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
ITT Exelis - Image Intensifier Tubes
ITT Exelis - AN/AVS-9 Aviator's Night Vision Systems
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
10160/M890
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
XR5 Image intensifier
OIP Sensor Systems NV
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
XR5 Image intensifier
Product » Fenn Night Vision
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
XR5 Image intensifier
NL-93A
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 this 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