Total light loss fiber optic spectroscopy: Progress towards a fiber optic raman organic sensor

1994 ◽  
Author(s):  
Kevin R. Kyle ◽  
Thomas M. Vess ◽  
S. M. Angel
Keyword(s):  
Fiber Optic ◽  
Total Light ◽  
Light Loss

Characterization of a Fiber-Optic System for the Distributed Measurement of Leakages in Tanks and Pipelines

1998 ◽  
Vol 52 (10) ◽  
pp. 1283-1298 ◽  
Author(s):  
E. Sensfelder ◽  
J. Bürck ◽  
H.-J. Ache
Keyword(s):  
Refractive Index ◽  
Light Pulse ◽  
Fiber Optic ◽  
Laser Light ◽  
Time Domain Reflectometry ◽  
Fiber Optic Sensor ◽  
Response Signal ◽  
Backscatter Signal ◽  
Light Loss ◽  
Distributed Measurement

A fiber-optic sensor system for the distributed measurement of organic chemicals is presented in this paper. The system uses the technique of optical time-domain reflectometry (OTDR) and a polymerclad optical fiber that is sensitive to nonpolar substances. The location of the chemicals is attained by measuring the time delay between a short laser light pulse entering the fiber and a discrete change in the backscatter signal caused by the enrichment of the analyte in the fiber cladding. Chemical substances enriched in the cladding of the sensor fiber lead to changes in the OTDR response signal, because the light-guiding properties of the fiber are affected through the evanescent wave. The enrichment of an analyte with a higher refractive index than the fiber cladding, for example, will induce a light loss because of mode stripping. This light loss is followed by a step drop in the OTDR response signal. If the analyte penetrating into the fiber cladding absorbs the emitted laser light pulse, a step drop also occurs in the backscatter signal because of the light loss due to the absorption. A fluorescent substance in the fiber cladding leads to a characteristic peak in the OTDR response signal. The intensity of the different signals is correlated with the refractive index and the concentration of the analyte, the interaction length between analyte and sensing fiber, and the temperature, fiber diameter, and bend radius of the fiber.

All-Fiber Optic Chemical Sensors for Public Safety Monitoring

2010 ◽  
Vol 123-125 ◽  
pp. 855-858 ◽  
Author(s):  
Jung Ryul Lee ◽  
Chang Yong Yoon ◽  
Dipesh Dhital ◽  
Dong Jin Yoon
Keyword(s):  
Public Safety ◽  
Chemical Sensor ◽  
Fiber Optic ◽  
Inner Core ◽  
Light Signal ◽  
Chemical Substances ◽  
Optical Time Domain Reflectometer ◽  
Sensing System ◽  
Hard Polymer ◽  
Light Loss

The leakage of toxic or flammable chemical substances that might affect or endanger public safety has always attracted the attention of the researchers to develop a chemical sensor that could prevent any life-threatening incidents. Due to its robust features, hard polymer clad fiber (HPCF) was used in this experiment to develop an all-fiber optical chemical sensor. The outer hard polymer clad was removed by using mechanical method to expose the inner core. The exposure lets contact between the leaked chemical and the core, both with different refractive indices (RI). The change in signal property of the passing light wave occurs at this point and hence can be detected using optical time-domain reflectometer (OTDR). In this way, HPCF was transformed into a fiber optic chemical sensor. OTDR was used as a sensing system that allowed the sensor to detect and localize the leakage of chemical substances in real-time, by measuring the light loss in backscattering light (signal) that was caused due to extraction of chemical on fiber cladding. This light loss is based on leaky wave mode principle. The reliability of the sensor was tested with Benzene, Toluene, Pyridine, Dimethylsulphoxide and several other toxic chemicals. The results showed that the sensor was able to detect the chemicals (in liquid state) and localize the event positioning. With the promising results, the sensor will be further tested with different types of chemicals to optimize the fiber chemical sensing system.

