Handheld Raman spectroscopy’s value for rapid field screening by safety and security personnel is well understood as evidenced by its implementation across the globe. Though Raman spectroscopy has the ability to nondestructively identify samples through transparent packaging, in real world scenarios challenging samples are frequently encountered. Raman screening must be effective for samples in a variety of packaging and for samples with coloration or impurities that give a high fluoresce that can overwhelm the Raman signal depending on the excitation laser wavelength. See through Raman technology has been developed to enable measurement through opaque packaging, sampling a larger area and with a deeper penetration depth of the Raman signal. Using a design of collinear sample illumination and Raman scattering collection at a higher efficiency, and spread over a larger sampling area, there is a lower power density of illumination on the sample, reducing issues of sample heating that can be problematic for dark samples. The measurement of a larger sample area provides more reliable identification of solids that are often inhomogeneous. This see through Raman technology and the use of a longer laser wavelength excitation overcomes many of the difficulties encountered in use of Raman spectroscopy for field testing.
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