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Microscopy and Microscope

[University of California at Berkeley]



- Microscopy vs Microscope

Microscopy is a related term of microscope. As nouns the difference between microscopy and microscope is that microscopy is the study of microscopes, their design and manufacture while microscope is an optical instrument used for observing small objects.

Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.

Although cells vary in size, they’re generally quite small. For instance, the diameter of a typical human red blood cell is about eight micrometers (0.008 millimeters). To give you some context, the head of a pin is about one millimeter in diameter, so about 125 red blood cells could be lined up in a row across the head of a pin. With a few exceptions, individual cells cannot be seen with the naked eye, so scientists must instead use microscopes (micro- = “small”; -scope = “to look at”) to study them. A microscope is an instrument that magnifies objects otherwise too small to be seen, producing an image in which the object appears larger. Most photographs of cells are taken using a microscope, and these pictures can also be called micrographs.

The world’s most powerful microscopes don’t see things with light or even electrons. They see things by feeling, feeling with a very sharp tip on the end of something that looks like a needle. Sometimes scientists put carbon nanotubes on the end to make them even sharper. A tip so sharp it is only a few atoms wide. A tip so sharp that as it is moved across something it feels its shape. 


- The Different Types of Microscopes

There are many different types of microscopes used in light microscopy, and the four most popular types are Compound, Stereo, Digital and the Pocket or handheld microscopes. Some types are best suited for biological applications, where others are best for classroom or personal hobby use.

Microscopes  may be grouped in different ways. One way is to describe the method an instrument uses to interact with a sample and produce images, either by sending a beam of light or electrons through a sample in its optical path, by detecting photon emissions from a sample, or by scanning across and a short distance from the surface of a sample using a probe. 

The most common microscope (and the first to be invented) is the optical microscope, which uses lenses to refract visible light that passed through a thinly sectioned sample to produce an observable image. Other major types of microscopes are the fluorescence microscope, electron microscope (both the transmission electron microscope and the scanning electron microscope) and various types of scanning probe microscopes.


- The Compound Light Microscope

Commonly binocular (two eyepieces), the compound light microscope, combines the power of lenses and light to enlarge the subject being viewed. Typically, the eyepiece itself allows for 10X or 15X magnification and when combined with the three or four objective lenses, which can be rotated into the field of view, produce higher magnification to a maximum of around 1000X generally. 

The compound light microscope is popular among botanists for studying plant cells, in biology to view bacteria and parasites as well as a variety of human/animal cells. It is a useful microscope in forensic labs for identifying drug structures. Compound light microscopes are one of the most familiar of the different types of microscopes as they are most often found in science and biology classrooms. For this reason, simple models are readily available and are inexpensive. As well, several microscopy imaging techniques benefit scientists and researchers using the compound microscope and are worth exploring.

- The Stereo Microscope

The Stereo microscope, also called a dissecting microscope, has two optical paths at slightly different angles allowing the image to be viewed three-dimensionally under the lenses. Stereo microscopes magnify at low power, typically between 10X and 200X, generally below 100x.

With this type of microscope you generally have the choice of purchasing the fixed or zoom variety from a manufacturer and are relatively inexpensive. Uses for this type of microscope include looking at surfaces, microsurgery, and watch making, plus building and inspecting circuit boards. Stereo microscopes allow students to observe plant photosynthesis in action.

[Milano, Italy, jan9.0]

- The Digital Microscope

Step into the 21st century with a digital microscope and enter a world of amazing detail. The digital microscope, invented in Japan in 1986, uses the power of the computer to view objects not visible to the naked eye. Among the different types of microscopes, this kind can be found with or without eyepieces to peer into. It connects to a computer monitor via a USB cable, much like connecting a printer or mouse. The computer software allows the monitor to display the magnified specimen. Moving images can be recorded or single images captured in the computer’s memory. 

An advantage of digital microscopes is the ability to email images, as well as comfortably watch moving images for long periods.

- The Electron Microscope

Electron microscopes ‘see’ things using electrons instead of light. Electrons are much smaller than the wavelength of visible light and so much smaller things can be seen with these electron microscopes. The pictures that you get from an electron microscope are black and white because we need visible light to have colors. Sometimes we see electron microscope pictures that have colors. Those colors are added by scientists, like Dennis Kunkel to help point out important things or sometimes because they just look cool. 

Among the different types of microscopes, the Electron Microscope(EM) is a powerful microscope available and used today, allowing researchers to view a specimen at nanometer size. 

  • The transmission electron microscope (TEM), the first type of EM, is capable of producing images 1 nanometer in size. The TEM is a popular choice for nanotechnology as well as semiconductor analysis and production. 
  • A second type of electron microscope is the scanning electron microscope (SEM) are approximately 10 times less powerful than TEMs, they produce high-resolution, sharp, black and white 3D images. 

The Transmission Electron Microscopes and Scanning Electron Microscopes have practical applications in such fields as biology, chemistry, gemology, metallurgy and industry as well as provide information on the topography, morphology, composition and crystallographic data of samples.


- The Scanning Probe Microscope (SPM)

Among the different types of microscopes and microscopy techniques, scanning probe microscope (SPM) is used today in academic and industrial settings for those sectors involving physics, biology and chemistry. These instruments are used in research and development as standard analysis tools. 

Images are highly magnified and are observed as three-dimensional-shaped-specimens in real time. SPMs employ a delicate probe to scan the surface of the specimen eliminating the limitations that are found in electron and light microscopy.


- The Acoustic Microscope

The Acoustic Microscope is less about resolution and more about finding faults, cracks or errors from samples during the manufacturing process. With the use of high ultrasound, this type of microscope is the easiest intra-cavity imaging tool available. It is a microscope that is under used primarily due to the fact that it is less known for its capabilities. Scanning acoustic microscopy, or SAM, is the most current type of acoustic microscopy available to today's scientists. They can use it to view a sample internally without staining it or causing it any damage thanks to point focusing technology, which relies on a beam to scan and penetrate the specimen while it is in water.


- The Atomic Force Microscope

The very powerful microscopes are called atomic force microscopes, because they can see things by the forces between atoms. So with an atomic force microscope you can see things as small as a strand of DNA or even individual atoms. These microscopes use computers to help convert the information from tapping on the sample to make a three-dimensional view of the object. So with the world’s most powerful microscope, scientists have been able to ‘see’ DNA and report that it is a double helix just like Watson and Crick showed over 50 years ago! 



[More to come ...]

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