PHOTOGRAPHY AND HOLOGRAPHY

Another important question that comes to the mind is what is the difference between Holography and photography?

A photograph has an actual physical image; a hologram contains information about the size, shape, brightness and contrast of the object being recorded. This information is stored in a very microscopic and complex pattern of interference. The interference pattern is made possible by the properties of light generated by a LASER.

When you shine a light on the hologram, the information that is stored as an interference pattern takes the incoming light and re-creates the original optical wave front that was reflected off the object. Your eyes and brain now perceives the object as being in front of you once again.

The difference between holography and photography is best understood by considering what a Black & White (B&W) photograph actually is: it is a point-to-point recording of the intensity of light rays that make up an image. Each point on the photograph records just one thing, the intensity (i.e. the square of the amplitude of the electric field) of the light wave that illuminates that particular point.

However, the light which makes up a real scene is not only specified by its amplitude and wavelength, but also by its phase. In a photograph, the phase of the light from the original scene is lost. In a hologram, both the amplitude and the phase of the light (usually at one particular wavelength) are recorded. When reconstructed, the resulting light field is identical to that which emanated from the original scene, giving a perfect three-dimensional image .