hi,
i need to make a standard commercially avaliable laser visible in a sealed container when viewed from any angle.
i cant pump smoke in there as it will eventually settle (wont it?) and make the cotainer dirty inside.
anyone know of a material i can fill the container (box with clear front) with to make the laser visible?
i was thinking of some sort of gel, possibly with tiny particles suspended in it.. any ideas?
or is there a film i can cover the box in that will make the laser visible?

i havent selected a laser type yet so any options that will only work with particular lasers should be fine?

also, anybody know if a laser light will travel through a regular two-way mirror when pointed at the clear and/or mirror side? if so, is it still dangerous if it scans your eye or will it diffract sufficiently?

thanks in advance.
Michael

green laser beams are more visable

mgt,

Yes scattering is the best idea. Instead of smoke how about mist (water vapor)?

A two-way mirror still transmits or reflects light and is hence dangerous to use without eye protection or at least caution.

The only way to see the beam is if it scatters off of something, and particulates are generally bad for optics. If it's a temporary thing, one can use dry ice or liquid nitrogen; condensates of the gas will scatter the light and not damage anything unless they get too cold.

If you just want to show the beam at some spots, having it pass through a (semi-) transparent sheet of glass (or similar) will show the spot.

wat i did was take an aerosol can and spray it upwards. the average time it the laser will be visible is bout thirty secoonds before having to spray again. but..........AXE body spray/deodorant last for 2 minutes. spray up ward. note that u must be in a room with very little to no draft or wind for this to work

You may be able to do it with a static charge generator. In other words, if all your tiny particles have the same charge they will never be able to settle but will occupy the volume in a uniform way. Many a pinch of carbon dust. If one ever opened a bag of carbon dust, i.e., activated carbon, wait a couple of days and it will be everywhere in the room.

Something simpler and very low tech may be dry ice. This will give off a CO2 smoke when placed in water.

There are also smoke generators used during Halloween that will emit smoke for long periods of time. A slow stream from a small unit with an air mixing fan for dilution, may give you hours of fun.

Some fountians (cheap) use ultrasonic gadget of some sort to create water vapor that looks like fog. I have used them to observe and track low air flows.

Google Laguna Ultrasonic Fog Generator at PetStore.com as an example.

I got mine at a county fair.
Good Luck

You didn't say how large it needs to be, pr whether you're looking for a particular aesthetic effect.

The easiest way to disperse laser light is to bounce it off a chrome-plated ball bearing roughly the same diameter as the beam. For instance, a Radio Shack pen laser pointer has a fairly uniform 3 mm dia. oblong spot, so if you bounce that off a shiny ball bearing smaller than that ( mounted in a transparent tube with a black stop behind it ), you get an essentially spherical outgoing wave. To make it eye-safe, use emery paper or acid-etching to to roughen the surface of the ball-bearing to the texture of satin-side aluminum foil. Make sure there are no shiny spots. That way the human eye can't focus the reflection to a point. Make the transparent tube a couple of cm in radius, so that nobody can get their eye really close. That should suffice for a 5 mw laser.

If you want to show the beam traversing a cloudy substance, I'd suggest mixing up a slow batch of clear epoxy ( not the yellowish stuff ). Mix in a little finely divided zinc oxide powder or titanium dioxide powder, and mix it up very thoroughly with a small-dia. stirring rod driven by an electric drill.

I'd be careful using electrostatic powders in air, because a great many powders turn explosive when finely divided in turbulent air or even nitrogen. If you're determined to make an air suspension, I'd suggest filling the chamber with helium. The problem is that electrostatic powders will eventually coat the aquarium or whatever. Even if you put a positive static charge on the inner walls of a transparent box, the fields from opposing sides of the box will cancel out.

Your best bet might be to make a cloud chamber, which is a type of science project used to show ionization trails from charged particles. The cloud chamber is basically a sturdy glass jar filled with alcohol vapor or other vapor, with a plunger that can suddenly lower the internal pressure slightly. That drops the temperature, super-saturating the vapor and causing a fog. The fog clears after awhile and leaves no residue, so you don't have to clean it.

