Electron microscopes and light microscopes are the most widely used microscopes globally. They are used in schools, research labs, and industries to observe different biological and non-biological samples. Compound microscopes are a type of light microscope used as microbiology microscopes to observe the structure of microbes. While electron microscopes also provide information about the morphology of microorganisms, their magnification power varies significantly.
Keep reading to learn all the differences between electron microscopes and compound microscopes.
What is an Electron Microscope?
Electron microscopes are high-precision and high-resolution microscopes that produce enlarged images of the specimen. Their magnification power is much higher than the ordinary optical microscopes used in school labs. Electron microscopes use a beam of electrons to illuminate the specimen placed on prepared slides, thus and produce precise images. They have wide applications in research labs to study molecules and compounds besides microorganisms. Their structure, function, and imaging differ vastly from compound microscopes.
Structure of Electron Microscope
Electron microscopes are complex equipment that uses a cathode or filament to bombard the sample with electrons. Other components of an electron microscope include:
- A specimen holder
- Condensing lens
- Electromagnetic magnification lenses
- Focusing apparatus
- Imaging system
Working of Electron Microscope
An electron microscope uses a thin beam of fast-moving electrons to illuminate the object instead of visible light. The specimen is prepared by drying and dehydration and placed in the vacuum chamber. The vacuum chamber facilitates the movement of electrons to reach the specimen. Next, the electromagnetic lens coils bend the electrons to form a thin beam and direct them toward the sample. Eventually, the electrons help produce an image called the electron micrograph on the screen.
Types of Electron Microscopes
Electron microscopes are of two types: scanning electron microscopes (SEM) and transmission electron microscopes (TEM). Both have the same basic structure, but their working is slightly different from each other.
Scanning Electron Microscope (SEM)
The electron beam does not pass the sample in the scanning electron microscope and studies the surface of the specimen. The lenses combine the electrons into a focused beam that falls on the specimen mounted in the chamber area. The vacuum in the chamber may vary depending on the design of the microscope. The coils of the electromagnetic lens allow them to scan the surface of the sample and produce signals. The detectors detect the signals and give the image.
Transmission Electron Microscope (TEM)
On the contrary, transmission electron microscopy allows the electrons to pass through the thinly sliced object under observation. The electron beams emitted from the electron gun travel through the vacuum tube. The electromagnetic lens focuses the electrons into a thin beam that passes through the specimen and hits the fluorescent screen to produce the image according to the density.
Advantages of Electron Microscope
Electron microscopes are quite advanced and have numerous advantages over compound microscopes. These include:
- High magnification and resolution
- Incredible precision
- Information about the greater depth of field
- Examination of the specimen on a molecular level
Disadvantages of Electron Microscope
Besides the immensely beneficial features, there are a few factors that may be counted as the disadvantages of electron microscopes:
- Inability to observe a live specimen
- Specimen preparation may take hours or days
- The ultra-thin dried specimen is needed
- Requires vacuum for electrons to travel
- Higher purchase and maintenance costs
Applications of Electron Microscope
Electron microscopes are typically used to understand the ultrastructure of organic and inorganic specimens. They have proved to help examine organelles like ribosomes and mitochondria. They are used in quality analysis in many industries because of their high magnification. Understanding viruses and bacteria in electron microscopes have eased diagnosis and disease prevention.
What is a Compound Microscope?
A compound microscope is one of the two types of light microscopes: stereo and compound microscopes. Stereo microscopes are used to study large objects, whereas a compound microscope provides information about the structure of microscopic organisms like bacteria. It allows you to view the specimen under a set of lenses that magnify the image and give insights into the tissues and cells. You can observe varying magnifications of the specimen under a microscope between 400x and 2500x. Most labs use 2000x compound microscopes.
Structure of a Compound Microscope
A compound microscope comprises different parts that work together to observe the sample. The various parts of a compound microscope include:
- Objective lens
- Condenser lens
- Focus knob
- Coarse knob
- Mechanical stage
- Stage clips
- Rotating head
Working on Compound Microscope
A compound microscope is also known as an optical or light microscope. It uses visible light to brighten objects and produce a magnified image on the eyepiece. The light passes from the source to the condenser lens that converges the light to fall onto the specimen. The objective lens magnifies the illuminated image and focuses on the ocular lens, further enlarging it. You can observe varying magnifications of the sample through different objective lenses attached.
