Dissecting microscope (Stereo or stereoscopic microscope)- Definition, Principle, Parts

A dissecting microscope, also known as a stereo microscope, is a type of optical microscope that allows the observation of three-dimensional objects at low magnification. Unlike compound microscopes that use transmitted light to illuminate thin specimens on slides, dissecting microscopes use reflected light to illuminate the surface of the object. This makes them suitable for viewing larger and thicker specimens, such as insects, plants, rocks, coins, etc.

• The dissecting microscope, also known as the stereo microscope, is a type of optical microscope that allows the observation of three-dimensional objects at low magnification using light reflected from the surface of the specimen.
• The first attempt to create a microscope with two separate eyepieces and objective lenses was made by Cherudin d’Orleans in 1677, but his design was not very successful.
• The principle of stereoscopic vision, which is the ability to perceive depth and distance by combining the images from two eyes, was described by Charles Wheatstone in 1838. He also invented a device called the stereoscope, which used two mirrors to project two slightly different images to the eyes.
• The first binocular microscope, which used two prisms to split the light from a single objective lens into two eyepieces, was invented by John Leonard Riddell in 1850. He published his invention in the Journal of Microscopical Science as "On Binocular Microscope".
• The first stereo microscope with two separate but identical optical paths was developed by Horatio S. Greenough, an American zoologist, in the 1890s . He collaborated with the Carl Zeiss Company in Germany to produce his design commercially. His stereo microscope was widely used for studying the morphology and development of living organisms, especially marine invertebrates.
• Since then, various improvements and modifications have been made to the stereo microscope, such as adding zoom lenses, digital cameras, LED illuminators, and different types of stands and stages. Today, stereo microscopes are widely used in various fields of science, industry, and education for viewing and manipulating solid specimens with complex surface topography.

The principle of a dissecting microscope (also known as a stereo microscope) is based on the use of two separate light paths to provide a three-dimensional view of the specimen. Each light path has its own objective lens and eyepiece that create different viewing angles for each eye. This arrangement produces a stereoscopic effect that enhances the depth perception and spatial orientation of the observer.

The dissecting microscope has two types of illumination: top light and bottom light. The top light is used for dissecting and viewing opaque or reflective specimens, such as insects, coins, or circuit boards. The bottom light is used for viewing transparent or translucent specimens, such as plant tissues, cells, or embryos. The top and bottom lights can be used separately or together, depending on the nature of the specimen.

The dissecting microscope has two types of magnification systems: fixed magnification and zoom magnification. The fixed magnification system consists of two objective lenses that provide a fixed degree of magnification, such as 10x or 30x. The zoom magnification system consists of an internal objective lens that can be adjusted to provide a continuous range of magnification, such as 6.7x to 45x. The total magnification of the microscope can be increased or decreased by adding auxiliary objectives or eyepieces.

The dissecting microscope uses a Galilean optical system between the fixed and zoom magnification systems. This system consists of fixed-focus lenses that confer fixed magnification for different sets of objectives and eyepieces. For example, two sets of objectives and eyepieces can offer four levels of magnification, while three sets can offer six levels.

The dissecting microscope can be equipped with a digital camera that captures images and videos of the specimen and displays them on a computer monitor or a tablet screen. The digital camera can produce two-dimensional or three-dimensional images, depending on the type and resolution of the camera.

A dissecting microscope consists of four main parts: the base, the arm, the head, and the stage. Each part has a specific function and contributes to the overall performance of the microscope.

Base

The base is the bottom part of the microscope that sits on your work surface. It houses mechanical components, such as the focus knobs and stage clips. The base also provides stability and support to the microscope. Some dissecting microscopes have a built-in light source in the base, which illuminates the specimen from below (transmitted light). This type of illumination is useful for viewing transparent or thin specimens.

Arm

The arm is the part that attaches the head to the base. It allows the head to be moved up and down along a vertical track for focusing. The arm also contains electrical wires that connect the light source to the power supply. Some dissecting microscopes have a flexible arm that can be adjusted to different angles and positions. This feature enables the user to view specimens from different perspectives.

