Aircraft and spacecraft carry high-resolution thermal imaging systems that were not available a few years ago. Today’s systems are the result of research using X-ray crystal diffraction for crystal characterization. These crystals are then used in the high-resolution or short-wave thermal imaging systems.
The wavelengths of visible light are too long to see features and effects at molecular or atomic levels. Shorter wavelengths allow crystal lattices to be measured, which helps engineers design crystals for specific purposes. These crystals become the key components for short wavelength measurement equipment that, combined with differential interference techniques, provide today’s higher level of imagery.
For example, the ability to characterize crystals using high energy X-rays is a direct outgrowth of large beam line facilities like the Advanced Light Source located at Lawrence Berkeley National Labs. These imaging systems must use short wavelengths to “see” neutrons.
Other large facilities use the intense beams of high energy X-rays to support research of items with feature sizes much smaller than wavelengths of visible light, including molecular structures. However, the X-ray beam is confined to a small diameter. The beam line is operated in a vacuum. To make full use of the beam crystal, samples must be positioned and manipulated in the beam.
Given the tiny features under research, it was necessary to build multi-axis scanning devices that can operate in a vacuum, handle intense X-ray radiation, and still provide high precision and high positional resolution.
LG Motion recently designed and built a 6-axis scanner for AWE Aldermaston, where it is to be used to determine properties of x-ray diffraction crystals prior to their installation into x-ray sensitive diagnostics for fielding on laser plasma experiments. The PC-controlled Two-Crystal Characterization Positioning System includes three stepper motor driven rotary tables and a 350-mm travel stepper driven linear axis that combines to support optical diffraction mounts and sensors—with two manually adjustable linear stages (35 mm travel) used to pre-position static optical equipment. The goal of the mechanical system is to allow remote motion control to sub-micron resolutions in the vacuum chamber. This was achieved using 25,000 steps per revolution micro stepping motor drives in combination with custom vacuum/radiation resistant motors supplied by Empire Magnetics.
Filed Under: Aerospace + defense, ALL INDUSTRIES, Design World articles, Drives (stepper) + amplifiers
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