MHATT-CAT first report of 2D focussing of a Li lens on 7ID

Eric Dufresne, Dohn Arms, Nino Pereira
MHATT-CAT, Ecopulse, APS
Started Dec. 20, 2002
(www.mhatt.aps.anl.gov/Sectors/Sector7/Operations/FY03_run1/2Dfocus/)

Thursday, Dec 19, 2002. 2D focusing with Li lens

On the last 24 hours of the run, some data was taken to document the results
demonstrated earlier in the run by Nino Pereira, Eric Dufresne and Dohn Arms. 
With 10.37 keV X-rays and a high resolution monochromator installed for Bernhard
Adams's experiment earlier (a Si (333) 10 bounce channel cut), we imaged the 
raw beam and focussed beam with a high resolution camera. This camera used a 
X2 microscope to image the visible fluorescence from X-rays absorbed in a YAG:Ce
single crystal. The pixel resolution was about 3.5 microns, and the digital 
camera used was our Qmax650 camera.

Fig. 1 shows an image of the raw beam. The structure on 
the beam seems worse than it normally is and we speculate that this is an effect
caused by the rough surfaces of the etched channel cut. The average 
intensity in a rectangle covering most of the beam 1330 cts/500ms. The maximum
is 3146 cts, the minimum 494 cts. The integrated intensity is 2.4994E07 
cts/500ms.  Slices of the beam along Y and X are shown in Fig. 1x
and Fig. 1y.

Fig. 2 shows an image of the 2D focussed beam. Two Li lenses
mounted perpendicular to each other, with a 1 mm pitch, 111 mm length, and 90
degree teeth angle were used. They were kept in He and adjusted with a 4 axes
orientation stage. The best focus is shown and slices of the figure are shown in
Fig. 2x and Fig. 2y. The peak intensity is 2134 cts/50ms thus the peak intensity gain is 2134 x 10 / 1330 = 16! The 
integrated flux is 1.464E7/500ms thus the lens focusses about 
1.464E7/2.4994E7 = 58.6% of the X-rays in the raw beam. This is very good 
performance. The focal spot FWHM are about 55 um (V) by 100 um (H) as seen in 
the two slices shown. The source-lens distance was about 51 m, while the
lens-camera distance was about 4.5m (the camera was on the exit wall of 7ID-C).
The demagnification is thus ~11.3:1. This is very good progress and should be
very useful as a long distance focussing optics with a large acceptance on 7ID.

Fig 1. This is a color image of the raw beam imaged by a high resolution
X-ray camera. Red is 3150 cts/500ms, blue zero cts.

Fig 1x. This is a vertical slice of Fig. 1 on the center of the image
The vertical scale is counts/500ms.

Fig 1y. This is an horizontal slice of Fig. 1 on the center of the image
The vertical scale is counts/500ms.

Fig 2. This is a color image of the focussed beam, imaged by a high resolution
X-ray camera. Red is 2150 cts/50ms, blue zero cts. Note the exposure here was reduced by 1 order of magnitude.

Fig 2x. This is a vertical slice of Fig. 2 on the center of the image
The vertical scale is counts/50ms.

Fig 2y. This is an horizontal slice of Fig. 2 on the center of the image
The vertical scale is counts/50ms.