Types of Compound Microscopes
While the most common type of compound microscope is a biological microscope used as a student microscope in schools, it is not the only compound microscope. Some other types of compound microscopes are:
A fluorescence microscope uses varying wavelengths of light to provide fluorescence to the sample to study it. Fluorescence is the light emission from an object with an absorbed light source. Sometimes, fluorescence microscopes also use phosphorescence, which is unique photoluminescence.
Phase Contrast Microscope
These microscopes have a phase contrast objective lens and a phase condenser to bring out the contrast in the specimen without staining it. Biologists prefer a phase contrast microscope to look at blood cells as it utilizes a special lens.
Polarizing compound microscopes use a polarizer and an analyzer to cross-polarize the light. It allows picking up the differences in the colors of the optical path of the sample to create an image. These microscopes are widely used in the pharmaceutical and chemical industries.
A metallurgical microscope gives transmitted or reflected light that shines on the objective lens. These are applied in an industrial setting to view metals that do not allow light to pass through them.
Advantages of Compound Microscopes
Though you cannot achieve high magnification in compound microscopes like electron microscopes, they have their unique advantages:
- Compound microscopes are easy to use and lightweight
- They do not require a vacuum to observe samples
- You can view live samples in compound microscopes
- The purchase cost and maintenance cost is less than electron microscopes
Disadvantages of Compound Microscope
Besides the numerous advantages of a compound microscope, there are also a few drawbacks. Some of them are:
- The magnification is limited to 2000x – 2500x at maximum
- You cannot observe atoms, molecules, or viruses in a compound microscope
Applications of Compound Microscopes
Apart from the extensive application of compound microscopes in school laboratories, they are used to study pathological tissues, including the observation of germs. Compound microscopes also help forensics in the detection of fingerprints as well.
Differences Between Electron Microscope and Compound Microscope
Electron microscopes use a beam of electrons to illuminate the specimen under observation.
On the other hand, compound microscopes use visible light to brighten the sample for examination.
Electron microscopes are used in the study of atoms and molecules. They also give information about the morphology of biological specimens.
However, compound microscopes do not offer that deep information about the samples. They are used to study the cells and tissues of given samples.
Electron microscopes magnify between 1 and 50 million with an immensely high resolution.
Conversely, compound microscopes offer quite low magnification, and you can observe specimens at 2500x maximum magnification.
Electron microscopes comprise an electron gun or filament, condenser lens, electromagnetic lenses, specimen chamber, and detection screen.
On the contrary, compound microscopes have an LED or halogen light source, condenser lens, objective lenses, ocular lens, mechanical stage, stage clips, coarse knob, fine knob, arm, neckpiece, and base.
Electron Microscopes use an electron gun, cathode, or filament to bombard the specimen with electrons.
Whereas compound microscopes illuminate the object with light (visible) of 400-700 nm wavelength produced through a halogen or LED source.
Electron microscopes use an electromagnetic lens to form a thin beam of electrons that falls on the samples.
At the same time, compound microscopes have objective lenses and eyepieces to produce magnification while the condenser lens converges the light.
Electron microscopes use an electron gun to shoot electrons at the prepared sample placed in the vacuum chamber. The sample may take or disperse the electrons, and the detection system detects an image.
In contrast, compound microscopes illuminate the object through the converged light from the light source. The illuminated sample produces an image on the object lens, which magnifies it. The image then travels to the eyepieces that further enlarge it.
Electron microscopes use heavy metals as a stain to ensure that the electrons stick to the sample. Commonly used stains include uranium and lead.
Contrarily, compound microscopes use liquid stains to impart colors to the samples before observing them under the microscope.
Size and Weight
Electron microscopes are large in size with considerably heavy weights. That is why they are utilized in high-performance labs only.
Opposed to electron microscopes, compound microscopes weigh less. They can be easily moved from one place to another, especially pocket microscopes.
Electron microscopes use advanced technology and cost a lot more than optical microscopes.
On the contrary, you can buy compound microscopes for as less as $100. However, professional compound microscopes cost a few hundred dollars.
The Bottom Line
Electron microscopes and compound microscopes are essential for studying organic and inorganic molecules in research labs. Electron microscopes provide high-resolution, high-quality images compared to compound microscopes. Electron microscopes use electromagnetic lenses instead of glass lenses to converge the illuminant. The former uses an electron gun, whereas the latter obtains illumination from LED or halogen light sources. Monocular, binocular, and trinocular compound microscopes are portable. On the contrary, electron microscopes are huge in size.
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