Dave Mitchell's DigitalMicrograph™ Scripting Website

Script to wobble the alpha (X) tilt on the goniometer of JEOL microscopes to allow setting of the eucentric height and to identify the tilt axis for tomography.

WARNING: Users MUST ensure that the delay parameter and tilt range limits chosen are suitable for their goniometer. If set incorrectly, there is potential to damage the goniometer/holder/aperture strip. The author accepts no responsibiltiy for any such damage.

This script has been designed for current generation JEOL microscopes (1400, 2100, 2200, ARM). It may work on other JEOLs which use Ethernet communication. It WILL NOT work on JEOL instruments which use serial communication/FasTEM - such as 2000, 2010, 3000 etc. It will wobble the goniometer alpha (x) tilt backwards and forwards. This is useful for locating the eucentric height at low magnification, particularly for low contrast/thick biological specimens, where other methods work less well. It is also very useful for visualising the tilt axis. Choosing regions for tomography along this tilt axis will greatly reduce specimen movement during tilting reducing the work the tracking software has to do.

This script MUST NOT be used on Philips or FEI instruments. In the first instance it is redundant, since the microscope interface has an alpha wobbler built-in. Secondly, the goniometer on such instruments does not provide instantaneous feedback on its position whilst it is moving. Therefore, this script is quite capable of slamming the goniometer into reverse while it is moving, and a delay value which works for a smaller tilt, will not be long enough for a bigger tilt.

The tilt range will be very dependent on the polepiece. Most JEOL HR polepieces have gaps of around 5mm. If your microscope is fitted with a UHR polepiece the gap will be around 2.5mm and your tilt range will be very limited. In fact tomography on such a machine may be impossible without specialised holders/specimens. The tilt range is also very dependent on stage position, being reduced when the x/y stage positions are close to their limits.

Detailed set-up instructions are provided in the script listing and these must be followed carefully. Microscope administrators only should install this script. They will need to determine the appropriate delay and tilt limits. These values need to be set and locked so that regular users can not choose inappropriate settings and crash the holder into the polepiece or aperture strip. This script is provided in good faith, and the author accepts no responsibility for any damage which this script may cause. Use it entirely at your own risk.