Head

The head is the upper part of the microscope that contains the optical components, such as the eyepieces, objective lenses, and prisms. The head can be rotated 360 degrees to change the orientation of the specimen. The head also has a built-in light source that illuminates the specimen from above (reflected light). This type of illumination is useful for viewing opaque or thick specimens.

The most distinctive feature of a dissecting microscope is that it has two separate light paths, each with its own eyepiece and objective lens. This arrangement provides a different viewing angle for each eye, resulting in a three-dimensional image of the specimen. The eyepieces are also called ocular lenses, and they are usually 10x or 15x magnification. The objective lenses are usually 1x or 2x magnification, but they can be changed by adding auxiliary lenses. The total magnification of a dissecting microscope is calculated by multiplying the eyepiece magnification by the objective magnification.

Stage

The stage is the platform where the specimen is placed for observation. It has stage clips or clamps that hold the specimen in place. The stage also has a glass plate that allows transmitted light to pass through. Some dissecting microscopes have a movable stage that can be shifted horizontally or vertically for better positioning of the specimen. The stage may also have a scale or a ruler for measuring the size of the specimen.

These are the main parts of a dissecting microscope and their functions. By understanding how they work together, you can use this instrument more effectively and efficiently for your purposes.

There are different types of dissecting microscopes, each with its own features and applications. Some of the common types are:

• Stereo Zoom Dissecting Microscope: These types of dissecting microscopes are either binocular or trinocular and they typically have a magnification range of 6x – 45x. They can be attached to a digital camera which takes photos of the viewing images. They have a dual-LED illuminator and they can rotate at 360°. Magnification can be changed by adding auxiliary objectives or different eyepieces.
• Stereo Zoom boom stand microscope: These have a large base and the largest stage for viewing large samples. They have LED lighting or optional dual-pipe lighting. They have a zooming range of 6x-45x which can be altered upward by adding auxiliary lenses or eyepieces.
• Digital Tablet Dissection Microscope: These are high-end dissecting microscopes. They have a touch screen LCD tablet camera with a continuous magnification of 6.7x-45x. They have auxiliary eyepieces whose magnification ranges can be increased or decreased. Auxiliary lenses can also be added to the objectives for modifying the magnification. They have a 5.0-megapixel digital camera for capturing images and recording videos directly into the tablet or a USB cable. They have an in-built LED illuminators both at the top and bottom of the microscope, each operating separately.
• Single Power Stereo Dissection Microscope: They have very low magnification power ranging from 10x-40x with inclined eyepieces at 45°C. They also have diopter adjustments of 50mm to 70mm.
• Dual Power Dissecting Microscope: It has a dual-powered dissecting microscope of 10x and 30x, with a 360° rotation ability, for focusing and viewing. They have a dual objective pair, parfocalled, parcentered, and achromatic. Rotating the lenses allows a change of image magnification. It also uses a high LED intensity light ring which fills the surface with light. With a flexible stand, it can be lifted head high for viewing larger specimens.
• Single Magnification Handheld Pocket Microscope: This is a single powered handheld dissecting microscope with two magnification powers and it does not require light. Manufactured in Japan, it has high optical quality glass with a lot of ease in usability and its compact size makes it portable.

These are some of the types of dissecting microscopes that are available in the market. Depending on your needs and budget, you can choose the one that suits you best. 😊

The dissecting microscope (stereo microscope) is a versatile instrument that can be used for various purposes in different fields of study and industry. Some of the common applications are:

