NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Discussion about Night Vision Goggles and Night Vision Binoculars / Monoculars

Moderator: Michael

NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Postby Blake » Sat Apr 27, 2013 3:09 pm

Hi All

Please could I request assistance from the members of this forum.

We are in the process of starting a NVG (ANVIS AN/AVS) program on our aeromedical helicopters to improve the safety, efficiency and effectiveness of our operations.

At the moment we operate unaided to urban well lit helipads as well as to rural hospitals that have some form of lighting, not necessarily located on the helipad though (i.e. flood lighting from surrounding building/street lighting etc).

In general the hospitals are located in or near small towns so there is some ground lighting, and our en route phase covers countryside with some scattered ground lighting from towns, industrial areas, villages, homesteads, farms, roads, etc

Considering the above environmental lighting conditions I have approached a number of suppliers from the USA, Europe and Israel for NVG (ANVIS AN/AVS) solutions that will best meet our requirements. Below is a list of the NVG (ANVIS AN/AVS) solutions which I have available at the moment and which are permitted for export to South Africa.

USA
1.
ITT EXELIS AN/AVS-9 (F4949)
Generation 3 image intensifier tubes MX 10160 F9800K
Figure Of Merit (FOM) of 1400
In the unlikely event that the State Department approves a FOM of 1600 then the Pinnacle F9800YG Photocathode Sensitivity of uA/lm of 1800.
Field of View 40 degrees
http://www.exelisinc.com/solutions/Imag ... fault.aspx
http://www.exelisinc.com/solutions/AN_A ... fault.aspx

2.
L-3 Model AN/AVS-9 FOM 1400, Class B M949
Generation 3 image intensifier tubes
FOM of 1400
Photocathode Sensitivity of uA/lm of 1350-1550.
Field of View 40 degrees
http://www.insighttechnology.com/l3-products/m890av-cs

Europe

3.
Helimun
Image intensifier tube from Photonis XR5
FOM 1600-2000
Photocathode Sensitivity of uA/lm 800
Field of View 40 Degrees or 60 Degrees
http://www.photonis.com/en/nightvision/75-xr5.html
http://www.oip.be/helimun.asp

4.
Fenn NG 2000A
Image intensifier tube from Photonis XR5
FOM 1600-2000
Photocathode Sensitivity of uA/lm 800
Field of View 47.5 degrees
http://www.photonis.com/en/nightvision/75-xr5.html
http://www.fenn-night-vision.co.uk/product/nvg/ng2000a

Israel

5.
New Noga Light (SDS) NL-93A
Image intensifier tube from Photonis XR5
FOM 1600-2000
Photocathode Sensitivity of uA/lm 800
Field of View 40 degrees
http://www.photonis.com/en/nightvision/75-xr5.html
http://newnogalight.com/index.php?optio ... &Itemid=17

My questions:

1. For helicopter air ambulance (HEMS) operations in the environmental conditions described above, which image intensifier listed above would suit our operation best?

2. Approximately how many electrons ( as a percentage ) that are transmitted from the Photocathode towards the MCP are lost to the ion barrier film.

If we take the MX 10160 F9800K, it states a PR of uA/lm of 1800, but how much of that enters the MCP?

Is this why images produced by the XR5 are comparable with Gen III images, due to electrons lost to the Ion Barrier Film?

3. I guess fundamentally I would also like to know if an American Gen III tube limited to a FOM of 1400 (if we get lucky 1600) without the auto gated power supply but with a uA/lm of 1350-1550 would outperform an XR5 with auto gated power supply and a FOM of 1600 in very dark conditions?

And if so, would an XR5 with a FOM of 2000 do any better against the Gen 111 with a FOM of 1600?

4. Can anyone rate the optics and housings of the goggles above, and indicate which would be the preferred option?

5. Are there any negatives to the larger Fields of View? I.e. 60 Degree Field of View offered by Helimun?
Why would one want a 40 degree Field of View if you could have 60 Degrees?

6. Any recommendations on which helmet to pair with the above goggles?

7. Anything else I should be considering?

My objective is to provide the very best NVG (ANVIS AN/AVS) equipment to the aircrews so any answers/comments/suggestions to achieve the above would be very much appreciated

Finally if you were in my shoes which would you choose, with which helmet and why?

Looking forward to your replies, all inputs welcomed.

