Measuring parameter, esp. pressure difference, using Fabry-Perot detector - controlling optical length of detector according to output parameter to determine working point on graph

摘要

Measuring a parameter which influences the optical length of a Fabry-Perot sensor involves modifying a light beam of infinite coherence length in the sensor and feeding it to a Fabry-Perot detector with a light sensitive element. The element produces an output signal dependent on the beam further modified by the detector. The detector's optical length is controlled using an electrical control parameter, with which it has a definite relationship, depending on the output parameter so that a distinguished point on a graph is defined as the working point. The measurement parameter is determined from the control parameter. The graph shows the relationship between the output and the difference between the sensor and detector optical lengths. USE/ADVANTAGE - Esp. for measuring press, differences in flow measurement devices. Simple, low-cost control and evaluation electronics can be used.