| Author | Message | ||
     Anonymous |
hey, i have a very bright light bulb (gives of a lot of heat) and a few lenses, is there any way i can build a laser? i can focus the light but the distance between me and the abject changes the beam gets biger is the any way to keep the beam at a small size regardless of the distance of the object it will fall on? | ||
| Simon Quellen Field (Sfield) |
Yes and no. A bright light, two mirrors, and a fluorescent transparent medium, such as a ruby rod, a day-glo plastic, or a tube of fluorescent dye, can be made to lase. But just a light and some lenses, no. Laser light is often coherent (waves in phase), but that is not what makes it "collimated" which seems to be what you are after. A collimated beam has very low divergence with distance. The spot stays small. The way a laser gets is collimation is in two ways. In the classic ruby or HeNe gas lasers, there are two mirrors, and the light bounces back and forth between the mirrors, getting amplified as it passes through the fluorescent medium. The two mirrors are the key. If you've ever stood between two parallel mirrors, and caught a glimpse of infinity, you will understand. The light bounces between the mirrors so many times that it travels many hundreds of feet before it escapes through one of the mirrors. It is as if that tiny mirror was an opening at the end of a mile long tunnel. A flashlight at one end of the tunnel, aimed at the tiny hole at the other end, would end up with a beam at the far end that had very little divergence, because only light rays that were parallel to the tunnel would make it all the way without hitting the wall. Since we are selecting for very straight light rays, that is what comes out the end. In diode lasers, the "mirrors" are just the cleaved ends of the crystal chip. The chip is the size of a grain of salt. The light bounces back and forth a lot, but the distance is so small that the beam emerges without much natural collimation, and the spot gets bigger quickly with distance. With these lasers, a lens is used to collimate the beam. The lens is not as good a collimator, so you can see the beam expand -- at the end of a long hallway, the spot is several times wider than at the laser. You can use a tiny lens from a toy microscope to collimate an ordinary LED so that it makes a fairly small spot on the wall at the end of the hallway. It won't be as bright as the laser, but it will be as collimated. | ||
| Anonymous |
ok i have A bright light, two mirrors, and a glow stick can u draw me a picture plz? | ||
| Simon Quellen Field (Sfield) |
See this page. | ||
| Anonymous |
how comes they never show the laser beam? is this able to cut tho any material? | ||
| Simon Quellen Field (Sfield) |
Beams of light are not visible. Light has to reflect off of something, or scatter, to get to your eye. If a laser beam is very bright (such as a 5 milliwatt laser pointer) you might be able to see the beam at night as it scatters off of dust and gas in the air. If you want to cut through razor blades and such, you might want to build a 20 watt water-cooled carbon dioxide gas laser. You won't be able to see the beam, since it is in the infrared portion of the spectrum, but when you focus the beam with a lens, the amount of energy you can concentrate in a small spot is enough to cut pieces of steel that do not have large thermal masses to absorb the heat and conduct it away from the spot. | ||
| Anonymous |
Check this out- new mid air projection technology http://www.io2technology.com/dojo/178/v.jsp | ||
| glytch Unregistered guest |
very clever!! I first thought it was done by blowing air up with lots of transparent strips being blown into the air which then has a image projected onto it. but no, just air and lasers apparently. maybe a make at home version? or at least a small "why it works"?? please? | ||
| lysdexia Unregistered guest |
We talked about the Heliodisplay on advancedphysics.org. I said a lot about it. The laser is infrared for tracking and emulating a touch screen. | ||
| 343 Guilty Spark Unregistered guest |
Is there any way you can focus it enough to create Heat/Pain,just for s***s and giggels. | ||
| alex (Alex) Junior Member Username: Alex Post Number: 4 Registered: 4-2007 |
In order to pump a DYE laser or a ruby laser you need a fast discharge high intensity flash lamp ... specialy designed for it or an UV laser Incandescent lights won't do it (not even the very powerfull halogen lamps) it's kind of tricky to try and explain (way to much to write) So ... build a TEA laser if you want to pump a solid state laser (NdYAG, ruby) or a Dye laser ... or build a very powerfulll fast discharge lamp For more info google for "home made dye laser" you find explanations for why it won't work with your usual lamps and you find schematics / instructions on building high speed flash lamps and TEA lasers (maybe the most simple laser to build) |
