Raman hyperspectral imaging

An alternative approach for NIR hyperspectral imaging to that described above is to use a Fourier transform NIR (FT-NIR) spectrometer. As the design of FT-NIR microspectrometers is more similar to that of instruments for mid-lR hyperspectral imaging than the dispersive instruments described above, they will be described later (see Section 1.6). 

Chemicon, Corp. (now Chemimage, Corp.) market a Raman imaging spectrometer that shares some of the features of the NIH instrument reported by Goldstein et al. but, nonetheless, has some significant differences. First and foremost, wavelength selechon is accomplished through the use of an LCTF rather than an AOTF. The spectral bandpass of this instrument is 9cm, and it has the capability of 

---

The bandpass of a typical AOTF ranges from several nanometers to tens of nanometers for the visible and NIR spectral regions. This resolution is suitable for fluorescence spectroscopy where bands are very broad, and is just adequate for Raman hyperspectral imaging, albeit with lower resolution than may be achieved with a monochromator (see Section 1.5). A NIR spectrometer based on an AOTF has also been sold commercially. However, the transmission of these devices for... 

Infrared (IR) hyperspectral imaging, of course, can provide valuable and complementary information to Raman hyperspectral imaging, especially with instruments that combine both Raman and IR microscopy while measuring the sample at the same location [3]. 

Empirical Approach to Successful Raman Hyperspectral Imaging 383... 

The goal of Raman hyperspectral imaging analysis is to obtain chemical images which provide both chemical and spatial characterization of the sample. In an ideal world, each of the chemical components is identified and its distribution visualized the analysis results then also provide the statistical and quantitative results. 

Empirical Approach to Succes ul Raman Hyperspectral Imaging 389... 

U.3 Empirical Approach to Succes u Raman Hyperspectral Imaging 395... 

Raman hyperspectral imaging provides an excellent means of characterizing the chemical and spatial composition of pharmaceutical products. The most important point when performing successful Raman hyperspectral imaging is to understand the intertwined relationship between spectroscopy and imaging, as the spectral quahty-and especially the spectral resolution and SNR-will have a direct impact on the spatial quality produced. 

The underlying assumptions for multivariate analysis are different for macro- and microanalyses. While Raman hyperspectral imaging is preferred for microanalysis and heterogeneous samples, macroanalysis has been shown preferable for homogeneous samples. However, whichever approach is utilized the... 

In addition, EDXRF hyperspectral imaging can be employed to detect the elemental distribution of the sample, with the results being used to complement Raman hyperspectral imaging. 

However, Raman and infrared images are often affected by intense and irregularly shaped baselines. This complex behavior is often attributed to fluorescence contributions in Raman hyperspectral images or to other phenomena, such as the Mie scattering [15], commonly found in biological IR images. For these situations, more sophisticated baseline correction methods that can handle complex baselines changing from pixel to pixel have appeared. 

---