Viewing a Ruby Laser's beam. (warning one of my long ones but interesting) / General Science and Electronics / Forums

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Viewing a Ruby Laser's beam. (warning one of my long ones but interesting)

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MikeT1982

Mon Jul 09 2007, 07:20PM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
Location:
Posts: 119

I am curious about this. Just a thought I'd like to discuss with you guys. For info's sake, the Pulsed Ruby Laser I am building will have somewhere between 30 and 40 Joules per pulse power, and is non-q-switchedoldschool simple mirrored rod for simplicity). I am putting just about 4,000 Joules into the flashlamp and have gotten info that the threshold where the rod will begin lasing is 500-600 Joules, and the maximum flash input where it would saturate and not make any more output beam power at about 6000 Joules. So according to Richard Anderson of Anderson Lasers (this guy is so helpful and is brilliant) my 4,000 Joules I stumbled/decided upon should be nice and efficent, especially given that the lamp is rated 10,000 Joules with a 25,000 - 30,000 Joules explosion energy.

Now to the point, I WANT to see the beam or the spot where it hits. What do you guys think is the risk of me aiming at a dull object and viewing without my Ruby Glasses. The reason I went with Ruby is because it is visible and have always been fascinated with them. Now I am purchasing 3 sets of >5 OD Ruby protective goggles (I can't afford the >7 ones!!! Like $475 a piece jesus!!) This way I can demo the laser for friends and family and be safer. However I wonder if I can get away with looking at the beam on a dull object without them just to witness its real power.

I researched specular (mirrored) and diffuse (softer) objects for reflection and have learned that the diffuse reflections can STILL be dangerous when dealing with Class IV lasers like this!!!

But back in the 1960's the articles say that "observers witnessed a nice red spot" on the wall as Ted Maiman pulsed his invention. (who just passed away by the way! I am very sad, he died this May 5th, 2007)

So whatdo ya think.....is it like riding a motorcycle without a helmet just be careful? Is it done in labs? When I made the 5 hour road trip to Anderson Lasers Lab to see for the first time in my life a Pulsed Solid State Laser real life NOT in a book (and I wanted to see one since I as like 10 years old), Mr. Anderson fired up a pulsed KTP frequency doubled Research Nd-YAG Unit for me that had a high rep rate of like 3 HZ, and we both dropped or glass for a second so I could see the mid air focused ionizing air breakdown ball in Full glory (I have it on MPEG I'd love to show it to you guys!!! its sucks though I just have Dial Up ISP here in the boonies) well it was bright as HELL!!! I mean like a camera flash, scary and LOUD LOUD LOUD we had to yell to hear each other

.......soo worth my 5 hour EACH WAY lone car drive through a freaking blizzard in 27 degrees F journey out to Ohio.....so anyways who knows...

Mike

...

Mon Jul 09 2007, 11:53PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

no. just no. it isn't worth your vision to see a frickin red dot.
You could shine another laser through the rod (I bet that 630nm laser would shine right through the mirrors) for aiming/etc. Heck, you could even pulse it for added realism ;) But you really have to choose between a burning laser and a laser you look at--it is a very bad idea to mix the two.

The FDA has done a study and determined it to be 'safe' to be exposed to <4mJ a day. So even if you only get .1% of the total power in the beam you are exposing yourself to 10x the 'safe' power level.

Also, keep in mind that you eyes can't detect 700nm light very well (it is about 1/20 as bright as green light) so that spot is more powerfull than it looks. Furthermore, the eye percieves brightness on a logarathmic scale, so that dot can have hundreds or thousands of times as much power as it looks like.

IamSmooth

Tue Jul 10 2007, 03:10AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

I agree with the above. You don't get second chances with your eyes. It isn't worth it. If you want to "see" the beam set up a video camera and put out some mist or smoke so you can track it. Just don't use your eyes.

Dr. Shark

Tue Jul 10 2007, 08:58AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Mike, I have not personaly dealt with high power pulsed lasers, but I have worked in a lab with several CW YAG lasers in the multiple Watt range shining at the walls and nobody ever bothered to put on googles. We also had a small q-switched laser which certainly exceeded your laser in peak power and we used to burn the paint off of business cards with it, also no goggles - so I would say you are safe, just treat it like you would treat a big camera flash. Once it is diffused, it is nothing more than that.

On the other hand, I highly doubt you will ever get 40J out of your system. 1% efficiency is optimistic even under lab conditions, where _everything_ is controlled for, so in a basement setup I think you should consider yourself lucky if you hit 1J. Even that would be quite a bang, good for popping ballons and the like.

Steve Conner

Tue Jul 10 2007, 09:22AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Whatever. Just remember that all safety information provided here is without warranty! Especially joe's

Marko

Tue Jul 10 2007, 12:28PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I appreciate all the safety here, but being over-cautious sometimes simply spoils the fun.
It's like locking up a Tesla coil in garage and firing it from outside in fear of electric shocks.

Even 40J isn't all that much when diffused. There are camera flashlamps putting out more energy in visible and those are directed into people's eyes.

Just use common sense, don't shine the beam at polished reflective things that may reflect the beam, don't stare into the spot from 20cm distance and you'll be fine.

MikeT1982

Tue Jul 10 2007, 11:24PM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
Location:
Posts: 119

Yeah guys thanks for all the replys. Thats how I see it from both ways, that I should adhere to the strict safety standards, yet don't want to spoil the ability to witness first hand something. So what I think I will do is start out with the ruby goggles and non-reflective objects like something black. Then shoot video with a Digicam at the same time, then if things don't seem to insane (who knows maybe I will only get 1 Joule, maybe 10,20,30) then I may try open viewing at my own risk and by myself. Wait no warranty Steve geez! :) LOL nah of course I know its my own risk if I do.

Adrian

Tue Jul 10 2007, 11:59PM

Registered Member #697 Joined: Thu May 10 2007, 12:28PM
Location: Australia
Posts: 22

Some black shiney things reflect quite well. Make sure its something black that will diffuse the light.

EEYORE

Wed Jul 11 2007, 01:28AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

I think you may be rather dissapointed in the "visible" part of the laser output. It will be a very dark red spot that is gone in the blink of an eye and more than likely eclipsed by the flash from whatever it is vaporising. You may have more fun with a c02 laser though...

Matt

Carbon_Rod

Wed Jul 11 2007, 05:09AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

A simple CCD camera works better than your eye at some nm....

Never risk your eyes, they can't be replaced at any price.

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