Light Microscopes


Part a: This light microscope has binocular lenses and four objective lenses. The sample stage is directly beneath the objective lens. The light microscope sits on a tabletop and can be easily carried. Part b: The electron microscope shown here sits in a museum. It is about the size of a desk, and a person can sit in front of it to operate it. A column taller than a person rises from the center of the scope.
(a) Most light microscopes in a college biology lab can magnify cells up to approximately 400 times and have a resolution of about 200 nanometers. (b) Electron microscopes provide a much higher magnification, 100,000x, and a have a resolution of 50 picometers. (credit a: modification of work by “GcG”/Wikimedia Commons; credit b: modification of work by Evan Bench)

OpenStax Biology 2e

To give you a sense of cell size, a typical human red blood cell is about eight millionths of a meter or eight micrometers (abbreviated as eight μm) in diameter. A pin head is about two thousandths of a meter (two mm) in diameter. That means about 250 red blood cells could fit on a pinhead.

Most student microscopes are light microscopes. Visible light passes and bends through the lens system to enable the user to see the specimen. Light microscopes are advantageous for viewing living organisms, but since individual cells are generally transparent, their components are not distinguishable unless they are colored with special stains. Staining, however, usually kills the cells.

– What is the branch of biology which studies the microscopic anatomy of biological tissues?

Light microscopes that undergraduates commonly use in the laboratory magnify up to approximately 400 times. Two parameters that are important in microscopy are magnification and resolving power. Magnification is the process of enlarging an object in appearance. Resolving power is the microscope’s ability to distinguish two adjacent structures as separate: the higher the resolution, the better the image’s clarity and detail. When one uses oil immersion lenses to study small objects, magnification usually increases to 1,000 times. In order to gain a better understanding of cellular structure and function, scientists typically use electron microscopes.

– What is a branch of biology studying the structure and function of the cell?

Super-resolution microscopy is a series of techniques in light microscopy that allow images to be taken with a higher resolution than the one imposed by the diffraction limit. Due to the diffraction of light, the resolution in conventional light microscopy is limited. Super-resolution imaging techniques rely on the near-field (photon tunneling microscopy as well as those that utilize the Pendry Superlens and near field scanning optical microscopy) or on the far-field.


Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at:


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