Holography is considered as one of the most remarkable discoveries in modern times. Nevertheless for its first decades it seems to be getting forgotten.

Originally stepped up back at the end of the 1940s to improve electron microscopy, it can not fulfill this function and the wish of its discoverer hungarian-british physicist Dennis Gábor. Due to sources of pure coherent light, which are indispensable for optical holography, being not yet available, not even Gábor himself can locate a field of application for this phenomenon. He can neither recognize at that point of time the meaning and the potential of his discovery and with it the influence this new medium would have on our daily lives one day. Nor can he imagine the plenty of phantasms emerging from this phenomenen. Phantasms, which seem to be mostly one step ahead of applied holography.

With the discovery of laser light at the beginning of the 1960s, for the first time ever it becomes possible to record and reconstruct a real three-dimensional image of an object. What once simply starts as a little rainbow coloured picture of a toy train, today finds its applications in a vast variety of different optical and acoustical fields.

It is as remarkable as the phenomenon of holography itself, that it could never prevail as a popular medium like movie, TV, radio, the internet, print media, etc. Especially when keeping in mind all the phantasmatic stories which emerge from this medium. A lot of dreams, hopes and promises that holography never made by itself, but some of them is trying to keep.

blog.holographie.eu accompanies my scientific work on holography, which would like to give holography an attention, that elsewhere is mostly refused to it. It is of course initially interested in based techniques and technologies of holography and how it works. Moreover it is also interested in these upcoming phantasms and their stories arising from possible abilities of holography. Especially against the backdrop of holography seems to be reaching a point, where its possibilities and abilities catch phantasms.

This blog would like to serve as a sketch book for unprotected ideas, of which some maybe become expanded, while others are not haunted any further, but wants to be told and should not be unmentioned forgotten.


please visit also www.holographie.eu

2010-06-03

Coherence

An Interference pattern can not be generated by random light source. Ordered conditions of illumination are needed.

To illustrate this, the example of two stones in entry on interference hitting the surface of the water should assist once again. A constant pattern solely occurs under the condition of synchronization and phasing. For the stones wouldn't hit the water simultaneously or for several stones would hit the water uncontrolled, of course wave fronts would meet and join to a new wave front, but this one wouldn't be constant. This behaviour of waves goes for both, water and light waves.

Viewing figures Partition of white light into different-coloured spectra by prism and Wave lengths of visible light against this backdrop, it becomes obvious that sun light or the light of a candle or an ordinary lamp - like any other light occurring in nature - is just very limited or even not at all suitable to generate constant interference pattern. All these lights consist of several light colours with several different wave lengths. There are superpositions, but they are high complex and chaotic, that no observable interference pattern could be generated with it.

This special property light has to have to generate such an interference pattern is called coherence. Coherent light is ordered and sorted light, which does not propagate in all directions in space, but in just one direction and that consists of waves with just one wave length, i. e. which is monochromatic. As yet is the laser the only source of coherent light.



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