An optical fiber trap operates by radiation pressure and transverse force gradient while conventional optical trap operates on longitudinal gradient to trap particles. This subtle difference translates into easy setup and many advantages over conventional single-beam optical tweezers. In this work, we present a brief review of the current situation of fiber optic trap and their applications. Subsequently, we discuss the effect of radiation pressure on micro-organic and inorganic particles. Using a single optical fiber, radiation pressure transfers movement to the micro-particles, so velocity and acceleration are quantified. After that, micro particles are trapped, but now using two optical fibers. Finally, we discuss the results and problems involved with this research.
A comparative analysis of ultraviolet light absorption is presented for distinct photosensitive optical fibers. Fibers are
irradiated by ultraviolet light, coming from a pulsed Nd:YAG Laser (90 mJ, 5-7 ns) at 266 nm. Absorption is analyzed
from ultraviolet to infrared region and it is compared for different photosensitive optical fibers. The final goal of this
work is to identify absorption spectral regions, which would be useful in order to improve fiber grating printing.
Bearings are elements of rotating machinery that are widely used as low friction joint elements between other machine
elements. Like any other machine element they posses a finite life which is dependent on a number of factors, among
them manufacture, assembling, maintenances, load, etc. Bearing failures are amongst the principal causes of machinery
overhaul. They by themselves are a source of vibration which is a function of surface conditions, clearances,
misalignment, etc. Each of these defects present a specific dynamic signature, and can be analyzed by a number of
techniques already in used, among them the laser vibrometry. This is a non-contact, non-disturbing method commonly
used for measurements of vibrations on static objects. The technique offers the possibility to measure vibrations on thin-walled
(light), and rotating objects as well as sound fields. Common vibration signal analysis in rotating machinery are
restricted to low frequencies, up to 3000 Hz, and in some cases when analyzing contact problems and fatigue at 7000 up
to 15000 Hz. In this work, are presented the primary results to employ laser interferometry to study the dynamic signals
generated by rolling bearings, and the feasibility to employ it to study high frequency problems of these machine elements.
A multipoint fiber laser sensor, which consists of two cavities coupled based in three Bragg gratings of fiber optics and interrogated by the longitudinal mode beating frequency is presented. We used one Bragg grating (reference) and two Bragg gratings (sensors), which have the lowest reflection wavelength. The reference grating with the two sensors grating make two cavities: first one is the internal cavity which has 4230 m of length and the next one is the external cavity which has 4277 m of length. Measuring the laser beating frequency with a radio frequency (rf) analyzer for a resonance cavity and moving the frequency peaks when the another cavity are put in resonance, we prove that the arrangement can be used as a two points sensor for determining the difference of temperature or stress between these two points. On the other hand, one principal peak and three harmonics with bandwidths of 52 Hz were obtained with the rf analyzer. Their bandwidth was controlled by an intra-caivty fiber Optical Delay Line (ODL) and was measured with the rf analyzer.
We investigate longitudinal mode beating frequency at the output of a linear Er-Doped fiber laser formed by a reference Bragg grating at one side of cavity and several Bragg gratings at another side when one of them is pulled. We detect the distance between the pulled and reference gratings by mode beating frequency measurements. (Summary only available)
In this paper a new quasi-distributed sensor suitable for multi-point detection and localizing of alarm conditions along large structures is presented. The sensor is based on a serial array of equal low-reflective fiber Bragg gratings. The sensor interrogation employs measurement of light intensity at a fixed reference wavelength. Difference between the reference wavelength and the Bragg wavelength in normal conditions set a threshold level for detection. Method was tested experimentally in two different configurations. A simple design of the sensor in combination with the economical interrogation technique makes this sensor interesting for real applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.