Development of a high resolution x-ray inspection system using a carbon nanotube based miniature x-ray tube

Abstract

A new concept for a non-destructive testing device using a novel carbon nanotube (CNT) based miniature x-ray tube is proposed. The device can be used for small-scale internal inspection of objects. To investigate the effectiveness of the proposed concept, the device was fabricated and its performance was systematically analyzed. The non-destructive testing device consists of a CNT based miniature x-ray tube, a scintillator, an optical lens, and a detector. The size of the focal spot needed to identify objects as small as 5 µm was calculated through simulation. An electron optics simulation software, E-GUN, was used to optimize the geometries of both the focusing cup and the x-ray target to achieve the desired focal spot size of the x-ray tube. The CNT based miniature x-ray tube was fabricated using the brazing process, and an NdFeB focusing lens was used to further reduce the focal spot size. XR images were obtained using the fabricated device and the spatial resolutions of the images were evaluated using the modulation transfer function (MTF). The fields of view (FOVs) per probe are 7.1 mm2 and 1.8 mm2 when using a 5× optical lens and a 10× optical lens, respectively. The FOV can be increased by increasing the number of probes incorporated into the device. MTF10 values were determined to be 105 lp/mm and 230 lp/mm when using the 5× optical lens and 10× optical lens, respectively. By using an optical lens to enlarge the XR images, the effect of focal spot was minimized and clear XR images were obtained.

ZnWO4 Nanoparticle Scintillators for High Resolution X-ray Imaging

“…The modulation transfer functions (MTFs) were measured to evaluate the spatial resolutions for the fabricated ZnWO 4 particles. This procedure is highly common in the field of X-ray imaging [ 12 , 23 , 36 , 37 , 38 ]. X-ray images of an edge of a 0.5 cm thick tungsten block were developed using the high-resolution X-ray imaging fitted with the fabricated ZnWO 4 scintillator screens.…”

“…Powder scintillators are used ubiquitously in various industries, especially in those involving medical diagnostics and non-destructive testing [ 5 , 6 , 7 , 8 , 9 ]. Currently, many efforts are being made to identify small components within objects utilizing non-destructive testing with X-rays [ 10 , 11 , 12 ]. The general approach to achieving this is to use micro-focus X-ray tubes [ 10 ], which are, unfortunately, expensive and bulky.…”

“…The general approach to achieving this is to use micro-focus X-ray tubes [ 10 ], which are, unfortunately, expensive and bulky. Another way of managing this is to utilize a high-resolution X-ray imaging system comprising a scintillator and a detector with a pixel size as small as several hundred nanometers when coupled with an optical lens [ 11 , 12 ]. The system utilizes X-rays to generate images with the scintillator positioned directly under the object of interest.…”

A molybdenum nanostructured-film target for tunable x-ray sources: surface-structure controllable preparing and radiation intensity selecting

“…In the field of x-ray imaging, the coordination between radiation intensity and focal spot size determines the image quality. A smaller focal spot helps to improve spatial resolution and imaging clarity, while a higher brightness per unit area helps to further shorten imaging time and improve efficiency [11,12]. In the field of x-ray lithography, a microfocus x-ray is expected to achieve maskless lithography with controllable exposure region size and linewidth of 20 nm or narrower [13].…”

“…The tunability of x-ray source performance can be achieved through the following two paths: One is for the electron source, specifically to select suitable cathode material [21,22], or to employ an electronic focusing system [11,23,24], to tune the exciting electron beam properties such as electron energy, energy spread, total current and spatial distribution. The other is for the anode target, to control its texture and structure, like geometric size, micro-nano structure, film thickness and surface roughness, in response to the electrons bombardment to radiate the x-rays [25,26].…”