When a road pebble or rock collides with a windshield, it chips the outer layer of glass, creating a chip or small crack. The chipped glass particles become surrounded by tiny air pockets, causing visual distortion.
The first step is to evacuate the trapped air and to fill the cavities with a specially formulated liquid resin which when cured with ultra-violet light, clears the distortion and bonds the loose glass preventing the damage from spreading.