The most special features of this scanning electron microscopy are that it is truly a tabletop SEM, it is portable and it is designed for minimal preparation of specimens. The microscope is lightweight by design, using a diaphragm pump instead of a rotary pump and a turbomolecular pump instead of a diffusion pump to achieve a useful vaccum for observation. Also the vacuum is on the low side, so it is a semi-environmental SEM and quite tolerant of moisture (unlike any of our other electron microscopes!). The SEM functions by a touch screen and features automated astigmation, focusing, start up and alignment. The TM3000 is a serious SEM but with a simple enough interface to allow its use in the classroom. The HITACHI TM3000 is used for normal sized specimens. There is no airlock. Specimens are mounted on a specialized holder adjusted in height to optimize operation and the SEM is then pumped down until the green progress bar indicates that the microscope is ready. A serious use for this instrument is screening plant and insect mutants in genetic studies where rapidity of specimen exchange is needed and high resolution is not. Minimal specimen preparation is required because the imaging mode used is tolerant of moisture and charging.
HITACHI TM3000 SEM Characteristics
This microscope joined the lab in 2010 and is used for demos, quick examination of genetic mutants, student projects and a myriad of samples needing a quick "look see".
The HITACHI TM3000 is a specialized SEM that uses mainly backscattered electrons to image the specimen, rather than secondary electrons, which require a better vaccum. This is called "charge reduction mode by Hitachi" and means that to prevent charging, that contaminants are tolerated to a greater degree in this particular SEM than the more expensive SEMs that operate in a higher vacuum environment. The screens below show the controls, which are all virtual (except for the two specimen movement knobs and the pump button) and are located on the computer screen. The microscope is controled by a touchscreen or a mouse, at the user's choice. It is well designed and a hit at Oklahoma Uglybug Contest Award assemblies in the schools! The HITACHI TM3000 accepts conventionally-sized specimens but it does not normally use stubs. Instead the materials are mounted directly to the specimen holder, which is adjusted to the appropriate height for focus using a height adjustment screw. No coating is necessary since charge compensation is used to dissipate charge accumulation as electrons bombard the specimen.
Unlike conventional SEMs, the TM3000 is almost entirely driven by its touchscreen.
Specimens are placed on the upper surface of this holder. Most of the focusing is done by adjusting the height adjustment screw before inserting the specimen into the SEM. The metal on the left side is a height indicator that shows the needed height.