Fiber-optic push-pull sensor systems

Fiber-optic push-pull sensors are those which exploit the intrinsically differential nature of an interferometer with concommitant benefits in common-mode rejection of undesired effects. Several fiber-optic accelerometer and hydrophone designs are described. Additionally, the recent development at the Naval Postgraduate School of a passive low-cost interferometric signal demodulator permits the development of economical fiber-optic sensor systems

Analysis and preliminary design of optical sensors for propulsion control

A fiber-optic sensor concept screening study was performed. Twenty sensor subsystems were identified and evaluated. Two concepts selected for further study were the Fabry-Perot fiber-optic temperature sensor and the pulse-width-modulated phosphorescent temperature sensor. Various designs suitable for a Fabry-Perot temperature sensor to be used as a remote fiber-optic transducer were investigated. As a result, a particular design was selected and constructed. Tests on this device show that spectral peaks are produced from visible white light, and the change in wavelength of the spectral peaks produced by a change in temperature is consistent with theory and is 36 nm/C for the first order peak. A literature search to determine a suitable phosphor for implementing the pulse-width-modulated fiber optic temperature sensor was conducted. This search indicated that such a device could be made to function for temperatures up to approximately 200 C. Materials like ZnCdS and ZnSe activated with copper will be particularly applicable to temperature sensing in the cryogenic to room temperature region. While this sensing concept is probably not applicable to jet engines, the simplicity and potential reliability make the concept highly desirable for other applications

Optical fiber sensor review

Technology of fiber optic are widely used for its applications which mostly known for carrying information over long distances for the best efficiency. It is also used for medical diagnostics, environmental monitoring, physical parameters detection, industrial applications, food safety, and security [1]. The fiber optic technology can also be a method for sensor application which is a fiber optic sensor..

High Sensitivity Hot-wire based Wind Velocity Sensor using Co-doped Fiber and Fiber Bragg Grating for use in mining applications

In this paper, a mathematical model of the temperature distribution in a fiber-optic version of the familiar 'hot-wire' wind velocity sensor has been established and a practical sensor device realized and investigated for use in coal mining applications. The relationship between the dynamic measurement range, the sensitivity, the sensor probe surface heat transfer coefficient and the wind speed (in the region where the sensor probe is located) has been investigated. The veracity of the predicted performance of the fiber-optic hot-wire mathematical model has then been verified by experiment. The sensitivity of the sensor probe to wind velocity was measured across several wind velocity ranges to be ∼1500pm per unit m/s wind velocity (in the range of 0 - 0.5 m/s), ∼330pm per unit m/s in the range 0.5 - 2 m/s and ∼50pm per unit m/s in the range of 2.0 - 4.5 m/s

Dissolved oxygen sensing using an optical fibre long period grating coated with hemoglobin

A long period grating fiber optic sensor coated with hemoglobin is used to detect dissolved oxygen. The sensitivity of this sensor to the ratio of dissolved carbon dioxide to dissolved oxygen is demonstrated via the conversion of carboxyhemoglobin to oxyhemoglobin on the sensor surface. The sensor shows good repeatability with a %CV of less than 1% for carboxyhemoglobin and oxyhemoglobin states with no measurable drift or hysteresis

Development of a fiber optic high temperature strain sensor

From 1 Apr. 1991 to 31 Aug. 1992, the Georgia Tech Research Institute conducted a research program to develop a high temperature fiber optic strain sensor as part of a measurement program for the space shuttle booster rocket motor. The major objectives of this program were divided into four tasks. Under Task 1, the literature on high-temperature fiber optic strain sensors was reviewed. Task 2 addressed the design and fabrication of the strain sensor. Tests and calibration were conducted under Task 3, and Task 4 was to generate recommendations for a follow-on study of a distributed strain sensor. Task 4 was submitted to NASA as a separate proposal

Closed loop fiber optic rotation sensor

An improved optical gyroscope is provided, of the type that passes two light components in opposite directions through an optic fiber coil, and which adds a small variable frequency to one of the light components to cancel the phase shift due to rotation of the coil. The amount of coil rotation from an initial orientation, is accurately determined by combining the two light components, one of which has a slightly increased frequency, to develop beats that each represent a predetermined angle of rotation. The direction of rotation is obtained by combining the two light components on a photodetector, intermittently phase shifting a single light component by 90 deg and comparing the direction of change of photodetector output (+ or -) caused by the 90 deg shift, with the slope (+ or -) of the photodetector output at about the same time, when there is a 90 deg shift

