A getter (50 or 74) situated in a cavity of a hollow structure, such as a flat-panel device, is activated by directing light energy locally through part of the hollow structure and onto the getter. The light energy is typically provided by a laser beam (60). The getter, typically of the non-evaporable type, is usually inserted as a single piece of gettering material into the cavity. The getter normally can be activated/re-activated multiple times in this manner, typically during the sealing of different parts of the structure together. The getter-containing cavity can be formed by a pair of plate structures (40 and 42) sandwiched around and outer wall (44), or by an auxiliary compartment (72) connected to a larger main compartment (70) typically constituted by the plate structures and outer wall.