20 November 2010, R. Ubic
12
Obtaining a Selected Area Diffraction Pattern (SADP)
Insert a Selected Area Aperture (
aka
Field Limiting Aperture). It is recommended that
the largest one possible which still excludes extraneous parts of the sample be used.
Use the X and Y positioning knobs on the aperture to center it on the region of interest.
Press the
SA DIFF
button (right-hand panel). An image of the back focal plane should
appear.
Adjust the
MAG/CAM L
knob (right-hand panel) to the desired camera length (120cm is
recommended for viewing but 25cm for recording an image).
The intensity of the pattern can be adjusted with the
BRIGHTNESS
knob.
Adjust the
DIFF FOCUS
knob (right-hand panel) to obtain the sharpest pattern.
Center the pattern by pressing
PLA
on the left-hand console and adjusting position with
ShiftX
and
ShiftY
knobs.
To record the pattern, use a small camera length (
≈
40 cm) and ALWAYS USE THE
BEAM STOP to block the central transmitted beam (failure to do this can cause
irreparable damage to the camera). See “Recording Images on the Orius SC1000
Digital Camera” below for more information.
Kinematical Bright-Field (BF) Imaging
Obtain an SADP as described above.
Insert an objective aperture and use the X and Y adjustment knobs to center it over the
transmitted beam. The smaller the aperture, the more contrast will be in the image, but
also the less intensity and the more potential for aberrations.
Press
MAG1
(right-hand panel) to return to image mode.
