Laser pros- drop by a sec

[Permanent Waves]

The 4 safety rating on these adequate? Hmmm, for a do-all item like that I think I might just go for it! Thank you!

 

[cistercian]

I'm kind of confused that none of the replies in this thread mention either just buying a IR filtered laser, or simply adding an IR filter ($3 plus a little glue/epoxy) to a non-filtered one... If you keep the IR from leaving the laser, that sort of eliminates the need for goggles that protect against it, correct?

I agree strongly.Why not just buy a properly filtered green to begin with?Then you don't need expensive ir/green goggles.
At close range while burning, the IR is dangerous.It does not focus to the same place as the green with any precision so the added burning power is just not worth the trouble(to me at least).

And you are right about the inexpensive IR filters.The high powered labbie green on e-bay(covered in the review thread) is just the kind of nice apparatus worth adding the filter to.

 

[cistercian]

Yeah, pay extra for rubber. Within 2 days of getting my mag I chipped it.

If you can't find the one you want that has rubber, go get this at your local HW store and do it yourself. Specialty Protective Coatings & Adhesives, Protective Foam Coatings, Dissipative Coatings

Neodymium Iron Boron is my favorite magnet.I like using them for levitation experiments.You can float a mirror and lase it to make a crude but sensitive seismograph, among other cool tricks.Epoxy covered are more durable than plated, but the penalty is the higher the grade, the more fragile they are.You just have to be very careful with them.I have a couple 2 inch diameter one inch thick N50's.They are finger crushers and very dangerous.I have even bigger ones, but they are only N36...but still fun.As I type this, a chip of pyrolytic graphite is flying on top of my refrigerator over 4 N53 1/2 cube magnets.Great fun!

 

[Permanent Waves]

A properly filtered green laser at 150mW+ doesn't seem possible for the $60 or so I paid...

WOW a seismograph, AWESOME idea! I think you just won the prize for most useful application of a laser and magnets. Great for the apocalypse when all the seismographs will have been swallowed up or destroyed by plagues, lava, and locusts.

 

[qumefox]

Yes. There are stories, but they are hard to find. :yabbem:

Why has nobody suggested Zone Stealth safety glasses?
They're only $42, and they protect against Green and IR. :bday:
Multiple Wavelength

$42 is still more expensive than a $5 ($3+$2 s&h) IR filter last I checked. Unless you plan to try to roll your own DPSS, or just want to play with IR diodes, few people would ever really need IR goggles.

And OD ratings are base 10 logarithm. So an OD4 rating means it attenuates light at that frequency by a factor of 10000. So 100mw at OD4 would appear as .01mw. At OD3, it would appear as .1mw, and at OD2 it would appear as 1mw.

A properly filtered green laser at 150mW+ doesn't seem possible for the $60 or so I paid...

WOW a seismograph, AWESOME idea! I think you just won the prize for most useful application of a laser and magnets. Great for the apocalypse when all the seismographs will have been swallowed up or destroyed by plagues, lava, and locusts.

It's possible for an additional $5 though heh. Gluing on an IR filter isn't exactly challenging after all.

 

[Permanent Waves]

I'm surprised at what an active, helpful, vibrant community you folks have built for yourselves here. Thanks for everything. I have learned a lot from this thread and I appreciate everyone taking the time to respond. I will try and post some photos and a review about my Rayfoss laser on a similarly named topic- thanks again!

 

[cistercian]

I'm surprised at what an active, helpful, vibrant community you folks have built for yourselves here. Thanks for everything. I have learned a lot from this thread and I appreciate everyone taking the time to respond. I will try and post some photos and a review about my Rayfoss laser on a similarly named topic- thanks again!

No problem...and I appreciate the enthusiasm.Science is just so freaking cool!

 

[PhysicsTeacher]

If you want to measure the actual wavelength of the laser light, as indicated by your post above, you can do it using a ruler, a screen, and a diffraction grating. I always had my students do this using a HeNe laser because there is so much good physics in the lab activity. The majority of the kids are able to get within 5% of 6328 angstroms (I show my age...). Of course, the result won't be much of a surprise.

You can use one of those cheap student gratings - just make sure its got a label for how many lines per mm (300 to 600 are typical), or you will have to work backwards from the known wavelength of laser light. Our classroom set was beat up, but it worked.

Shine laser through grating and on to a screen, look at interference pattern on the screen (line of evenly spaced dots), and measure two distances:

Wavelength = xd/L, where x=distance from principal to first order (or between any two dots on the screen), d=slit width (1/300mm or 1/600mm), and L=distance between grating and screen. Convert all measurements to the same units before you plug and chug.

Your beam may be a bit too bright to make the proper measurements - we used the old Metrologic 0.5mW lasers, and they gave very small, sharp first and second order images.

Fun bonus activity: If you can find a set of large acrylic classroom prisms and shapes that are doped with a very small amount of a colloid, you can have hours of fun watching the beam inside otherwise transparent optics. I treasured my set - It was like magic watching the kids use these with the old HeNe lasers. Our school was the oldest in the district, and I had physics toys that they don't make today. Brings index of refraction and critical angle to life in ways that pins, glass blocks, and pencils can't.

 

[Permanent Waves]

That's great info, perhaps a little more than I am prepared to work out for, as you mention , a ballpark figure which we can pretty much tell by the color but useful nonetheless. I am considering purchasing diffraction gratings and maybe a fog machine for effect-style fun. I think it would be amazing to do a "time tunnel" on our front door for Halloween. Can anyone recommend a kit for a "time tunnel" effect, a diffraction gratings kit, and if it is safe to view laser light bouncing off of fog? I see laser light shows using 100-200mW+ lasers and question how this can be safe (these are commercial units not homemade)?