The invisible world surrounds us in every environment. Little structures that hold the secrets of life. A binocular microscope allows all eyes to behold this mysterious world. 

These extraordinary instruments have changed how we explore microscopic specimens. Pinnacling out these instruments happens by scientists, students, and hobbyists every day. 

A binocular microscope brings comfort and precision together. The discovery process begins when you look through two eyepieces. The amazing details await your discovery process.

Getting to Know Binocular Microscopes: A Primer

What is a Binocular Microscope

A binocular microscope has two eye pieces. You look through both eyepieces at the same time. A monocular microscope has only one eyepiece that you look through.

A binocular microscope mimics our natural viewing experience, as both eyes are being used simultaneously. 

This also means that the two eyes are working together and viewing the specimen more naturally, reducing eye strain when viewing for prolonged periods of time.

A brief history of the binocular microscope

Binocular microscopes first appeared in the late 1800s. Original inventors saw the importance of improving comfort. Ernst Leitz debuted changes to incorporate binocular viewing in the 1920s.

Carl Zeiss made several significant improvements to binocular design. Both companies drove technology forward through the twenty century, building on the foundation laid by others in the past. 

Before there were binocular microscopes, there were simple, single-lens magnifying glasses. Then there were microscopes that had one objective lens and a single ocular. 

Next, the compound or multi-lens microscope emerged. Binocular use was a natural evolution, and each stage improved viewing clarity, comfort and use.

Why are binocular designs important? 

Human eyes function naturally as a pair. Oddly enough, we shut one eye when looking through a microscope can be tiring and unnatural. 

By using a binocular microscope, we are able to utilize our eyes as they were designed. This natural relaxed viewing reduces eye strain during prolonged use.

The processing of double images by our brain is easy. There should be less movement. Less fatigue. Details become sharper and more defined. Many colors will be more bright and true. We will be “in focus” most of the time, this is often a comfort that is taken for granted.

Professional users will find this especially useful as laboratory technicians do this for hours at a time. Students should use them to concentrate and learn with class and during night labs. 

Researchers can be reliant on accuracy in valuable hours spent in critical studies, this strengthening by binocular viewing is evident.

Types of Binocular Microscopes

Compound Binocular Microscopes

In a compound microscope multiple lenses are used together. They produce very large magnification levels, generally from 40x up to 1000x.

There are even more advanced microscopes that can go even further. Light shines from underneath the thin specimen. Providing a clear cellular image.

Compound microscopes are especially helpful for looking at transparent objects. Blood cells can be observed excellently. Bacteria become visible with terrific detail. Plant tissues reveal structure. Very thin sections of tissue highlight even finer details.

Compound microscopes include several objective lenses on a rotating turret. The user simply switches magnification in a fraction of a second. 

Each objective lens provides the  same specimen. Higher power objectives show smaller details, while lower powers show larger views of the specimen.

Much of the laboratory testing relies on this compound microscope. The world of medical diagnostics depends on it. Research facilities may utilize them every day. 

Educational institutions stock them extensively. The quality of microscopes varies greatly in the different price ranges.

Stereo Binocular Microscopes

A stereo binocular microscope forms three-dimensional images. Each eyepiece of the microscope sees the object from a slightly different angle. 

Our brains combine images to create depth perception, similar to our normal human vision.  It gives the impression that objects are solid and three-dimensional.

They traditionally provide the lowest power magnification, that range from 7x to 45x. Magnification is much lower than that of the compound desks, however there are several other advantages to this as well. 

The working distance is much greater. You can manipulate the object under the microscope while viewing clearly.

These microscopes handle larger specimens easily. Insects show their complete structure. Electronic components reveal surface details. Coins display their texture clearly. Jewelry shows every facet and flaw.

Top lighting illuminates opaque specimens. Bottom lighting works for transparent ones. Many models offer both options. Some include fiber optic systems. LED lights provide cool, bright illumination.

Quality control applications love stereo microscopes. Electronics repair technicians use them constantly. Biology students dissect specimens under them. Collectors examine stamps and coins. Artists work on detailed miniatures.

Advanced Binocular Microscopes

Phase contrast models reveal transparent biological specimens. For instance, it enables one to view living cells without having to stain them. 

Their internal stages are clearly depicted. This imaging technique revolutionized cell biology research studies. The vast majority of biological research laboratories consider them essential.

Fluorescence microscopes take advantage of a special type of lighting. Then, the specimen will fluoresce with special specific colors. 

From fluorescing, particular structures will emit specific hues. It creates some of the most mesmerizing scientific images. Medical research relies on this technology.

Polarizing microscopes analyze crystalline materials under polarized light. Minerals will reveal their unique optical properties. The study of geology relies on this type of instrumentation. 

The study of materials science took or used polarizing microscopes extensively. Quality control checks will use these machines to examine stress pattern analysis.

The digital integration models have come with built-in cameras. They can directly photograph a specimen, and save it directly to a computer. 

The integrated software can automatically measure and analyze the measurements. This permits remote viewing of specimens. Modern research laboratories are now embracing this technology.

Binocular Microscope Anatomy: Major Components

Optical system components

Eyepieces (Oculars)

Eyepieces are simply that, the eyepieces mounted on the top of the microscope. You will look directly through these lenses. The majority provide a 10x magnification standard, and some offer 15x or 20x power. Keep in mind, as magnification goes up, the field of view goes down.

