Microscopes are used widely nowadays for research as well as academic experiments in schools and colleges. While the Simple microscope and Compound microscope are used commonly for studies but the stereo microscope is no less.
There are a lot of microscopes on the market right now and a stereo microscope like others is different and beneficial in its way to scientists. It is known for low magnification but serves many different and important purposes.
A stereo microscope also known as Dissecting microscope is an optical instrument used for the observation of objects in low magnification, in which the instrument uses the light reflected from the surface rather than using the transmitted light from the object. It helps in examining objects in 3D such as rocks, fibers, soil, electronic items, etc.
The 3D examination of objects by a Stereo microscope makes it unique to other microscopes. Here, in this article, we will talk about its principle, working, and applications.
What is a Stereo Microscope?
There are two types of light microscopes i.e., Compound microscope and Stereo microscope. Both have their own characteristics and have certain advantages over each other.
A stereo microscope is a variant of an optical microscope that uses the light reflected from the surface for examination in 3-Dimension. It also uses two separate optical paths so that the object is viewed from different angles.
The microscope also has a characteristic feature of photography to record and examine the samples for a detailed examination. They have two light sources among which one is above the sample reflected onto the eyepiece while the other is below the sample for illumination.
History of the Stereo Microscope
The first stereoscopic microscope was built by Cherubin d Orleans in 1671. It had two eyepieces and matching objectives. However, the design had major flaws such that the image erection was done only by the use of supplemental lenses.
Another flaw included the projection of the image. This flaw projected the right side of the image to the left eyepiece while the left side of the image was projected to the right side.
In the mid-19th century, Francis Herbert Wenham from London designed a true stereo microscope in which he used the achromatic prism to split the beam of light at the rear of a single objective.
In the early 1890s, Horatio S. Greenough of America invented the modern Stereo microscopic design and convinced the Zeiss company of Jena, Germany to produce the microscope. The company accepted the offer and produced the microscope with little modification with the help of the company’s engineers.
Instead of using Greenough’s Lens erecting system, they produced it by inverting the prisms that produce an erect image. This particular design of stereo microscopes is still used.
Parts of a Stereo Microscope
The different parts of a stereo microscope include:
- Stand/Arm: It can be considered the backbone due to the fact that it supports the upper part of a microscope by connecting it with the base.
- Base: It is the lower part of the microscope that holds the other parts of the microscope thus providing stability during the examination.
- Stage: The stage in a stereo microscope is the base. The sample is kept on the base for examination. They are large and can hold large specimens.
- Light Source: Most of these microscopes use LED illuminators as their light source.
- Focus Knob: These kinds of microscopes have a single focus knob that moves the head up and down for exact focus.
- Objective Lens: It has a different objective lens with different magnification powers.
- Eyepiece: It consists of two eye lenses with their own magnification.
- Diopter Settings: It helps in the focusing difference between the left and the right eye.
- Digital Camera: These microscopes include a digital camera for recording and capturing the images of specimens.
The stereo microscopes also include Prism, Relay lens, and Reticle. Prism is used for bending light and changing the orientation of the image whereas a Relay lens is used to invert the image while Reticle is a small piece of glass that is used to make measurements.
Working Principle of Stereo Microscope
- The principle of a stereo microscope depends on the 2 different paths of light from the objective lens and the eyepiece. Both these lights provide a different angle of viewing in which the bottom light is used for viewing the samples while the top light is used during dissecting.
- The two eyepieces enable in this microscope enable a comforting view of the sample from different angles simultaneously.
- It also consists of a digital camera that is used for viewing the images of the samples in the computer for close observation. The image produced is a little larger than normal and is recorded.
- The dissecting microscope has two magnifications known as Fixed magnification and Zoom magnification. Fixed magnification is used in the eyepiece to provide a degree of magnification while Zoom magnification offers different magnifications at different ranges.
Magnification of Dissecting/Stereo Microscope
The total magnification power of a dissecting microscope is the combination of both the lenses present in the microscope i.e., the objective lens and the eyepiece.
If the objective lens is 10x and the eyepiece is 6x then the total magnification power of a dissecting microscope is:
M = 10x * 6x = 60x
Applications of Stereo Microscope
Like any other optical instrument, the dissecting microscope is also used in various fields of medicine, manufacturing, quality control, etc. Some of its applications include:
- It is used for the dissection of samples.
- It is used for the inspection of fractures.
- It is used for microsurgery in hospitals.
- It is used to clean and analyze fossils.
- It is used by biologists for dissection.
- It is used in all kinds of industries for quality control.
- It is used by dermatologists for examining skin diseases.
- It is used by watchmakers due to the small components of the watches.
- It is used to study flowers and other plants.
- It is used in studying insects.
- It is used in Forensic engineering.
- It is used to study the topography of solid samples.
- It is used by technicians to repair circuit boards.
Conclusion
A stereo microscope or Dissecting microscope is used widely in various departments of research and has a lot of applications. It has many more advantages over other microscopes and it has brought wonders in microscopy.
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