Brief history of X-ray tube patents

Optics & Photonics News, 2002

2014

Following the discovery of a “new kind of rays,” to be named by him as x-radiation, and others as Roentgen’s rays, Dr. Roentgen embarked on an intense investigation in a series of innovative experiments to determine its properties and characteristics and how it compared to other known radiations, specifically light and cathode rays. He demonstrated that the radiation produced fluorescence and exposed photographic plates. The revolutionary discovery was that it penetrated normally opaque objects and produced shadow images of things within. It was these characteristics alone that were the foundation of x-ray imaging that soon changed and enhanced the practice of medicine around the world. For additional experiments he developed a variety of test devices that continue to be used by physicists for evaluating the performance of x-ray equipment and devices. These included a pinhole camera, step wedge, and an innovative device to become known as a penetrameter. A major focus of his work wa...

2021

Wilhelm Conrad Roentgen-Discovery of X-Rays Like very few discoveries in the history of science, just after its announcement in 1896, Roentgen's discovery of X-rays (1895) has achieved such global affirmation and came into practical use in numerous fields of science and technology, starting from medicine, on which it had an essential impact, through palaeontology, archaeology and art history to industry. For the first time, physicians could, without the use of surgical knife, see the inside of a live human body, study the work of individual organs, localise and, with greater certainty, treat a disease or an injury of the tissue, while soon afterwards it was discovered that the rays themselves also have a therapeutic effect. Besides, Roentgen's discovery inspired scientists to further research that has led to new discoveries. Already in 1896, Henri Becquerel discovered radioactivity, Thomas Edison invented radioscopy (observing the inside of the body using a fluorescent screen), Mihajlo Pupin and Nikola Tesla discovered certain characteristics of X-rays and improved the technology for obtaining X-ray images, while in 1897, Joseph J. Thomson discovered electrons. The chance to see inside the body was the starting point for development of new methods of biomedical visualisation in the 20th and 21st century, based not just on the use of X-rays, but other physical phenomena as well. Roentgen was the first winner of the Nobel Prize for Physics (1901), which was awarded to him "in recognition of exceptional services that he has provided by discovering incredible rays that were later named after him". One third of the monetary part of the prize, which was 150,000 Swedish kroner, 1 he bequeathed in his will to the University Julius Maximilian in Wurzburg, where he was teaching physics at the time of his discovery. He did not patent his discovery because he wanted it to be freely used for the benefit of the mankind.

2007

Professor Wilhelm Conrad Roentgen (1845-1923) was working at Wuerzburg University in Germany. Working with a cathode-ray tube in his laboratory, Roentgen observed a fluorescent glow of crystals on a table near his tube. The tube that Roentgen was working with consisted of a glass envelope with positive and negative electrodes encapsulated in it. On November 8, 1895, he was conducting experiments in his laboratory on the effects of cathode rays. The air in the tube was evacuated, and when a high voltage was applied, the tube produced a fluorescent glow. The new type of ray was being emitted from the tube. Roentgen shielded the tube with heavy black paper, and discovered a green coloured fluorescent light generated by a material located a few feet away from the tube. At the first time he investigated his hand, and he surprised to see his hand bones. It was the beginnings of the new investigate picture form inside, without cutting and open the body. Roentgen’s discovery was to open up ...

1. Röntgen's discovery The discovery of invisible rays penetrating opaque bodies made by Wilhelm Konrad Röntgen became known to public early in January 1896: some scientists received personal communications from Röntgen, while the majority learned about it from newspapers. While it was the penetrative power of X-rays, revealed by Röntgen's photographs, that struck the imagination of everyone, scientists found another amazing feature of the new phenomena. On the one hand, the X-rays behaved like light, producing sharp images on a photographic plate. On the other hand, these rays considerably differed from light, in particular, they could not be regularly reflected or refracted; and they showed no sign of either polarization or interference. Röntgen concluded that, despite their ability to produce fluorescence and chemical reactions and discharge electrified plates, the X-rays could not be transverse waves similar to ultraviolet light. Nor could they be cathode rays exiting the tube, because X-rays penetrated air much easier than cathode rays, and they did not deviate even in a strong magnetic field. Röntgen decided that the only reasonable choice open was that the X-rays are produced by longitudinal waves in the ether. 2. Waves or particles? While some physicists agreed with Röntgen, a number of other hypotheses came to life, of which I'll briefly review only transverse waves and particles, as the most relevant for this paper. Several physicists, including Arthur Schuster, Goldhammer, George Fitzgerald, tried rehabilitating the hypothesis of transverse waves refuted by Röntgen. The idea was to assume that the wavelength of X-rays is comparable with the size of molecules. Such waves could travel in the substance with the same speed as in vacuum, without any noticeable refraction. Also, according to Fresnel's theory of diffraction, for extremely small wavelengths diffraction effects become insignificant. Experimenters found, however, great technical difficulties in measuring the wavelength of X-rays either from refraction or from diffraction. A very low intensity of diffracted rays required a long exposure, and quite often it was not clear whether an image broadening was due to diffraction or to overdevelopment of a photographic plate. Another problem was lack of homogeneity of X-rays. As the result, the wavelengths obtained varied widely (from 10 Å to 8300 Å) which of course provided no proof of the wave nature of X-rays. The first wavelengths of X-rays that were in the correct range (about 1Å) were obtained by Haga and Wind (in Holland) in 1899-1902 using diffraction on a narrow slit. The situation with polarization was no better than with interference or diffraction. The early positive results of Galitzine and Karnojitsky were never confirmed. The absorption of X-rays by two overlapping crystals did not depend on the mutual orientation of their optical axes, nor did a single crystal change its absorption when its axis made different angles with the beam of X-rays. Attempts to use fluorescence or diffraction grating to uncover polarization of X-rays also failed. The first positive (albeit indirect) signs of polarization of X-rays were obtained by Charles

Endeavour, 2010

The technical study and physical care of paintings', The Art Bulletin 2 (1920), pp. 160-170. 6 John Brewer, The American Leonardo. A 20th Century Tale of Obsession, Art and Money (London, 2009). 7 The case was finally settled with an off-court agreement. 8 Charles F. Bridgman, 'The amazing patent on the radiography of paintings', Studies in Conservation 9 (1964), pp. 135-139. 9 Michael Graf von der Goltz, Kunsterhaltung-Machtkonflikte. Gemä lde-Restaurierung zur Zeit der Weimarer Republik (Berlin, 2002), pp. 90-92.

2011

RadioGraphics, 2008

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