Introduction to Holography

Holography is the comprehensive recording and reconstruction of a 3D light field, including both amplitude and phase. The term hologram is derived from two Greek words; holos, meaning whole, and gramma, meaning message.

Holography was independently discovered twice. It was first discovered in 1947 by the British scientist of Hungarian descent Dennis Gabor (Nobel Prize in 1971) while working to improve the resolution of an electron microscope. Gabor's holography was limited to film transparencies using a mercury arc lamp as the light source and his holograms contained distortions and an extraneous twin image. As a result, development in the field was was held up for more than a decade until the invention of the laser.

Holography was discovered for a second time by Yuri Denisyuk from Russia. He had not read Gabor's paper; the idea for holography came to him after reading a science fiction novel. Denisyuk's approach produced a white-light reflection hologram which, for the first time, could be viewed in sunlight or in light from an ordinary incandescent light bulb and formed excellent 3D images. His results were published in 1962.

Yuri Denisyuk holding a self-portrait hologram (from wikipedia.org)

Nowadays, advances in imaging technology and computers have provided a renewed impetus for holography, particularly in its application to microscopy. Digital holography, in which an image can be reconstructed from a digitally recorded hologram, provides many new opportunities to extract features of the sample through the selection of appropriate reconstruction algorithms. In OBEL, we have combined digital Fourier holography with light scattering spectroscopy to study the microarchitecture of biological tissue over a wide field of view.

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Dennis Gabor