Hi
Sounds like an ambitious school project.
First I think you need to clarify what your AOI system will be able to do and not do.
If this is for use in electronic production you will need a good understanding of the challenges and common faults that can occur in pcb assembly.
With AOI I think of inline machines in SMT production lines. Not exactly hobby stuff.
The new generation of AOI's can generate a 3D image of the pcb by having extra angle mounted careras.
Look at systems from Viscom, Cyberoptics, Yamaha, Omron etc.
At work we have 3x 3D AOI system per SMT line:
1st AOI is a solder paste inspection (SPI) between screen printer and pick and place machines that inspects the pr. pad paste volume, height, xy offset, bridging etc.
2nd AOI is between pick and place and reflow oven. This inspects the placement of components, x, y, rotation, height, coplanarity, polarity marks, missing parts etc. This could all be done on the post reflow AOI, but its much easier and cheaper to fix problems before soldering. So this extra AOI machine is economical in an high volume production.
3rd AOI inspects the soldering joints volume, height, shape, lifted leads etc. and again the placement of the component for tombstone's etc. that could happen in the reflow process.
To really need an AOI system you need some volume of SMT production. So you will probably already have spent at least 50-100K$ on pick and place machine, feeders, reflow oven, screen printer etc. before you even start to look at an AOI system.
If you do want to make a simple open AOI system for "hobby/garage" manufactures take a look at the OpenPnP project and look in the Manufacturing & Assembly part of the forum.