Find the interference function for different emission modes

[DragonBlight]

Homework Statement:: Find the interference function $I(\delta)$ where The emission is analyze by a Michelson interferometer.
Relevant Equations:: $I(\delta) = \frac{1}{2} \int_{-\infty}^{\infty} G(k) r^{ik \delta} dk$ $I(\vec{r}) = I_1 + I_i + 2 \sqrt(I_1 I_i) cos (k\delta)$

I have 5 modes where there frequency are V, V+5ghz, V-5ghz. V+10ghz, V-10ghz and there intensity are, I, I/2, I/2, I/4, I/4.
The emission is analyze by a Michelson interferometer.

Since there are different modes what should be the way to find the interference function $I(\delta)$ I'm used to find $I(\delta)$ for some emission lines analyzed at one point, thus we can sum all the $I_i$.

I'm not quite sure if the question is clear.

 

[DragonBlight]

Section 2.3 of this document the author is talking about 2 frequencies but if instead of the 2 frequencies we have 5 different modes.

 

[DragonBlight]

I have another question. Can the modes be used as 5 different sources?