Microscope Facts

A microscope is a laboratory instrument used to examine small objects, and microscopy is the science of investigating such objects.

There are a variety of microscopes, and they can be categorized in different ways. There is an optical microscope, a fluorescence microscope, an electron microscope, and various types of scanning probe microscopes.

Microscopes Facts for Kids

• Van Leeuwenhoek invented a 200x magnifying microscope in the 1660s.
• After the microscope was created, people began to see viruses and bacteria.
• The term ‘microscope’ is attributed to Galileo Galilei’s.
• Close structures can be distinguished by a microscope.
• Photographing a sample under a microscope is called taking a micrograph.
• Ernst Ruska invented the transmission electronic microscope in 1931.
• Max Knoll invented the scanning electron microscope in 1935.
• Gerd Binnig and Heinrich Rohrer invented the scanning probe microscope in the 1980s.
• Gerd Bennig created the atomic force microscope in 1986.

History

The earliest known use of simple microscopes dates back to the widespread use of lenses in eyeglasses in the 13th century. Compound microscopes were invented in 1620 by Zacharias Janssen, Hans Martens, Cornelis Drebbel, and Galileo Galilei.

Early Microscopes

The microscope was invented by Giambattista Odierna in 1644 and was used by naturalists to study biology, beginning with Marcello Malpighi. Using his microscope, Antonie van Leeuwenhoek discovered red blood cells and spermatozoa, and helped popularise the use of microscopes to view biological ultrastructure.

A light microscope’s performance depends on the quality and correct use of the condensor lens and objective lens system. Electric lamps as light sources were developed from the late 19th to very early 20th century.

Types of Microscopes

Electron Microscopes

In the early 20th century, the German physicist Ernst Ruska developed the transmission electron microscope in 1931. This microscope uses a beam of electrons to generate images.

The development of the transmission electron microscope and the scanning electron microscope (SEM) was quickly followed by the development of the scanning electron microscope by Max Knoll.

An electron microscope can be used to identify viruses and thus can be a more efficient way of detecting pathogens.

Scanning probe microscopes

Gerd Binnig and Heinrich Rohrer invented a scanning probe microscope from 1981 to 1983 that used ultra-fine probes to read the force between a probe and a sample, resulting in the invention of the atomic force microscope in 1985.

Fluorescence Microscopes

The most recent developments in light microscopes largely center on fluorescence microscopy in biology. These techniques make use of fluorescent staining of particular cell structures, such as DNA.

Fluorescence microscopy drove the development of the confocal microscope, which was the first practical laser scanning microscope.

Super-resolution Microscopes

Current research on optical microscopy techniques focused on superresolution analysis of fluorescently labeled samples and stimulated emission depletion microscopy, which achieves resolutions approaching electron microscopy.

X-ray Microscopes

X-ray microscopes use soft X-ray radiation to image objects, and they are used to produce three-dimensional images of biological materials that have not been chemically fixed.

Microscopes can be separated into several groups based on what interacts with the sample to generate the image, e.g., a light beam (optical microscopes), an electron beam (electron microscopes), or a scanning probe (scanning probe microscopes).

The theory of lenses is used in wide-field optical microscopes and transmission electron microscopes to magnify samples by passing electromagnetic waves through the samples or reflected by the samples.

Scanning optical and electron microscopes use lenses to focus a beam onto the sample, then display the data from the beam over a large screen.

Scanning probe microscopes use electromagnetic or electron radiation to analyze single points in a sample.

Optical Microscopes

The most common type of microscope is the optical microscope, which uses one or more lenses to magnify a sample. There are different resolution levels, such as 0.250 micrometers (or 250 nanometres), which limits practical magnification to a maximum of 1500x.

Sarfus is an optical technique that uses a non-reflecting substrate for cross-polarized light microscopy to visualize nanometric objects.

Ultraviolet light can enable the imaging of microscopic features on transparent samples, and near-infrared light can be used to visualize circuitry embedded in bonded silicon devices.

Phase-contrast microscopy can be used to study the cell cycle in live cells without staining the slide.

The traditional optical microscope has evolved into the digital microscope, where an image is obtained with a digital camera and then displayed on a computer monitor.

Digital microscopy is possible in extremely low light levels by using photon-counting digital cameras and a light source providing pairs of entangled photons.

Electron Microscopes

A transmission electron microscope allows the electrons to pass through the sample, revealing clear organelle membranes and proteins, such as ribosomes. A scanning electron microscope allows the electrons to scan the surface of a bulk object with a fine electron beam.

Scanning Probe Microscopes

There are three types of scanning probe microscopes — atomic force microscopes, near-field scanning optical microscopes, and scanning tunneling microscopes. The three most common types are atomic force microscopes, near-field scanning optical microscopes, and scanning tunneling microscopes.

Other types of microscopes

Scanning acoustic microscopes use sound waves to detect defects, such as those found in integrated circuits.