Roadie Special takes on some live matches.

	Duration: 05:53 minutes Upload Time: 2007-02-27 18:33:37 User: RoadRunnerLaser :::: Favorites :::: Top Videos of Day
Description: The new Roadie Special variable power, variable focus, stabilised laser takes on some live matches. The reason for the orange colour is because in certain situations, I protect the CCD of my camera as well as my retina with the correct goggles. Only an insignificant portion of the original green remains (Optical Density 6+ at 450-532nm). The orange 'flare' you see is the fluorescence from the object itself, not the original laser. This is the target material becoming so energetic that it starts to emit its own photons. Normally we wouldn't see that with the naked eye because the brightness of the green would drown it out. This would normally only be seen from wavelengths to which we are not so sensitive, like blues and violets (and beyond into UV, of course) or even very deep reds into infra-red. The beam of a laser is not hot, as can be witnessed from the fact that this is a live match and the cut I am making is probably only a millimetre or two below the edge of the readily-flammable compound. The reason that the laser cuts is because the target material cannot dissipate energy as fast as the photons from the beam are delivering it. In most cases, the object oxidises, melts, vaporises, sublimates, turns into plasma or generally does whatever such material does if it absorbs energy at the wavelength you're currently delivering... If you're delivering enough power, that is. What is of vital importance, is not HOW MUCH POWER ? But... How much power over what area ? Like weight on a soft surface. If you spread that weight you don't have as high a pressure on the surface. Pounds per square inch = Amount of weight over given area. For damage thresholds on various objects we express this as energy in Watts (or mW, or kW, MW etc...) over unit area - Usually Metres, centimeters, mm etc.... The term for this expression is "Irradiance". A laser emitting 1kW can do LESS DAMAGE than a laser emitting less than 1/10000th of its power at the same distance to the same target object if the power of the 1kW laser was spread over sufficiently large enough area and the power of the 100mw laser was concentrated into sufficiently small enough area. Thus, it would be said that the 100mw laser, although lower in power output, has a higher irradiance than the 1kw laser under these conditions. The concentration of light within a beam is not uniform. Usually, a beam is brighter at its centre and softens at the edges. Thus, the irradiance at the centre of a target spot is higher than at the edges. Note how in a later portion of this video, you see the beam emerge from the other side of a match and it's thinner and weaker when it emerges than when it enters. This is because the edges of the beam do not have high enough irradiance to cut through as quickly as the centre yet they are plenty visible enough to see. You'll see that even with that apparently weakened portion of the remaining beam, there is more than enough power to continue to ignite live matches. DARN YOUTUBE ! Didn't we used to have a 'science&technology' category ???? This isn't a "HowTo or DIY" and the closest fit category is based on the fact that this is a technological gadget but it is not a toy ! LASERS ARE FUN AND FASCINATING BUT YOU MUST TAKE STRICT AND COMPREHENSIVE PRECAUTIONS. UNDERSTAND HOW LOW POWERED UNITS FUNCTION FIRST. TREAT THEM LIKE DEATH-RAYS BECAUSE THEY ARE. THEN START MOVING TO HIGHER POWERS. OPERATING LASERS WITHOUT PROPER PRECAUTIONS CAN CAUSE INJURY, FIRE, BLINDNESS OR IN CATESTROPHIC CIRCUMSTANCES - DEATH.
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