Back to results
US 7,187,816 B2Granted
In-fiber whitelight interferometry using long-period fiber grating
AssigneePurdue Research Foundation
InventorHaiying Huang
Life of this patent
Estimating the term…
Abstract
An optical fiber sensor is provided for displacement measurement, pressure measurement, refractive index measurement, bio/chemical detection, and/or microscopy.
Claims27
A sensing method using an optical fiber sensor, the method comprising:
- providing a probe including an optical fiber having an inner core region, an outer cladding region, and a long period fiber grating (LPFG) embedded at selected distances from a distal end of the optical fiber;
- forming a reflective surface over the cladding region at the distal end of the optical fiber;
- positioning the distal end of the optical fiber adjacent a sample;
- supplying light to the core of the optical fiber so that upon encountering the LPFG, a first portion of the light wave travels through the core of the optical fiber toward a distal end and a second portion of the light wave is coupled into the cladding region and travels through the cladding region toward distal end;
- emitting the first portion of the light wave moving through core from the distal end of the optical fiber, the first portion of the light wave striking a surface of the sample and being reflected back into the core, the sample reflective wave moving through the core in a direction away from the distal end;
- reflecting the second portion of the light wave off the reflective surface so that a cladding reflective wave moves back through the cladding region in a direction away from the distal end, a portion of the cladding reflective wave being coupled back to core at the LPFG;
- and
- determining a distance between the distal end of the optical fiber and the surface of the sample based on a phase shift between the cladding reflective wave and the sample reflective wave.
5 more elements
An optical fiber sensor comprising:
- a probe including an optical fiber having an inner core region, an outer cladding region, a long period fiber grating (LPFG) embedded at selected distances from a distal end of the optical fiber, and a reflective surface located over the cladding region at the distal end of the optical fiber;
- a light source coupled to the optical fiber, the light source supplying light to the core of the optical fiber so that, upon encountering the LPFG, a first portion of the light wave travels through the core region in a direction toward a distal end and a second portion of the light wave is coupled into the cladding region and travels through the cladding region in a direction toward distal end, the first portion of the wave being emitted from core at the distal end of the optical fiber, the first portion of the light wave striking a surface of a sample and being reflected back into the core, the sample reflective wave moving back through the core region in a direction away from the distal end, and the second portion of the light wave being reflected by the reflective surface to form a cladding reflective wave that moves back through the cladding region in a direction away from the distal end, a portion of the cladding reflective wave being coupled back to core at the LPFG;
- and
- an analyzer optically coupled to the probe to determine a distance between the distal end of the optical fiber and the surface of the sample based on a phase shift between the cladding reflective wave and the sample reflective wave.
1 more element
Dependencies are inferred from the claim text.