1. Hollography 2. The Michealson Interferometer 3. The Fabre Porte interferometer

1. Holography
Muqadass Tahir (L1F20BSPH0033)

2. By Definition: • Optical holography is a technique
which enables an optical
wavefront to be recorded and
later re-constructed. Holography
is best known as a method of
generating three-dimensional
images but it also has a wide
range of other applications.

4. Principles of holography (recording):
• Holography recording leverages the
characteristics of light interference. The source
light (i.e., a laser beam) is divided by a half-
mirror beam splitter into that illuminating the
target object and that irradiating the recording
medium.
• Here, the light reflected by the object toward
the recording medium is called object light,
while that irradiating the recording medium is
called reference light. At this time, both types of
light interfere with each other on the plane of
the recording medium and produce fine patterns
called interference fringes. The media where
these fringes are recorded are called holograms.

5. Principles of holography
(reconstruction):
• Holography reconstruction leverages the
characteristics of light diffraction. A light source is
placed in the same location as the reference beam
during recording, and the hologram is irradiated with
reproduction illumination light.
• At this time, part of the light passes through the
hologram, whose fine interference fringes cause partial
scattering in different directions. This diffracted light has
the same wavefront as that of the recorded object light,
allowing the observer to see the recorded object behind
the hologram even though it is not physically present. As
the light is the same as that reflected by the object, it
satisfies the physiological conditions necessary for
human vision, enabling people to view it easily.

6. Salvador Dali
was one of the
first to use
holography as
art.

7. Applications:
• One of the most common applications of holography is art. Three-dimensional
holograms allow artists to capture interesting objects and scenes which can be viewed
from many angles.
• The famous surrealist artist Salvador Dali was one of the first to employ this as art in
1972. A wide variety of holographic artwork can be explored at a number of museums
and other locations throughout the world.

8. • Holographic Projections, otherwise known as
Holograms, have been around for decades and have
mostly been associated with futuristic fantasy worlds.
As technology progresses, holograms are becoming an
increasingly common sight, especially in the
entertainment industry. Case in point, you’ve probably
heard or even seen the Tupac hologram performance
at the 2012 Coachella Music Festival – a performance
that’s still talked about to this very day. While 3D
technology has come a long way since that iconic
performance 8 years ago, holographic projection still
faces considerable barriers to achieve the level of
realism shown in films and TV shows. Nevertheless,
groundbreaking progress has been made, and we’ll be
covering that later.

9. Ford looks to
put holograms
on top of cars
• Ford has been pursuing holographic
technology in its cars for a while; it explored
Microsoft’s HoloLens headset as a way to
blueprint cars from the perspective of the
average driver.
• Ford designers and engineers would utilize the
mixed reality device to interact with digital
designs, making mere concepts as close to
tactile as possible, long before a single
assembly line is fired up. With its patent
application, Ford looks to put holography in
the hands of customers, and it already has
competitors right out the gate, with Mercedes-
Benz and BMW also working to supplement
their cars with holographic technology.

11. Uses of Holography:
• There are a number of proven application of holography.
• It includes information storage
• capturing of images in depth
• the use of holograms as optical components.
• In addition we observed other applications such as
performing accurate interferometric measurements on
three-dimensional artifacts of any shape. Most recently
there are other improvement in the area of surface
finishing which has multiple application in various
industries, including mode, entertainment and more. It is a
highly efficient tool for visualizing extremely precise
measurements.

12. IN FUTURE:
• Research into new applications of holography is ongoing.
• Many scientists believe that holograms can be used to create realistic moving
projections of people and objects.
• In the future, data that previously required 100 DVD disks can be contained in a
single flat hologram.
• The development of optical computing may lead to even more uses, and
dramatically increase the processing speed and storage capacity of computers.

13. The Michaelson Interferometer
Abdulhannan Mirza (L1F20BSPH0016)
Muhammad Uzair (L1F20BSPH0018)

14. Introduction
• Michelson used his interferometer to measure the length of the
international standard meter in terms of wavelengths of cadmium light,
and in 1920 he was the first to measure the angular diameter of a distant
star, also using an interferometer.
• Optical interferometry is a technique where two or more light waves are
combined to produce an interference pattern.This interference pattern can
be measured to extract information on the light.

