Introduction
The fiber optic systems are systems which use light as a mode of communication. The system includes fiber cables which allow for the transmission of light through them. Inside the cable are special coatings for protection and also to enable the transmission of light through total internal reflection (Hoss and Lacy). The light is then converted into electrical signals through the use of light detectors having in mind that the signal was produced by a light emitting diode. The use of optics is very wide since the use of light is much more efficient and also flexible being that light can be diffracted reflected and refracted using very basing concepts to achieve very versatile functionalities. The uses of the fiber optic include data transmission, for medical analysis and also sensors in industries.
Apparatus
1. Trainer board
2. Fiber optics of various lengths
3. Function generator and LED circuit
4. Radio
5. Wood, board, and tape
6. Reflective material
7. Paper
8. AC voltmeter
9. Cables
Procedure
Procedure A
We chose a flat level location of approximately 60 x 90 each separated by 2.5 meters. Then the brown banana plug was inserted into the brown jack then the fiber optic photo detector and the receiver gain turn clockwise.
Two-pronged ends were then inserted into the female end of the 25-foot extension code, then the free end of the optical fiber was held at about 15 cm away from the fluorescent light.
The fiber was then moved closer and then away from the fluorescent light.
Then using an incandescent lamp, the procedure above was repeated at about 10 cm away.
Procedure B
One end of the orange – yellow test lead was inserted into the jack of the momentary switch and the other end into the yellow jack of the signal generator; then its knob turned fully counterclockwise
Then the knob was slowly turned clockwise as the reference LED was being watched. This process was stopped at the point where the LED stopped blinking.
All the previously plugs were disconnected then; the AC power adaptor was reconnected to the lab module and the yellow LED above it lit up. The speaker then hums at a low frequency.
On turning the frequency knob clockwise from the left, the noise from the speaker slowly dies out.
Procedure c
The power cable was unplugged from the Lab module. Then the banana plug was now inserted into the orange transmitter jack. After which the cinch nut of the optic LED was loosened till the fiber tip touched the interior wall then the cinch was tightened again.
The signal generator was then turned to 3 o’clock position and the receiver gain knob turned to high.
Both the free ends of the fiber optics were taped on top of two level books then the AC power was reconnected to the module and the yellow LED light up.
Results
Part A results
We found that the sound intensity is proportional to the receiver gain and also that the sound intensity is commensurate with the radio volume. Additionally, the maxing out radio Volume distorts voices/audio and that the fiber optic cable tip at receiver is illuminated visibly carrying sound. The sound quality and was modulated by the audio signal.
Part B results
The distance of the fiber optic from the incandescent light was found to be inversely proportional to the intensity of the hum of the speaker.
Answering question 9;
When one moves closer to the incandescent bulb, the audible hum increases in volume.
Question 10;
It was surprising hear sounds from the speaker when the optical fiber was pointed towards it since there was no audible sound produced before we used the optic fiber.
Question 11;
Describing the sounds made by the speaker, we would say that there was a constant humming sound when the fiber was pointed to the speaker
Question 12;
Defining the amplitude and frequency of the sounds from the speaker as we moved the fiber to the various points as displayed on the television screen and comparing the differences between the sounds we heard on the television and computer screens. It is correct to state that the closer the fiber tip is to the images on the screen, the louder the speaker gets, and consequently the amplitude also increases. Then using an oscilloscope screen with a repeated pulse running across it a repeated pulse of sound was audible through the speaker. Also, constant images on the screen produced a constant hum or buzz.
Comparing to computer screens, the oscilloscope screen has got lower amplitude but a higher frequency.
Question 13;
The sound is audible at a constant frequency. The addition of a page between the fiber and light resulted in a reduction of amplitude/volume. We could no longer hear anything from the speaker.
The effect of changing the time scale on the oscilloscope trace was that the frequency of the sound from the speaker also changed. The frequency of the pulse is proportional to the frequency of the sound.
Question 14:
The LED blinks at 30 Hz where we could barely see if it is on or off.
Question 15:
Yes, we could still hear the digital output through the speaker even though we couldn’t see the LED blinking. This tells us that the frequency response of our ears is better than that of our eyes.
Question 16:
When the object is placed between the transmitter and receiver no sound is transmitted.
Question 17:
Existing light in the room does not affect the sensing of an object moving between the two fibers.
Question 18:
The presence of plastic cannot be detected as it was with paper.
Question 19:
The presence of black paper is detectable
Question 21:
This sensor can be used in a manufacturing company because the interruptions in the signal could be counted and translated into the number of objects which have passed.
Question 22:
Rather than facing each other as they are in Fig. 12, the fiber tips are confronting the same direction in Fig. 13 but angled together. With Fig. 12 the volume decreases with an object placed, whereas for Fig 13. The volume increases with an object placed. They are opposite.
Conclusion
Reference
"Communication Networks Products | Fiber And Wireless Cable Systems | Corning". Corning.com. N.p., 2016. Web. 4 Apr. 2016.
Eastorn, Rogers. "Physical Optics". N.p., 2016. Web. 4 Apr. 2016.
Hoss, Robert J, and Edward A Lacy. Fiber Optics. Englewood Cliffs, N.J.: P T R Prentice-Hall, 1993. Print.
