Dennis Gabor 19001979 an Innovator Evan Reyes Who

Dennis Gabor (19001979) an Innovator Evan Reyes

Who is Dennis Gabor?

Dennis Gabor: The Inventor of Holography This presentation will include the following: • A short section of biographical information • A section of some of the research conducted by Dennis Gabor • How Gabor came across the invention of holography • The very first method used to create holograms

Childhood and Schooling • Dennis Gabor was born June 5, 1900 in Budapest, Hungary • Spent his schooling career in Budapest until he turned 21 years old • At 21 he moved to Berlin, Germany and eventually received his Diploma from Technische Hochschule

Research Years • In response to the election of Adolf Hitler, in 1933 Gabor moved to Rugby, England to conduct research at the British Thomson-Houston Company • In 1947 Gabor invented Holography while researching ways to improve electron microscope resolution • In 1948 Gabor relocated his conduction of research to the Imperial College of London, England

Mid Life to Death • In 1956 he was elected to be a Fellow of the Royal Society, an honorary English society run by the British government to support the advancement of science • In 1958 he became a professor of Applied Electron Physics at Imperial College • In 1972 Gabor was awarded the Nobel prize in Physics for his invention of Holography • That same year, Salvador Dalí exhibited his work of holograms, which he created in collaboration with Dennis Gabor • February 9, 1979 Dennis Gabor dies

Research Dennis Gabor began his interest in the field of applied electron physics while studying at a Technische Hochschule (Institute of Technology) in Berlin, Germany. This is where he began his long journey of research of plasma lamps and improving functionality.

A side note The plasma lamp is a type of lamp that uses noble gas and often times metals, sodium, or sulfur to create light. This light is generated by electrons that excite the noble gas atoms which release energy in the form of radiation. The color and intensity can be changed by altering what is being excited by the electrons.

Research (cont. ) Dennis Gabor’s research was consistently innovative in that the research conducted often contributed greatly to the field in which he worked. Most of his greater accomplishments occurred during and after the year 1934, during his time spent researching at the British Thomson-Houston Company in Rugby, England. the British Thomson-Houston insignia

Research (cont. ) Much of the research conducted at the British Thomson-Houston Company was focused on the advancement of plasma lamps and further improvement of electron multipliers. http: //www. youtube. com/watch? v=k 4 m. KDFPi. Bj 8&list=PL 212 AE 426663 B 340 D

Research (Cont. ) Gabor researched many different subjects, but the one that led directly to the creation of holography was his work on electron microscopy (the study of electron microscopes). Gabor spent a lot of his time researching at BTH how to give the electron microscope better resolution when obtaining images.

The Electron Microscope The idea behind the electron microscope is that electrons are shot out in a beam towards a specimen to be viewed. There are two different ways the electrons can interact with the specimen. There are electrons that bounce off of the specimen to shoot back towards the microscope, and there are electrons that make it all the way through the object. This allows observers to obtain information about the internal structure and the surface at very high resolutions.

What makes the resolution so high? First of all, resolution is the precision, or correctness, at which something can be measured. For example, the resolution on a ruler that measures inches is very low because there is a lot of room within the inch for error, but resolution on a pair of dial calipers is much higher as it can measure up to 1/1000 of an inch with precision. Electron microscopes used electrons, which are extremely tiny, to create an image. The electrons shoot out of a beam and go towards a sensor after retaining information about the with which they have interacted.

The Electromagnetic Lens In order to create images with extreme magnification the electrons that are read in by the microscope must be redirected so that the image created is larger. To do this the electron microscope uses what is called the electromagnetic lens where permanent magnets create a magnetic field that cause the electrons flying towards the sensor to move away from each other resulting in a larger image.

The Issue Electron microscopes uses electron lenses to focus on and capture images at very small scales. The problem at the time was that when the images were captured the resolution of the images was too small to promote advancement in science. So Gabor studied what is now holography in his attempt to create ultra high resolution images.

The Very First Hologram The initial process proposed by Gabor involved a closely coherent light wave to be split off and hit a transparent object and then hit photosensitive film. There would also be another closely coherent light wave coming in at a different angle. The interaction between these two light waves causes the photosensitive film to permanently alter its surface and whenever it receives light from a point source similarly to how it was first developed it will create a virtual image of the object behind the film as if it was still there.

The Very First Hologram (cont. ) It wasn’t until after the creation of the first hologram when Gabor coined the term “hologram. ” Any guesses as to where the word comes from?

The Very First Hologram (cont. ) The word “hologram” stems from Greek roots. • “holos” meaning “whole” • “graphein” meaning “to write” Just looking at the root word it is clear that Gabor’s intent was to create an image of incredible resolution.

But wait… Did anyone catch the issue with this process?

The Problem The problem is that the first laser was developed in 1960, but Gabor invented holography in 1948, 12 years before the first laser even created. So how did he conduct his experiment. This is actually the reason why holography did not gain popularity until shortly after the 1960’s.

The “Almost” Coherent Light Source While conducting his experiment, Dennis had to use the most coherent light source he could find, which at the time was the mercury arc lamp with light shining through a pinhole.

Mercury Arc Lamp The mercury arc lamp, sometimes known as the mercury vapor lamp, uses argon and mercury vapor to emit radiation. A current is put through a noble gas which after a while heats up and then causes the mercury inside to vaporize which causes the gas to emit certain wavelengths of light, which will be shown next.

Electromagnetic Spectrum Notice what kind of radiation is emitted by the mercury arc lamp. What do the wavelengths correspond to in the spectrum of light?

Mercury Vapor Lamp http: //www. youtube. com/watch? v=L 1 IQG 7_DA 9 o This video will show exactly mercury vapor lamps work when a current is passed through one.

The Main Issues The main issues that come with using a mercury arc lamp are that it naturally has light which is not coherent and it also emits a lot of ultraviolet light, which can be harmful to people. The only good thing about the Mercury Arc Lamp is that is gave off a narrow spectrum of visible light which makes it easier to obtain coherency through filtration.

Collaboration with Dalí An interesting fact: In 1972 Salvador Dalí exhibited his holographic artwork at the Knoedler Gallery in New York. These holograms were created in collaboration with Dennis Gabor.

Questions?