Lenses: Difference between revisions
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cleanup, add TIR picture
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==Flat lens== | ==Flat lens== | ||
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==Aspheric lens== | ==Aspheric lens== | ||
Instead of a flat lens, an aspheric lens can be used that will focus the light into a tighter beam. By moving the lens with respect to the emitter, a tight beam or wider flood can be obtained. Lights with a movable lens are called flood-to-throw lights. Though frequently called aspheric, many times the lens involved has the traditional curvilinear shape and therefore isn't really aspheric. | Instead of a flat lens, an aspheric lens can be used that will focus the light into a tighter beam. By moving the lens with respect to the emitter, a tight beam or wider flood can be obtained. Lights with a movable lens are called flood-to-throw lights. When properly focused for maximum throw, an image of the emitter is projected showing bonding wires and strips of the LED. Though frequently called aspheric, many times the lens involved has the traditional curvilinear shape and therefore isn't really aspheric. | ||
==TIR optic== | ==TIR optic== | ||
Also called a "collimating lens", a TIR optic takes advantage of "total internal reflection" where light | [[File:Tir-optic.jpg|thumb|Plastic TIR optic gives a very tight hotspot]]Also called a "collimating lens", a TIR optic takes advantage of "total internal reflection" where light that strikes a surface at a shallow angle will bounce off the surface and continue through the material instead of scattering. The optic collimates the light and sends a concentrated beam of light out in the same direction, giving a tight hotspot with greater throw. With a TIR optic in place, a reflector is not needed. A typical TIR lens looks like a cone with a hole where the point should be extending about halfway through the lens. This hole fits over the LED and any rays that strike the flat bottom of the hole will go straight out the front, giving a small hotspot. | ||