LASER SAFETY

A discussion group for all nightvision users. Find 'Best scope for nv?' here also.
Craggrat
Posts: 107
Joined: 11 Nov 2011, 20:59
Location: Doncaster

LASER SAFETY

Post by Craggrat » 27 Dec 2011, 09:24

Laser safety.
Being new to night vision and IR LASERs, I've joined a laser forum, just to learn a bit more about what we are plying about with.
I was enquiring about IR lasers and this is a reply I got from a forum member called Sigurthr,


IR lasers are actually more dangerous than visible spectrum lasers.

a 5mW IR laser is FAR more dangerous than a 5mW visible laser. So yes, a 300mW IR is enough to blind you instantly, and the worst part... you would NEVER know it was happening until your vision just blacked out.

the 5mW "rule" is based on the fact that your eyes blink fast enough when a bright light is shone into them at 5mW and under. The thing is, only visible light makes you blink. UV and IR do not cause the blink reflex. So, a 5mW laser beam could be reflecting directly into your eyes and you would never know it, never look away, and never blink, until the damage was already done.

You can still use IR lasers for illumination but you must be damned sure it cannot reflect to any eyeballs at all. Also, night vision equipment (incl. nightshot cams) require very very little light to work. I'd try at most maybe a 50mW, and I wouldn't be comfortable being indoors with it without a pair of OD3+ IR goggles on my face. Outdoors, if pointed the oposite way and nothing in it's path for at least several hundred feet... maybe I'd bump it up to 100mW, but only if absolutely needed. The adjustable focus is a good call though, especially when used for illumination. Plus a very spread beam lessens danger level.... minutely.

Seeing some of the videos you guys put on you tube which are great to watch. Bbut I think you need to be more careful when filming each other with night vision

Craggrat
Posts: 107
Joined: 11 Nov 2011, 20:59
Location: Doncaster

Re: LASER SAFETY

Post by Craggrat » 27 Dec 2011, 09:31

CLASS II (2) LASERS: Class II lasers are lasers that emit accessible visible laser light with power levels less than 1 mW that normally would not produce a hazard if viewed for only momentary periods with the unaided eye.

Laser Laws fro the UK
UK and most of Europe are now harmonized on Class 2 (<1 mW) for General presentation use laser pointers or laser pens. There are no specific UK laws relating to laser pointers; however, Health and Safety regulation insists on use of Class 2 anywhere the public can come in contact with laser light, and the DTI have urged Trading Standards authorities to use their existing powers under the General Product Safety Regulations 2005 to remove lasers above class 2 from the general market.

andy s
Posts: 31
Joined: 15 Oct 2011, 21:44
Location: Somerset

Re: LASER SAFETY

Post by andy s » 27 Dec 2011, 12:35

All IR lasers are potentially dangerous to eyes if used irresponsibly. The 100 mw lasers that we have been using for a long time are more than capable of causing eye damage. You should not film people at close range using any IR laser for illumination.
I believe it is a great advantage to have the extra power of the 300mw lasers and want one ASAP to improve the performance of my various NV equipment.
We should remember that not everyone is aware of eye safety issues with IR lasers and that all lasers should be sold with a warning to take care and sensible precautions when using such equipment.
I for one welcome this post to warn the uninformed of these dangers and to remind the more experienced as well, thanks Craggrat for raising the subject.
Let us all keep a balanced approach to the subject. Andy
Last edited by andy s on 27 Dec 2011, 12:58, edited 1 time in total.

Gloop
Posts: 2025
Joined: 02 Nov 2011, 13:09
Location: Andover

Re: LASER SAFETY

Post by Gloop » 27 Dec 2011, 13:25

I am up for someone educating me on laser safety seeing as it is such an important part of our life. Anybody fancy doing a write up on lasers?

Craggrat
Posts: 107
Joined: 11 Nov 2011, 20:59
Location: Doncaster

Re: LASER SAFETY

Post by Craggrat » 27 Dec 2011, 18:30

Thanks for your positive comments. Yes we need to sort out some form safety. To cover ourselves against accidents and any legalities that might arise.
The 300mw laser is a great piece of kit but we need to know how to use it correctly in a safe manner.
It's definitely improved night vision filming, let's hope it can be used safetly and no one gets injured.
There's already been one of our members injured using lasers let's hope it's the last. ones enough in my book keep safe and understand what you've got on your scope.
Craggrat

PESCA

Re: LASER SAFETY

Post by PESCA » 27 Dec 2011, 18:30

Well, here are the classifications (not my work, I hasten to add). You'll find that it's the Class 3B lasers that apply to our applications the most:

