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NeedsGlasses (talk | contribs) Undid revision 1217876039 by Mathmensch (talk) i believe the original was correct. Solid objects cannot be lit from below but transparent ones can be. When viewing solid objects the light comes through the objective via a beam splitter and then reflects off the solid object and back up through the objective lens. |
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{{Use dmy dates|date=March 2019}}
[[File:Scientists are working in the lab.9.jpg|thumb|300px|
The '''optical microscope''', also referred to as a '''light microscope''', is a type of [[microscope]] that commonly uses [[visible spectrum|visible light]] and a system of [[lens (optics)|lenses]] to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve [[optical resolution|resolution]] and sample [[contrast (vision)|contrast]].
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==Types==
[[File:Microscope simple diagram.png|thumb|right|150px|Diagram of a simple microscope]]
There are two basic types of optical microscopes: simple microscopes and compound microscopes. A simple microscope uses the [[optical power]] of a single lens or group of lenses for magnification. A compound microscope uses a system of lenses (one set enlarging the image produced by another) to achieve a much higher magnification of an object. The vast majority of modern [[research]] microscopes are compound microscopes, while some cheaper commercial [[digital microscope]]s are simple single
===Simple microscope===
A simple microscope uses a lens or set of lenses to enlarge an object through angular magnification alone, giving the viewer an erect enlarged [[virtual image]].<ref>{{cite web |url=http://www.msnucleus.org/membership/html/jh/biological/microscopes/lesson2/microscopes2c.html |publisher=msnucleus.org |access-date=15 January 2017 |title=Lesson 2 – Page 3, CLASSIFICATION OF MICROSCOPES |author=JR Blueford |url-status=live |archive-url=https://web.archive.org/web/20160510210018/http://msnucleus.org/membership/html/jh/biological/microscopes/lesson2/microscopes2c.html |archive-date=10 May 2016 }}</ref><ref>{{cite book|author=Trisha Knowledge Systems|title=The IIT Foundation Series - Physics Class 8, 2/e|url=https://books.google.com/books?id=NKh9dQKnTdEC&pg=PA213|publisher=Pearson Education India|isbn=978-81-317-6147-2|page=213}}</ref> The use of a single convex lens or groups of lenses are found in simple magnification devices such as the [[magnifying glass]], [[loupe]]s, and [[eyepiece]]s for
===Compound microscope===
[[File:Microscope compound diagram.png|thumb|left|150px|Diagram of a compound microscope]]
A compound microscope uses a lens close to the object being viewed to collect light (called the [[Objective (optics)|objective]] lens), which focuses a [[real image]] of the object inside the microscope (image 1). That image is then magnified by a second lens or group of lenses (called the [[eyepiece]]) that gives the viewer an enlarged inverted virtual image of the object (image 2).<ref name=Watt>{{cite book|author=Ian M. Watt|title=The Principles and Practice of Electron Microscopy|url=https://books.google.com/books?id=Y6-sE4gUX-QC&pg=PA6|year=1997|publisher=Cambridge University Press|isbn=978-0-521-43591-8|page=6}}</ref> The use of a compound objective/eyepiece combination allows for much higher magnification. Common compound microscopes often feature exchangeable objective lenses, allowing the user to quickly adjust the magnification.<ref name=Watt/> A compound microscope also enables more advanced illumination setups, such as [[phase contrast]].
===Other microscope variants===
There are many variants of the compound optical microscope design for specialized purposes. Some of these are physical design differences allowing specialization for certain purposes:
* [[Stereo microscope]], a low-powered microscope which provides a stereoscopic view of the sample, commonly used for dissection.
* [[Comparison microscope]]
* [[Inverted microscope]], for studying samples from below; useful for cell cultures in liquid
* Fiber optic connector inspection microscope, designed for connector end-face inspection
* [[Traveling microscope]], for studying samples of high [[optical resolution]].
Other microscope variants are designed for different illumination techniques:
* [[Petrographic microscope]], whose design usually includes a polarizing filter, rotating stage, and gypsum plate to facilitate the study of minerals or other crystalline materials whose optical properties can vary with orientation.
* [[Polarizing microscope]], similar to the petrographic microscope.
