Take a look at a wiimote controller...
Look for it's IR sensor camera and please tell more about your application, cause I don't think we can help
you will limited info...
The only sensors you could use for military purpose are CMOS cams... really... with a IR only bypass filter
you can do what you need...
With proper filters you can also do human body sensing... But you would also need image processing...
What do you really need to do... sounds like a bomber auto protector turrent against fighters ans incoming missile...
Generally, with a CMOS camera you can do a lot... But get your hands on one first...
Also, would you be using a computer or a microcontroller and/or FPGA?
Image processing needs a little bit of processing power...
Best Regards, Lefteris
Greece