HOW IT WORKS



The light from the bulb first passes though a Fresnel lens, then it passes though the SIRA screen.



bottom - shows a light unit taken apart (actually this is an LED unit which is identical apart from the anti-glare screen isn't colored as the LEDs emit colored light, when normal bulbs emit white light. also this LED unit is sealed when normal ones can be opened to change the light bulb)



middle left - diagram of fresnel lens, this makes better use of the light.



middle right - the anti-glare screen, this stops sunlight getting in the way.



The anti-glare screen works by reflecting the emited light into holes, so that when sunlight hits it, only half of the sunlight would hit the emitted light (the other half just hits black). this reduces the effect of not being able to see what color the traffic light is. (this is not just a filter, which would reduce the brightness of the emited light. On the back there is textured glass which sends all of the emited light though the holes, without reducing the brightness).