The objective of this project is to maximize the efficiency of LED flashlights. A 60° field-of-illumination LED is positioned just below the barrel, and is aimed at the off-axis parabola, which reflects all of the light in a focused beam. No light is wasted. If desired, a diffusing lens can be used to create a soft glow around the central bright spot.
If you look directly into the front of the flashlight (with the light off, for your safety) you will see that the entire diameter reflects the LED. There is no central dead spot from the LED as with conventional flashlights.
The improved efficiency of the off-axis flashlight allows the manufacturer to:
Increase the brightness using the same-wattage (60° vs 120°) LED.
– – – or – – –
Maintain the same brightness with a less-expensive, lower-wattage (60° vs 120°) LED for longer battery life, or redesign using smaller, lighter-weight batteries.