Trying to Find Class 1 Laser Diode

How about a filter over the end of more common laser pointer to reduce the power?

I'm trying to think of good 'easy' filter. If you only need a few I can put a 'piece of plastic' in the mail. You'll have to cut and tape pieces over the end of the ~5 mW laser.

George H.

What color?

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Thanks a lot for your response. Color isn't so important as long as his pointer would still be easily visible when it hits an object (plastic communication board because my fiend is aphasic) about 3 inches away.

Trish

Thanks so much, George! I'll reply separately.

Trish

At that distance, and depending on ambient lighting, you might find a "super bright" high efficiency LED that would work,

A small plastic magnifying glass for a focusing lens, PVC pipe to hold it in alignment ... Add a pushbutton switch .... Projected you get a picture of the LED die, about a 1mm square with ordinary 5mm type LEDs

A similar technique might work with a laser diode and make it much safer. Diffuse or spread the beam then sharply focus it at 3". Further away it would spread enough to be safe (depending on his ability to keep it on target and how close together the targets are)

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Hi Trish, We sell a bunch of plastic neutral density (ND) filters. We get big sheets from Tiffin and then chop 'em up... There is always some edge bits that we can't use and these are just sitting going to waste on our shelves... These are listed as ND=3D0.70, the neutral density is a log of intensity ratio, an ND=3D1 lets through 10% of the power, ND 0.7 lets through about 20%. But there's plenty of variation from piece to piece. I stuck a few pieces in front of a HeNe laser and had intensity at the output varied from 22% to 15%.

I'm not sure how you are going to measure the intensity of any laser you might find. I don't suppose you have a photodiode laying around?

Maybe you can try sticking one or two together and see how you like it. I put two in in front of the 0.5mW HeNe and could still easily see the beam on the wall.

Perhaps the one issue to worry about is too much intensity. At higher intensities I've 'burnt a hole' in the plastic. Not a real hole mind you but the gelatin that makes up the ND filter changes somehow if it gets too hot. I can't give you some hard and fast number for this intensity as it depends on the spot size of your laser.

George H.

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Use a red laser pointer I've heard reports that the cheap green ones sometimes have some of the NIR laser light at the output.

George H.

I have some misgivings about proceeding with a modified Class 2 laser. Before I'd always read statements like "Eye damage is impossible with Class 1 lasers even after hours of exposure), due to their low output power.' Never a statement about power. However, delving into it further to make sure that the 25% reduction of a Class

2 (< 1mW of power) would be the equivalent or better than a Class 1, I finally found this on the OSHA web site: "Class I: cannot emit laser radiation at known hazard levels (typically continuous wave: cw 0.4 =B5W at visible wavelengths). . . ." So I'm now thinking I best try to make the best of the super bright LEDs, at least 'til I can find a configuration for the laser pointer that I can determine is, for sure, safefor my friend.

Thank you again for your kind offer and your help in understanding this.

Pat

Class I: cannot emit laser radiati> >

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Thanks a lot for the idea about the super bright LED. I have tried 'pretty bright LED flashlights' without much success, but I'll give your suggestion a go.

Thank you.

Trish

You can find the guts of cheap laser pointers with a quick web search. They're available with

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Yeah, laser's are a bit scary, I wish people would be more careful.

The bit's of plastic are in the mail. If you stack up three of the filters that will be more than 2.0 ND only 1% of the power will be coming through. You can try stacking more.

Part of laser saftey is counting on peoples blink reflex. Which is why green laser diodes that leak some of the NIR fundamental are scarier. I have no idea if the plastic bits block the 1064 nm light. See under green here,

George H.

I missed the 0.4uW number. With a 5mW input laser you'd need an ND of a bit more than 4. that will be six layers of ND=3D0.7 plastic, you can at least see if that's enough light.

George H.

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Thanks, George. I'll try it!

Trish

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I'll try 6 layers of the plastic with a RED laser.

Thank you, George!

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One more little glitch. Now I'm Googling for a Class 2 red pointer. I find a few, but one of them has this warning (no doubt a translation from Chinese): "The laser can bright enough when you light it in normal temperature, so you had better do not light it continually in

30 seconds". Will 'constant-on' be a problem. My friend (who's a quadriplegic) can neither speak nor operate a push button. The goal is for him to use this pointer to select letters on a communication board. Will this be a problem for the Class 2 laser?

Thanks. Trish

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I don't know any laser pointers to recommend.

We use red diode lasers from Quarton.

Something like this,

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But you have to apply your own power.

Can you do any basic electronics?

George H.

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Most I've seen do have such warnings. I'm looking for a green laser and have run into this (even with reds, which don't "meet requirements"). This disclaimer is on the

cheap laser pointers have an adjustable lens that could be defocussesed that may be enough.

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Thank you again, George. Your filters arrived today and I just found a constant-on Class 2 pen which should arrive 7/6. I'll let you know how it all works out. &;-)

Trish