* [[Phase-contrast microscope]], which applies the phase contrast illumination method.
* [[Epifluorescence microscope]], designed for analysis of samples
* [[Confocal microscope]], a widely used variant of epifluorescent illumination
* [[Two-photon excitation microscopy|Two-photon microscope]], used to image fluorescence deeper in scattering media and reduce photobleaching, especially in living samples.
* Student microscope – an often low-power microscope with simplified controls and sometimes low
* [[Ultramicroscope]], an adapted light microscope that uses [[light scattering]] to allow viewing of tiny particles whose diameter is below or near the wavelength of visible light (around 500 nanometers); mostly obsolete since the advent of [[electron microscope]]s
* [[Tip-enhanced Raman spectroscopy|Tip-enhanced Raman microscope]], is a variant of optical microscope based on [[tip-enhanced Raman spectroscopy]], without traditional wavelength-based resolution limits.<ref>{{Cite journal|last1=Kumar|first1=Naresh|last2=Weckhuysen|first2=Bert M.|last3=Wain|first3=Andrew J.|last4=Pollard|first4=Andrew J.|date=April 2019|title=Nanoscale chemical imaging using tip-enhanced Raman spectroscopy|journal=Nature Protocols|volume=14|issue=4|pages=1169–1193|doi=10.1038/s41596-019-0132-z|pmid=30911174|issn=1750-2799|doi-access=free}}</ref><ref>{{Cite journal|last1=Lee|first1=Joonhee|last2=Crampton|first2=Kevin T.|last3=Tallarida|first3=Nicholas|last4=Apkarian|first4=V. Ara|date=April 2019|title=Visualizing vibrational normal modes of a single molecule with atomically confined light|journal=Nature|volume=568|issue=7750|pages=78–82|doi=10.1038/s41586-019-1059-9|pmid=30944493|bibcode=2019Natur.568...78L |s2cid=92998248 |issn=1476-4687}}</ref> This microscope primarily realized on the [[Scanning probe microscopy|scanning-probe microscope]] platforms using all optical tools.
===Digital microscope===
[[File:2008Computex DnI Award AnMo Dino-Lite Digital Microscope.jpg|thumb|right|200px|A miniature [[USB microscope]]
{{Main|Digital microscope}}
A
Low-powered digital microscopes, [[USB microscope]]s, are also commercially available. These are essentially [[webcam]]s with a high-powered [[macro lens]] and generally do not use [[transillumination]]. The camera is attached directly to
Digital microscopy with very low light levels to avoid damage to vulnerable biological samples is available using sensitive [[photon counting|photon-counting]] digital cameras. It has been demonstrated that a light source providing pairs of [[Photon entanglement|entangled photons]] may minimize the risk of damage to the most light-sensitive samples. In this application of [[ghost imaging]] to photon-sparse microscopy, the sample is illuminated with infrared photons, each
==History==
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===Invention===
The earliest microscopes were single [[lens (optics)|lens]] [[magnifying glass]]es with limited magnification, which date at least as far back as the widespread use of lenses in [[eyeglasses]] in the 13th century.<ref>Atti Della Fondazione Giorgio Ronchi E Contributi Dell'Istituto Nazionale Di Ottica, Volume 30, La Fondazione-1975, page 554</ref>
Compound microscopes first appeared in Europe around 1620<ref>{{cite book|author1=Albert Van Helden|author2=Sven Dupré|author3=Rob van Gent|title=The Origins of the Telescope|url=https://books.google.com/books?id=XguxYlYd-9EC&pg=PA24|year=2010|publisher=Amsterdam University Press|isbn=978-90-6984-615-6|page=24}}</ref><ref>William Rosenthal, Spectacles and Other Vision Aids: A History and Guide to Collecting, Norman Publishing, 1996, pp. 391–392</ref> including one demonstrated by [[Cornelis Drebbel]] in London (around 1621) and one exhibited in Rome in 1624.<ref name="Raymond J. Seeger 2016, page 24">Raymond J. Seeger, Men of Physics: Galileo Galilei, His Life and His Works, Elsevier - 2016, page 24</ref><ref name="J. William Rosenthal 1996, page 391">J. William Rosenthal, Spectacles and Other Vision Aids: A History and Guide to Collecting, Norman Publishing, 1996, page 391</ref>
The actual inventor of the compound microscope is unknown although many claims have been made over the years. These include a claim 35<ref>{{cite book|author1=Albert Van Helden|author2=Sven Dupré|author3=Rob van Gent|title=The Origins of the Telescope|url=https://books.google.com/books?id=XguxYlYd-9EC&pg=PA36|year=2010|publisher=Amsterdam University Press|isbn=978-90-6984-615-6|pages=32–36, 43}}</ref> years after they appeared by [[Dutch people|Dutch]] spectacle-maker Johannes Zachariassen that his father, [[Zacharias Janssen]], invented the compound microscope and/or the telescope as early as 1590. Johannes'
[[Galileo Galilei]] is
[[Christiaan Huygens]], another Dutchman, developed a simple 2-lens ocular system in the late 17th century that was [[Achromatic lens|achromatically]] corrected, and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and other minor disadvantages.
