Guarding for laser cutter

[TrevorhParticipant @trevorh]

Evening all, my son is designing a CNC laser cutter/profiler for his hobby and has asked where he can get some Orange coloured plastic to put around the laser as a form of eye protection basically so you dont hurt your eyes when watching it cut

I guess to act similar to burning/cutting goggles but for laser emmitters

any help please

Trevor

[TrevorhParticipant @trevorh]

[Jeff DaymanParticipant @jeffdayman43397]

Having worked with high power lasers for cinema projectors, and had the full laser safety briefing for that work, I would say that just having orange plastic guards is not sufficient for eye safety with a laser cutter. I would suggest he find out what wavelength his emitters produce and buy the appropriate laser safety glasses to suit. These are available from suppliers of personal protective equipment. Non repairable retina injuries can result even from very low power lasers at certain wavelengths. Don't underestimate the danger of lasers to eyes in DIY laser engravers and cutters. Get the correct laser safety glasses.

Further, I would recommend sheetmetal guards for the enclosure rather than translucent plastic, to be safer for pets and bystanders who might not have the correct safety glasses. The enclosure should have a switch interlock that cuts power to the laser when the cover / door is opened, acting early enough during opening that no laser energy escapes. To block laser light, all the joints need to be designed so that all escaping light must make two 90 degree bends so it is stopped before anyone can see it.

If watching the laser working is important, I suggest a camera inside the enclosure rather than looking in. If a camera gets wrecked from laser exposure, it can be replaced. If your eyes get wrecked, they can not.

When cutting or engraving flammable items (wood, plastics, plastic or paint coated metals) with a laser, don't forget to make some provision to vent the fumes outdoors, like an extraction fan, and also to have a fire extinguisher close by. I would never operate a laser unattended , but especially not when cutting flammable materials.

Edited By Jeff Dayman on 30/10/2019 21:08:05

[Robert Atkinson 2Participant @robertatkinson2]

I second what Jeff says. You cannot go by the visual colour or density of plastic to determine light blocking. It is highly dependent on the base material, pigments and wavelengths that need to be blocked. For example black acrylic (Perspex) while appearing completely opaque to visible light will pass infra-red light with virtually no attenuation. Virtually all of the coloured plastic sold for filtering lights also pass IR light. If they didn't they would melt in front of the lamp. Conversely some grades of plastic which look crystal clear will totally block UV light. Then you have to make sure the laser can't burn through the plastic or degrade the dye(s) in the plastic. Overall solid metal is the safe option. Even then you have to make sure all the joints and seams are light tight. This is easier said than done. One check is to put a bright light under the cover. close it, and then inspect in a totally dark room for any leaks of light. Don't forget to wait in the dark for at least 10 minutes to let your eyes become sensitive. Some black anodised finishes are IR reflective too.
I've done laser safety design as part of my day job for instruments with high power UV lights and various lasers.

A related problem with some lasers like some blue or green ones is that the lightis generated by frequency doubling a infrared laser and with low quality ones they don't fit filters for the IR on the output so you can get dangerous levels of invisible IR light as well as the visible light.

You only get one pair of eyes

Robert G8RPI.

[not done it yetParticipant @notdoneityet]

Now that the first two posts have sorted the OP’s query I will also mention IR LED emitters (for the likes of security cameras or night-sights on guns equipped with IR detection systems) as potentially similar risk if looked at from directly in line with the beam at short range. One will not see anything, but the eye will concentrate these heating rays on the retina, possibly cooking some nerve endings (light receptors).

[TrevorhParticipant @trevorh]

Many thanks to all of you,

The ref to orange plastic was my feeble attempt to understand what my son was asking about as he did quote wave length and the like but it went over my head

know where he should start with obtaining such safety equipment?

I will mention about the venting of the vapours/fumes as this is quite a good point to be taken into consideration as well as the eye protection both on and off the equipment

Once again thank you

Trevor

[RMAParticipant @rma]

Posted by not done it yet on 31/10/2019 05:27:17:

Now that the first two posts have sorted the OP’s query I will also mention IR LED emitters (for the likes of security cameras or night-sights on guns equipped with IR detection systems) as potentially similar risk if looked at from directly in line with the beam at short range. One will not see anything, but the eye will concentrate these heating rays on the retina, possibly cooking some nerve endings (light receptors).

I don't want to wander off the OP's subject, but I would like to know what 'close' means in the case of home security cameras. I have four of them and you can't help walking close/under them. I also occasionally check to see if all the LED's are working.

[VicParticipant @vic]

On the subject of fumes from laser cutters, even using stuff like low odour MDF and having a dedicated extraction and filter unit the size of a fridge attached to it the laser cutter where I used to work still made a stink. Don’t underestimate the potential danger from fumes. You can look away from a laser cutter but you can’t stop breathing.

[not done it yetParticipant @notdoneityet]

Posted by RMA on 31/10/2019 09:53:12:

I don't want to wander off the OP's subject, but I would like to know what 'close' means in the case of home security cameras. I have four of them and you can't help walking close/under them. I also occasionally check to see if all the LED's are working.

As always, one has to think about what one might be doing. Most are wide angle emitters, some IR frequencies are absorbed by aqua, so the problem may be 1) the frequency (or wavelength), 2) the power of the device 3) the inverse square law (as applied to your particular circumstance).

I don’t think that people walking under the installations would be at risk, or the installers would be responsible for any elf’n’safty issues, so I doubt you have anything to worry about looking from a distance. I have some 940nm IR illuminators which actually warn of the dangers of peering into the beam from the ‘torch’.

[Robert Atkinson 2Participant @robertatkinson2]

Posted by Trevorh on 31/10/2019 08:41:39:

Many thanks to all of you,

The ref to orange plastic was my feeble attempt to understand what my son was asking about as he did quote wave length and the like but it went over my head

know where he should start with obtaining such safety equipment?

I will mention about the venting of the vapours/fumes as this is quite a good point to be taken into consideration as well as the eye protection both on and off the equipment

Once again thank you

Trevor

Hi,

Where you start looking is the details of the wavelength and power output of the laser(s) he is using. You cannot do anything without these details. I have 4 different pairs of laser safety glasses just for the lasers I play with at home and none of those are capable of cutting. well maybe a thin piece of paper if focused properly.

Robert G8RPI.

[TrevorhParticipant @trevorh]

Hi Robert

good to know as he is now talking about both cutting and a separate one for engraving

I will report back as this project progresses

Trevor

[Jeff DaymanParticipant @jeffdayman43397]

For a source in the UK for laser filters, laser safety glasses etc, found this firm:

**LINK**

Have not used them myself though.

In the USA and Canada I have bought various bits of laser safety gear from Newport, the well known optical firm.

Hope the info helps.

[Adam MaraParticipant @adammara]

And another warning! Be very carefull cutting unknown plastics, many give of poisonous gases. The works laser engraver with a 900mm x 600mm bed has a very powerful 150mm extraction system, with 95% of the work carried out on acrylics. There is some technical information on the Trotec Laser UK website

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