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Posted: 11/21/2012 3:18:02 PM EST
Hello,

Quick question!

Is it possible to damage my PVS-14 during the day while the unit is off and batteries are inside the unit? For example, if it is pointed at the sun while on my head when it is off?

Thanks!

-HB65
Link Posted: 11/21/2012 3:22:37 PM EST
That is what the objective lens cover is for, are you keeping it on the unit under these conditions?
Link Posted: 11/21/2012 3:27:29 PM EST
[Last Edit: 11/21/2012 3:27:58 PM EST by ShadowAngel]
To my understanding, even with the objective cover off if the unit is powered down sunlight does absolutely nothing to it. I still err towards caution and keep mine on.
Link Posted: 11/21/2012 4:03:47 PM EST
Originally Posted By SkyPup:
That is what the objective lens cover is for, are you keeping it on the unit under these conditions?


Is this the black cover with the little hole?

If so, no I do not keep it on 24/7.

I just want to know if light will damage the unit while it is off.
Link Posted: 11/21/2012 4:24:48 PM EST
Small quantities of light, eg, daylight, will not harm it at all if it's off.

Large quantities of focused energy, eg, pointing it directly at the sun, while the cover is off? well, the lens is a magnifying glass and you know what a magnifying glass does to ants, and it's perfectly focused, so if left long enough, it would probably cause some damage if it was pointed directly at the sun.

After all, the photocathode is only a few microns thick.

But for fleeting exposure and when the nod is moving around then the heat probably can't build up on one spot too much.

I might do an experiment with an old tube and see if the photocathode is easily damaged like that.

Regards
David
Link Posted: 11/21/2012 4:34:34 PM EST
Originally Posted By ShadowAngel:
To my understanding, even with the objective cover off if the unit is powered down sunlight does absolutely nothing to it. I still err towards caution and keep mine on.


The Owners Manual specifically states:

"To protect the image intensifier, keep the lens cap on the objective lens when the monocular is not in use or when checked out in daylight conditions."


Gallium Arsenide in the photocathode tube is a stable crystal, but I would imagine direct sunlight focused through the objective lens contains lots of UV, VIS, and IR wavelengths that should not be left exposed to the unit.


I may be wrong, but I always keep the objective lens cap ON when I am not using it, especially so during daylight....the lens is always focusing light onto the image intensifier when the cap is off.
Link Posted: 11/21/2012 7:23:30 PM EST
[Last Edit: 11/21/2012 7:27:56 PM EST by ShadowAngel]
Originally Posted By SkyPup:
Originally Posted By ShadowAngel:
To my understanding, even with the objective cover off if the unit is powered down sunlight does absolutely nothing to it. I still err towards caution and keep mine on.


The Owners Manual specifically states:

"To protect the image intensifier, keep the lens cap on the objective lens when the monocular is not in use or when checked out in daylight conditions."


Gallium Arsenide in the photocathode tube is a stable crystal, but I would imagine direct sunlight focused through the objective lens contains lots of UV, VIS, and IR wavelengths that should not be left exposed to the unit.


I may be wrong, but I always keep the objective lens cap ON when I am not using it, especially so during daylight....the lens is always focusing light onto the image intensifier when the cap is off.


I wasn't saying one should aim it directly at the sun and leave it pointing there all day. I was saying that...sunlight in the type of exposure one would imagine the unit to being exposed to during the day, it wasn't likely to damage the tube from what i've read and heard. But like I also said.. I keep mine on at all times when not in use. No point taking chances. The bit of the manual you posted, I interpreted as a standard bit in the manual of pretty much any optic, where they advise keeping covers on scopes, aimpoints, ect to protect the lenses and the unit as a whole. If the unit is "checked out in daylight conditions", one could presume it probably is imagined the unit has a battery installled, and is subject to accidental activation. I doubt most soldiers issued PVS-14's pull the batteries every day, and put them back in every night, you know?
Link Posted: 11/22/2012 4:22:18 AM EST
When in doubt, I read the manual.
Link Posted: 11/22/2012 4:32:42 PM EST
Get in the habit of ALWAYS replacing your lens cap and you will have no issues. Powered down ambient light has no effect on tube. As mentioned I would not point it at the sun for extended periods regardless.
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