Class 1 lasers are products where the irradiance (measured in watts per metre square) of the accessible laser beam (the accessible emission) does not exceed the Maximum Permissible Exposure (MPE) value. Therefore, for Class 1 laser products the output power is below the level at which it is believed eye damage will occur. Exposure to the beam of a Class 1 laser will not result in eye injury and may therefore be considered safe. However, some Class 1 laser products may contain laser systems of a higher class but there are adequate engineering control measures to ensure that access to the beam is not reasonably likely. Examples of such products include laser printers and compact disc players. Anyone who dismantles a Class 1 laser product that contains a higher class laser system is potentially at risk of exposure to a hazardous laser beam. A laser that is inherently safe and cannot exceed the MPE under any circumstances is exempt from the classification system.

Class 1M lasers are products which produce either a highly divergent beam or a large diameter beam. Therefore, only a small part of the whole laser beam can enter the eye. However, these laser products can be harmful to the eye if the beam is viewed using magnifying optical instruments. Some of the lasers used for fibre-optic communication systems are Class 1M laser products.

Class 2 lasers are limited to a maximum output power of 1 milliwatt (abbreviated to mW, one thousandth of a watt) and the beam must have a wavelength between 400 and 700 nm. A person receiving an eye exposure from a Class 2 laser beam, either accidentally or as a result of someone else's deliberate action (misuse) will be protected from injury by their own natural aversion response. This is a natural involuntary response that causes the individual to blink and avert their head thereby terminating the eye exposure. Repeated, deliberate exposure to the laser beam may not be safe. Some laser pointers and barcode scanners are Class 2 laser products.

Class 2M lasers are products which produce either a highly divergent beam or a large diameter beam within the wavelength range 400 to 700 nm. Therefore, only a small part of the whole laser beam can enter the eye and this is limited to 1 mW, similar to a Class 2 laser product. However, these products can be harmful to the eye if the beam is viewed using magnifying optical instruments or for long periods of time. Some lasers used for civil engineering applications, such as level and orientation instruments are Class 2M laser products.

Class 3R lasers are higher powered devices than Class 1 and Class 2 and may have a maximum output power of 5 mW or five times the Accessible Emission Limit (AEL) for a Class 1 product. The laser beams from these products exceed the maximum permissible exposure for accidental viewing and can potentially cause eye injuries, but the actual risk of injury following a short, accidental exposure, is still small.

Class 3B lasers may have an output power of up to 500 mW (half a watt). Class 3B lasers may have sufficient power to cause an eye injury, both from the direct beam and from reflections. The higher the output power of the device the greater the risk of injury. Class 3B lasers are therefore considered hazardous to the eye. However, the extent and severity of any eye injury arising from an exposure to the laser beam of a Class 3B laser will depend upon several factors including the radiant power entering the eye and the duration of the exposure. Examples of Class 3B products include lasers used for physiotherapy treatments and many research lasers.

Class 4 lasers have an output power greater than 500 mW (half a watt). There is no upper restriction on output power. Class 4 lasers are capable of causing injury to both the eye and skin and will also present a fire hazard if sufficiently high output powers are used. Lasers used for many laser displays, laser surgery and cutting metals may be Class 4 products. Many Class 4 laser products are safe during normal use, but may not have all of the protection measures required for a Class 1 product. An example would be an enclosure with an open roof; it is possible that someone could get a ladder and climb over the enclosure to get access to the laser beam.

George

PESCA

Re: LASER SAFETY

Post by PESCA » 30 Dec 2011, 08:54

This thread is now a 'sticky'.

As you lads quite rightly point out, we use lasers in many forms for our nv gear and should be aware of any potential threat to our eyesight.

Please feel free to add any more useful facts.

George

Craggrat
Posts: 107
Joined: 11 Nov 2011, 20:59
Location: Doncaster

Re: LASER SAFETY

Post by Craggrat » 30 Dec 2011, 09:36

[edit]Laser radiation hazards

Laser radiation predominantly causes injury via thermal effects. Even moderately powered lasers can cause injury to the eye. High power lasers can also burn the skin. Some lasers are so powerful that even the diffuse reflection from a surface can be hazardous to the eye.