Iefan Blake
Blake
 
Posts: 2
Joined: Mon Apr 15, 2013 1:59 pm

Re: NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Postby cj7hawk » Sun Apr 28, 2013 10:30 pm

Hi Lefan,

Some complicated questions you ask there - It's not possible to directly consider the MCP thin film losses and compare via PC sensitivity, and FOM doesn't affect PC sensitivity, but more S/N, with resolution being fairly much equal.

Also, aviation grade XR5 exceed FOM 2000 by a considerable margin - the starting point is FOM2088 and all XR5 aviation tubes ( Golden Bullet - xx2540B series ) should be well in excess of that.

If you can get high-end XR5's then they would be superior in most circumstances to US Gen3, although in ultra-dark circumstances, the US Gen3 can outperform XR5 - though it has more to do with the way the brain re-assembles the image under such circumstances. So based on that, XR5 is a good choice, if it's the right XR5 tube. ( ie, xx2540B series aviation tubes )

The other factor is the light loss through the goggles. If manufacturers quote system gain, that is useful. Finally, in a helicopter looking at close up objects, I suspect the wider field of view might be more beneficial to the pilots. Studies have shown that vehicular control is enhanced by having a wider FOV.

I haven't tested the systems you mention, but suspect that the FENN model you linked to might be the best. Also consider the time to replace parts, maintenance and replacement tubes and don't forget damaged tubes, because you can count on tubes getting damaged by bright lights. XR5 are far more resiliant to such damage than US tubes, and are autogated also ( US tubes supplied at FOM 1400 may not be ) -

This is a critical aspect of what you are looking at, because autogated tubes will extend pilot visibility and resolution into dawn and dusk times, which is going to support your application far more than would DC tubes.

Consider cost also - Cheap systems are going to save lives in the long run, because you will have more serviceable sets distributed to pilots and air crew - and less downtime due to damaged tubes. This extends all the way to helmets and helmet adapters ( mounts can get damaged too! ) and whether COTS items are available for an emergency.

Here's a panorama to help you understand effective image quality under ultra-dark circumstances also - with similar monoculars and US MX10160A Aviation tube, PVS-14 style tube and XR5 aviation tube. Conditions are restricted starlight and the image shows a montage of all three tubes looking over the same view to provide an effective comparison.

http://aunv.blackice.com.au/userfiles/d ... rama-s.jpg
Image

Feel free to ask any questions. I'll answer your more detailed questions later when I get home.

Regards
David
cj7hawk
 
Posts: 1646
Joined: Thu Jul 03, 2008 6:42 am
Location: A land downunder.

Re: NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Postby cj7hawk » Tue Apr 30, 2013 5:54 pm

OK, Some more direct answers now I have a moment.

My questions:

1. For helicopter air ambulance (HEMS) operations in the environmental conditions described above, which image intensifier listed above would suit our operation best?

A: Probably XR5 with the wider FOV as I mentioned above.

2. Approximately how many electrons ( as a percentage ) that are transmitted from the Photocathode towards the MCP are lost to the ion barrier film.

A: This is academic, as it's not a metric you can use to understand your choice, but approximately 40-50% given the tubes you were considering.

If we take the MX 10160 F9800K, it states a PR of uA/lm of 1800, but how much of that enters the MCP?

A: It's not just the PR, it has to do with the wavelength of light that generated the light as well. This is possibly more important. But if you really wanted, I could probably perform a quick calculation as to how many electrons make it into the MCP. It's going to be a big number though. We're talking way more than billions per second.

Is this why images produced by the XR5 are comparable with Gen III images, due to electrons lost to the Ion Barrier Film?

A: No. XR5 are comparable with GenIII images due to low S/N and high MTF under similar gain levels. Again, the sensitivity over the range of spectral response is important. Super S25 is similar to a "scaled" version of GaAs.

3. I guess fundamentally I would also like to know if an American Gen III tube limited to a FOM of 1400 (if we get lucky 1600) without the auto gated power supply but with a uA/lm of 1350-1550 would outperform an XR5 with auto gated power supply and a FOM of 1600 in very dark conditions?

A: There's a point at which it probably will, but it's got to get pretty dark for that to happen. If it gets that dark in a Helicopter, I sure wouldn't want to be in it... Because it's probably flying underground.

And if so, would an XR5 with a FOM of 2000 do any better against the Gen 111 with a FOM of 1600?

A: Yes, For your purposes, FOM is a reasonable comparison figure, at least between XR5 and Gen III, though S/N might be a better figure.

