Holography is a technique that uses the properties of light interference and diffraction to record three-dimensional information of an object. The document discusses the history and principles of holography, how holograms are constructed and reconstructed, different types of holograms and their applications in microscopy, interferometry and more. Holography allows the recording and reconstruction of three-dimensional images from a two-dimensional surface, providing depth perception and parallax.

1. HOLOGRAPHYFROM : MUKUL TRIPATHI B.TECH FINAL YEAR (ECE) 06ESBEC049

2. indexHistory of holographyConventional photographyHolographic photographyPrinciples of holographyHologramHologram constructionHologram reconstructionTypes of hologramApplication of hologramConclusionreferences

3. History of Holography Invented in 1948 by Dennis Gabor for use in electron microscopy, before the invention of the lASERLeith and Upatnieks (1962) applied laser light to holography and introduced an important off-axis technique

4. Conventional photography2-d version of a 3-d scene

5. Photograph lacks depth perception or parallax

6. Film sensitive only to radiant energy

7. Phase relation (i.e. interference) are lost Holographic photography Freezes the intricate wavefront of light that carries all the visual information of the scene

8. To view a hologram, the wavefront is reconstructed

9. View what we would have seen if present at the original scene through the window defined by the hologram

10. Provides depth perception and parallax Principle of holographyFundamental technology1 : Diffraction grating – bends light 2 : Can be superposed 3 : Effect (bending) persists superposition 4 : Hologram  super complex diffraction grating

11. HologramConverts phase information into amplitude information (in-phase - maximum amplitude, out-of-phase – minimum amplitude)

12. Interfere wavefront of light from a scene with a reference wave

13. The hologram is a complex interference pattern of microscopically spaced fringes

14. “holos” – Greek for whole message

15. Hologram constructionWhen developed the photographic plate will have a transmittance which depends on the intensity distribution in the recorded plate tb – backgrond transmittance due to |R|2 term B – parameter which is a function of the recording an developing process

16. Hologram reconstructionDirect wave – identical to reference wave (propagates along z) except for an overall change in amplitude Object wave – Spherical wave except for a change in intensity B|r|2 i.e. reconstructed wavefront Conjugate wave – spherical wave collapsing to a point at a distance z to the right of the hologram 1 : a real image 2 : displaced by a phase angle 2kz

17. Types of hologramTransmission hologramReflection hologramHolographic StereogramsRainbow hologramColour hologramsLens hologramFourier hologram

18. Transmission hologramreference and object waves traverse the film from the same side

19. Reflection hologramreference and object waves traverse the emulsion from opposite sides

20. Holographic StereogramsRecording of multiple views through slit

21. Reconstruction: only single focus depth Rainbow hologram2 Stages of recording 1 : Record regular hologram 2 : Record rainbow hologram through slit Visible on white light: multiple color images Colour hologramCommon hologram: rainbow due to diffraction

22. 3 holograms + 3 wavelengths: larger gamut

23. Achromatic holograms: holographic stereograms1 : Overlapping/coplanar colors

24. Lens hologramDifferent optical material: slowdown/diffraction of waves

25. Use of thin lens: assumption on lack of diffraction

26. Back focal plane = F{front focal plane} Fourier hologramRecording through lens

27. F{planar image} + F{point source}

28. Reconstruction through lens

29. Both virtual & real image in focus Applications of hologramMicroscopy M = r/sIncrease magnification by viewing hologram with longer wavelength Produce hologram with x-ray laser, when viewed with visible light M ~ 1063-d images of microscopic objects – DNA, viruses InterferometrySmall changes in OPL can be measured by viewing the direct image of the object and the holographic image (interference pattern produce finges  Δl) E.g. stress points, wings of fruit fly in motion, compression waves around a speeding bullet, convection currents around a hot filament

30. conclusionHolography is the only visual recording and playback process that can record our three-dimensional world on a two-dimensional recording medium and playback the original object or scene to the unaided eyes as a three dimensional image. The image demonstrates complete parallax and depth-of-field and floats in space either behind, in front of, or straddling the recording medium.

31. referencesBOOKS REFERED 1 : Barrekette’s application of holography 2 : Ostrovsky’s holographyNoble lecture by DENIS GABOR on his holographic modulewww.google.com

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