Introduction to Fibre Optics
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Introduction to Fibre Optics

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Questions and Answers

What is the main limitation of traditional photography that holography overcomes?

  • The loss of phase information of light. (correct)
  • The requirement of natural light for recording.
  • The inability to capture colors accurately.
  • The limited depth of field in images.

    • Who developed the concept of holography and received a Nobel Prize for it?

  • Dennis Gabor (correct)
  • Albert Einstein
  • Max Planck
  • Nikola Tesla

    • What does the term 'Holos' in Greek refer to in the context of holography?

  • Light beam
  • Record
  • Whole (correct)
  • Image

    • What is the role of the reference wave in the construction of a hologram?

    <p>It interferes with the object wave to create an interference pattern.</p> Signup and view all the answers

    What type of recording does a hologram represent?

    <p>A three-dimensional representation encoded in two dimensions.</p> Signup and view all the answers

    What characterizes the core of a graded-index optical fibre?

    <p>It has a non-uniform refractive index that gradually decreases from the center.</p> Signup and view all the answers

    How is the attenuation of an optical signal quantitatively represented?

    <p>$α = rac{10 log rac{P_i}{P_0}}{L}$</p> Signup and view all the answers

    What is the main consequence of dispersion in optical fibres?

    <p>It broadens the pulse during propagation.</p> Signup and view all the answers

    Which of the following is NOT an application of optical fibres?

    <p>Space Exploration</p> Signup and view all the answers

    What aspect of light is lost in conventional photography?

    <p>Relative phases of the light waves.</p> Signup and view all the answers

    Which of the following best describes optical communication?

    <p>It uses light waves to convey information.</p> Signup and view all the answers

    What is the primary purpose of the cladding in an optical fibre?

    <p>To maintain a constant refractive index.</p> Signup and view all the answers

    In holography, what type of recording is typically lost in conventional photography?

    <p>Three-dimensional perspective.</p> Signup and view all the answers

    What is the primary function of the cladding in an optical fibre?

    <p>To keep the light waves within the core</p> Signup and view all the answers

    Which of the following is NOT a characteristic of optical fibres?

    <p>They are rigid and difficult to manipulate.</p> Signup and view all the answers

    What is the main advantage of using optical fibres for transmitting information?

    <p>They are less susceptible to environmental factors than light beams in open air.</p> Signup and view all the answers

    How is the numerical aperture (NA) of a fibre useful in comparison to the acceptance angle?

    <p>It simplifies analysis by combining multiple parameters.</p> Signup and view all the answers

    In a step-index optical fibre, what characteristics are associated with the core and cladding?

    <p>Both the core and cladding have constant refractive indices.</p> Signup and view all the answers

    What material compositions are typically used in the core of optical fibres?

    <p>Glass or plastic</p> Signup and view all the answers

    Which of the following correctly describes the function of the protective jacket in an optical fibre?

    <p>To provide protection against physical damage</p> Signup and view all the answers

    What are the diameter ranges typically found in optical fibre cores?

    <p>5 µm to 100 µm</p> Signup and view all the answers

    Study Notes

    Introduction to Fibre Optics

    • Optical fibre used for light wave propagation due to its high transmittance and lack of interference from natural elements
    • Optical fibre is a thin, flexible transparent glass or plastic filament
    • Light is transmitted through multiple total internal refections
    • Optical fibre consists of a core, cladding, and a protective jacket
    • The core, which transmits light, has a higher refractive index than the cladding
    • The cladding prevents light from escaping the core by total internal reflection
    • The jacket protects the fibre from external damage
    • Typical core diameter ranges from 5µm to 100µm while the cladding diameter is approximately 125µm

    Numerical Aperture

    • Used to describe the acceptance angle and refractive indices of the core and cladding

    Step-Index Optical Fibre (SI Fibre)

    • Core has a homogenous, constant refractive index
    • Cladding also has a constant, but lower, refractive index

    Graded-Index Optical Fibre (GRIN Fibre)

    • Core has a non-uniform refractive index gradually decreasing from the centre to the edge
    • Cladding has constant refractive index

    Attenuation in Optical Fibre

    • Reduction in signal strength during light propagation due to losses in the fibre
    • Fibre attenuation (ααα) is calculated using the formula: α=10logPiP0Lα = \frac{10 log \frac{P_i}{P_0}}{L}α=L10logP0​Pi​​​
    • PiP_iPi​ is input optical power, P0P_0P0​ is output optical power, and LLL is the length of the fibre (km)

    Dispersion in Optical Fibres

    • Broadening of light pulses during propagation
    • Causes distortion in signal due to different wavelengths travelling at different speeds through the fibre

    Optical Communications

    • Transferring information using light waves
    • High information-carrying capacity makes it a unique communication system

    Applications of Optical Fibres

    • Optical Communication: high-speed data transmission over long distances
    • Medical Applications: endoscopy and fibre optic surgery for internal visualisation
    • Military Applications: covert communication and data transfer
    • Entertainment/Television Applications: cable television and high-speed internet services
    • Industrial Applications: remote sensing and control, process monitoring
    • Computer Networking: backbone networks and high-speed internet connections

    Introduction to Holography

    • Photograph is a two-dimensional representation of a three-dimensional scene
    • Conventional photography records only the intensity of light, losing phase information
    • This results in a loss of depth perception and parallax information

    Basic Principle of Holography

    • Records the complete wave field, including both intensity and phase of the light scattered by the object
    • Developed by Dennis Gabor (Nobel Prize in 1971)
    • Converts phase information into intensity variations using coherent illumination
    • Produces a three-dimensional image from a two-dimensional recording

    Construction and Reconstruction of Image on Hologram

    • The holographic recording process involves the interference of the object wave (scattered light) and a reference wave (plane wave)
    • This interference pattern is recorded on a photographic plate, creating a hologram
    • The hologram contains information on both the phase and amplitude of the object wave
    • Unlike a photograph, a hologram does not resemble the object and contains coded information

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    Related Documents

    Fibre Optics PDF - A Textbook of Applied Physics

    Description

    Explore the fundamentals of fibre optics, including how optical fibres transmit light through multiple total internal reflections. Learn about the components of optical fiber, such as the core, cladding, and protective jacket, alongside the concepts of numerical aperture and different types of optical fibres like step-index and graded-index.

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