Abstract: An SBS cell (20) for use in combination with a laser system (10) on a mobile platform. The SBS cell (20) includes inner and outer tubes (32, 34) that define inner and outer chambers (38, 40). The inner tube (32) is completely filled with an SBS fluid (76) and the outer tube (34) is filled to a level that is above the fill hole (42) of the inner tube (32). The outer tube (34) is sized to trap enough air to provide a compressible volume for cell fluid expansion from temperature changes in the laser environment. The SBS cell (20) is filled in an upside-down position, and the cell (20) is rotated 180° to its operating position. In this position, the fill hole (42) is pointed downward, and since the air bubbles float to the top, the distance between the inner tube fill hole (42) and the trapped air is sufficient enough to prevent air bubbles from migrating to the fill hole (42) and entering the inner tube (32).