Composition analysis of materials in the CMRA’s electron microscopes has been 
greatly enhanced by the addition of the latest digital signal processors, computers, and 
software, purchased with ONR funds from iXRF Inc, to the x-ray detectors on both the SEM 
and the TEM.

	In the case of traditional analog signal processing, the preamplifier output signal is 
further processed in the main amplifier to obtain the proper pulse amplitude and shape. The output 
of the amplifier is digitized with an analog-to-digital converter (ADC) and fed into a host computer 
for processing and display. 

	In the digital system, all processing is done within the digital module. Once the preamplifier 
signal is digitized, all further manipulation of the signal is linear and noise free. Digital filtering is
precise and reproducible compared with the non-ideal behavior associated with analog components and 
finite tolerance. Moreover, digital filtering is not constrained to those filter shapes realizable with 
physical components, therefore,  pulses are resolved better in time and amplitude to give improved 
throughput, greater light element sensitivity, and lower of detectability.

	The new system attached to the JSM 840A SEM (see figure) provides vastly improved X-ray 
spectrum acquisition from individual locations, lines and areas of samples. In addition, use of the new 
system with the SEM allows researchers easily to obtain composition profiles and elemental and material 
phase maps and simultaneous digital images – all from a Windows XP environment that makes data 
processing, archiving, and electronic file transfer by e-mail, ftp or web transfer straightforward. 

	The new system on the JEM2010 TEM will allow better more readily quantified data to be 
acquired, especially for the lightest elements – down to atomic number 4. At small cost, this system 
could be further upgraded for line profiling of elemental composition, across interfaces for example.