IR Missile Sensor Obscurement?

[mbga9pgf]

Hi, was wondering if anyone could answer my question, one that has vexed me for a while and one I cannot seem to get an answer to!

Modern IR missiles typicaly work in band IV, although traditional (older) missiles work in lower bands, going for the hot sections of aircraft as opposed to surface friction. However, the missile itself, in particular the sensor window is party to kinetic heating effects, raising the temperature a couple of hundred degrees.

How is it then possible for the sensor to maintain an 'image' of the target? Surely the frequency spread and intensity as a result of heating of the sensor head would far outweigh the radiation collected from an infra-red target?

This is purely a question to answer a question tat has been in my mind for some time...

Regards,

MBGA

 

[KENAT]

Been a while since I looked at this stuff, I suspect IRstuff or someone will have the full/correct answer.

However I will say this, many IR/Thermal Imaging sensers are cooled.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[IRstuff]

Anything that occurs on the dome is sensed uniformly by all the pixels, so it's just a pedestal offset. Additionally, the dome is transparent, and, therefore, does not have a high emissivity. So the overall impact of the dome emission could be quite low.

TTFN

FAQ731-376

 

[mbga9pgf]

Awesome.

That hadnt occured to me.

Been vexing me for years that has!

cheers,
mbga