These sensors are embedded within or are part of the fiber optic system, resulting in modifications to the optical fiber itself. The fiber itself acts as the sensing element, directly affected by the measurand (the quantity being measured). Fibers have many uses in remote sensing. Think of it like a photoresistor, which changes its resistance based. What rotation rate can be measured? the propagation direction Information from ABB: Energize, Jan/Feb 2005, p 26 I: Current (A) EJ Casey & CH Titus: US Patent 3324393, 1967 Jose Miguel Lopez-Higuera: Handbook of Optical Fiber Sensing Technology, John Wiley & Sons, 2002., small, lightweight, resistant to high temperatures and pressure, electromagnetically passive, among others. Sensing is achieved by exploring the properties of light to obtain measurements of parameters, such as. Distributed Temperature Sensing (DTS), Distributed Temperature and Strain Sensing (DTSS) and Distributed Acoustic Sensing (DAS) are all various types of fiber optic sensing technologies which use the physical properties of light as it travels along a fiber to detect changes in temperature, strain. Distributed and quasi-distributed fiber optic sensors are systems that connect opto-electronic interrogators to an optical fiber (or cable), converting the fiber to an array of distributed sensors.