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11 August 2020 Artifact-less coded aperture imaging in the x-ray band with multiple different random patterns
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The coded aperture imaging technique is a useful method of x-ray imaging in observational astrophysics. However, the presence of imaging noise or so-called artifacts in a decoded image is a drawback of this method. We propose a coded aperture imaging method using multiple different random patterns for significantly reducing the image artifacts. This aperture mask contains multiple different patterns each of which generates a different artifact distribution in its decoded image. By summing all decoded images of the different patterns, the artifact distributions are cancelled out, and we obtain a remarkably accurate image. We demonstrate this concept with imaging experiments of a monochromatic 16-keV hard x-ray beam at the synchrotron photon facility SPring-8, using the combination of a complementary metal-oxide-semiconductor image sensor and an aperture mask that has four different random patterns composed of holes with a diameter of 27  μm and a separation of 39  μm. The entire imaging system is installed in a 25-cm-long compact size and achieves an angular resolution of <30  arc sec (full-width at half-maximum). In addition, we show by Monte Carlo simulation that the artifacts can be reduced more effectively if the number of different patterns increases to 8 or 16.

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE) 2329-4124/2020/$28.00 © 2020 SPIE
Tomoaki Kasuga, Hirokazu Odaka, Kosuke Hatauchi, Satoshi Takashima, Tsubasa Tamba, Yuki Aizawa, Soichiro Hashiba, Aya Bamba, Yuanhui Zhou, and Toru Tamagawa "Artifact-less coded aperture imaging in the x-ray band with multiple different random patterns," Journal of Astronomical Telescopes, Instruments, and Systems 6(3), 035002 (11 August 2020).
Received: 20 February 2020; Accepted: 29 July 2020; Published: 11 August 2020

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