Photos are scattered across the levels of Cut the Rope: Experiments. The player sees them as sheets of paper stuck to the background of the level. If you click on them, you will be shown pictures of Om Nom related to the theme of the level.
Below is a list of the photographs found in Cut the Rope: Experiments.
Note: Finding photos requires a lot of persistence as they are mostly located at the edges of the screen and are difficult to find.