Editing Optical microscope (section)

==Operation==
[[Image:CBP checking authenticity of a travel document.jpg|thumb|right|250px|U.S. [[U.S. Customs and Border Protection|CBP]] [[Office of Field Operations]] agent checking the [[Authentication|authenticity]] of a [[travel document]] at an [[international airport]] using a [[stereo microscope]]]]

===Illumination techniques===
{{main|Microscopy}}
Many techniques are available which modify the light path to generate an improved [[contrast (vision)|contrast]] image from a sample. Major techniques for generating increased contrast from the sample include [[Polarized light microscopy|cross-polarized light]], [[dark field]], [[phase contrast]] and [[differential interference contrast]] illumination. A recent technique ([[Sarfus]]) combines [[Polarized light microscopy|cross-polarized light]] and specific contrast-enhanced slides for the visualization of nanometric samples.{{cn|date=December 2024}}
<gallery caption="Four examples of transilumination techniques used to generate contrast in a sample of [[tissue paper]]. 1.559 μm/pixel." align="center">
File:Paper Micrograph Bright.png|[[Bright field microscopy|Bright field]] illumination, sample contrast comes from [[absorbance]] of light in the sample.
File:Paper Micrograph Cross-Polarised.png|[[Polarized light microscopy|Cross-polarized light]] illumination, sample contrast comes from rotation of [[Polarization (waves)|polarized]] light through the sample.
File:Paper Micrograph Dark.png|[[Dark field]] illumination, sample contrast comes from light [[scattered radiation|scattered]] by the sample.
File:Paper Micrograph Phase.png|[[Phase contrast]] illumination, sample contrast comes from [[Interference (wave propagation)|interference]] of different path lengths of light through the sample.
</gallery>

===Other techniques===
Modern microscopes allow more than just observation of transmitted light image of a sample; there are many techniques which can be used to extract other kinds of data. Most of these require additional equipment in addition to a basic compound microscope.{{cn|date=December 2024}}
* Reflected light, or incident, illumination (for analysis of surface structures)
* Fluorescence microscopy, both:
:*[[Epifluorescence microscopy]]
:*[[Confocal microscopy]]
* [[Ultraviolet–visible spectroscopy|Microspectroscopy]] (where a UV-visible spectrophotometer is integrated with an optical microscope)
* Ultraviolet microscopy
* Near-Infrared microscopy
* Multiple transmission microscopy<ref>{{Cite journal|last1=Pégard|first1=Nicolas C.|last2=Fleischer|first2=Jason W.|date=2011-05-01|title=Contrast Enhancement by Multi-Pass Phase-Conjugation Microscopy|url=https://opg.optica.org/abstract.cfm?uri=CLEO_SI-2011-CThW6|journal=CLEO:2011 - Laser Applications to Photonic Applications (2011), Paper CThW6|language=EN|publisher=Optica Publishing Group|pages=CThW6|doi=10.1364/CLEO_SI.2011.CThW6|isbn=978-1-55752-910-7 |s2cid=13366261 |url-access=subscription}}</ref> for contrast enhancement and aberration reduction.
* Automation (for automatic scanning of a large sample or image capture)