To extend this activity, try looking at a variety of brands and models of smart/mobile devices. Are there any differences between the technologies of various models, like the shape, size, and spacing of the pixels and subpixels?
How does a device with a very sharp image compare with one that is not as clear?
Can you determine the relative ages of two devices just by observing the microscope images?
Here are a few magnified images of white light coming from several different phones (click to enlarge each image):
Samsung Galaxy Note 4 (2015)
Samsung Galaxy Nexus (2012)
Apple iPhone 5 (2012)