4. Can anyone rate the optics and housings of the goggles above, and indicate which would be the preferred option?

A: No. I'm not familiar with all of them. They all look good. Consider spare parts and maintenance when choosing.

5. Are there any negatives to the larger Fields of View? I.e. 60 Degree Field of View offered by Helimun?
Why would one want a 40 degree Field of View if you could have 60 Degrees?

A: Yes. Detail at a distance is lost. In terms of controlling a vehicle, greater FOV is desired. Also, when considering a helicopter, consider HALO effect and that this will be larger with larger FOV. Might be worth considering around ground lights.

6. Any recommendations on which helmet to pair with the above goggles?

A: Gentex Sound Protection Helmet... With suitable NV adapter. I'm not familiar with recent models. Contact them. Also, I'm sure the sellers will be able to recommend fittings.

7. Anything else I should be considering?

A: Cockpit lighting, and suitable filters to reduce the glare... This is very important and you may have to refit the aircraft to change the cockpit lighting spectrum for night operations. Also, I've mentioned some other things in both posts to consider. Keep in mind that you probably want more than just the pilot wearing NVG's and also I assume you will want to fit the helicopter with thermal camera's at some time, and may want to consider how the operator will view this without the glare causing cockpit issues. I know they do night operations where I am - ( Police Air Wing ) and many of those people are more familiar with the requirements. Reach out to your fellow aviators :)

I can only answer technical questions. I am not a helicopter pilot.

Regards
David
cj7hawk
 
Posts: 1646
Joined: Thu Jul 03, 2008 6:42 am
Location: A land downunder.

Re: NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Postby wellyot » Wed May 01, 2013 12:52 am

i have used the fenns and avs9 - both are great but i personally would allways go for the normal avs ball detent mount over the one my fenns had where it just pushed up on a friction washer and also did not turn off automatically when pushed up - i think fenn do the avs mount aswell now . extra field of view on the fenns is nice but i found they seemed to weigh little more.
wellyot
 
Posts: 167
Joined: Tue Dec 12, 2006 1:59 am

Re: NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Postby Blake » Thu May 02, 2013 2:12 pm

Hi Dave
Thank you very much for all the valuable information, it has improved my understanding and answered many of the questions I had. Please could you assist with the below questions.

If you can get high-end XR5's then they would be superior in most circumstances to US Gen3, although in ultra-dark circumstances, the US Gen3 can outperform XR5 - though it has more to do with the way the brain re-assembles the image under such circumstances. So based on that, XR5 is a good choice, if it's the right XR5 tube. ( ie, xx2540B series aviation tubes )


I've received a quote from OIP Sensor Systems that indicates a XX2540G. What does the XX2540 indicate? Is it the FOM? Also what does the letter after the numbers indicate? Is there much significance between the G and the B?

I haven't tested the systems you mention, but suspect that the FENN model you linked to might be the best. Also consider the time to replace parts, maintenance and replacement tubes and don't forget damaged tubes, because you can count on tubes getting damaged by bright lights. XR5 are far more resiliant to such damage than US tubes, and are autogated also ( US tubes supplied at FOM 1400 may not be ) -


Great info. The States will not export gated Goggles to South Africa so the Photonis intensifiers are our only choice if we want a gated power supply.
The pricing of the XR5 goggles is significantly more expensive than the American Gen III ($15000 vs $10000) so I was wondering if you had any information on how well an aviation spec XD4 would compare to an American Gen III? If we are not able to afford the XR5 then I would hope than we could purchase auto gated XD4 as it seems the gated power supply adds significant benefits specifically for our conditions.

Thank you for the great image. It would be interesting to see what would happen to the images if you introduced a couple of ambulances with red emergency lights and white headlights indicating a landing area for a helicopter. I assume the gated goggles would provide a reasonable picture, but not so for the goggles without the gated power supply?

A: Probably XR5 with the wider FOV as I mentioned above.


Would it be correct to say the FOV is increased by the optics, so 1.5x wider FOV means also an image resolution (in lp/mm) decreased 1.5 times?

A: This is academic, as it's not a metric you can use to understand your choice, but approximately 40-50% given the tubes you were considering.


Thank you for clearing this up for me.

Also, when considering a helicopter, consider HALO effect and that this will be larger with larger FOV.



Excellent point, thank you.

