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Compound light microscope
A typical modern compound light microscope with 3 different lenses and moveable stage

What Is a Microscope?

A microscope is a device used to magnify and observe small objects or structures that are not visible to the naked eye. It utilizes lenses or a combination of lenses and mirrors to gather and focus light, enabling the viewer to see details at a much higher magnification and resolution.

Microscopes play a crucial role in various scientific fields, such as biology, medicine, chemistry, and materials science. They allow scientists and researchers to study the intricate structures of cells, microorganisms, crystals, and other tiny specimens, leading to groundbreaking discoveries and advancements in many areas of science.

Parts of a Microscope

Microscopes consist of several essential components that work together to produce clear and magnified images. Here are the main parts of a microscope:

  1. Objective Lens: The objective lens is located near the specimen and is primarily responsible for gathering and magnifying the light coming from the specimen.
  2. Eyepiece or Ocular Lens: The eyepiece is the lens through which the viewer observes the magnified image. It further magnifies the image produced by the objective lens.
  3. Stage: The stage is a flat platform where the specimen is placed for observation. It often includes mechanical controls to move the specimen and keep it steady during the examination.
  4. Condenser: The condenser is located beneath the stage and focuses light from the microscope's light source onto the specimen, enhancing the illumination.

Types of Microscopes

Microscopes come in various forms, each designed for specific purposes and catering to different observational needs. Here are some common types of microscopes:

  • Compound Microscopes: Compound microscopes are the most common type of microscopes and are used for general laboratory purposes. They use multiple lenses to magnify the specimen, typically employing an objective lens and an eyepiece lens.
  • Stereoscopic Microscopes: Stereoscopic microscopes, also known as dissecting microscopes, provide a three-dimensional view of the specimen. They are ideal for studying larger objects or observing the surface details of a specimen.
  • Electron Microscopes: Electron microscopes use a beam of electrons instead of light to magnify the specimen. They offer extremely high magnification and resolution, allowing for detailed imaging of the specimen's internal structure.
  • Confocal Microscopes: Confocal microscopes use a laser beam to scan the specimen point by point, creating a high-resolution, three-dimensional image. They are particularly useful for studying fluorescently labeled samples and examining thick specimens.
  • Scanning Probe Microscopes: Scanning probe microscopes, such as atomic force microscopes and scanning tunneling microscopes, work by scanning a sharp probe over the surface of a specimen to detect and map its features at the atomic or molecular scale.
Early English microscope
An early English simple microscope

The History of Microscopes

Although basic ideas behind lenses were understood over 4,000 years ago, the first simple microscopes appeared with the invention of eyeglasses and magnifying lenses in the 13th century. Though its inventor remains unknown, the first compound microscope emerged in Europe around 1620. Galileo Galilei contributed to its development and in 1625, the botanist Giovanni Faber coined the term "microscope" for Galileo's compound microscope.

Microscopes gained popularity in the 1660s when naturalists in Italy, the Netherlands, and England began using them to study biology. One notable figure was Robert Hooke, an English scientist, philosopher, and architect, who published Micrographia in 1665. Hooke made remarkable discoveries using his simple microscope, including the observation of microorganisms and the first clear visualization of plant cells. He was the first to use the term "cell" to describe these basic building blocks of life.

The 1930s saw the invention of the electron microscope, which uses a beam of electrons to achieve extremely high magnification and reveal ultra-fine details of cells and even molecules and atoms. Scanning electron microscopes (SEM) and scanning tunneling microscopes (STM) were developed in the 1960s, allowing scientists to further explore surfaces at the atomic and molecular levels.

Top Facts About Microscope for Kids

  • 1. Advanced microscopes can cost millions or even tens of millions of dollars.

    These high-end microscopes often involve cutting-edge technologies, such as electron microscopes with "cryo-electron microscopy" capabilities, enabling detailed imaging of biological samples at the atomic level. The cost includes not only the microscope itself but also the associated infrastructure, maintenance, and support required for its operation.

    In 2009, for example, the Lawrence Berkeley National Laboratory in Berkeley, CA, acquired a new electron microscope. The microscope is reportedly about 3.65 m tall (12 ft) and cost around $27 million!

  • 2. The Guinness World Record for highest resolution microscope image is held by researchers at Cornell.

    Using a technique called "electron ptychography," in 2021 researchers at Cornell University in Ithaca, NY achieved the highest-resolution image of atoms ever captured. By magnifying a crystal sample 100 million times, they doubled the resolution that earned them the same record in 2018. Electron ptychography involves shooting a beam of electrons at a target material, creating a speckle pattern that, when analyzed by machine-learning algorithms, reveals the positions and shapes of atoms in the sample.

  • 3. Microorganisms were first referred to as "Beasties."

    Antonie van Leeuwenhoek, a Dutch scientist known as the "Father of Microbiology," made many observations using his microscopes and documented his findings in letters to the Royal Society of London. After viewing a sample of pond scum, he wrote the society detailing his discovery of microorganisms in water, referring to them as "animalcules" or "beasties."