Chemical Sensing on the Factory Floor.

Historically, process control in factory environments has been dominated by tests performed on the product of the process or group of processes. Such "after the fact" tests can prove costly, and may not be able to pin point the exact nature of a process problem. Ideally, one would like to able to monitor the critical parameters within the process and, provided one had a suitable process model, adjust those parameters to insure that the product met the necessary requirements. On-line process sensing places severe demands on the analytical method employed and the hardware used. Reliability often overrides all other concerns. In the chemical process sensors we have developed for manufacturing applications, we have focused on techniques which provide such reliability. Fiber optic based measurement techniques for determination of refractive index and chemical composition offer significant advantages in certain applications due to their sensitivity and resistance to electrical interference.