Analytical Technologies Singapore

Raster scanning VS Global Imaging

Raster scanning is done by taking sequential measurements of the spectra of adjacent regions of a sample by moving the sample point by point or line by line until the region of interest has been covered.

On the other hand, imaging consists of focusing the image of a sample on an array detector and measuring for each pixel the intensity of light at one particular wavelength, much like taking a photograph, but at a single wavelength. In some applications, the power of the laser used in imaging can be orders of magnitude stronger than in mapping, since the power is spread on the whole region instead of a single point or line, thus avoiding the damaging of a sample. Imaging also permits a higher resolution, reduces the acquisition time by orders of magnitude and requires no prior knowledge of the sample contrary to mapping.

With global imaging, the gain in acquiring 3D data, 2D spatial and 1D spectral, is important since only a  few monochromatic images are required to cover the complete spectral range where one needs to take the full spectrum for each point or line in the image with other technologies

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