The best fog generator for open air is simply a few chunks of dry ice in a bucket of hot water, in an aquarium or something. You could also use an ultrasonic humidifier feeding into an aquarium, with a small impeller to keep the visible vapor stirred up. I'd avoid using powder spray deodorant or anything like that -- yes the powder stays in the air, but it has a nasty habit of getting into mechanical switches, CD players and other sensitive electronics.

Another possibility would be a thoroughly emulsified mix of clear oil and water, with a few drops of emulsion, very thoroughly mixed so the result looks milky. Ideally, you'd want two imiscible liquids with very similar densities and different refractive index. You can keep them mixed with a simple magnetic stirrer.

Be very careful to mix thoroughly -- you don't want any shiny bubble boundaries or layer boundaries that could reflect or refact a beam rather than scatter it. Total internal reflection can occur at glancing angles, which is potentially dangerous.

With any aquarium-type demo, be sure the beam is backstopped. Don't count on complete scattering, because your scatterer might settle out. If you make a device, make sure nobody else can use it incorrectly, or dismount the laser and play with it. Even a laser pointer can be dangerous if someone shines it at a concave reflective surface. What people don't realize is that if the human eye gets caught unawares while focused on infinity, even a weak parallel beam can get focused to a point inside the eye, frying a few pixels of someone's retina. They may not realize there are 'small holes' in their vision, and keep playing with the thing.

By the way, laser levels are more fun because they throw a very thin flat sheet of light. Try shining a laser level into a really dense mass of spiderwebs. If you align the plane of the light with a planar spiderweb, it looks pretty amazing -- whitish spider silk makes a pretty good fiberoptic.

That'd be a cool Halloween display -- a laser-lit aquarium full of web-building spiders, abd some insects to prey on.

Again, be VERY careful about the design of such devices.

Hi freinds,

As to you as physicists' forum members I think that it is essential bringing to your knowledge that my technique would be applicable in any use when micron-sized fog droplets are required.

You are kindly invited to visit the site at www.shira-inc.com

Should you have any question, don't hesitate to be in contact with me.

Amiram Keshet

What about a solid cube? If nothing but the laser beam will be visible in the box's space, would it help to have a box of solid acrylic, with a tiny bit of impurities mixed in to catch the laser light? Since you mentioned a gel, I wondered if it might be simpler and more durable to simply make a solid, nearly transparent "box".

About those ultrasonic water vaporizers, or any device you might construct that will use water: don't forget that they must be cleaned daily. Humid spaces can breed diseases, particularly legionella [see Wikipedia for details on that]. I worked for a retail store in the 1980s that sold ultrasonic humidifiers, and we were quite suddenly trained to clean all the humidifiers, every day, without fail, because of dangers related to legionella. Systems that move air [such as heating and air conditioning systems] must also account for the possibility that stagnant water somewhere in the system could breed legionella, which is later distributed when the air is moved [as when a humidifier is turned on, or when an AC system starts blowing].

I would like to be able to view lasers such as the ones used to operate sport hunting range finders from a remote location so as to locate poachers. Is this possible and is the technology already available? Would these lasers be visible by using infrared technology or low light vision equipment? Could something like this be made so the user could see multiple different wave length lasers such as targeting aimpoint laser sights as well as the laser that is invisible to the naked eye such as those in range finders?

Do you suppose a range finder would make the laser indicator in some radar detectors alarm?

Simply find an element or compound which emits light in the visible spectrum, when in the presence and upon being excited by, the (invisible) wavelength the laser source is emitting.

If you were a qualified scientist or researcher, you'd already know to do these things. The fact you don't, indicates you most likely lack the basic understanding and knowledge necessary to accomplish what it is you're attempting to achieve.

Be aware when working with laser technology, you're undergoing the risk of possibly loosing your own eyesight, or that of another innocent victim. Consider the possibility this might perhaps be one of your own children, who happened to be around observing and intrigued by what your were doing at the time, without your being aware of it. How would that make you feel? Is what you're attempting to achieve worth that risk? Know your limitations and stay within the confines of them, to avoid such a disastrous outcome.

If you're truly serious and want to succeed at this endeavor, begin the process by acquiring some basic foundation of knowledge pertaining to the problem at hand, including all safety precautions necessary. Without acquiring that basic foundation, you're efforts are doomed to failure and perhaps even disaster.

If you're unable to make such an investment, then hire a qualified professional who has such knowledge and abilities.