Focussing set up for a microdiffraction experiment in 7ID-C in late July 2002

Focussing set up for a microdiffraction experiment in 7ID-C
in late July 2002

Below are some pictures from setting up the CARS style KB mirror in the 
MHATT-CAT 7ID-C hutch. To reach a spot size below 10 microns, the mirrors had 
to be mounted directly on the Kappa input bench. These pictures show the set up
and the achieved spot size. The vertical spot size is a factor 3 wider than the
demagnified source size, but we believe it could be easily improved by a more
careful alignment. The KB mirror was installed about 0.5 m from the center of
rotation, and it should be possible in the future to focus down to around 2
microns, depending on the constraint of the sample environment and reciprocal 
space coverage.

Special thanks should be given to Tom Trainer from GSECARS for giving us 
access to  his table record which worked very well and made the Kappa alignment
easy considering that the doubly reflected beam changes the propagation
direction of the incident beam. The MHATT-CAT team was lead in this important
technical achievement by Don Walko and included Jesse Guzman, Yoosuf Picard,
Eric Dufresne, and Steve Yahlisove.
MEMS set up photos in late July 02 on 07/30/02.

Looking at the Kappa from downstream, the microscope (X5) was focussed on the pin.

MEMS set up photos in late July 02 on 07/30/02.

The pin removed, a thin YAG crystal was inserted in the plane of the PIN and the YAG
surface is imaged on the CCD.

MEMS set up photos in late July 02 on 07/30/02.

The YAG is mounted on a hole in the Al plate.

MEMS set up photos in late July 02 on 07/30/02.

The KB-mirror system mount designed and fabricated by Jesse Guzman and
Don Walko.

MEMS set up photos in late July 02 on 07/30/02.

In front of the Kappa bench, mounted on the SAXS optical table, a slit opened
to 0.39 mm by 0.39 mm limits the beam on the KB mirrors. MEMS set up photos in late July 02 on 07/30/02.

Focussing was done in real time by looking at the video camera output on a monitor.
Before removing the goniometer pin, the pin outline was marked on the screen.
The focussed beam is on the tip of the pin.

MEMS set up photos in late July 02 on 07/30/02. MEMS set up photos in late July 02 on 07/30/02.

The horizontal profile of the beam taken with an edge scan using a GaAs (100)
cleaved wafer. The horizontal spot size is 6 um FWHM. The demagnified
source size for this geometry is 5.3 microns. Clearly, the focal spot
matches the demagnified source size very well. The calculated horizontal divergence
is 0.76 mrad.

MEMS set up photos in late July 02 on 07/30/02.

The vertical profile of the beam taken with the same edge wafer. The beam
was about 15 um FWHM in the vertical. The horizontal alignment was done more
carefully than the vertical one which we believe caused the large discrepency.
The calculated vertical divergence is 0.63 mrad.