An electron beam, when incident on a solid sample, gets absorbed in the sample in a 'tear drop' shape. The lateral spread and the depth of this absorption region depend upon the energy of the incident electron beam. Thus absorbed energy shows off in various ways, such as, Auger emission, Secondary electron emission, Back scattered electron emission, Characteristics X-rays and the continuum X-rays. Generally, the Secondary electron detector forms the basic image recording system. At C-MET, Pune, the SEM (Phillips, X-30) has a Back scattered electron detector and an energy dispersive X-ray detector  (EDX), apart from the Secondary electron detector. 

The XL 30 is a versatile scanning electron microscope with optimum performance for both imaging and analysis. This makes the system ideal for dedicated research as well as for routine-operation such as control monitoring of a manufacturing process. Operating under full software control, the instrument is an excellent tool for the analysis. The fixed final lens aperture column design and the computer controlled alignment guarantee rapid selection of kV and spot size for the full range of kV and spot size, no realignment by the user is necessary, even up to high beam currents. In addition, an embedded EDX system can offer the user a total analytical capability with one single instrument. The following are important details of the microscope:

• Variable accelerating voltage: 0.2 – 30 KV. Image rotation & focus automatically compensated over the full range.

• Stage: Fully motorized, with complete software control and added 'Scan rotation' function with a range of –180 to +180 degrees.

• Magnification: Can be controlled by the user-defined presets, stepped or by continuous adjustment. Automatically scaled micron marker on screen measurement standard Max. Range 5x to > 4,00,000x. 

• Basic Detection Mode: Secondary and back scattered electrons with high efficiency detector. Automatic control of contrast & brightness. Grid bias control continuous from –150 V to + 300 V. Dedicated 13 mm solid state backscatter detector with segment switching.

• Video outputs: User selectable displays from a max of 8 available images.

• Recording options: Video hardcopy unit, 35mm camera, 600dpi laser printer or storage of digital images on hard disk or on floppy disk. Digital image store in TIFF formats for transfer to other software packages.

• Sample dimensions etc: Solid samples of dimensions of about 7mm max. Whether conducting or non-conducting should be mentioned. Volatile samples, as stored or after receiving energy from the electron beam, are detrimental to the instrument. Therefore, stability of the samples under such conditions should b ensured.