• Forensic science: The dissecting microscope can be used to examine and manipulate small samples of evidence, such as fibers, hairs, bullets, or fingerprints. It can also help to identify the origin and characteristics of the samples by comparing them with reference materials.
• Gemology: The dissecting microscope can be used to evaluate and grade gemstones by observing their color, clarity, cut, and carat. It can also help to detect any flaws, treatments, or imitations of the gemstones by examining their surface features and internal structures.
• Surgical applications: The dissecting microscope can be used to perform microsurgical procedures, such as suturing, grafting, or implanting. It can also help to visualize the anatomy and pathology of the tissues and organs involved in the surgery.
• Schools and labs: The dissecting microscope can be used to teach and learn about the morphology and anatomy of various specimens, such as plants, animals, insects, or minerals. It can also help to conduct experiments and observations on living or preserved specimens by allowing manipulation and dissection.
• Manufacturing and inspection: The dissecting microscope can be used to create and inspect small or delicate products, such as watches, circuit boards, or jewelry. It can also help to detect any defects, errors, or damages in the products by magnifying their details and features.
• Fractography: The dissecting microscope can be used to study the fracture surfaces of materials that have failed due to stress, fatigue, corrosion, or impact. It can also help to determine the cause and mechanism of the failure by analyzing the fracture patterns and features.
• Forensic engineering: The dissecting microscope can be used to investigate and analyze the failure of structures or systems that have caused accidents, injuries, or deaths. It can also help to identify the factors and conditions that contributed to the failure by examining the evidence and clues.

Some other applications of the dissecting microscope include:

• Entomology: The dissecting microscope can be used to study the diversity and behavior of insects by observing their external and internal features. It can also help to classify and identify different species of insects by comparing their morphological characteristics.
• Skin pathology: The dissecting microscope can be used to diagnose and treat skin diseases and cancers by detecting basal and squamous cell carcinomas and tumors in margins. It can also help to visualize the three-dimensional structure of the skin tissues and lesions by magnifying their surface details.
• Macrophotography: The dissecting microscope can be used to capture high-quality images of small or large specimens by using a digital camera attached to the eyepiece or objective lens. It can also help to create artistic and realistic representations of the specimens by enhancing their colors and contrasts.

Like any other type of microscope, the dissecting microscope has its own pros and cons that should be considered before using it. Some of the advantages and disadvantages are:

Advantages

• It can be used in a wide range of fields making it one of the most versatile microscopic techniques. For example, it can be used for dissection, microsurgery, manufacturing, inspection, fractography, forensic engineering, etc.
• The use of two light pathways offers great depth perception and a three-dimensional image of the specimen. This allows for better focus and less eye strain.
• The attachment of a digital camera allows recording and imaging the image produced. The images can be viewed live on a computer monitor screen or stored for later analysis. The digital camera can also capture 2D and 3D images depending on the type of camera that is installed.
• It is easily portable and easy to use. Some dissecting microscopes are handheld and do not require light sources. They have a compact size and high optical quality glass.
• They are used to view whole specimens and not in pieces. They have a large stage and a long working distance that can accommodate large specimens and allow manipulation by the observer while being viewed. Live specimens can also be observed.

Disadvantages

• The Galilean optical systems which are an essential part of the microscope are quite expensive to purchase. They provide fixed-focus lenses that confer fixed magnification for different sets of magnification.
• Generally, the microscope is costly to purchase. It requires high-quality lenses, prisms, illuminators, digital cameras, etc. that add to the cost of the microscope.
• They have a low magnification power hence they are not able to view images of high magnification, above 100x. They cannot be used to view tissue structures and other microscopic details that require higher magnification.

In this article, we have learned about the dissecting microscope (stereo microscope), its history, principle, parts, types, applications, advantages and disadvantages. We have seen that this type of microscope is useful for viewing and dissecting specimens that are too large or thick for a compound microscope, and that it provides a three-dimensional image of the surface of the sample. We have also learned how to make a wet mount slide of a cork slice and observe its cells with a dissecting microscope.

To test your knowledge and understanding of the dissecting microscope (stereo microscope), you can download and print our free worksheet. This worksheet contains questions and activities related to the topics covered in this article. You can use it as a review, a quiz, or a homework assignment. The answer key is provided at the end of the worksheet.

We hope you have enjoyed learning about the dissecting microscope (stereo microscope) and that you will continue to explore the fascinating world of microscopy. If you have any questions or feedback, please feel free to leave a comment below. Happy microscoping! 😊

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