Dynamic Interferometry Handles Vibration

Mechanical vibration and turbulent airflow present significant problems for most interferometric test methods. Conditions on the factory floor and in industrial clean rooms with high-capacity air filtration systems, for example, can hamper the use of interferometry. Another key problem area is the testing of large-aperture mirrors (1-10 m) when it is difficult to mechanically isolate such mirrors and the structures needed to support the optical test; in addition, long optical paths produce air-turbulence problems. To make things worse, the next generation of large-aperture lightweight mirrors for space-telescope applications must be tested in large vacuum chambers at cryogenic temperatures - a situation in which vibration is virtually impossible to control.