Have you tried looking at the Illinois in the Civl War site. There as you scroll down you will find a link for photo's. Click on that and then choose by Regiment. IF you don't find it there, try the Abraham Lincoln Presidential Library in Springfield. You will have to hunt for that there. If they have it, you would have to go to the museum to view it as far as I know. If they have one, perhaps you could write to them and maybe they can make you a copy. I am not sure about that but good hunting.