CL color and intensity are not only dependent on the characteristics of the sample but also on the working conditions of the microscope in use. Here, acceleration voltage and beam current of the electron beam are of major importance.
The lumic CL microscope - unlike other common devices in the market - is equipped with a "hot cathode", which is an electrically heated tungsten filament. All electric parameters which are decisive for the intensity of the emitted luminescence can be exactly controlled. So the most suitable beam current density for each specific sample is obtained by varying acceleration voltage and beam current.
Manganese activated carbonates e.g. mostly are excited at relatively low beam current energies, but quartz e.g. often requires relatively high beam currents to emit visible intensities of luminescence. The lumic CL microscope is very successful in showing the weak luminescence features of such poorly activated minerals.
Compared to a CL accessory attached to a scanning electron microscope (SEM), our optical CL microscope benefits from its ability to show actual visible color features immediately through the eyepiece. In a SEM CL colors can only be evaluated using a spectrograph. However, if an exact examination of the color is required, we can supply the complete spectrographic equipment for our microscope.
The lumic Microscope
The complete HC3-LM device as shown consists of a modified OLYMPUS light microscope with conical vacuum distributor and sample chamber. A stainless steel electron gun attached to the distributor is supplied by a high performance HV power supply in a 19” casing that also contains the electronics for beam deflection and vacuum control. Vacuum is provided by a high-vacuum turbomolecular pumping system. For convenient working the microscope and the casing are placed side by side on the working desk, and the vacuum system rests on the floor. The picture shows the digital imaging system consisting of a high sensitivity CCD camera and a computer with LCD display being available as an optional accessory (highly recommended).
For details follow these links:
• microscope
• power supply
• high vacuum system
• additional equipment