Papi with led light source and aperture plates

Abstract

A precision approach path indicator (PAPI) employs an LED light source with first and second arrays of LEDs or other efficient light sources, disposed one above the other and emitting their respective color lights along an optic axis to a collimating lens of focal length f. First and (optional) second aperture plates positioned along the optic axis, each being a respective frame with a cut-out defining a horizontally elongated aperture for light passing along the optic axis. Intermediate aperture plate(s) can be positioned between the first and second aperture plates. The first frame is positioned between the light source and the collimating lens at the focal distance f from the lens. The optional second aperture plate is positioned at the collimating lens and covers top, bottom, and side edge portions of the lens. A planar blade extends from the light source to the first frame and has a distal edge extending across the aperture of the first aperture plate, substantially at the focus of the collimating lens, dividing the beam into white and red sectors. The intermediate aperture plate(s) can be adjusted for optimal separation. The PAPI can be considered to have an illumination portion formed of the light source(s), blade, and first frame; and an imaging portion formed of an enclosure and a lens positioned at its focal length distant from the front frame aperture and edge of the blade.