theoretical impulse response and its normalization

omg!

greetings, helpful people around the world,

we all have heard once in our lives that the signal that is measure from your instrument, be it a spectrometer, optical microscope or an NMR machine, is not the real signal distribution, but the convolution of the real signal with an instrument function, sometimes called impulse response, resolution function, or who knows what.

my (first) question concerns the absolute scaling of the impulse response. is it a normalized function? if you had an instrument with a tunable impulse response, say an optical microscope with a tunable objective numerical aperture, how does the impusel response change as numerical aperture is varied? the width of the function obviously will vary, but what happens with its amplitude?

thank you all!!