Most eyepieces are adjustable for distance to protect one’s eyes. Each person’s outer eye distance is different. Proper eyepiece adjustment can prevent eye strain. The difference in comfort from proper adjustment of spacing is enormous.

Diopter correction adjusts for differences in vision. In most cases, only one eyepiece adjustment can be done independently. This factor addresses differences in prescriptions, for example. 

If you wear contact lenses, you will reap the benefits of the eyepiece enlarging the field of view, often eliminating the need for reading glasses. 

Many wide-field eyepieces provide a larger area of the specimen. Compared to standard eyepieces, they often cost less money. The field of view affects what you can see. 

The larger field of view like eyepieces help you navigate around your specimens successfully. Most professional users prefer wide-field eyepieces as a standard.

Objective Lenses

An objective lenses provide the main magnification. Objective lenses mount to a rotating turret system. Objective lenses commonly come in 4x, 10x, 40x, and 100x powers. 

The higher the number, the more magnification you have. With higher levels of magnification you will see more detail.

Achromatic goals/ objectives in microscopy eliminate basic color pathways. Plan achromatic lenses flatten the edges of the field. 

Fluorite objectives have better color correction than those two (though plan achromatic objectives are generally more expensive). The differences in the lenses become more apparent through use and amount paid. 

The number value of your numerical aperture determines your resolution ability. Lenses with a higher numerical aperture ability will trap more light and produce sharper and clearer images. 

Most likely you will find most professional objectives with a higher numerical aperture. Some research applications fully utilize objectives that provide the highest available resolution.

Oil immersion objective lenses require the use of oil. The 100x lens typically requires an oil immersion lens. The oil acts as a bonding agent and eliminates the air space between the lens and the specimen. 

Oil is required to improve the quality of the image you are observing. It may require more effort, and a proper clean-up technique of the objective is necessary for safe and correct use.

Optical Tubes and Prisms

Light travels the optical path in the microscope. The prisms redirect the light and flip the image back to the correct orientation. 

Without the prisms,everything would be upside down. The prism arrangements can be quite complicated to maintain the proper orientation. Good prisms are made from good optical glass.

Beam splitters allow for the adding of accessories to the optical path. Cameras connect into the prism beam splitter. Drawing tubes connect the same way. 

Light is split between the eyepieces and accessories. This allows the user to look at the specimen, while simultaneously photographing the same specimen.

Mechanical Components

Stage and Specimen Holders

The stage holds the specimen while the user is observing the specimen. Plain stages are just moved about by hand. Good stages have mechanical controls to move the specimen. 

Precision and repeatability are important. The fine controls allow for small movement after the observation point is found.

Stage clips hold the slides in place to prevent unintended slide movement and/or shifting. Some stages have slide holders to hold the slides. 

Some slide holders will firmly hold the slides in place. Estimated movement is not possible. Smooth movement of specimens will help reduce the time it takes to observe and examine the specimen.

Stage x and y axis controls allow for comfortable and accurate movement of specimens. Most measurements of specimens will have scale markings. 

The scale will help with estimating the distance moved or adjusted. The user can systematically move specimens with repeatability enhancing their observations. This sort of precision is a requirement for professional work.

Focusing Mechanisms

Coarse focus moves the stage very quickly and increases the magnitude of the adjustment very quickly. Coarse focus gets the specimen near where the user wants to observe. 

Fine focus allows for the precise adjustments of microscope focusing functions. Fine adjustments can change from 5 nm to 100 nanometers bringing specimens quickly into sharp focus. Coarse and fine movements are designed to be used together smoothly.

A little refocusing and saves time during observations. Good objectives are “parfocal.” Cheap and/or inferior objectives are not usually “parfocal.”

Focus limits to prevent the stage from hitting the objective. The lower and upper mechanical stops protect your equipment, the specimen, and the objective. Tension adjustment lets you modify the feel of the focus knob. Adjusted properly, this adjustment prevents focus drift.

Illumination systems

Light Sources 

Modern microscopes are equipped with LED illumination, which is typically what you’ll find. These lights last much longer and put out little to no heat. The color temperature can be held stable. Energy consumption is well below conventional light bulbs.

Halogen bulbs are still found in older models. They produce heat energy i.e. heat output. The bulb life is much shorter than LEDs. 

The color temperature will vary depending on how much voltage you give it. Dimming the lights reduces how well you see the color temperature with a constant wattage.

Brightness controls change the intensity of illumination. Too much light will wash out the details. Too little light covers up the finer important features of the specimen. 

Proper adjustment will help you find the best contrast. Each specimen will have differing illumination controls for proper settings.

Condenser and Filters

The Abbe condenser directs the light in a focused manner onto the specimen, it is usually directly beneath the stage of the microscope. 

It will have a numerical aperture which will match the objective lenses of the microscope. Properly adjusting the Abbe condenser will help improve image quality. Height and centering are both aspects that you will want to keep in mind.

Iris / diaphragms control the angles of coming light cones. If you open it too wide it will be too bright. If you close it too tight you’ll make the contrast worse. 

Finding the right balance of aperture settings can increase or decrease image quality for the objective. Each objective may require differing settings as well.