Chemical Imaging Assignment HelpChemical imaging
is the analytical capability for creating a visual image of components distribution from simultaneous measurement of spectra and spatial and spectra time information. The main idea of chemical imaging, that analyst may prefer to take as many data spectrum is measured at a particular chemical component in the spatial location at the time; this is useful for chemical quantification and identification. For selecting an image plane at a particular data, spectrum can map the spatial distribution of sample components which provides that their spectral signatures are different at the selected data spectrum.
The Software for chemical imaging is distinguished and most specific from chemical methods such as chemo metrics. The Hyperspectral imaging is most often applied to either solid or gel or solid samples; It has applications in biology, chemistry, medicine, pharmacy
, food science, agriculture and industry, biotechnology. Raman, IR, and NIR chemical imaging is also referred to as hyper-spectral.
Other selective imaging techniques and ultra-sensitive are also in use that involve fluorescence micro spectroscopy or UV- visible. Many imaging techniques may be used for analyzing samples of all sizes, from the single molecule to the cellular level in medicine and biology, and to the images of planetary systems in astronomy, different instrumentation is employed for making observations on such widely different systems.
Imaging instrumentation has three components, a spectrally selective element, a radiation source to illuminate the sample and typically a detector array for collecting the images. When many stacked spectral channel is collected for different locations of the micro-spectrometer focus on planar array or a line in the focal plane, the data is known as hyperspectral; fewer wavelength data sets are also called multi-spectral.
The hyper-cube is the data format. The set data can be visualized as a data cube. The three-dimensional block of data spanning with a series of wavelengths (lambda), two spatial dimensions (x and y), makes up the third (spectral) axis. The hypercube can be mathematically and visually treated as a series of spectrally resolved images or a series of spatially resolved spectra. Many materials, both naturally occurring and manufactured develop their functionality from the spatial distribution of sample components. For example, the extended release pharmaceutical formulation is achieved by using a coating. This coating acts as a barrier layer.
The active ingredient is controlled by imperfections in the coating, and the presence of this barrier and such discontinuities may result in altered performance. Irregularities or contaminants in silicon wafers or printed micro-circuits in the semi-conductor industry, can lead to the failure of these components. Even small changes in distribution and chemical composition may be an early indicator of the disease. The material that is dependent upon chemical gradients for functionality may be amenable to study by an analytical technique that couples chemical characterization
and spatial. The ‘what’ and the ‘where’ must be measured, to efficiently and effectively design and manufacture such materials. As manufactured materials become more complex, the demand for this type of analysis is increasing. Chemical imaging techniques is critical to understand modern manufactured products. In some cases it is a non-destructive technique so that samples are preserved for further testing.
In the early 1990s, commercially available laboratory-based chemical imaging systems emerged. As sophisticated computers and high- speed electronics became more commonplace, and infrared cameras became readily available, laboratory chemical imaging systems were introduced. The Chemical imaging in less than a decade became more commonplace analytical technique that is used for quality assurance (QA), R& D and quality control (QC).
The Chemical imaging provides additional information by way of the simultaneous acquisition of spatially resolved spectra and shares the fundamentals of vibrational spectroscopic techniques. With the attributes of spectroscopic measurements, it combines the advantages of digital imaging. The interaction of light with matter is measured by vibrational spectroscopy. The Photons that interact with a sample are scattered and absorbed, and the pattern of absorption provides fingerprint or information, on the molecules that are present in the sample. The chemical imaging can be carried out in one of the following modes in terms of observation setup:, emission (fluorescence), (optical) transmission or scattering, (optical) absorption.
The Raman scattering modes and fluorescence (emission) are the most expensive, sensitive and powerful. The radiation goes through a sample in a transmission measurement. It is measured on the far side of the sample by a detector placed. The selection of wavelength can be accomplished with a tunable filter, fixed filter, an interferometer, spectrograph or other devices. It is not efficient to collect a significant number of wavelengths for a fixed filter approach; the multispectral data are usually collected. TheInterferometer-based chemical imaging requires that the entire spectral ranges be collected, and therefore results in hyperspectral
Depending on analytical requirements, tunable filters have the flexibility to provide either, or hyperspectral
or multi data.Based on a Focal Plane Array
, Spectra are generally measured with an imaging spectrometer
. For their use in chemical imaging, some words common in optical microscopy, spectroscopy and photography have been adapted or their scope has been modified. They include: field of view, resolution and magnification. In chemical imaging, there are two types of resolution. The minimum distance between two objects which is required for them to be detected as distinct objects is known as spatial resolution. It is influenced by the field of view, area probed by the analysis, the physical measure of the size.