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Title: Lensless magneto-optic speed sensor

Abstract

Lensless magneto-optic speed sensor is disclosed. The construction of a viable Faraday sensor has been achieved. Multimode fiber bundles are used to collect the light. If coupled directly into a 100 or 200 {micro}m core fiber, light from a light emitting diode (LED) is sufficient to operate the sensor. In addition, LEDs ensure that no birefringence effects in the input fiber are possible, as the output from such light sources have random polarization. No lens is required since the large diameter optical fibers and thin crystals of materials having high Verdet constants (such as iron garnets) employed permit the collection of a substantial quantity of light. No coupler is required. The maximum amount of light which could reach a detector using a coupler is 25%, while the measured throughput of the fiber-optic bundle without a coupler is about 42%. All of the elements employed in the present sensor are planar, and no particular orientation of these elements is required. The present sensor operates over a wide range of distances from magnetic field sources, and observed signals are large. When a tone wheel is utilized, the signals are independent of wheel speed, and the modulation is observed to be about 75%.more » No sensitivity to bends in the input or output optical fiber leads was observed. Reliable operation was achieved down to zero frequency, or no wheel rotation. 5 figs.« less

Inventors:
; ;
Issue Date:
Research Org.:
Univ. of California (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
570410
Patent Number(s):
5719497
Application Number:
PAN: 8-647,364
Assignee:
Univ. of California, Los Alamos, NM (United States)
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 17 Feb 1998
Country of Publication:
United States
Language:
English
Subject:
44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; VELOCIMETERS; DESIGN; FARADAY EFFECT; MAGNETO-OPTICAL EFFECTS; OPTICAL FIBERS

Citation Formats

Veeser, L R, Forman, P R, and Rodriguez, P J. Lensless magneto-optic speed sensor. United States: N. p., 1998. Web.
Veeser, L R, Forman, P R, & Rodriguez, P J. Lensless magneto-optic speed sensor. United States.
Veeser, L R, Forman, P R, and Rodriguez, P J. Tue . "Lensless magneto-optic speed sensor". United States.
@article{osti_570410,
title = {Lensless magneto-optic speed sensor},
author = {Veeser, L R and Forman, P R and Rodriguez, P J},
abstractNote = {Lensless magneto-optic speed sensor is disclosed. The construction of a viable Faraday sensor has been achieved. Multimode fiber bundles are used to collect the light. If coupled directly into a 100 or 200 {micro}m core fiber, light from a light emitting diode (LED) is sufficient to operate the sensor. In addition, LEDs ensure that no birefringence effects in the input fiber are possible, as the output from such light sources have random polarization. No lens is required since the large diameter optical fibers and thin crystals of materials having high Verdet constants (such as iron garnets) employed permit the collection of a substantial quantity of light. No coupler is required. The maximum amount of light which could reach a detector using a coupler is 25%, while the measured throughput of the fiber-optic bundle without a coupler is about 42%. All of the elements employed in the present sensor are planar, and no particular orientation of these elements is required. The present sensor operates over a wide range of distances from magnetic field sources, and observed signals are large. When a tone wheel is utilized, the signals are independent of wheel speed, and the modulation is observed to be about 75%. No sensitivity to bends in the input or output optical fiber leads was observed. Reliable operation was achieved down to zero frequency, or no wheel rotation. 5 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {2}
}