Editing Microscopy (section)

== Infrared microscopy ==
The term ''infrared microscopy'' refers to microscopy performed at [[infrared]] wavelengths. In the typical instrument configuration, a [[Fourier-transform infrared spectroscopy|Fourier Transform Infrared Spectrometer]] (FTIR) is combined with an optical microscope and an [[infrared detector]]. The infrared detector can be a single point detector, a linear array or a 2D focal plane array. FTIR provides the ability to perform chemical analysis via [[infrared spectroscopy]] and the microscope and point or array detector enable this chemical analysis to be spatially resolved, i.e. performed at different regions of the sample. As such, the technique is also called infrared microspectroscopy<ref name="G Kazarian 2014">H M Pollock and S G Kazarian, Microspectroscopy in the Mid-Infrared, in Encyclopedia of Analytical Chemistry (Robert A. Meyers, Ed, 1-26 (2014), John Wiley & Sons Ltd,</ref><ref name="wiley1">{{cite encyclopedia|doi=10.1002/9780470027318.a5609.pub2 | title=Microspectroscopy in the Mid-Infrared | encyclopedia=Encyclopedia of Analytical Chemistry | pages=1–26 | year=2014 | author=Pollock Hubert M| isbn=9780470027318 }}</ref>
An alternative architecture called [[Laser Direct Infrared (LDIR) Imaging]] involves the combination of a tuneable infrared light source and single point detector on a flying objective. This technique is frequently used for infrared [[chemical imaging]], where the image contrast is determined by the response of individual sample regions to particular IR wavelengths selected by the user, usually specific IR absorption bands and associated [[molecular resonance]]s. A key limitation of conventional infrared microspectroscopy is that the spatial resolution is [[diffraction-limited]]. Specifically the spatial resolution is limited to a figure related to the wavelength of the light. For practical IR microscopes, the spatial resolution is limited to 1-3x the wavelength, depending on the specific technique and instrument used. For mid-IR wavelengths, this sets a practical spatial resolution limit of ~3-30 μm.

IR versions of sub-diffraction microscopy also exist.<ref name="G Kazarian 2014"/><ref name="wiley1"/> These include IR [[Near-field scanning optical microscope|Near-field scanning optical microscope (NSOM)]],<ref>H M Pollock and D A Smith, The use of near-field probes for vibrational spectroscopy and photothermal imaging, in Handbook of vibrational spectroscopy, J.M. Chalmers and P.R. Griffiths (eds), John Wiley & Sons Ltd, Vol. 2, pp. 1472 - 1492 (2002)</ref> [[photothermal microspectroscopy]] and [[AFM-IR|atomic force microscope based infrared spectroscopy (AFM-IR)]], as well as scattering-type Scanning Near-field Optical Microscopy (s-SNOM)<ref>{{Cite journal|last1=Keilmann|first1=Fritz|last2=Hillenbrand|first2=Rainer|date=2004-04-15|editor-last=Richards|editor-first=David|editor2-last=Zayats|editor2-first=Anatoly|title=Near-field microscopy by elastic light scattering from a tip|url=https://royalsocietypublishing.org/doi/10.1098/rsta.2003.1347|journal=Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences|language=en|volume=362|issue=1817|pages=787–805|doi=10.1098/rsta.2003.1347|pmid=15306494|s2cid=20211405|issn=1364-503X|access-date=2020-11-02|archive-date=2020-11-09|archive-url=https://web.archive.org/web/20201109004419/https://royalsocietypublishing.org/doi/10.1098/rsta.2003.1347|url-status=live}}</ref> & [[nano-FTIR]] that provide nanoscale spatial resolution at IR wavelengths.