SEM Substages

Auto-relocating substage for FEI Quanta and XL SEMs
A new substage is now available that allows particles to be relocated to within 50 microns accuracy, after the samples have been removed from the microscope chamber and reinserted. The new substages aid the relocation of particles of interest after the samples have been stored, following the initial search of the stubs.

		The sub-stage is designed to operate with any FEI SEM that supports the new 2-pin relocation system. That includes all currently manufactured Quantas as well as most XLs. The system uses a pedestal with two pins that lock into the SEM's stage to an accuracy of 20uM. The relocating specimen holder plate of the substage is then inserted onto the pedestal. As it happens the absolute relocation accuracy is only partly a function of the relocating mechanism. There is also a relocation error due to the reproducability of the SEM stage door closure. In tests, an accuracy of 50uM has been achieved, which should be sufficient to relocate particles of interest except in the most heavily loaded gunshot residue (GSR) stubs. We would expect greater accuracies to be achieved after further optimization.

The new substage is available with either 20(+1), or 8(+1) (shown above) stub positions. The (+1) position is a screw mount intended for the GSR backscattered electron detector (BSD) calibration standard.

The 20(+1) position substage is designed for the Quanta, XL30/XL40 with 100 x 100 stage. The stub positions are located at a 16.6mm pitch, in a rectangular array, making the substage suitable for 12.5mm (any nominal half-inch type) pin stubs.

The 8(+1) substage is designed for the Quanta 200 and XL30 with 50 x 50 stage, as well as other models. It accommodates 8 pin stubs (any nominal half-inch type) at a pitch of 16.6mm, in a 3 x 3 rectangular array. The central position is intended for the GSR BSD calibration stub and is a 3mm screw mount. The standard remains screwed into the pedestal, so that it is not necessary to re-index its position after changing specimen holder plates.The photographs below illustrate the various parts of the substage.

For both substages the stubs are held in a highly stable, easy to insert, spring loaded mount, avoiding the difficulties of securing stubs with grub screws.

Photographs of a 20 hole 100 mm substage. The photo on the right is a normal optical image, while the one on the left is a backscattered electron montage, taken within the chamber using a new addition to the GSR software. For further information please contact Eastern Analytical.