Showing papers by "Mikhail G. Shlyagin published in 2009"

Sensor de fibraóptica distribuido para la localización de fugas de hidrocarburo basado en mediciones de transmisión / reflexión

Abstract: SE PRESENTA UN NUEVO SENSOR DE FIBRA OPTICA DISTRIBUIDO PARA LA DETECCION Y LOCALIZACION DE FUGAS DE HIDROCARBURO , BASADO EN LA MEDICION DE LAS POTENCIAS TRANSMITIDA Y DE RETRODISPERSION DE RAYLEIGH. LA ESTRUCTURA DEL SENSOR INCLUYE UN POLIMERO SENSIBLE, EL CUAL SE EXPANDE REVERSIBLEMENTE EN PRESENCIA DE HIDROCARBURO E INDUCE PERDIDAS POR CURVATURA EN LA FIBRA. LA LOCALIZACION DE LA REGION DE PERDIDAS SE DETERMINA DESDE UNA RELACION UNICA ENTRE LAS POTENCIAS DE TRANSMISION Y RETRODISPERSION DE RAYLEIGH NORMALIZADAS PARA DIFERENTES POSICIONES DE LA PERTURBACION A LO LARGO DE LA FIBRA DE PRUEBA. SE DEMUESTRA LA LOCALIZACION DE UNA FUERTE PERTURBACION CON UNA PRECISION DE 1M A LO LARGO DE UNA FIBRA MODOMODAL DE 2.844 KM. Abstract A NOVEL TYPE OF DISTRIBUTED FIBER OPTIC SENSOR FOR PETROLEUM HYDROCARBON LEAK DETECTION AND LOCALIZATION BASED ON THE MEASUREMENT OF TRANSMITTED AND RAYLEIGH BACKSCATTERED POWER IS PRESENTED. THE SENSOR STRUCTURE INCLUDES A SENSITIVE POLYMER, WHICH REVERSIBLY EXPANDS IN HYDROCARBON PRESENCE AND INDUCES THE BENDING LOSSES IN THE FIBER. THE LOCATION OF THE LOSS REGION IS DETERMINED FROM UNIQUE RELATIONSHIPS BETWEEN NORMALIZED TRANSMITTED AND RAYLEIGH BACKSCATTERED POWERS FOR DIFFERENT POSITIONS OF THE DISTURBANCE ALONG THE TEST FIBER. THE LOCALIZATION OF A STRONG DISTURBANCE WITH AN ESTIMATED ACCURACY OF 1 M ALONG A 2.844 KM-LENGTH SINGLE-MODE FIBER WAS DEMONSTRATED.

Sensor láser de fibraóptica con una cavidad de 8.6 km por dos rejillas de bragg usadas como espejos

Abstract: SE REPORTA LA OPERACION DE UN SENSOR LASER DE FIBRA OPTICA FORMADO POR UNA FIBRA DOPADA CON ERBIO BOMBEADA A 980NM, 8;67KMDE FIBRA PASIVA Y DOS REJILLAS DE BRAGG COLOCADAS EN LOS EXTREMOS DE LA CAVIDAD LASER. BAJO CONDICIONES NORMALES, LAS REJILLAS TIENEN DISTINTAS LONGITUDES DE ONDA DE REFLEXION Y NO HAY GENERACION DE EMISION LASER. LAS DOS REJILLAS PUEDEN SER PUESTAS A LA MISMA LONGITUD DE ONDA DE REFLEXION, SOMETIENDO A TENSION A LA REJILLA CON LONGITUD DE ONDA DE REFLEXION MENOR, LA CUAL SE USA COMO EL ELEMENTO SENSOR. LA GENERACION LASER MUESTRA QUE LA REJILLA ESTA BAJO TENSION. ADEMAS NUESTRA CONFIGURACION NOS DA LA POSIBILIDAD DE CONOCER LA DISTANCIA ENTRE LAS REJILLAS MIDIENDO LA FRECUENCIA DE ESPACIAMIENTO ENTRE MODOS DEL LASER. EN ESTE TRABAJO SE DEMUESTRA QUE PUEDE SER ALCANZADA UNA DISTANCIA MINIMA DE 25M ENTRE REJILLAS DE BRAGG CONSECUTIVAS CUANDO SE ANALIZA EL OCTAVO ARMONICO DETECTADO POR UN ANALIZADOR DE RF. Abstract WE REPORT THE OPERATION OF A FIBER LASER SENSOR MADE BY AN ERBIUM DOPED FIBER PUMPED AT 980NM, AN 8;67KM PASSIVE FIBER AND TWO FIBER BRAGG GRATINGS PLACED AT THE ENDS OF THE LASER CAVITY. UNDER NORMAL CONDITIONS, THE BRAGG GRATINGS HAVE DIFFERENT REFLECTION WAVELENGTHS AND LASER EMISSION IS NOT GENERATED. THE TWO BRAGG GRATINGS CAN BE PLACED AT THE SAME REFLECTION WAVELENGTH WHEN THE BRAGG GRATING WITH THE LOWEST REFLECTIVE WAVELENGTH IS STRAINED WHICH CAN BE USED AS A SENSOR ELEMENT. THE LASER GENERATION THUS SHOWS THAT THE BRAGG GRATING IS UNDER STRAIN. FURTHERMORE, OUR CONFIGURATION GIVES US THE POSSIBILITY FOR KNOWING THE DISTANCE BETWEEN TWO BRAGG GRATINGS WHEN THE LASER BEATING FREQUENCY IS MEASURED. A MEASUREMENT PRECISION BETTER THAN 25M IN 8;67KM IS SHOWN TO BE FEASIBLE.

Wide range refractive index sensor using a twin-grating interferometer for intensity reference

Abstract: An optical fiber refractometer based on the Fresnel reflection in the fiber tip and twin FBG interferometer located near the fiber tip for light intensity referencing is reported. A wavelength scanning DFB diode laser was used for RI sensor interrogation. Signal processing in the Fourier domain allows intensity-independent accurate measurements for liquids and gases with practically any RI. A resolution of 5 - 10 5-5 was demonstrated experimentally using different liquids including an anti-reflection index-matching liquid. Simple construction and the use of low-cost components make it interesting for many applications.