Diagram of a human eye.
The coherence, the low divergence angle of laser light and the focusing mechanism of the eye means that laser light can be concentrated into an extremely small spot on the retina. A transient increase of only 10 °C can destroy retinal photoreceptor cells. If the laser is sufficiently powerful, permanent damage can occur within a fraction of a second, literally faster than the blink of an eye.[1] Sufficiently powerful in the visible to near infrared laser radiation (400-1400 nm) will penetrate the eyeball and may cause heating of the retina, whereas exposure to laser radiation with wavelengths less than 400 nm and greater than 1400 nm are largely absorbed by the cornea and lens, leading to the development of cataracts or burn injuries.[2]
Infrared lasers are particularly hazardous, since the body's protective "blink reflex" response is triggered only by visible light. For example, some people exposed to high power Nd:YAG laser emitting invisible 1064 nm radiation, may not feel pain or notice immediate damage to their eyesight. A pop or click noise emanating from the eyeball may be the only indication that retinal damage has occurred i.e. the retina was heated to over 100 °C resulting in localized explosive boiling accompanied by the immediate creation of a permanent blind spot.[3]
[edit]Damage mechanisms
Lasers can cause damage in biological tissues, both to the eye and to the skin, due to several mechanisms. [4] Thermal damage, or burn, occurs when tissues are heated to the point where denaturation of proteins occurs. Another mechanism is photochemical damage, where light triggers chemical reactions in tissue. Photochemical damage occurs mostly with short-wavelength (blue) and ultra-violet light and can be accumulated over the course of hours. Laser pulses shorter than about 1 μs can cause a rapid rise in temperature, resulting in explosive boiling of water. The shock wave from the explosion can subsequently cause damage relatively far away from the point of impact. Ultrashort pulses can also exhibit self-focusing in the transparent parts of the eye, leading to an increase of the damage potential compared to longer pulses with the same energy.
The eye focuses visible and near-infrared light onto the retina. A laser beam can be focused to an intensity on the retina which may be up to 200,000 times higher than at the point where the laser beam enters the eye. Most of the light is absorbed by melanin pigments in the pigment epithelium just behind the photoreceptors,[4] and causes burns in the retina. Ultraviolet light with wavelengths shorter than 400 nm tends to be absorbed in the cornea and lens, where it can produce injuries at relatively low powers due to photochemical damage. Infrared light mainly causes thermal damage to the retina at near-infrared wavelengths and to more frontal parts of the eye at longer wavelengths. The table below summarizes the various medical conditions caused by lasers at different wavelengths, not including injuries due to pulsed lasers.
Wavelength range Pathological effect
180–315 nm (UV-B, UV-C) photokeratitis (inflammation of the cornea, equivalent to sunburn)
315–400 nm (UV-A) photochemical cataract (clouding of the eye lens)
400–780 nm (visible) photochemical damage to the retina, retinal burn
780–1400 nm (near-IR) cataract, retinal burn
1.4–3.0μm (IR) aqueous flare (protein in the aqueous humour), cataract, corneal burn
3.0 μm–1 mm corneal burn
The skin is usually much less sensitive to laser light than the eye, but excessive exposure to ultraviolet light from any source (laser or non-laser) can cause short- and long-term effects similar to sunburn, while visible and infrared wavelengths are mainly harmful due to thermal damage.[4]

duke
Posts: 50
Joined: 04 Jan 2012, 17:01
Location: barnsley more rotheram nearer doncaster

Re: LASER SAFETY

Post by duke » 19 Jan 2012, 09:36

kev this is a good read and not all people understand, there is people out there who have no idea of this and could just point an high powered laser at people just for fun, maybe some kind of instruction manual will need making up ,just incase people buy with out knowing the implications, pete

Craggrat
Posts: 107
Joined: 11 Nov 2011, 20:59
Location: Doncaster

Re: LASER SAFETY

Post by Craggrat » 19 Jan 2012, 11:31

Hi pete
Your right, people need to be aware of the health and safety issues with these IR laser/led.
But you can't see the the beam, the damage is done. if your eye sees light that will damage it. It blinks or closes. Your eye does not detect IR light so you don't blink and the damage is done.
How many shooters are going to wear safety glasses when they go out shooting.
Are they going to inform people where they shoot that they need to wear special glasses because ' I'm putting out a high powerd laser/led in your area.
Pete you could have a safety pamphlet an inch thick, it won't help you if your out one night and someone hits you in the eye with a high powered laser that you can't see.
mw is a measurement of power/light it does not matter if it comes from a led candle laser halogen it's still a mw. It's no safer just because it comes from a led and not a laser.
the IR laser/led that they are using is amazing, the video footage is better than anything on the Market. It's going to be a success.
If I was marketing any thing as high powerd as that laser/led as well as safety instruction, I would supply safety glasses. Then I'd be covered. Every individual is responsible for there own safety and the safety of others. If the safety wear is in place and they get a bang in the eye from not using it, it's there problem. You've covered your back. It will be only a matter of time before someone gets it in the eyes. It may not be direct it could be reflected.
Kev

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