# US 8,770,024 B1 · Fiber optic accelerometer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,024 B1 - Document ID: US8770024B1 - Status: Granted - Kind: B1 - Application number: 13/935,955 - Filed: 2013-07-05 - Granted: 2014-07-08 - Earliest claimed: 2013-07-05 - Assignees: Vibrosound Ltd. - Applicants: Vibrosound Ltd - Inventors: Alexander Paritsky; Alexander Kots; Yuvi Kahana - Web page: https://patentgrep.com/patent/US8770024B1 ## CPC - G01P 15/093: by photoelectric pick-up - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract A fiber optic accelerometer has a hollow body that supports an optical fiber therein so as to form a cantilever section, a fiber optic splitter coupled to a first end of the optical fiber and a light source for directing light into the optical fiber via a first branch of the optical splitter. A photo detector receives light conveyed through the optical fiber via a second branch of the optical splitter and measures an intensity of the received light. A reflective target supported at a second end of the hollow body is axially aligned with the second end of the optical fiber in the absence of force. Upon acceleration the cantilever section moves such that its position relative to the reflective target changes thereby reducing the instantaneous intensity of light reflected by the target into the second end of the optical fiber and measured by the photo detector. ## Claims ### Claim 1 A fiber optic accelerometer comprising: a hollow body, an optical fiber having a first end and a second end remote from the first end, said optical fiber being supported toward the second end inside the hollow body so as to form a cantilever section, a fiber optic splitter coupled to the first end of the optical fiber, a light source for directing light into the optical fiber via a first branch of the optical splitter, a photo detector arranged for receiving light conveyed through the optical fiber via a second branch of the optical splitter and measuring an intensity of the received light, and a reflective target disposed within and supported at a second end of the hollow body so as to be axially aligned with the second end of the optical fiber when no force is applied to the accelerometer; whereby upon vibration or acceleration of the accelerometer the cantilever section moves such that its position relative to the reflective target changes thereby reducing the instantaneous intensity of light reflected by the target into the second end of the optical fiber and measured by the photo detector; wherein: the reflective target is formed of an optical fiber stub having a first end proximate the free second end of the optical fiber and a second end remote therefrom; and the first end of the optical fiber stub has a slanted surface formed at an angle to an optical axis of the optical fiber stub and the second end of the optical fiber stub is cut perpendicularly to said optical axis and is coated with a highly polished efficient light reflecting material. ### Claim 2 (depends on 1) The fiber optic accelerometer as claimed in claim 1, wherein a point of fixation of the optical fiber in the hollow body is adjustable thereby allowing adjustment of the length of the cantilever section. ### Claim 3 (depends on 1) The fiber optic accelerometer as claimed in claim 1, wherein a distance between the second end of the optical fiber and the light reflective target is fixed by an annular spacer during assembly. ### Claim 4 (depends on 1) The fiber optic as claimed in claim 1, wherein the optical fiber stub is axially rotatable so as to change an orientation of the slanted surface of the first end of the optical fiber stub thereby adjusting a directional sensitivity of the accelerometer. ### Claim 5 A fiber optic accelerometer comprising: a hollow body, an optical fiber having a first end and a second end remote from the first end, said optical fiber being supported toward the second end inside the hollow body so as to form a cantilever section, a fiber optic splitter coupled to the first end of the optical fiber, a light source for directing light into the optical fiber via a first branch of the optical splitter, a photo detector arranged for receiving light conveyed through the optical fiber via a second branch of the optical splitter and measuring an intensity of the received light, and a reflective target disposed within and supported at a second end of the hollow body so as to be axially aligned with the second end of the optical fiber when no force is applied to the accelerometer; whereby upon vibration or acceleration of the accelerometer the cantilever section moves such that its position relative to the reflective target changes thereby reducing the instantaneous intensity of light reflected by the target into the second end of the optical fiber and measured by the photo detector; wherein: the reflective target is formed of an optical fiber stub having a first end proximate the free second end of the optical fiber and a second end remote therefrom; and the first end of the optical fiber stub has a stepped cut so as to present a first surface portion closer to the end of the optical fiber and a more distant second surface section and the second end of the optical fiber stub is cut perpendicularly to said optical axis and is coated with a highly polished efficient light reflecting material. ### Claim 6 (depends on 5) The fiber optic accelerometer as claimed in claim 5, wherein a point of fixation of the optical fiber in the hollow body is adjustable thereby allowing adjustment of the length of the cantilever section. ### Claim 7 (depends on 5) The fiber optic accelerometer as claimed in claim 5, wherein a distance between the second end of the optical fiber and the light reflective target is fixed by an annular spacer during assembly. ### Claim 8 (depends on 5) The fiber optic as claimed in claim 5, wherein the optical fiber stub is axially rotatable so as to change an orientation of the stepped surface of the first end of the optical fiber stub thereby adjusting a directional sensitivity of the accelerometer.