Basic Concepts of Holography and Holograms
Images formed by a hologram are heuristically very fascinating and
appealing. This is due in part to the ability to record the full spatial content
of a scene and to retain the parallax of the objects. Parts of an image are
visible from one perspective in viewing the hologram but not from another
Holography is the process of recording and reconstructing a three
dimensional image. The ability to record the full spatial information about
an object has many advantages for applications requiring image analysis or
interpretation. Dennis Gabor invented the concept of holography (whole
image) in 1947 when attempting to form electron microscope images
without using a lens.
A hologram is a physical component or device that stores information about
the holographic image. For example a hologram can be a grating recorded on
a piece of film.
It is especially useful to be able to record a full image of an object in a short
exposure if the object or space changes in time.
Another advantage of holography is the ability to multiplex several images
or images of information in the same holographic storage element.
Difference Between Holographic Imaging and Imaging with a Lens
A Refractive or Reflective imaging system converts a single object point to a
single image point. (Conjugate imaging relation)
A Hologram on the other hand can convert a single source point (or many
object points of arbitrary configuration) to an entire image distribution.
Concepts of Imaging
• Conventional Photography – A record of the intensity pattern of a
scene is made. ( ,
I x y
• Relative Phase Information is Lost – This is equivalent to loosing
information on optical path length differences from different parts of
• Holography – Records information on the complete wave front: Both
amplitude and phase.
• Problem – Recording materials only respond to the intensity