1 SLIDE MATTER

A fiber optic sensor is a sensor that uses optical fiber either as the sensing element ("intrinsic

sensors"), or as a means of relaying signals from a remote sensor to the electronics that process the

signals ("extrinsic sensors"). Fibers have many uses in remote sensing.

Recently, fibre optical sensors (FOS) have gained increased popularity and market acceptance. In

comparison to conventional sensors they offer a number of distinct advantages which makes them

unique for certain types of applications, mainly where conventional sensors are difficult or impossible

to deploy or can not provide the same wealth of information.

Having many advantages made this to develop into its own branch of science

4 SLIDE:

These were first developed in mid 1960’s. to be exact the date on which it is patented is June

27,1967. It was based on bifurcated fiber bundles with half the bundle used to illuminate a surface

and the reflection from this surface received by the other half of the bundle. After calibration it gave

very precise values. After a decade the first single mode optical fibers were appeared. From then on

rapid development and research is going on to develop more advanced techniques in building these

optical sensors.

5 SLIDE:

The properties or physical quantities that can be used to measure using optical sensor are:

Read out some list and say this is only small list only. Reaasearch is going on to develop more

applications

6 SLIDE

WORKING PRICIPLE: Light is taken to a modulation region using an optical fiber and modulated

therein by a physical, chemical, or biological phenomena, and the modulated light is transmitted

back to a receiver, detected, and demodulated. Hopefully, there is a one-to-one correlation between

the phenomenon of interest and the demodulated signal.

modulation is the process of varying one or more properties of a periodic waveform, called the carrier

signal(high frequency signal), with a modulating signal that typically contains information to be

transmitted.

7 & 8 SLIDE

Here we can classify into two types the optical sensors:

Fiber optic sensors (FOS) can be generally

classified in two large groups:

1) extrinsic FOS

2) intrinsic FOS

Extrinsic FOS are basically optical sensor where we deliver (and collect) light signal by optical fiber,

while the modulation of the light signal occurs outside optical fiber. To date, those sensors present

most successfully commercial FOS. Typical examples are fiberized versions of Dopler anemometers

and non-contact vibration measurements systems. These sensors tend to be rather expensive and

are used in industries such as aerospace and automotive. Their major advantage is that the flexible

and dielectric link provided by the fiber allows the instruments to be used where access is difficult or

prohibitiveby means of electrical signals. Intrinsic FOS are “true” fiber optic sensors, meaning that

the modulation of light takes place inside fiber in accordance to measured parameter

9 slide

Comparisions just read out some

10 slide

Now the question is What characteristics propelled the immense applications of these sensors?

It is immune to electromagnetic interference

Fiber optic sensors are also immune to electromagnetic interference, and do not conduct electricity so

they can be used in places where there is high voltage electricity or inflammable material such as jet

fuel. Fiber optic sensors can be designed to withstand high temperatures as well.

No need of power supply to run it

Its hair thin and can be compact.

multiplexing (sometimes contracted to muxing) is a method by which multiple analog message

signals or digital data streams are combined into one signal over a shared medium. The aim is to

share an expensive resource. For example, in telecommunications, several telephone calls may be

carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in

communications.

Wide dynamic range: covers a large pectrum of frequencies

11 slide

It is used in night vision camera where by using optical sensors the advantages it got over

conventional cameras are:

Exceptional daylight resolution, high contrast levels no haloing or scintillations( the white smudgy

colors on photo)

Continue with 12 SLIDE READ FROM SLIDE.

THERE ARE IMMENSE APPLICATIONS ITS IMPOSSIBLE TO MENTION ALL OF THEM HERE!

13 SLIDE

THIS SHOWS THE TREND IN RESEARCH AND DEVELOPMENT AND THEIR PATENTS OVER THE YEARS.

14 SLIDE

THIS SHOWS THE GEOGRAPHICAL DISTRIBUTION OF DEVELOPMENT CONCENTRATED.As we can see

mostly from US and UK are the two countries in this list. India being in the other countries bar.

15 slide

This shows the distribuion of optical sensors developed based on its application over the years.

Read out the conclusions.

References:

http://qxwave.com/downloads/fsrEVIEW.pdf

http://en.wikipedia.org/wiki/Multiplexing

http://en.wikipedia.org/wiki/Fiber_optic_sensor

http://www.sensorland.com/HowPage072.html

http://lpa.feri.uni-mb.si/Summer_School/p8_donlagic.pdf

http://wr.lib.tsinghua.edu.cn/sites/default/files/1066744871461.pdf