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A Laser as a Demonstration

H

HeavyLight

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I'm taking a public speaking course and our first speech is just an informative one. I intend to teach the class a little bit about how lasers work. This is next month and I want to have a laser with significant power (1 to 2 Watts) to use as a visual aid. I already have a 20mW 405nm laser gun that I made a while ago. I've had a plan to get a jayrob host kit and a 445 diode from one of the people recommended and now I'm going to push that plan up. My questions for the community are:
What are your recommendations for the diode I should get? I've been reading around but more information couldn't possibly hurt.
What are some good ways to ensure a safe display other than getting cheap goggles to distribute to the class?
 





DrSid

DrSid

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What about playing some videos instead ?

Everybody would have to wear goggles. And there is always some moron who will try to not to use them, but you will be responsible.
 
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pschlosser

pschlosser

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HeavyLight said:
What are some good ways to ensure a safe display other than getting cheap goggles to distribute to the class?
Click to expand...

keep it under 5mW.

Also, bear in mind, a fat juicy laser isn't going to teach them much more than a 5mW one. Virtually everyone (in the USA, anyway) has seen a laser pointer and knows what it is. I suspect few, however, know how they work, or how the light is generated.

I'd go for an assortment of colors in 5mW and teach them about the colors and why they come out at the specific wavelengths they do.
 
InfinitusEquitas

InfinitusEquitas

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For a public demonstration, if there is even a chance you will not be in control of the laser, keep it to 5mW.

To make the beam stand out more, buy a fog machine.
 
H

HeavyLight

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I had suspected as much but they expressed interest in a live demonstration and I wanted to see if there was a way. A video will suit my needs just as well. :thanks: for giving me these tips and ideas. :)
 
HitShane

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HeavyLight said:
I had suspected as much but they expressed interest in a live demonstration and I wanted to see if there was a way. A video will suit my needs just as well. :thanks: for giving me these tips and ideas. :)
Click to expand...

Buy a high power one and use it to make a video(s)... Bring low power ones for the demo... Def buy a fog machine to awe the crowd with the 5mw lasers :) You could have the 5mw lasers already set up before your audience arrives, maybe even have them on when you start. Then turn on the fog machine. It would show the beams to everyone that didnt notice they were already on...
 
Khoonda

Khoonda

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Just last week I brought in all my lasers for my Earth/Space science class to demonstrate how minute differences in wavelength can change the colors we see. For 445nm I did bring a 1,100mW laser but this was carefully aimed at a dark colored brick sitting on the counter. Take caution and you will be fine

The teacher liked it so much she asked if I could come in for the first five minutes of her other classes and do the same. These were 11th/12th graders and none of them asked if they could hold the laser or play with it, which was surprising. (Probably because they saw keys being used on some.) I did get questions about where to buy/etc...
 
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InfinitusEquitas

InfinitusEquitas

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Personally, I would speak with the professor/teacher first. If they are ok with it, and you can control the setup, with a beamdump... that would work.

Alternatively, you can buy one of those cheap ~$30 firefly lasers (Link) and a fog machine. (Link.)

Aim the laser at the ceiling - obviously non reflective ceiling.

Have the people come in, start talking. Once everyone is in, turn on fog machine and turn off lights.

Then, in the dark, with fog, you will have a very interesting looking spectacle for them.
 
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DrSid

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Showing the beam is nothing .. and if that is the goal, green is always better.
When I'm showing my lasers to people, I show burning. But then I take 1 person at a time.
 
Teslanium

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Imo, the most interesting things about lasers do not require high power. Way back in grade school when all they had/could get (if that!) was a 5mW bench top HeNe, the qualities of the coherent light and how it was produced were interesting enough, and no goggles were required. Best to not take chances, but I certainly understand the allure of power, especially since the advent of multi-watt lasers in performances and on the web.

Those earliest experiences would plant the seed for my own experiences with lasers that continue up to today and beyond.

Today with all the liability crap going on it might be best to at least provide a handout for the kids with safety info included - and emphasized.

Good luck with the demo, let us know how it goes!

T.
 
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HitShane

HitShane

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InfinitusEquitas said:
Personally, I would speak with the professor/teacher first. If they are ok with it, and you can control the setup, with a beamdump... that would work.

Alternatively, you can buy one of those cheap ~$30 firefly lasers (Link) and a fog machine. (Link.)

Aim the laser at the ceiling - obviously non reflective ceiling.

Have the people come in, start talking. Once everyone is in, turn on fog machine and turn off lights.

Then, in the dark, with fog, you will have a very interesting looking spectacle for them.
Click to expand...

That is really cheap for the power isnt it? I like how it has a mic input! Guessing it would pattern to sound!!!
 
InfinitusEquitas

InfinitusEquitas

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Yup, it has a mic and will respond to sound. I had mixed luck with these, but for the price, no big deal. The three I tested with LPM without removing diffraction grating, were all under 5mW.

You can find these on amazon also, for about the same price.
 
H

HeavyLight

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Teslanium said:
Today with all the liability crap going on it might be best to at least provide a handout for the kids with safety info included - and emphasized.

Good luck with the demo, let us know how it goes!

T.
Click to expand...

I probably should have mentioned that it's a college course so all the people are adults but a handout would serve well. It doesn't help that our speeches are supposed to be between 4 and 6 minutes. I have a feeling that I'll end up going over that. :D
 
InfinitusEquitas

InfinitusEquitas

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HeavyLight said:
I probably should have mentioned that it's a college course so all the people are adults but a handout would serve well. It doesn't help that our speeches are supposed to be between 4 and 6 minutes. I have a feeling that I'll end up going over that. :D
Click to expand...

College student /= adult. Not even close.
 
ARG

ARG

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Lab lasers are safe enough to use for a demo without goggles. Just bolt it down so it doesn't mive and make sure the beam is terminated into a beam dump or on a piece of metal painted flat black. The beam dump must also be bolted down.

As long as nothing reflective gets in the path of the beam it's safe. Make sure to mark out the beam path as well and have an emergency stop button.
 
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