Electronic wavelength scanning image

Fig. 3 A conventional scanning electron micrograph (a), a PM image (b), and a hyperspectral wavelength-shift image of the band-gap emission (c) at a triple-grain junction in polycrystalline BaTiOs. Micrograph and maps were taken at the same location.

Other modulation techniques are oscillation (tilting) of an interference filter [3] and modulation of the electron beam scan pattern in a vidicon or image-disk-sector photomultiplier spectrophotometer [34]. This was the first nonmechanical wavelength modulation. Wavelength modulation induces a synchronous modulation of the amplitude. If these intensities are expanded, for instance, in the form of a Taylor series in Aq, and the powers of the sine functions are expressed as sine and cosine functions of the corresponding multiple angles, then the derivatives can be obtained from the Fourier coefficients (see Sec. 2.1.3.3) of these series. The second derivative is obtained from the second harmonic of the induced intensity. 

Wavelength scanning in NIR hyperspectral imaging spectrometers has also been accomplished with both a scanning monochromator and an acousto-optic tunable filter (AOTF). AOTFs are electro-optical devices that function as electronically tunable filters. They rely on a birefringent crystal, the optical properties of which vary upon interaction of the crystal with an acoustic wave. The resulting... 

The electron-optical performance of the EPMA system is indistinguishable from that of a conventional scanning electron microscope (SEM) thus, EPMA combines all of the imaging capabilities of a SEM with quantitative elemental analysis using both energy- and wavelength-dispersive X-ray spectrometry. ... 

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