The JEOL 4000FX IVEM has been very reliable. Maintenance is primarily preventive, and unplanned downtime is very rare. Performance is tested periodically to ensure optimum operation at all times. Training and documentation for the various modes of operation is provided, and improved methods of operation are devised as needed. Need for hardware improvements to keep pace with future needs of the Resource are identified. The performance of the goniometer has been an obstacle to the use of fully-automated tomography. Although the specimen movement during tilt is well-compensated, a focus change occurs at high tilt which is difficult to accommodate with the present automated tomography software. A software solution would require complex programming, and would unacceptably slow data collection because of the additional commands which would have to be sent to the microscope computer over its slow serial port. We have reports that at least one other JEM4000 has (or at least had) a goniometer which performs well. Therefore, we made a detailed investigation of our goniometer to see if improvements could be made. JEOL replaced the goniometer with a brand-new spare. We made plots of tilt angle vs. focus change and image displacement, with different stage alignment positions and at different locations on the specimen grid, using both goniometers. The new goniometer did not work any better than the original. JEOL left our goniometer disassembled so we could examine the components over a period of several weeks. The goniometer was also brought to Peter Fullam of the E.F. Fullam company for analysis. The parts of the tilting system which remain in the microscope when the goniometer is removed (the specimen-holder tip receiver, and the inner bearing pads) were also examined. No firm conclusions could be reached about what is causing the problems, but it is possible that the inner bearing pads are not quite at the ideal height. These pads are not adjustable, and we know of no way to determine the correct height with sufficient accuracy. At present, the consensus is that the basic design was never intended to perform perfectly at high tilt, and that the mechanical tolerances of the two goniometers we have tried just happen to combine less favorably than the one reported to work well. Our willingness, at the moment, to live with the goniometer problem is due to our experience that even cryo tilt-series can be conveniently collected at very low dose with semi-automated tomography. Replacement of the goniometer with the latest version would require a new objective lens. JEOL would require that the microscope be sent back to Japan and be completely rebuilt into the latest 4010 model, at a cost of $400-$450,000. However, JEOL USA is working on a new interface between the microscopes internal computer and external computers. There is a good likelihood that this interface will be applicable to our microscope. If so, the communication between the tomography computer and the EM could be greatly speeded up, making a full software solution to the goniometer problem practical. A new scintillator was purchased for the Tietz CCD camera. This was required because of gradual deterioration due to electron irradiation. With respect to the beam intensity at which electron shot-noise starts to appear in the image, the sensitivity is the same as the original scintillator. However, the resolution is slightly worse. Nevertheless, the sensitivity seems to be greater when operating at a typical low-dose exposure level. The decreased resolution affects mainly lower-magnification high-dose images, while power the spectra of low-dose images as measured on carbon films or background plastic resin is improved. TN Analyzer service repaired the x-ray microanalysis system. We can now make X-ray elemental maps in the STEM mode, and overlay the elemental map on the image. To improve x-ray microanalysis sensitivity, the microscope was aligned in spot mode, and a protocol was developed for microanalysis in STEM mode. Use of the x-ray microanalysis system has been steadily increasing. An air dryer for the compressed air system was purchased, to avoid future problems with sticking pneumatic valves. A used SGI workstation was purchased to replace the defunct VAX workstation. This workstation is used for telemicroscopy and on-line analysis of images using WEB and SPIDER. The Tietz CCD system and the screen current exposure meter were calibrated against a Faraday cage for dose estimation during routine microscopy. An A/D converter board was purchased for the Tietz computer system to enable digital acquisition of STEM images. The connections to the microscope's ASID unit were made, but software implementation has been delayed because of necessary information not yet sent by the Tietz company.
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