Two-Photon Pattern Bleaching for Characterizing Structural Changes in Polymer Films

Using two-photon absorption, an array of spots in a dye-doped polymer film can be bleached, creating a three-dimensional structure that can be imaged with two-photon or confocal microscopy. Microscopic deformations resulting from various treatments to the film can be characterized, for example swelling or shrinking. This technique is demonstrated on dye-doped poly(vinyl alcohol), in which the effect of swelling with the addition of water to the film is shown.