page_title: Optical microscope
section_title: Applications
hierarchical_section_title: Optical microscope / Applications
caption_attribution_description: English: Vaginal wet mount (using a potassium hydroxide preparation and light microscopy at 40x magnification) showing slings of pseudohyphae of Candida albicans surrounded by round vaginal epithelial cells, conferring a diagnosis of candidal vulvovaginitis.
context_page_description: The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of 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 resolution and sample contrast.
  The object is placed on a stage and may be directly viewed through one or two eyepieces on the microscope. In high-power microscopes, both eyepieces typically show the same image, but with a stereo microscope, slightly different images are used to create a 3-D effect. A camera is typically used to capture the image.
  The sample can be lit in a variety of ways. Transparent objects can be lit from below and solid objects can be lit with light coming through or around the objective lens. Polarised light may be used to determine crystal orientation of metallic objects. Phase-contrast imaging can be used to increase image contrast by highlighting small details of differing refractive index.
context_section_description: Optical microscopy is used extensively in microelectronics, nanophysics, biotechnology, pharmaceutic research, mineralogy and microbiology.
  Optical microscopy is used for medical diagnosis, the field being termed histopathology when dealing with tissues, or in smear tests on free cells or tissue fragments.
  In industrial use, binocular microscopes are common. Aside from applications needing true depth perception, the use of dual eyepieces reduces eye strain associated with long workdays at a microscopy station. In certain applications, long-working-distance or long-focus microscopes are beneficial.  An item may need to be examined behind a window, or industrial subjects may be a hazard to the objective.  Such optics resemble telescopes with close-focus capabilities.
  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.  The other (and older) type has simple crosshairs and a micrometer mechanism for moving the subject relative to the microscope.
caption: A 40x magnification image of cells in a medical smear test taken through an optical microscope using a wet mount technique, placing the specimen on a glass slide and mixing with a salt solution
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