How to report light loss values for optical fibers used in fiber optic lighting applications

1998 ◽  
Author(s):  
Andrew Bierman ◽  
Nadarajah Narendran ◽  
Nishantha Maliyagoda
Keyword(s):  
Optical Fibers ◽  
Fiber Optic ◽  
Light Loss

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Roughness measurements of nonlinear optical polymer films by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 22-23
Author(s):  
I. H. Musselman ◽  
R.-T. Chen ◽  
P. E. Russell
Keyword(s):  
Surface Roughness ◽  
Scanning Tunneling Microscopy ◽  
Nonlinear Optical ◽  
Polymer Surface ◽  
Light Extinction ◽  
Scanning Tunneling ◽  
Silicon Substrates ◽  
Tunneling Microscopy ◽  
Optical Polymer ◽  
Total Light

Scanning tunneling microscopy (STM) has been used to characterize the surface roughness of nonlinear optical (NLO) polymers. A review of STM of polymer surfaces is included in this volume. The NLO polymers are instrumental in the development of electrooptical waveguide devices, the most fundamental of which is the modulator. The most common modulator design is the Mach Zehnder interferometer, in which the input light is split into two legs and then recombined into a common output within the two dimensional waveguide. A π phase retardation, resulting in total light extinction at the output of the interferometer, can be achieved by changing the refractive index of one leg with respect to the other using the electrooptic effect. For best device performance, it is essential that the NLO polymer exhibit minimal surface roughness in order to reduce light scattering. Scanning tunneling microscopy, with its high lateral and vertical resolution, is capable of quantifying the NLO polymer surface roughness induced by processing. Results are presented below in which STM was used to measure the surface roughness of films produced by spin-coating NLO-active polymers onto silicon substrates.

Synthesis, performance and growth mechanism of silver nanoparticle coated SERS fiber probe

2019 ◽  
Vol 107 (3) ◽  
pp. 305
Author(s):  
Mengmei Geng ◽  
Yuting Long ◽  
Tongqing Liu ◽  
Zijuan Du ◽  
Hong Li ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Reaction Time ◽  
Growth Mechanism ◽  
Fiber Optic ◽  
Fiber Optic Probe ◽  
Visible Absorption ◽  
Fiber Probe ◽  
Surface Enhanced Raman ◽  
Optic Probe

Surface-enhanced Raman Scattering (SERS) fiber probe provides abundant interaction area between light and materials, permits detection within limited space and is especially useful for remote or in situ detection. A silver decorated SERS fiber optic probe was prepared by hydrothermal method. This method manages to accomplish the growth of silver nanoparticles and its adherence on fiber optic tip within one step, simplifying the synthetic procedure. The effects of reaction time on phase composition, surface plasmon resonance property and morphology were investigated by X-ray diffraction analysis (XRD), ultraviolet-visible absorption spectrum (UV-VIS absorption spectrum) and scanning electron microscope (SEM). The results showed that when reaction time is prolonged from 4–8 hours at 180 °C, crystals size and size distribution of silver nanoparticles increase. Furthermore, the morphology, crystal size and distribution density of silver nanoparticles evolve along with reaction time. A growth mechanism based on two factors, equilibrium between nucleation and growth, and the existence of PVP, is hypothesized. The SERS fiber probe can detect rhodamin 6G (R6G) at the concentration of 10−6 M. This SERS fiber probe exhibits promising potential in organic dye and pesticide residue detection.

Increasing the information capacity of a fiber-optic multi-sensor converter of binary mechanical signals into electrical signals

2020 ◽  
pp. 15-23
Author(s):  
V. M. Grechishnikov ◽  
E. G. Komarov
Keyword(s):  
Fiber Optic ◽  
Information Capacity ◽  
Parallel Structure ◽  
Optical Scheme ◽  
Digital To Analog Converter ◽  
Electrical Signals ◽  
Mechanical Signals ◽  
Analog Converter ◽  
Output Code ◽  
Digital To Analog

The design and operation principle of a multi-sensor Converter of binary mechanical signals into electrical signals based on a partitioned fiber-optic digital-to-analog Converter with a parallel structure is considered. The digital-to-analog Converter is made from a set of simple and technological (three to five digit) fiber-optic digital-to-analog sections. The advantages of the optical scheme of the proposed. Converter in terms of metrological and energy characteristics in comparison with single multi-bit converters are justified. It is shown that by increasing the number of digital-analog sections, it is possible to repeatedly increase the information capacity of a multi-sensor Converter without tightening the requirements for its manufacturing technology and element base. A mathematical model of the proposed Converter is developed that reflects the features of its operation in the mode of sequential time conversion of the input code vectors of individual fiber-optic sections into electrical analogues and the formation of the resulting output code vector.

