Synchrotrons versus globars, point-detectors versus focal plane arrays: Selecting the best source and detector for specific infrared microspectroscopy and imaging applications

Organic Carbon Chemistry in Soils Observed by Synchrotron-Based Spectroscopy

“…This technique enables probing and identifying the chemical makeup or molecular constituents of biological or complex heterogeneous soil or geological samples from their spatially resolved vibrational spectra on a microscopic scale (Johnston and Aochi, 1996;Lehmann et al, 2007;Marinkovic et al, 2002). Conventional benchtop infrared spectrometers are commonly equipped with thermal (globar) sources that provide infrared light that is comparable to the infrared radiation emitted from a synchrotron (Miller and Dumas, 2006;Miller and Smith, 2005). Yet, if the aperture for spatial investigations is decreased to limit the field of view to a small region of interest, the brightness of conventional benchtop infrared sources is by two to three orders of magnitude too low compared to synchrotron radiation (Bonetta et al, 2002;Raab and Martin, 2001), thus resulting in diffraction effects.…”

IR microscopy utilizing intense supercontinuum light source

“…High spatial resolution measurements require small apertures and drastically reduce the amount of light available for imaging. This results in long acquisition times [18] and calls for a more intense and spatially coherent light source such as synchrotron radiation. The synchrotron sources are in many ways ideal for infrared microscopy [3,18], but price, complexity, and availability seriously limits the spreading of IR microscopes based on such sources.…”

“…This results in long acquisition times [18] and calls for a more intense and spatially coherent light source such as synchrotron radiation. The synchrotron sources are in many ways ideal for infrared microscopy [3,18], but price, complexity, and availability seriously limits the spreading of IR microscopes based on such sources. A more widespread method for increasing the spatial resolution is based on the attenuated total internal reflection technique [19].…”

“…1b, the generated SC ranges from 1.4 μm to 4.0 μm. The spectral density at 3.5 μm corresponds to a spectral brightness of 300 kW/(nm m 2 sr), which is of the same order of magnitude as synchrotron sources used for IR microscopy [18,20]. The SC output from the fiber is collimated with an aspherical ZnSe lens, having a focal length of 6 mm and NA = 0.25.…”

All fiber based supercontinuum light source utilized for IR microscopy

“…High resolution infrared (IR) microscopy requires intense and spatial coherent sources of infrared radiation [2]. However, most IR microscopes are based on thermal IR sources with very low brightness and is therefore not suitable for high resolution measurements.…”