Analisis Efisiensi Daya Pada Transmisi Daya Optik Lewat Bundel Serat Optik

Salah satu aplikasi dari serat optic dalam bidang instrumentasi dan kedokteran adalah sensor optic. Sensor optic dibagi dalam dua kategori dasar, yaitu sensor modulasi intensitas dan sensor modulasi fasa. Dibandingkan sensor modulasi fasa, sensor modulasi intensitas lebih banyak membutuhkan cahaya. Hal ini mengakibatkan sensor modulasi intensitas menggunakan inti serat moda jamak yang besar (bundle serat optic). Pada penelitian yang dilakukan oleh Heri Suyanto dkk14 telah dilakukan penelitian tentangpengaruh ukuran diameter gukungan dan jumlah lilitan fiber optic terhadap efisiensi dan rugi-rugi (atenuasi)transmisi daya laser dalam serat optic moda jamak. Penelitian efiensi ini lebih menekankan pada pengaruh lilitan dan diameternya hanya pada serat tunggal. Pada penelitian ini, analisis efisiensi daya pada transmisi daya optic lewat dilakukan pada bundle serat optic moda jamak. Eksperimen dilakukan dengan melewatkan cahaya pada bundle serat optic dengan bahan plastic yang berdiameter inti (core) 120μm dan diameter selubung (cladding) 510μmpada tiga proses, yaitu proses transmisi, proses transmisi-refleksi dan proses transmisi-refleksi-transmisi. Pada proses transmisi, cahaya dengan panjang gelombang 630 nm dari sumber optic dilewatkan kolimator dan diterima oleh bundle transmisi. Keluaran bundle transmisi diterima oleh detector. Pada proses transmisi-refleksi, keluaran dari bundle transmisi diarahkan ke reflector. Cahaya yang terpantul dari reflector diterima oleh detector. Pada proses transmisi-refleksi-transmisi, keluaran dari bundle transmisi diarahkan ke reflector dan cahaya yang terpantul dari reflector diterima oleh bundle penerima. Daya keluaran dari bundle penerima diterima detector dan ditunjukkan oleh power meter digital. Faktor-faktor yang berpengaruh pada hasil efisiensi daya optic pada ketiga proses tersebut adalah jumlah serat dalam bundle, susunan geometris serat dalam bundle dan penggandengan antara sumber dengan bundle. Area aktif dengan susunan geometris dan penggandengan yang memenuhi sudut penerimaan maksimum atau aperture numeric (NA) akan meningkatkan kemampuan bundle menerima daya optic. Dari hasil eksperimen, pada proses transmisi dicapai efisiensi daya optic sebesar η = -24,84 dB, pada proses transmisi-refleksi sebesar η = -37,30 dB dan pada proses transmisi-refleksi-transmisi sebesar η = -46,20 dB. Secara teoritis, pada transmisi dicapai hasil sebesar η = -11,5 dB, pada proses transmisi-refleksi sebesar η = -20,77 dB dan pada proses transmisi- refleksi-transmisi η = -32,33 dB

Power system applications of fiber optic sensors

This document is a progress report of work done in 1985 on the Communications and Control for Electric Power Systems Project at the Jet Propulsion Laboratory. These topics are covered: Electric Field Measurement, Fiber Optic Temperature Sensing, and Optical Power transfer. Work was done on the measurement of ac and dc electric fields. A prototype sensor for measuring alternating fields was made using a very simple electroscope approach. An electronic field mill sensor for dc fields was made using a fiber optic readout, so that the entire probe could be operated isolated from ground. There are several instances in which more precise knowledge of the temperature of electrical power apparatus would be useful. This report describes a number of methods whereby the distributed temperature profile can be obtained using a fiber optic sensor. The ability to energize electronics by means of an optical fiber has the advantage that electrical isolation is maintained at low cost. In order to accomplish this, it is necessary to convert the light energy into electrical form by means of photovoltaic cells. JPL has developed an array of PV cells in gallium arsenide specifically for this purpose. This work is described

Fiber optic control system integration

A total fiber optic, integrated propulsion/flight control system concept for advanced fighter aircraft is presented. Fiber optic technology pertaining to this system is identified and evaluated for application readiness. A fiber optic sensor vendor survey was completed, and the results are reported. The advantages of centralized/direct architecture are reviewed, and the concept of the protocol branch is explained. Preliminary protocol branch selections are made based on the F-18/F404 application. Concepts for new optical tools are described. Development plans for the optical technology and the described system are included