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===Popularization===
[[File:Stelluti bees1630.jpg|thumb|right|The oldest published image known to have been made with a microscope: bees by [[Francesco Stelluti]], 1630<ref>Gould, Stephen Jay (2000) ''[[The Lying Stones of Marrakech]]''. Harmony Books. {{ISBN|0-609-60142-3}}.</ref>]]
[[Antonie van Leeuwenhoek]] (1632–1724) is credited with bringing the microscope to the attention of biologists, even though simple magnifying lenses were already being produced in the 16th century. Van Leeuwenhoek's home-made microscopes were simple microscopes, with a single very small, yet strong lens. They were awkward in use, but enabled van Leeuwenhoek to see detailed images. It took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes, due to difficulties in configuring multiple lenses. In the 1850s, [[John Leonard Riddell]], Professor of Chemistry at [[Tulane University]], invented the first practical binocular microscope while carrying out one of the earliest and most extensive American microscopic investigations of [[cholera]].<ref name="Riddell">{{cite journal | author = Riddell JL | title = On the binocular microscope | journal = Q J Microsc Sci | volume = 2 | pages = 18–24 | year = 1854}}</ref><ref name="Cassedy">{{cite journal | author = Cassedy JH | title = John L. Riddell's Vibrio biceps: Two documents on American microscopy and cholera etiology 1849–59 | journal = J Hist Med | volume = 28 | pages = 101–108 | year = 1973 | issue=2| doi = 10.1093/jhmas/xxviii.2.101 | pmid = 4572620 }}</ref>
===Lighting techniques===
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[[File:Optical microscope nikon alphaphot.jpg|thumb|right|300px|Basic optical transmission microscope elements (1990s)]]
All modern optical microscopes designed for viewing samples by transmitted light share the same basic components of the light path. In addition, the vast majority of microscopes have the same 'structural' components<ref>
* Eyepiece (ocular lens) (1)
* Objective turret, revolver, or revolving nose piece (to hold multiple objective lenses) (2)
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Focusing starts at lower magnification in order to center the specimen by the user on the stage. Moving to a higher magnification requires the stage to be moved higher vertically for re-focus at the higher magnification and may also require slight horizontal specimen position adjustment. Horizontal specimen position adjustments are the reason for having a mechanical stage.
Due to the difficulty in preparing specimens and mounting them on slides, for children it
===Light source===
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* Ultraviolet microscopy
* Near-Infrared microscopy
* Multiple transmission microscopy<ref>
* Automation (for automatic scanning of a large sample or image capture)
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Measuring microscopes are used for precision measurement. There are two basic types.
