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Title: Fiber optic sensor system for detecting movement or position of a rotating wheel bearing

An improved fiber optic sensor system and integrated sensor bearing assembly for detecting movement or position of a rotating wheel bearing having a multi-pole tone ring which produces an alternating magnetic field indicative of movement and position of the rotating member. A magneto-optical material, such as a bismuth garnet iron (B.I.G.) crystal, having discrete magnetic domains is positioned in the vicinity of the tone ring so that the domains align themselves to the magnetic field generated by the tone ring. A single fiber optic cable, preferably single mode fiber, carries light generated by a source of light to the B.I.G. crystal. The light passes through the B.I.G. crystal and is refracted at domain boundaries in the crystal. The intensity of the refracted light is indicative of the amount of alignment of the domains and therefore the strength of the magnetic field. The refracted light is carried by the fiber optic cable to an optic receiver where the intensity is measured and an electrical signal is generated and sent to a controller indicating the frequency of the changes in light intensity and therefore the rotational speed of the rotating wheel bearing.
 [1];  [2];  [1];  [3];  [4]
  1. (Los Alamos, NM)
  2. (Santa Fe, NM)
  3. (Ann Arbor, MI)
  4. (Ypsilanti, MI)
Issue Date:
OSTI Identifier:
NTN Technical Center (USA) (Ann Arbor, MI) LANL
Patent Number(s):
US 5602946
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM
Country of Publication:
United States
fiber; optic; sensor; detecting; movement; position; rotating; wheel; bearing; improved; integrated; assembly; multi-pole; tone; produces; alternating; magnetic; field; indicative; magneto-optical; material; bismuth; garnet; iron; crystal; discrete; domains; positioned; vicinity; align; generated; single; cable; preferably; mode; carries; light; source; passes; refracted; domain; boundaries; intensity; amount; alignment; strength; carried; receiver; measured; electrical; signal; controller; indicating; frequency; changes; rotational; speed; bearing assembly; mode fiber; light passes; rotational speed; electrical signal; fiber optic; magnetic field; single mode; light intensity; alternating magnetic; optic cable; light generated; field generated; optic sensor; rotating wheel; single fiber; wheel bearing; improved fiber; detecting movement; domain boundaries; /385/250/324/