Hydrostatic Fiber Optic Liquid Level Sensor with position sensitive detector

Metrologiya ◽  
2020 ◽  
pp. 38-51
Author(s):  
V. N. Astapov ◽  
I. N. Kozlova
Keyword(s):  
Fiber Optic ◽  
Effective Area ◽  
Raw Material ◽  
Position Sensitive Detector ◽  
Fiber Optic Sensor ◽  
Liquid Level ◽  
Problem Solution ◽  
Sensitive Detector ◽  
Position Sensitive ◽  
Triangulation Sensor

This article presents the rationale and methodology for developing an intrinsically safe device, namely, a hydrostatic fiber optic sensor with a position-sensitive detector for monitoring the level of oil products in large-capacity tanks at oil depots and during pumping in a raw material warehouses. This device suitable for continuous monitoring of the liquid level, based on the measurement of a hydrostatic column of liquid with automatic offset of changes in the density of the liquid. Offset is carried out by means of a displacer (a fully submerged float), inside which a housing with a position-sensitive detector (PSD) is integrated. Theoretical validation of the bellows suspension usage for a displacer is given. During filling a container with a liquid whose level is measured, liquid bellows, the movement of which is recorded by an optical triangulation sensor using the reflected infrared ray incident on the bottom of the bellows. The principle of the triangulation sensor operation is based on the geometric properties of the triangles. The pulses of infrared radiation come through a fiber optic cable. In order to measure the movement of the surface (the bottom of the bellows) by measuring the movement of the reflected beam, a position-sensitive detector is used, which is located in a remote controller. In this device for the intrinsic safety problem solution, optical inputs of a fiber optic flat cable are located in the active zone of the sensor, which is connected to the optical inputs of a position-sensitive detector, operated on the principles of photoelectric effect. The light spot moving along the sensitive zone and converted by the detector into a one-dimensional signal proportional to the distance to the object. hydrostatically applies pressure over the entire effective area of the measuring

High-voltage monitoring by the fiber-optic recirculating measuring system

2020 ◽  
pp. 38-44
Author(s):  
A. V. Polyakov ◽  
M. A. Ksenofontov
Keyword(s):  
Optical Fibers ◽  
High Voltage ◽  
Optical Sensors ◽  
Electromagnetic Interference ◽  
Fiber Optic ◽  
Electric Power Industry ◽  
Measuring System ◽  
Voltage Range ◽  
External Electromagnetic Fields ◽  
Optic Communication

Optical technologies for measuring electrical quantities attract great attention due to their unique properties and significant advantages over other technologies used in high-voltage electric power industry: the use of optical fibers ensures high stability of measuring equipment to electromagnetic interference and galvanic isolation of high-voltage sensors; external electromagnetic fields do not influence the data transmitted from optical sensors via fiber-optic communication lines; problems associated with ground loops are eliminated, there are no side electromagnetic radiation and crosstalk between the channels. The structure and operation principle of a quasi-distributed fiber-optic high-voltage monitoring system is presented. The sensitive element is a combination of a piezo-ceramic tube with an optical fiber wound around it. The device uses reverse transverse piezoelectric effect. The measurement principle is based on recording the change in the recirculation frequency under the applied voltage influence. When the measuring sections are arranged in ascending order of the measured effective voltages relative to the receiving-transmitting unit, a relative resolution of 0,3–0,45 % is achieved for the PZT-5H and 0,8–1,2 % for the PZT-4 in the voltage range 20–150 kV.

Sign in / Sign up

Export Citation Format

Share Document