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    With Flash light next up previous contents
    Next: With the telescope Up: Alignment of the cryostat Previous: Alignment of the cryostat   Contents

    With Flash light

    Figure 4.1:

    \epsfig{file=cryostat.ps, width=3.47in}
    \epsfig{file=screw.eps , width=3.47in}
    (a) Cryostat position (b) Allen wrench adjusting the top-right screw of the cryostat alignment

    \epsfig{file=camera.ps , width=3.47in}
    \epsfig{file=he.eps , width=3.47in}
    (c) CCD camera (d) Halogen lamp used in lightning the Cryostat with its DC power supply

    \epsfig{file=badalign.ps,width=3.47in}
    \epsfig{file=goodalign.ps, width=3.47in}
    (a) Bad (b) good alignment of the cryostat

    4.1We have noticed that the cryostat dis-aligns each time after mounting a sample. So, it is very practical to take a flash-light picture after each mounting to make sure that the cryostat did not move. To do that place the flash-light in-lieu of cover of the hole close to the telescope. Connect the camera to the computer with appropriate wire (labeled BNMR). Take a picture of the cryostat with the flash-light on (don't forget to turn it off after you are done with it) using a time exposure of $ \sim$ 0.1 sec, and see if the sample holder is in the middle of the bright flash-light circle (black circle as in Fig. 4.1-a). If it is shifted from the center, then adjusting the cryostat is mandatory. Loosing or tightening the screws of the cryostat is the way to get it centered (see Fig. 4.1). The screws to adjust are shown in Fig. 4.1, and rotating the top or bottom ones (two sizes small and bigger, each with two in front and two in the bottom with a square drive) in 45$ ^o$ using an Allen wrench is enough to make the cryostat move up or down (3-4mm). There are 4 locking screws (big one in picture) that must first first loosened with an 5/32 Allan wrench. The small screws ( where Allan wrench, size 3/32, in figure is pointed) can move the cryostat by $ \sim$ 2mm for half turn. Adjusting these screws must be experienced by small turns and taking pictures with CCD camera. After adjustment you should be able to center the cryostat and get a picture similar to Fig.4.1-b. A more robust and time consuming way would be using the telescope, which is explained next.
    next up previous contents
    Next: With the telescope Up: Alignment of the cryostat Previous: Alignment of the cryostat   Contents
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    Page last modified: 07/23/09 02:45 by Andrew MacFarlane.