One has a [[reticle]] graduated to allow measuring distances in the focal plane.<ref>{{cite book|first=Gustaf |last=Ollsson
Very small, portable microscopes have found some usage in places where a laboratory microscope would be a burden.<ref>{{Cite web|last=Linder|first=Courtney|date=2019-11-22|title=If You've Ever Wanted a Smartphone Microscope, Now's Your Chance|url=https://www.popularmechanics.com/technology/gear/a29873640/smartphone-microscope-diple/|access-date=2020-11-03|website=Popular Mechanics|language=en-US}}</ref>
==Limitations==
[[File:Ernst-Abbe-Denkmal Jena Fürstengraben - 20140802 125709.jpg|thumb|The diffraction limit set in stone on a monument for [[Ernst Abbe]]
At very high magnifications with transmitted light, point objects are seen as fuzzy discs surrounded by [[diffraction]] rings. These are called [[Airy disk]]s. The ''resolving power'' of a microscope is taken as the ability to distinguish between two closely spaced Airy disks (or, in other words the ability of the microscope to reveal adjacent structural detail as distinct and separate). It is these impacts of diffraction that limit the ability to resolve fine details. The extent and magnitude of the diffraction patterns are affected by both the [[wavelength]] of [[light]] (λ), the refractive materials used to manufacture the objective lens and the [[numerical aperture]] (NA) of the objective lens. There is therefore a finite limit beyond which it is impossible to resolve separate points in the objective field, known as the [[Diffraction-limited system|diffraction limit]]. Assuming that optical aberrations in the whole optical set-up are negligible, the resolution ''d'', can be stated as:
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====Structured illumination SMI====
SMI (spatially modulated illumination microscopy) is a light optical process of the so-called [[point spread function]] (PSF) engineering. These are processes which modify the PSF of a [[microscope]] in a suitable manner to either increase the optical resolution, to maximize the precision of [[distance]] measurements of fluorescent objects that are small relative to the [[wavelength]] of the illuminating light, or to extract other structural parameters in the nanometer range.<ref>{{cite book|doi=10.1117/12.336833|title=Laterally modulated excitation microscopy: improvement of resolution by using a diffraction grating|year=1999|last1=Heintzmann|first1=Rainer|editor-first1=Irving J. |editor-first2=Herbert |editor-first3=Jan |editor-first4=Katarina |editor-first5=Pierre M. |editor-last1=Bigio |editor-last2=Schneckenburger |editor-last3=Slavik |editor-last4=Svanberg |editor-last5=Viallet |volume=3568|pages=185–196|series=Optical Biopsies and Microscopic Techniques III|s2cid=128763403 }}</ref><ref>Cremer, Christoph; Hausmann, Michael; Bradl, Joachim and Schneider, Bernhard "Wave field microscope with detection point spread function", {{US patent|7342717}}, priority date 10 July 1997</ref>
====Localization microscopy SPDMphymod====
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SPDM (spectral precision distance microscopy), the basic localization microscopy technology is a light optical process of [[fluorescence microscopy]] which allows position, distance and angle measurements on "optically isolated" particles (e.g. molecules) well below the theoretical [[limit of resolution]] for light microscopy. "Optically isolated" means that at a given point in time, only a single particle/molecule within a region of a size determined by conventional optical resolution (typically approx. 200–250 nm [[diameter]]) is being registered. This is possible when [[molecules]] within such a region all carry different spectral markers (e.g. different colors or other usable differences in the [[light emission]] of different particles).<ref>{{cite journal |doi=10.1007/s00340-008-3152-x|title=SPDM: light microscopy with single-molecule resolution at the nanoscale|year=2008|journal=Applied Physics B|volume=93|issue=1|pages=1–12|last1=Lemmer|first1=P.|last2=Gunkel|first2=M.|last3=Baddeley|first3=D.|last4=Kaufmann|first4=R.|last5=Urich|first5=A.|last6=Weiland|first6=Y.|last7=Reymann|first7=J.|last8=Müller|first8=P.|last9=Hausmann|first9=M.|last10=Cremer|first10=C.