A: Cockpit lighting, and suitable filters to reduce the glare... This is very important and you may have to refit the aircraft to change the cockpit lighting spectrum for night operations. Also, I've mentioned some other things in both posts to consider. Keep in mind that you probably want more than just the pilot wearing NVG's and also I assume you will want to fit the helicopter with thermal camera's at some time, and may want to consider how the operator will view this without the glare causing cockpit issues. I know they do night operations where I am - ( Police Air Wing ) and many of those people are more familiar with the requirements. Reach out to your fellow aviators :)


Thanks Dave for all the info. We are having our cockpits modified for Class B filters, and equipping our medical crew with NVG.

I'm a bit pressed for time at the moment but would appreciate a few more answers. Will post again soon. Thanks again.

wellyot
Thank you for the feedback, exactly the type of information I was hoping to get. Cheers
Blake
 
Posts: 2
Joined: Mon Apr 15, 2013 1:59 pm

Re: NVG (ANVIS AN/AVS) for HEMS, which is best USA vs. Europe vs

Postby cj7hawk » Sat May 04, 2013 4:26 am

Blake wrote:Hi Dave
Thank you very much for all the valuable information, it has improved my understanding and answered many of the questions I had. Please could you assist with the below questions.

If you can get high-end XR5's then they would be superior in most circumstances to US Gen3, although in ultra-dark circumstances, the US Gen3 can outperform XR5 - though it has more to do with the way the brain re-assembles the image under such circumstances. So based on that, XR5 is a good choice, if it's the right XR5 tube. ( ie, xx2540B series aviation tubes )


I've received a quote from OIP Sensor Systems that indicates a XX2540G. What does the XX2540 indicate? Is it the FOM? Also what does the letter after the numbers indicate? Is there much significance between the G and the B?



xx2540 is the type of tube - xx2540 basically means "MX10160" where XR5 tubes are concerned.

The letter after the type denotes it's performance and product spec.

xx2540D is a MX10160
xx2540B is a "Golden Bullet" or aviation-spec MX10160.

eg: http://webcache.googleusercontent.com/s ... tguide.pdf

As for 2540G? Speak tot he supplier and ask them specifically what it means, with relation to the xx2540B series. They might be xx2540BG, in which case, they are aviator tubes, subspec G.


I haven't tested the systems you mention, but suspect that the FENN model you linked to might be the best. Also consider the time to replace parts, maintenance and replacement tubes and don't forget damaged tubes, because you can count on tubes getting damaged by bright lights. XR5 are far more resiliant to such damage than US tubes, and are autogated also ( US tubes supplied at FOM 1400 may not be ) -


Great info. The States will not export gated Goggles to South Africa so the Photonis intensifiers are our only choice if we want a gated power supply.
The pricing of the XR5 goggles is significantly more expensive than the American Gen III ($15000 vs $10000) so I was wondering if you had any information on how well an aviation spec XD4 would compare to an American Gen III? If we are not able to afford the XR5 then I would hope than we could purchase auto gated XD4 as it seems the gated power supply adds significant benefits specifically for our conditions.

Thank you for the great image. It would be interesting to see what would happen to the images if you introduced a couple of ambulances with red emergency lights and white headlights indicating a landing area for a helicopter. I assume the gated goggles would provide a reasonable picture, but not so for the goggles without the gated power supply?


XR5 would provide the best image under those circumstances. I once accidently turned the lights on with my XR5 goggles at night, inside, and had my other eye closed. It took me a moment to work out what I had done, because the tube adjusted for brightness near-instantly. Strobing lights affect performance though. Not much you can do about that in your circumstances. Regardless, XR5 handle that better than US Gen3.


A: Probably XR5 with the wider FOV as I mentioned above.


Would it be correct to say the FOV is increased by the optics, so 1.5x wider FOV means also an image resolution (in lp/mm) decreased 1.5 times?



Yes, that's pretty accurate. Keep in mind that XR5 provides superior MTF to much US Gen3 as well, which is important to understand in this context.



Also, when considering a helicopter, consider HALO effect and that this will be larger with larger FOV.



Excellent point, thank you.



Additionally, this can affect helicopter pilot perception as the halo's seems to get smaller, the closer the pilot gets to them, while everything else seems to get bigger, leading to misjudging distances to any object that causes a halo - this also affects helicopter pilots approaching buildings that have landing lights. Though if your pilots are rated for NV use, I expect they probably already know that.

Regards
David
cj7hawk
 
Posts: 1646
Joined: Thu Jul 03, 2008 6:42 am
Location: A land downunder.


Return to Goggles & Binoculars

Who is online

Users browsing this forum: Bing [Bot] and 1 guest