July 22nd- Day 18

Imaging optic measurements.

Alex had finished aligning the new Si(220) optic and was ready to take the final measurements. This optic was being manufactured for Bruker for some imaging purpose. Vertical and horizontal spot size measurements were taken at 30mm, 70mm and 3mm. The OFD of 30mm produced the smallest spot (x- 152.4um, y- 217.4um) as expected. Measurements were taken at these distances to see how well aligned the source was and to see how good the optic is. A Mo source was used. This beam is used for divergence. The company has a sharp tolerance for the location of the beam. It needs to be in the center of the detector, so it can be blocked easily. If the beam was allowed to hit the detector, the detector would become over-saturated. When the beam is stopped, one can see the rings of the pattern diffraction on the beam stop.
The flux was calculated to be 4.85E7. To find the tilt, we focused and zeroed the detector at the normal OFD. Then the detector was moved back 500mm and the beam was scanned using the detector to locate the center. The difference between the two points of focus and the length of 500mm was used to construct a triangle of the vertical tilt. The angle was found to be 0.04 degrees. Calculating the tilt in x makes no sense because the error is so large.
__________calculations_________________
To calculate divergence, the optic was rotated to find the peak. While the beam was slightly focusing, the divergence was still calculable. The divergence shows the crystal diffract different energies. Doing a horizontal scans shows a shoulder off to the left of the main peak we were looking at. This was Mo K alpha2. Each angle represents a different energy. An intensity measurement was taken to observe the number of photons hitting the detector. The divergence can be taken for the 90th, 95th, or 99th percentile.
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The vertical divergence was calculated to be 0.66 and the horizontal divergence was 0.63.