Laser flare width ?

sarabande

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I am looking at a laser flare which has a spec as follows

Beam width 0.87 inch at a distance of 27 inches.

That looks like a beam width of 115 inches at 100 yards, which doesn't look very strong.


Have I miscalculated ?
 
I think you have miscalculated - (assuming a point source), unless I've tripped up on ye-olde-units!
 
No, that is right.

A beam width if 0.87 inches at 27 inches is darn wide (assuming it started as a point, which it did not exactly).

But can you actually aim it any better than that? (1 degree, similar to pistol accuracy)
 
laser flare is a bit of a contradiction to me. If you are using for attracting attention from a helicopter, it will turn away from you, even a sar one. Having had some muppet shine a laser into my eyes one night last winter, can I suggest you use some other means of attracting attention should you need rescuing.
 
Perhaps, boomerang, you might suggest alternative technical strategies to the RYA, Coastguard, and a number of tech companies who are selling these things ?

I am not thinking of just pointing a lecturing laser into the sky; these are proper marine emergency lasers.
 
I am looking at a laser flare which has a spec as follows

Beam width 0.87 inch at a distance of 27 inches.

That looks like a beam width of 115 inches at 100 yards, which doesn't look very strong.


Have I miscalculated ?
Close but no cigar?
I make it116 inches.
0.87/27x100x36
 
I have an ODEO LED flare, I keep it in the same container as the pyrotechnic flares.
It uses a ring of high power LEDs which can be set to flash the Morse code for SOS.
You don't have to point at anyone, and testing it, it is blindingly bright at close range.
It seemed to me to be a logical addition to standard flares, it will run for 5hrs, not a few 10's of seconds.
Although not as bright as handheld or rocket flares, just its shear persistence, means that it is more likely to be seen, especially from the air.
 
Perhaps, boomerang, you might suggest alternative technical strategies to the RYA, Coastguard, and a number of tech companies who are selling these things ?

I am not thinking of just pointing a lecturing laser into the sky; these are proper marine emergency lasers.

I can’t say why they are, just that as a SAR helicopter pilot, we were briefed to turn away from a laser. There’s no way of telling what sort of laser is being pointed at you and its ability to temporarily impair vision is not known until it might be too late.
 
Surely no-one is going to go offshore in the hope of blinding helicopter pilots. If there is a laser offshore someone wants to draw attention to themselves. There cannot be any ambiguity. On shore you can distract a pilot and hide - there is no hiding at sea - hopefully you are easily found, and then fined, if you are a muppet. How the helicopter confirms that it has seen the laser flare (and please turn it off), identifies there is someone in distress is a different matter.

The beauty of flares are they are finite. 5hrs is not finite.

I don't know laser flares - but it might be advantageous that the laser can be turned off and replaced with a less harmful lamp (strobe?) that is pilot friendly.

Jonathan
 
I have an ODEO LED flare, I keep it in the same container as the pyrotechnic flares.
It uses a ring of high power LEDs which can be set to flash the Morse code for SOS.
You don't have to point at anyone, and testing it, it is blindingly bright at close range.
It seemed to me to be a logical addition to standard flares, it will run for 5hrs, not a few 10's of seconds.
Although not as bright as handheld or rocket flares, just its shear persistence, means that it is more likely to be seen, especially from the air.
the problem with purely red LEDs is that they are not picked up very well by current generation night vision goggles. I think some of the more modern LED flares have some white LEDs which are visible on goggles. Crews do scan under the goggle with naked eye to check from time to time so should see bright red LEDs. But I have seen someone waving their phone at me three miles away on goggles on a remote hillside. White works really well

I don’t know how much testing the RYA or the MCA have done to ascertain how well modern “E flares” integrate with current rescue assets. It might be none, but I hope my knowledge is out of date.
I get the attraction of Eflares - they are in theory a brilliant idea. But if they haven’t been designed and tested to fit with search asset equipment, then the good idea sells well but might offer a false sense of security. Let’s hope my concerns are unfounded and this stuff on the market really will help get help to you when you need it most.
 
