Freznel lens on military vessels

[CASPER]

On many military vessels today,there is a large light mounted somewhere aft of the ship,
On the German Type 123 it can be seen centre and above the hanger doors.
On a `Niels Juel` class,it is mounted inside the main mast structure behind a perpex cover.

To my learned colleages, Is this in fact a Freznel lens? used for close formation work in night or foggy conditions?
and used for convoy formation in WWII.
Is my pronunciation correct?
               Thanks,  Casper.

[Charles McAllister]

Casper,

I'm not sure about the use on the mast of the Danish corvettes, but on the Canadian Halifax class frigates (quite similar in design, armament, and mission to the German Type 123) the aft facing light system over the hanger is primarily for helicopter operations in low visibility conditions.  The assemblies include several lens (including fresnel) and LED configurations, for "normal" vision and for use with Night Vision Goggles worn by pilots.  Here are some descriptions of lighting systems:
http://www.oxley.co.uk/marine_lighting/index.html  

I think the aircraft use is most common, as most naval operations today are with ships dispersed, rather than close in.`

There might be other uses for those lights, but this is the only one I know for certain.  By the way, I have seen the lens type spelled both "freznel" and "fresnel"

Hope this helps,

Regards,

Charles