A Line pair indicator made of Gd film for evaluating spatial resolution

Yasuda, Ryo; Matsubayashi, Masahito  ; Sakai, Takuro; Nojima, Takehiro; Iikura, Hiroshi  ; Katagiri, Masaki*; Takano, Katsuyoshi*; Pikuz, T.; Faenov, A.*

A device for evaluating spatial resolution of a neutron imaging system was developed. By laser processes the line-pair patterns were fabricated on the 5 micrometer thick Gd film evaporated on a glass plate. Large line-pairs ranging from 0.2 to 2 mm wide were machined by Nd:YVO laser with 30 micometer in spot size and displayed on a brightness field. Small line-pairs ranging from 0.01 to 0.1 mm wide were done by eximer laser as a dark field. In the results of SEM observation, although the large line-pairs machined by Nd:YVO laser chipped on the corner of the Gd bars, difference between the measured and designed line-pair eidthe controled within 20 micormeter absolutely. In small line-pairs below 0.1 mm processed by the eximer laser, sharper edge could be formed than that in the large line-pairs. In neutron imaging tests using a LiF/ZnS(Ag) scintillator and a CCD camera system, good contrast images were obtained at brightness field even in 5 micrometer thick. Small line-pairs on the dark field were observed at a LiF single crystal detector, which has ultra-high spatial resolution around 5 micrometer. Split of the small line-pairs even in 0.01 mm wide were shown with good contrast on the image.