I can’t say why they are, just that as a SAR helicopter pilot, we were briefed to turn away from a laser. There’s no way of telling what sort of laser is being pointed at you and its ability to temporarily impair vision is not known until it might be too late.
But you would have no reason to perceive a “laser flare” as a laser - they are specifically designed NOT to operate like a collimated laser pointer and so to the distant observer are simply a bright red light, usually with a decree of oscillation on the signal which gives a perception similar to a burning flare. In contrast if your cockpit is illuminated with a laser the whole interior of the cockpit would light up the colour of the laser (red/green etc).

do you not know anyone still operating SAR assets you could go and ask what the current thinking is and how well the tech matches the capabilities rather than speculating?
 
The spread which is / should be just in the vertical plane is intentional.
See here as the use of has a technique that should be practiced !
Review: Rescue Laser Flare - Practical Sailor

That's a very interesting and thought provoking review, but presumably well out of date (2004) in terms of what's now available.

I was quite shocked at how badly designed/thought out the ones they tested were, even if the basic principle is useful. (The journalist was remarkably polite about that, but got the message about impracticality across.) I would hope such basics would have moved on a long way since then.

I hadn't appreciated how difficult they were to aim, even when standing on solid ground. Is that still the case?

I agree with the review that such things seem a potentially very useful complement to pyrotechnic flares, rather than a substitute.

The far superior performance of the green lasers (or rather our dark-adjusted eyes in detecting green) was interesting, as was their disadvantages for the purpose.

I wonder whether the maritime authorities are giving thought to coming up with a scheme of new/amended visible distress signals better adapted to the available technologies (to complement the amazing radio-based methods now available (at a price), but which can never be a complete substitute for things that can be detected by humans).
 
But you would have no reason to perceive a “laser flare” as a laser - they are specifically designed NOT to operate like a collimated laser pointer and so to the distant observer are simply a bright red light, usually with a decree of oscillation on the signal which gives a perception similar to a burning flare. In contrast if your cockpit is illuminated with a laser the whole interior of the cockpit would light up the colour of the laser (red/green etc).

do you not know anyone still operating SAR assets you could go and ask what the current thinking is and how well the tech matches the capabilities rather than speculating?
I know the current thinking about lasers. What I don’t know is what the manufacturers have done to make sure their product is suitable. What testing has been done? That is something potential customers should be asking the suppliers - it is their responsibility of the manufacturer and consumer to make sure their product is suitable as a distress signal, not the rescuers. Why would a rescue agency want to get involved with investigating the suitability of a myriad of different products from different suppliers built to no specific standard? They would never be able to keep up with an expanding market. If a device is SOLAS approved then it will be recognised as a distress signal by other mariners and rescue agencies. If it is not SOLAS approved then there is a question mark over its suitability. I know we as leisure users don’t necessarily have to comply with SOLAS, but if we want rescuing by the established rescue network, we need to accept that the network is based on some predefined standard of what constitutes a suitable distress signal. You can go and buy a SOLAS approved white strobe light for a dozen pounds - much cheaper than a LED or laser flare and it’s recognised as a distress signal. Clever technology means that we can now have extremely bright lights (lasers) which are so “good” they became potentially hazardous to the human body (which is much slower to adapt) and thereby become counterproductive. Lasers remain a hazard to all human eyeballs whether a pilot, lifeboat crew or other mariner, particularly at close range. If we see a red fan or beam coming towards us (unmistakably a laser) we have to assume that it might temporarily impair our vision and that might render us useless. Remember these laser flares are claimed to have a range of 20 miles or more. That’s not just a bright red light. If you want to use a laser flare, ask the supplier if it has been tested with aircraft and lifeboats. They should know if it has or not.
 
