The Materials Science & Engineering Teaching SEM

Implementation

The Teaching SEM is basically a Philips XL30 scanning electron microscope. The control philosophy behind Philips design of this instrument means it is one of the few, if not the only, instrument that may be currently used for real-time Telepresence Microscopy. All of the basic operating functions of the microscope are controlled by custom microprocessors and control systems, the operators interface to the microscope is a Microsoft Windows based application. Menus, buttons, scroll bars, etc. in the graphical interface of the Windows program allow the user to control the microscope operating conditions. The application sends these commands to the dedicated instrument computers via a Small Computer Systems Interface (SCSI or scuzzy) bus. The video output of the microscope is output on to the screen of the Windows computer by superimposing (or keying) the video on to one of the unused colors of the VGA monitor. This video overlay is performed by using a Coreco MX video overlay frame grabber. This basic functionality of the Philips microscope is essential to this project.
Remote control of the SEM is effected by keeping the video signal and windows program information separate until it is displayed on the screen of the remote computer. Both the microscope Windows computer and the remote control computer are connected to the University campus-wide via a 3Com Etherlink III ISA Ethernet card. Networking software drivers for TCP/IP and the Novell IPX protocol are loaded on both computers. Remote control of the microscope computer is achieved by the use of Timbuktu Pro for Networks, a software application from Farallon Computing. Both the microscope computer and the remote control computer run Timbuktu Pro, the microscope as the master computer and the remote computer as a client.
The microscope video is transmitted to the remote computer via the University of Michigan Cable Television Network (UMTV). A Jerrold C6M cable modulator converts the microscope video signal and transmits it on a channel of the campus cable network. At the remote control location a demodulator (actually a good quality VCR) decodes the cable TV signal which is then connected to a Coreco MX video card identical the one in the microscope computer. The video is overlaid on to the Windows data with the same video keying software employed on the microscope computer. A complete schematic for the microscope and control system is shown in the accompanying figure.
The remote computer screen is almost identical to the screen that the user sees when sitting at the microscope itself. While it is obviously not possible to exchange samples remotely, a large multiple sample holder, capable of holding 10 individual sample stubs, allows the mounting of sufficient samples for most lectures and classes.

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