate a pair of detectors differentially. Although the plastic material of the lens is surely frequency-selective, its principal function is lensing, not filtering. Simply replacing your 'filter' with, say, 35mm film or Roscos might well make the detector motion-blind. FWIW. Tom