Four types of spectrometers are available to the analyst. From the 1950’s to 1960’s nearly all the x-ray spectrometers were wavelength dispersive spectrometers.
In a wavelength dispersive spectrometer, a crystal separates the wavelengths of the fluorescence from the sample, similar to grating spectrometers for visible light. The other x-ray spectrometer available at that time was the electron microprobe, which uses a focused electron beam to excite x-rays in a solid sample as small as 10^-12 cm^3. The first microprobe was built by R. Castaing in 1951 and became commercially available in 1958. In the early 1970’s, energy dispersive spectrometers became available, which use Li-drifted silicon or germanium detectors. The advantage these instruments brought was the ability to measure the entire spectrum simultaneously. With the help of computers, deconvolution methods can be performed to extract the net intensities of individual x-rays.