LED flashlights to the maximum power!
The traditional battery operated flashlight has became a tool of high technology, thanks to the invention of white LED. The term LED (Light Emetting Diode) shows a solid-state semiconductor that issues photons (light) when crossed by the electric current. Unlike the normal incandescence bulbs the LED not burns (issue little heat), consume little energy as regards light that they produce, they has a light colour similiar to the solar one (so they do not alter the colours of the objects), last for long time (until one hundred thousand hours, that is 11 years!) without degrading their characteristics or breaking them.

But have them some faults? Unfortunately yes. The greater fault is the high price, due to hi-tech building (see the table below); their dimension is limited to few millimeters and this makes them not much suitable for lighting big areas; the issued light is directional, concentrated on a zone and not diffuse in all the directions.

These faults make difficult the use of LEDs as substitute of the energy saving lamps, but they become secondary if one wants to realize a portable flashlight with a long autonomy.

 

Tech Focus:
The white LED is actually a Blue LED dominated by a screen of special phosphorescent substance. The blue emission excites the molecules of the phosphorus and the result is a white light, analogously to how much happens in the neon tubes (which the ionized gas excites the layer of fluorescent substance on the tube walls). The invention of the blue LED light and the complex system to obtain the white light owes Shuji Nakamura, a Japanese ingenious researcher. Together with the red and green, the blue LED consent to realize luminous RGB systems (Red Green Blue) able to reproduce all the colours for additive synthesis, how it happens in the television set.

The Luxeon LED

Produced in USA from Lumileds (http://www.lumileds.com) is the more used in the lighting systems and the flashlights. It owns a high power, a solar white light issues (other colours are also available) and is easy to mount thanks to the two models "emitter" (the more compact) and "star" (shaped as a star, to realize LED panels.)

In the following the main data of the Luxeon LED
Amount of light: About 25 lumen
Operating voltage: About 3,5 volt
Lifecycle: Until 100000 hours
Heat emission: Almost absent
Time of ignition: Instantaneous
Emission of UV radiation: Absent
Absorbed current: About 350 mA
Absorbed power: 1 W
Colour temperature: 5000 °K


Focus on the measures:

The lumen indicates the light quantity  issued by the light sources. A normal lamp of 150 W issues 2000 lumen, so it has an efficiency of 2000:150= 13 lumen a watt. Our Luxeon has an efficiency of 25:1= 25 lumen a watt. In practice the LED is the double more efficient.

The colour temperature is a measure that shows the white quality emitted in degrees Kelvin. Colour temperatures lower than 5000 °K pays a reddish colouring, to higher temperatures the light colours of blue. A normal edison lamp has a colour temperature of about 3000 °K.

 

Nearby to the "I" model (1 Watt of power) exist Luxeon III (3 Watt) and Luxeon V (5 watt.) To the raising of the power increases the produced light but also the current drain, and to these powers the heat produced also becomes mattering.

But now we see closely one of these new hi-tech flashlights...


LED LENSER V6 POWER CHIP
A tool of portable lighting that uses the Luxeon LED and owns peculiar characteristics. Made in Germany by Zweibrüder Optoelectronics (http://www.zweibrueder.com) it can be defined "the Mercedes of the flashlights" for the extreme cures in the design and building.  
The Wrapping puts the stainless steel structure in prominence, the flashlight turns out solid and robust. Here are the base characteristics.
Light source: Luxeon white LED to 1,25 W
Power source: 3 AAA batteries
Length 10,3 cm/ Diameter 2,5 cm/ Weight 150 g
Switch power button with gold plated contacts
Duration of the batteries: Until 70 hours
Duration of the LED: About 100000 hours
Supplied accessories: Pocket nylon and karabiner
Kind of luminous beam: Mixed spot flood
Body in smooth, waterproof stainless steel

The bunch of light issued by the V6 is so brilliant to constitute a risk if looked closely. For this reason on the metal body is shown the high intensity light symbol, how it happens for the lasers.

The form of the light beam is a combination spot-flood (concentrate and wide) obtained thanks to a particular lens, studied to exalt the characteristics of the LED. The light is well visible to the center (spot) and degrades in a wide circular zone (flood). In the following illustrations you can see the form of the projected beam and the frontal lens.
Batteries lasts until 70 hours with gradual brightness decrease. The power switch offers a pleasant feedback to the touch without risks of casual activation.

OTHER APPLICATIONS
I am sure that the technology of solid state light will take remarkable advantages in the lighting systems. Some examples:

- In the motor sector will be made LED car lights (see the prototype of Audi 4 Nuvolari:
( http://www.newstreet.it/Home/Articolo_Id_403.html )

- In interiors we will be able to enjoy the purity of LED colours with lamps or lighting panels:
( http://www.epsilonelectronic.com )

- In the multimedia will be realized LED displays with very high luminosity and greater chromatic purity
( http://www.lumileds.com/solutions/solution.cfm?id=2 )

- In outside will be used street lamps and traffic LED lights with little needs of maintenance.
( http://www.scae.net/lanterne_led.htm )

For more curious people there is a link to see what today is already available in United States
( http://www.ledtronics.com )


What do you think?
On the solid-state light it would be there very much to write: special Optics, electronic circuits that increase the power of light, tactical flashlights used by the soldiers, ultraviolet LEDs, ecc. This article will be enriched from other tests and widenings on the basis of your interest.
After trying a LED flashlight one remains struck by the amount of light that a such compact object  bursts out, a flashlight to the maximum power!
The cost for each review is 100 EURO, including VAT, product test, research and deepenings (possible creation of user manuals), graphics and photographic production, italian translation. Please ask for multimedia and conference delivering.