I know the current thinking about lasers. What I don’t know is what the manufacturers have done to make sure their product is suitable. What testing has been done? That is something potential customers should be asking the suppliers - it is their responsibility of the manufacturer and consumer to make sure their product is suitable as a distress signal, not the rescuers. Why would a rescue agency want to get involved with investigating the suitability of a myriad of different products from different suppliers built to no specific standard? They would never be able to keep up with an expanding market. If a device is SOLAS approved then it will be recognised as a distress signal by other mariners and rescue agencies. If it is not SOLAS approved then there is a question mark over its suitability. I know we as leisure users don’t necessarily have to comply with SOLAS, but if we want rescuing by the established rescue network, we need to accept that the network is based on some predefined standard of what constitutes a suitable distress signal. You can go and buy a SOLAS approved white strobe light for a dozen pounds - much cheaper than a LED or laser flare and it’s recognised as a distress signal. Clever technology means that we can now have extremely bright lights (lasers) which are so “good” they became potentially hazardous to the human body (which is much slower to adapt) and thereby become counterproductive. Lasers remain a hazard to all human eyeballs whether a pilot, lifeboat crew or other mariner, particularly at close range. If we see a red fan or beam coming towards us (unmistakably a laser) we have to assume that it might temporarily impair our vision and that might render us useless. Remember these laser flares are claimed to have a range of 20 miles or more. That’s not just a bright red light. If you want to use a laser flare, ask the supplier if it has been tested with aircraft and lifeboats. They should know if it has or not.
All the LED Flares I know about have a function to flash in an SOS pattern. If you look at the list of SOLAS distress signals (the one we're all supposed to carry), a light flashing SOS is an internationally recognized distress signal. Therefore, LED flares are SOLAS approved distress signals.

There is a misapprehension here. Despite widely being called "laser flares" they are NOT lasers, the light emitted is not collimated or highly monochromatic and only differs from the output of a torch in its intensity and colour. The one I have is also not directional; as others have noted they have a pattern of high-power LEDs that emits high-intensity light around 360 degrees. The one I have (Ocean Safety EDF1) also has upward pointing LEDs specifically for visibility from aircraft. I note that the intensity is enough to be painful to the eye at close range.
 
All the LED Flares I know about have a function to flash in an SOS pattern. If you look at the list of SOLAS distress signals (the one we're all supposed to carry), a light flashing SOS is an internationally recognized distress signal. Therefore, LED flares are SOLAS approved distress signals.

There is a misapprehension here. Despite widely being called "laser flares" they are NOT lasers, the light emitted is not collimated or highly monochromatic and only differs from the output of a torch in its intensity and colour. The one I have is also not directional; as others have noted they have a pattern of high-power LEDs that emits high-intensity light around 360 degrees. The one I have (Ocean Safety EDF1) also has upward pointing LEDs specifically for visibility from aircraft. I note that the intensity is enough to be painful to the eye at close range.
If that’s the case, why aren’t they marketed as SOLAS approved, which immediately open up their market to commercial mariners and be a useful tag line for the rest of us? Are you perhaps confusing SOLAS and Colregs? The key thing here is the issue with red LEDs being very difficult to see with NVIS, which is why some LED flares are now fitted with IR and white LEDs as well as the red ones. But the issue remains, if they were built to an agreed standard, they could be tested and become integrated into the rescue system. But they aren’t and are not claimed to be. Caveat Emptor. Don’t get me wrong, I think these devices should be brought into SOLAS/IMO regulations so that we can be comfortable that they will expedite succour in a time of need.

From a practical standpoint I am sure a LED flare will aid location by another vessel which is great. Lasers which are still marketed as rescue flares are different imo.
 
Your faith in something being effective simply because it has a SOLAS sticker on it impresses me, almost as much as my surprise that you think new international standards can be developed and SOLAS and Colregs can be quickly updated to add new technology.

Now I think I've worked out what you are trying to say, which is you are making a distinction between an LED based Electronic Visuals Distress Signal (EVDS) and Laser Based EVDS, or probably some of the very simple Laser EVDS which were effectively line style lasers you manually swept around. I'm sure you are not so out of touch to realise that colloquially people describe all EVDS as "laser flares" regardless of the coherency of the optical source which is within it. Perhaps that's not helpful, but its reality. If collectively SAR pilots have a genuine and real concern about modern commercially marketed EVDS in general either because of their eye safety or their ability to be detected on night vision systems then I'm sure the magazines, the RYA, the RNLI and others who have been fairly positive about the potential of EVDS would be helpful conduits in getting that information out to the boat equipment buying public.

Until then I will continue to burn my SOLAS approved barrel of tar should I need to summon assistance ;-)
 
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