Fresnel lens arrays for passive infrared (PIR) applications have achieved broad applicability in devices such as automatic lighting switches and sensors for burglar alarms. They are used to produce a broad, tailored field of view through the accumulation of many repeated narrow fields of view. The infrared energy emitted by a person moving within a room, for instance, is repeatedly imaged onto a thermal detector (usually a pyroelectric detector). The electrical signals thus produced can be used to detect and verify the presence of a person. Devices of this type are generally referred to as motion sensors, because the pyroelectric detector usually used has no dc response and therefore does not produce an electrical signal from a stationary warm body.
We presently offer six lines of PIR Fresnel lens arrays, plus a few assorted types. The six lines are our XX 1.2 GI 12 VX series, with a focal length of 1.2 inches (30.5 mm) and a downward tilt of 12°; our XX 0.9 GO VX series, with a focal length of 0.9 inches (23 mm), intended to be used with the grooved side of the lens array facing outward; our XX 0.9 GI 6 TX series, with a focal length of 0.9 inches (23 mm) and a downward tilt of 6°; our ceiling-mount line, CM 0.77 GI VX, with a 0.77 inch (19.6 mm) focal length; our XX 0.5 GI VX line, which is hemispherical, extremely rugged, board-mounted, and contains a variety of detection patterns; and our XX 0.25 GI VX line, which mounts directly on a TO-5/TO-39 package pyroelectric detector (often referred to as a push-on or clip-on lens array) and which also contains a variety of detection patterns. XX 0.25 GI VX is available both with and without a flange that can be helpful for sealing against air or water intrusion. Its overall size is smaller without the flange (-NF added to the end of the pattern designation). The XX 0.25 GI VX series is also available in a version that works with surface mount pyroelectric detectors from various manufacturers (-SMD added to the end of the pattern designation).
The assorted types include (among others) our popular WA 0.9 GI 6 V2, with a focal length of 0.9 inches (23 mm) and a 6° downward tilt; WA 0.9 GI T1, also with a focal length of 0.9 inches; AA 0.53 GI V1, with a focal length of 0.53 inches (13.5 mm); and EWA 0.3 GI V1, which has a focal length of 0.3 inches (7.6 mm), and is suitable for use in some wall switch-type applications. We have more recently added quite a few lens arrays that do not fit into a series to this brochure—take a look if you haven't in a while.
Even though we offer a large number of standard lenses and lens arrays for passive infrared applications, we recognize that you may need a type which does not exist. We are pleased to help in this situation, and we will gladly call on our 23 years of PIR Fresnel lens array design experience in helping you achieve a satisfactory design. If you purchase tooling and the resulting lens array from us, there is no charge for the design.
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