Laser safety

[SamsarandaParticipant @samsaranda]

I am just about to start constructing a laser centre finder to use on my mill. It will consist of a demountable unit which will be held in the chuck or collets, whichever is fitted at the time, and will consist of a small laser unit projecting a cross image and this will be driven by a small battery pack. The laser unit that I intend to use has a wavelength of 650 nm and 5 mw power and is classified as a class 111a product. My question to all who are electronically conversant is, are there any safety precautions that I need to be aware in respect of the laser emissions other than obviously not staring up the beam into the emitter. It would appear to be on the upper limit at 5 mw in regards of classification and avoids the mandatory safety requirements of higher classifications, how reliable are Chinese statements of compliance to specifications when it comes to these mass produced laser emitters?

Dave W

[SamsarandaParticipant @samsaranda]

[SillyOldDufferModerator @sillyoldduffer]

I think a 5mW laser is far too powerful for use as a centre-finder. Looking directly into the beam is positively dangerous and I'd be concerned about catching a reflection off anything shiny. Like the metal object you might be planning to machine. I think the risk and impact are both high. You have a very bright tightly focussed beam aimed at a sort of mirror. That you're looking at. And you're up close and personal.

Why not use something more pedestrian like a Class 1 Laser?

Dave

[SamsarandaParticipant @samsaranda]

Thanks Dave, just the sort of advice I was seeking, my knowledge of lasers is virtually nil which is why I posted this topic, looks like back to the drawing board with a lower spec of laser. Many thanks.

Dave W

[Stuart BridgerParticipant @stuartbridger82290]

There is a good summary here

**LINK**

[DMBParticipant @dmb]

Does it have to be laser, if anyone is so concerned about safety with the OPs intended use of such?

Could an led be used, with a small magnifier to concentrate/focus the beam in much the same way as the laser light source? Would this be possible?

Perhaps a more knowledgeable person on here could advise us all.

[OldironParticipant @oldiron]

Sorry, don't want to hijack this thread but I have a problem (Houston). I clicked on the post in "Latest Forum Posts"

BUT there are only 3 posts in the thread. ? The 1st is by SOD @ 18.34 dated today. There does not appear to be an original post here ie- the page/s previous to this one are not anywhere to be found. No previous or subsequent page numbers for navigation. Any ideas anyone. ?

Will add screen grab to my album :-

regards

Edited By Oldiron on 08/03/2018 22:27:52

Edited By Oldiron on 08/03/2018 22:32:55

Edited By Oldiron on 08/03/2018 22:35:25

[Clive HartlandParticipant @clivehartland94829]

My work on Lasers, the limit for power for safe working was set to just under 1. mw. The power meter absorbed the laser and gave an analogue reading and I used a polaroid rotating filter to set it. The viewing of a Laser of that power should be less than a few seconds,. and no sustained viewing should be undertaken. In fact you can get flashed by a Laser of a bright surface just as bad as looking at it.

I am not sure now if there are any regulations regarding Lasers but in 1999 there were only recommendations outlined which we conformed to. Labelling was strictly adhered to with class and power and warning of not to look into a Laser. This may all have changed now after all this time so do not quote me on this.

There are smaller power Lasers available for such things as centring devices, but I would prefer to go the optical way. A right angle viewing scope with an adjustable graticule mounted on a Morse taper for use. I made one from a viewing scope off a tribrach, these can be made to focus to about 300 mm.

[SamsarandaParticipant @samsaranda]

.Clive, many thanks for your input, perhaps a rethink and optical would be the way to go, much safer with no dangerous light to worry about. Grey cells are working on a design.

Stuart , many thanks for the link to Laser Safety, interesting information.

Dave W

[Martin KyteParticipant @martinkyte99762]

Sounds like you have already opted out but for the benifit of others.

Totally agree with the 1mW limit for this use. non defocussed reflections should be assumed to occur so an intrinsically safe device is recommended.

Stuart Bridges LINK is good and there is an overview from .gov here.

**LINK**

Class 3a is an american classification and :-

Class IIIa laser product means any laser product that permits human access during operation to levels of visible laser radiation in excess of the accessible emission limits contained in Table II of 21 CFR Subchapter J Part 1040.10, but does not permit human access during operation to levels of laser radiation in excess of the accessible emission limits contained in Table III-A of 21 CFR Subchapter J Part 1040.10. Class IIIa levels of laser radiation are considered to be, depending upon the irradiance, either an acute intrabeam viewing hazard or chronic viewing hazard, and an acute viewing hazard if viewed directly with optical instruments.

Taken from

**LINK**

regards Martin

Edited By Martin Kyte on 09/03/2018 11:09:42

[Martin KyteParticipant @martinkyte99762]

Oh and do be carefull where you obtain your laser diodes/pointers. We routinely measure plaser pointers before use here at work and you would be amazed at how many far eastern cheap pointers are in excess of 1mW.

regards Martin

[SamsarandaParticipant @samsaranda]

Martin, one reason for my posting was to ascertain how compliant Chinese laser diodes were in respect of specification, your post demonstrates that they probably vary widely and even if I used a 1 mw diode then I couldn’t rely on it being within classification. Many thanks.

Dave W

[Martin KyteParticipant @martinkyte99762]

Hi Samsaranda

If it's got a classification it should be complient. There seem to be laser pointers around that are not marketed with a classification. If you source from reasonable suppliers you should get what you order.

regards Martin

[SillyOldDufferModerator @sillyoldduffer]

Posted by Samsaranda on 09/03/2018 11:28:52:

Martin, one reason for my posting was to ascertain how compliant Chinese laser diodes were in respect of specification, your post demonstrates that they probably vary widely and even if I used a 1 mw diode then I couldn’t rely on it being within classification. Many thanks.

Dave W

Well I doubt they vary much in the sense that a 0.8mW laser is completely safe whilst a 1.5mW laser is powerful enough to shoot down a police helicopter!

They're more likely to be underpowered than over and power output drops as they warm up. However 1mW is the continuous rating; suitable electronics or a fault could output a much stronger pulse, albeit very short. It's not a toy.

I don't think you can generalise about Chinese manufacturing these days. True they produce a lot of stuff that's too cheap. But China's come a long way since Chairman Mao failed to mass-produce steel using backyard techniques inside a closed Communist economy. Now they play the international market and are buying-in, using and improving Western technology. They can and do make and sell quality products to specification; that's were the money is . Quite likely a Chinese operated semi-conductor plant is as good as any, certainly not blokes mixing chemicals in a shed. Putting the laser into a cheap pointer is more dodgy; it could well end up in something shoddy.

Don't be put off making a laser centre-finder; you only need enough light to illuminate the target, which a small diode will do easily.

Dave

[SamsarandaParticipant @samsaranda]

Dave, aka SOD many thanks for your input, maybe consider resurrecting the project as a laser device but with an upper limit on the diode of 1 mw or less because this limit would appear to be much safer than a 5 mw diode.

Dave W

[John HaineParticipant @johnhaine32865]

Why not use an electrical contact device? More accurate than a laser. You can buy ones that have a built in buzzer and light that just go in a collet, or make your own. I routinely use this method for referencing my CNC mill, using a sensor I made with a known diameter concentric tip, isolated from the shank. For manual machining when it matters I use it with a multimeter with a buzzer on the lowest range.  One day I'll get round to describing how I made it, but will post a photo.

Edited By John Haine on 09/03/2018 13:37:24

[John HaineParticipant @johnhaine32865]

I just posted a photo on another thread – best edge finder for oldie.

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