Traditional microscopes project a magnified image of an object onto a sensor.

FORBES: Magazine Article

This allows you to instantly see a magnified portion of the image, which is helpful in knowing if a part of an image is in focus.

WSJ: The Digital Solution: Letting Your Fingers Do the Photo Editing

The image reflection is then focused through a lens, where it is magnified and projected onto the display, where there is virtually no space between pixels.

ENGADGET: D-ILA and DLP: what are they? HD