my most recent infatuation is with lasers, specifically the pointer pen variety. i started out with one shaped like a golden mouse [the whiskers kind] that shoots a 670nm deep red beam, but it is very weak at <1mw power output. then i got a neat violet one [405 nm] that puts out 5mw of black light, and on things that aren't naturally fluorescent [like dark fabrics and grass and dirt and such] it displays a dim deep violet splotch that becomes larger with distance [its collimation is subpar]. but shine it on anything bright white like paper or porcelein and it is a sharp bright glowing blue little circle of light
. shining it on my ceiling tiles makes a big splotch glow in a most unearthly way.
i determined that 200mw [1/5 of a watt] lasers were the best combo of inexpensiveness, power and practicality [IOW that power rating is the highest to run on cheap alkaline AAA batteries]. $25 will get you a red or green or blue or violet laser at that power level, so i ordered red/green while giving my 5mw violet to my rock/gem-collecting sister and then ordered a 200mw violet. a 200mw green one just arrived, and i fired it up and was alarmed at how bright the beam was- even in daylight i can see the beam from the side [due to a phenomenon called "rayleigh scattering"], and the beam is clearly visible [in daylight!] when shone on trees up to a 1/4 mile away! from across the room i put holes in my garbage bags from just a short zap
from another place i ordered a 1 watt [1000mw] blue [459 nm] laser because i want to see just what it can burn. lasers are considered "burning" if they put out at least 30 mw [3/100ths of a watt]- the difference between a 30mw laser and a 1 watt laser seems to be mostly about time and distance, with the later capable of quickly burning holes through things and setting things afire from across the street whereas the 30mw job can do these things only much more slowly and no more than a few inches away from the object. when my 1 watt blue job comes in the mail, i will experiment with it, to see what it does to things like flies and mosquitos and such, as well as lighting up the kindling in my sister's fireplace.
it should be noted here, that lasers above 5 mw [1/200ths of a watt] are potential hazards to one's eyes and to anybody else in the general direction of the laser beam, out to several hundred feet
and to always use caution when having fun with one's laser- after all, several nations [notably australia] have banned the things due to a few bad players. 30mw and above also should be used with safety glasses on, because one never knows what reflective objects are off in the distance and if they are angled just so as to reach a person's retinas which deserve to be protected at all costs. but keep in mind that even with the goggles on, the unfiltered IR component [Infra-Red] of most high-powered pen lasers will pass through all but the most expensive glasses, so caution is still in order, don't let the goggles give you a false sense of security. and NEVER use anything above 5mw as a toy with your pets!
here is a fun and educational laser video for your enjoyment
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[youtube]http://www.youtube.com/watch?v=woiTedSKPrk&feature=related[/youtube]
and another-
[youtube]http://www.youtube.com/watch?v=gHOdDiV4Oro&feature=relmfu[/youtube]