Patent ID: 7308162

Claim:
A method comprising the steps of: performing the steps of: forming a mask over an optical fiber, the optical fiber having a core surrounded by a cladding, the mask having a single opening; exposing the opening to light propagating outside the optical fiber such that a refractive index of a portion of the fiber corresponding to the opening is changed to form a Fabry-Perot cavity sensor, whereby light propagating in the optical fiber after the Fabry-Perot cavity sensor is formed is reflected at a first end and at a second end of the portion and propagates backward along the optical fiber, light reflected at the first end of the portion interfering with light reflected from the second end of the portion such that changes in a length of the portion result in observable changes in an amplitude of such reflected light; to form a first Fabry-Perot sensor in an optical fiber; repeating the forming and exposing steps at least once such that a plurality of sensors are formed in the optical fiber; the plurality of sensors being spaced apart; launching an optical pulse into the optical fiber, the optical fiber having a plurality of optical sensors formed therein, the pulse having a duration less than a time required to travel a smallest distance between the two most closely spaced sensors; and measuring amplitudes of backward-propagating reflection peaks in the fiber at a plurality of times, each of the times corresponding to a location of one of the plurality of sensors.