A guy looking in a microscope.
The man looking through the microscope.
In and through are both appropriate terms for analyzing something under a microscope.
exists e1 x1 x2 x3.(a_topic(x1) & in(e1,x3) & n_microscope(x3) & Actor(e1,x2) & v_look(e1) & (x1 = x2) & n_guy(x1))
exists e1 x1 x2 x3.(n_microscope(x3) & n_man(x1) & a_topic(x1) & through(e1,x3) & Actor(e1,x2) & v_look(e1) & (x1 = x2))