16. Principle
• In this instrument, light from an extended source is divided into two parts by
partial reflection and transmission.These two beams are sent at right angles
to each other in the two directions.They get reflected from the mirror and
form interference fringes which are observed and investigated

17. Construction
• It consists of a semi silver plate P placed at an angle of 45 degrees to the
horizontal.
• M1 and M2 are two highly polished silver mirrors.These Mirrors are
provided with a labeling screw at the back.
• Mirror M1 can be moved towards or away from plate BS with the help of
micrometer screws. CP is another glass plate whose thickness is exactly
equal to the thickness of plate BS.
• It is transparent and parallel to P. S is a monochromatic source of light, say
sodium lamp.

18. Working
• Light from an extended monochromatic source S rendered parallel by the
lens L is made to fall on semi-silvered plate P.
• As these two waves entering the telescope are derived from the same
source S, hence these waves are coherent waves.
• Which does not get any difficulty if we are using monochromatic light but if
white light is used.

20. • To overcome this difficulty another plate P1 is introduced between P and
mirror M2.This plate P1 is called a compensating plate.
• The function of the compensating plate is that the Ray of light traveling
towards M1 and M2 must travel equally pass through the glass plate.
• The phase changes on reflection at mirror M1 and M2 are smaller, the
phase changes due to reflection in air and class are also similar, is equal
to π.
• The path difference between the two rays reaching the telescope is me.
Where M is the integer and λ is the wavelength of light used.

21. Formation of fringes
• When mirror M2 and M1 are exactly perpendicular to each other, then circular fringes are formed.
The path difference between light waves is:
Δ = 2d Cos θ
When one light wave is reflected from the denser medium to rarer medium, an additional path
difference of λ/2 will be produced so the path difference is:
Δ = 2d Cos θ + λ/2
For Maxima
2d Cos θ + λ/2
2d Cos θ = (2n – 1) λ/2
For Minima
2d Cos θ + λ/2 = (2n – 1) λ/2

22. •Since we know the condition of dark fringe at the center is:
2d Cos θ = nλ
For central fringe (θ = 0)
2d = nλ
λ = 2d/n

23. Types of fringes
• Circular Fringes
• Localized Fringes
• White Light Fringes

24. Applications
• Wavelength of monochromatic light.
• The refractive index of a thin film.
• Resolution of spectral lines.
• The evolution of meters in terms of the wavelength of light.
• The angular diameter of stars.
• Presence of ether.
• The accuracy of the surface of the prism and lens

25. Fabry-Pérot
interferometer
Muhammad Ahmad (L1F20BSPH0040)

26. Principle
• R1 and R2 are aligned parallel.
• Distance between mirrors is d.
• Laser of wavelength λ at an
incident angle θ.

27. Construction
• Optical Rail (1 meter)
• Fabry-Perot setup (Fixed
Mirror mount with Two
Etalon)
• Movable Mirror
• Diode Laser mount with
Kinematic (5 V) Power
Supply
• Achromatic Lens mount

29. • The phase difference is given by:
𝛿 = ( 2π /λ ) ∆
• Thus, the resultant transmitted light intensity IT
where, I0 is the incident intensity, R is the reflectivity of the mirrors. It can be noticed
that IT varies with 𝛿

30. Measurement of λ
• Initial separation between the mirrors is d1
If one counts the number of fringes (say maxima) appearing or
disappearing at the center (θ ≈0) by varying the distance between the
mirrors to d2, then λ can be determined as follows:
2d1 =m1 λ
2d2=m2 λ
m2 − m1 = Number of
maxima counted

31. Applications
• A Fabry–Pérot etalon can be used to make a spectrometer capable of
observing the Zeeman effect, where the spectral lines are far too close
together to distinguish with a normal spectrometer.
• In astronomy an etalon is used to select a single atomic transition for
imaging.
• In gravitational wave detection, a Fabry–Pérot cavity is used
to store photons for almost a millisecond while they bounce up and down
between the mirrors.

32. Shukriya