Optica & fotonica

Toen Wilhelm Röntgen tegen het einde van de 19e eeuw de naar hem vernoemde straling ontdekte en ermee experimenteerde, was hij een van de weinige pioniers op dit gebied die consequent een beschermende loden mantel gebruikte. De precieze reden daarvoor wist hij wellicht niet, maar hij vermoedde wel dat deze stralingsvorm schadelijk was voor de menselijke gezondheid – en zijn vermoeden was gegrond. Röntgenstralen zijn echter ook van grote waarde in de geneeskunde: ze zijn een van de meest effectieve instrumenten in de medische diagnostiek en vaak onontbeerlijk voor een goede behandeling. Als het erom gaat met een zo laag mogelijke dosis röntgenstraling optimale beelden te verkrijgen, dan zijn er vrijwel zeker objectieven in het spel die door de Italiaanse onderneming Optec zijn vervaardigd. Als aandrijving voor hun diafragma-, focus-, fi lter- en zoomfuncties maken zij gebruik van FAULHABER-motoren.

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If you turn on your pocket torch for just a second and point it towards the sky, your beam reaches all the way to the moon. How fast would you need to switch the torch on and off in order for the beam to be shorter than the thickness of a human hair? It's not something you could accomplish with your thumb, that much is certain. Ultra-short beams, or pulses, of this order of magnitude are emitted by so-called femtosecond lasers, which split the laser light into compressed, high-energy wave packets. They can be used to work on any material – from the cornea of the human eye to super-hard ceramics – with micron accuracy. The French manufacturer of precision devices, ISP System, produces the actuators with which the prisms, mirrors and fi lters in such high-performance lasers are precisely aligned so that the light pulses reach the right point with the right power. Reliable drive is ensured by the stepper motors from FAULHABER.

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The automated lens positioning unit allows surgeons the effortless viewing of retina and cornea without neck contortions.

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Modern microscopes have become an indispensable part of medical research. The procedure for quickly and precisely examining the relevant sections of a sample has always been to adjust the slide’s position by moving the stage under the lens. But thanks to technological advancements, manual adjustments are quickly becoming a thing of the past. The task is now given to microdrives. But not all microdrives are created equal. In order to avoid mechanical play and ensure quick movement with utmost precision, a new concept uses small linear DC-Servomotors. With drive lengths in the decimeter range, it boasts a repeat accuracy of a few microns.

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The trend towards high-precision procedures and miniaturization in medicine and industry has continued unabated over recent years. Keyhole surgery and dental technology as well as industrial microtechnology are prime examples. Unfortunately, it takes considerable effort to identify small structures with the naked eye. Magnifying glasses, with their one-dimensional vision, are often problematic. Unwieldy stationary stereoscopic microscopes are equally impractical, particularly in the field of medicine. However, a new kind of optical system is now revolutionizing work on microscopic structures; it is worn as a head set. Miniature stepper motors control magnification and focus for each eye. A crystalclear 3D view allows operations on even the smallest of vessels as well as the investigation or assembly of microscopic structures – without straining the eyes.

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Modern astronomy is struggling with the same problems as the first celestial explorers did centuries ago. The stars shine only faintly, and the further away the star, the less light hits the Earth. This issue can only be addressed by focusing the light – in other words, the telescopes keep getting larger. Today's technology is so advanced that dealing with the ever-growing scale of telescopes is relatively simple. However, giant telescopes with stationary lenses are inflexible. Hence flexible solutions are increasingly being used, specifically the mirrors are becoming thin and adjustable and the objective lens itself is designed through individual components to be movable. Micro-drives are used to adjust the optics in order to minimise material variances, gravitational distortion or refraction fluctuations of the atmosphere. The focus is on miniature drives with backlash-free gears and long-term reliability.

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If you want to set things in motion, you will always require some form of drive. However, conventional technology employs relatively large designs and is too cumbersome for many applications. The trend toward miniaturization, though, has definitely made its mark on motion control engineering. Small, powerful electric motors with a diameter of only a few millimeters guarantee pioneering innovations in a wide variety of fields. It is not only industrial automation that benefits but, to an increasing extent, other sectors as well. Nowadays modern miniature drives are even enhancing science, as demonstrated by the following example of an application in the field of astronomy. A combination of miniature DC motor, encoder, and a low-backlash planetary gearhead ensures that optical assemblies are positioned with precision.

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