Rubidium is used to make inexpensive rubidium atomic clocks. These atomic clocks are used for a variety of purposes such as in global navigation systems (GPS and GLONASS) and within the telecommunication industry (cell phone base stations and television stations). It is also used in laser cooling, which is used to cool molecular and atomic samples. Rubidium salts are used to make certain types of glassware and ceramic products. Rubidium is also used to remove trace gasses in vacuum tubes. An isotope of rubidium, Rb82, is used in specific types of medical imaging. This isotope is commonly used to detect brain tumors and to improve medical imaging of the heart in overweight patients. The metal is also used in the manufacture of photocells and to provide the purple color in fireworks.