|bibcode=2008ApPhB..93....1L|s2cid=13805053 }}</ref><ref>{{cite book|doi=10.1117/12.260797|chapter=Comparative study of three-dimensional localization accuracy in conventional, confocal laser scanning and axial tomographic fluorescence light microscopy|year=1996|last1=Bradl|first1=Joachim|editor5-first=Pierre M|editor5-last=Viallet|editor4-first=Katarina|editor4-last=Svanberg|editor3-first=Herbert|editor3-last=Schneckenburger|editor2-first=Warren S|editor2-last=Grundfest|editor1-first=Irving J|editor1-last=Bigio|title=Optical Biopsies and Microscopic Techniques|volume=2926|pages=201–206|series=Optical Biopsies and Microscopic Techniques|s2cid=55468495 }}</ref><ref>{{cite journal|author1=Heintzmann, R.|author2=Münch, H.|author3=Cremer, C.|year=1997|title=High-precision measurements in epifluorescent microscopy – simulation and experiment|journal=Cell Vision|volume=4|pages=252–253|url=http://www.kip.uni-heidelberg.de/AG_Cremer/sites/default/files/Bilder/pdf_1997/CellVisionVol4No2Heintzmann.pdf|url-status=live|archive-url=https://web.archive.org/web/20160216030456/http://www.kip.uni-heidelberg.de/AG_Cremer/sites/default/files/Bilder/pdf_1997/CellVisionVol4No2Heintzmann.pdf|archive-date=16 February 2016}}</ref><ref>Cremer, Christoph; Hausmann, Michael; Bradl, Joachim and Rinke, Bernd "Method and devices for measuring distances between object structures", {{US patent|6424421}} priority date 23 December 1996</ref>
Many standard fluorescent dyes like [[Green fluorescent protein|GFP]], Alexa dyes, Atto dyes, Cy2/Cy3 and fluorescein molecules can be used for localization microscopy, provided certain photo-physical conditions are present. Using this so-called SPDMphymod (physically modifiable fluorophores) technology a single laser wavelength of suitable intensity is sufficient for nanoimaging.<ref>{{cite journal|author=Manuel Gunkel|pmid=19548231|year=2009|title=Dual color localization microscopy of cellular nanostructures|volume=4|issue=6|pages=927–38|doi=10.1002/biot.200900005|journal=Biotechnology Journal|s2cid=18162278 |display-authors=etal|url=https://hal.archives-ouvertes.fr/hal-00494027/file/PEER_stage2_10.1002%252Fbiot.200900005.pdf |archive-url=https://web.archive.org/web/20190503232308/https://hal.archives-ouvertes.fr/hal-00494027/file/PEER_stage2_10.1002%252Fbiot.200900005.pdf |archive-date=2019-05-03 |url-status=live}}</ref>
====3D super resolution microscopy====
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====STED====
[[File:MAX 052913 STED Phallloidin.png|thumb|right|300px|Stimulated emission depletion (STED) microscopy image of actin filaments within a cell
[[STED microscope|Stimulated emission depletion]] is a simple example of how higher resolution surpassing the diffraction limit is possible, but it has major limitations. STED is a fluorescence microscopy technique which uses a combination of light pulses to induce fluorescence in a small sub-population of fluorescent molecules in a sample. Each molecule produces a diffraction-limited spot of light in the image, and the centre of each of these spots corresponds to the location of the molecule. As the number of fluorescing molecules is low the spots of light are unlikely to overlap and therefore can be placed accurately. This process is then repeated many times to generate the image. [[Stefan Hell]] of the Max Planck Institute for Biophysical Chemistry was awarded the 10th German Future Prize in 2006 and Nobel Prize for Chemistry in 2014 for his development of the STED microscope and associated methodologies.<ref>{{cite web|url = http://www.heise.de/english/newsticker/news/81528|title = German Future Prize for crossing Abbe's Limit|access-date = 24 February 2009|url-status = live|archive-url = https://web.archive.org/web/20090307040808/http://www.heise.de/english/newsticker/news/81528|archive-date = 7 March 2009|df = dmy-all}}</ref>
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* [http://golubcollection.berkeley.edu The Golub Collection], A collection of 17th through 19th century microscopes, including extensive descriptions
* [http://micro.magnet.fsu.edu/primer/anatomy/anatomy.html ''Molecular Expressions''], concepts in optical microscopy
* [https
* [http://openwetware.org/wiki/Microscopy OpenWetWare]
* [http://ccdb.ucsd.edu/sand/main?stype=lite&keyword=light%20microscopy&Submit=Go&event=display&start=1 Cell Centered Database]
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[[Category:Microscopes]]
[[Category:Dutch inventions]]
[[Category:Optical microscopy]]
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