When you watch cars go by at night, you can see a variety of
headlight designs on display. For example, old cars use sealed beams which are
often rather yellow in appearance. Then there are the whiter designs with
A projector headlight is easily recognised because of its convex glass lens.
replaceable halogen bulbs, while recent luxury cars feature high intensity
discharge lights which have a brilliant blue/white colour.
There are also lights which, when viewed at an angle, have red
or blue beams graduating to white as the car is seen face-on. These headlights
have an abrupt beam cut-off and a very even spread of light within the beam.
They are known as "projector" headlights and use a simple reflector teamed with
a large convex glass lens.
Want to know something? Those large glass lenses can be
obtained for nearly nothing from broken headlights at car wreckers. Want to know
something else? They make excellent lenses for use in bike lights, torches and
handheld spotlights.
