Zone Plate Testing at 1 BMB Preliminary Results

Zone Plate Testing at 1 -BM-B Preliminary Results Michael J. Wojcik, Shashidhara Marathe, Naresh Gandhi Kujala,

Testing Goals § § Measure focus spot size and efficiency Explore multiple methods for efficiency and focus spot size Image downstream propagation of X-rays from zone plate Explore the possibility of optics characterization with grating interferometry via wavefront measurement 2

Zone Plate Characterized 3 zone plates fabricated for intermediate stacking. Slightly different focal lengths. ~150 um diameter 80 nm outer zone width 800 nm thick at outer zones 3

Setup 4

Zone Plates 5

Focused X-rays from Zone Plate • Details of zone plate can be seen in image • Even intensity over line • Nothing blocking zero order light though pinhole • Image using 500 um separation zone plate • Large background from ambient light during measurements • ~17% efficiency from ROI statistics in image 6

Pinhole Scans § § § § § 30 um pinhole at focus was scanned with piezo stage All three zone plates scanned 10 and 20 nm scan steps will be shown Used pin diode downstream for counting, all scans used 1 sec of counting ~14% total focusing efficiency measured with this technique, assuming pinhole is really 30 um in diameter Efficiency calculated by comparing the counts of zone plate + pinhole versus just pinhole and assuming flat intensity X-ray field over zone plate Data from scans not fully analyzed, though preliminary results show a FWHM between 280 -350 nm Still understanding what spot size reflects in total system ~200 dark counts versus 10000 for counts through pinhole and 90000 for focused x -ray counts 7

Pinhole Scans – 300 um Separation Zone Plate 2 um scan 20 nm steps 3 um scan 10 nm steps 8

Pinhole Scans – 500 um Separation Zone Plate 2 um scan 20 nm steps 3 um scan 10 nm steps 9

Pinhole Scans – 1 mm Separation Zone Plate 2 um scan 20 nm steps 3 um scan 10 nm steps 10

Grating Interferometry Image Using Zone Plate • Shashi is analyzing • Preliminary results suggest not enough flux for good results • Background might be too large to accumulate enough useful counts? 11

Problems/Issues to Address § § § § Large background in Andor camera images A central stop to block zero order light Understanding the effect of previously measured 100 nm vibration with 30 Hz frequency on measurements, namely on line scans Need more light for grating interferometry measurements Finish analyzing focus scans Noisy pinhole scans! Is pinhole best object to use for scanning? Better y-axis control of zone plate position 12