The microscope is one of the most important scientific discoveries ever. It has addressed a significant portion of basic human curiosity about things that are too minuscule to view with the naked eye, but it has also aided in saving lives. Microscopes made it possible to study bacteria and viruses, which led to major medical breakthroughs in the fight against diseases.
The microscope is composed of several parts, one of which is the condenser. Condensers enable microscopes to gather much more light than would otherwise be possible. It directs highly concentrated, bright light from beneath the stage through a condenser lens, an objective specimen lens, and an eyepiece to the eye.
This article will discuss what a condenser microscope is, what it’s used for, the different types available, and how it works.
What is a Condenser of a Microscope?
The condenser of a microscope is an optical lens that converts a divergent beam from a point source into a parallel or converging beam to illuminate an object. It’s also known as a substage condenser.
The condenser regulates the amount of light allowed to travel through the aperture, affecting its brightness and contrast.
In darkfield microscopy, the contrast between diverse dull-colored objects in the visual field matters most, not their appearance. They are utilized to extract pictures that might not be visible when the equipment is used only to bombard the slide with as much light as the eyes above it can withstand, leaving the viewer to hope for the best outcomes.
Simply put, it is the microscope part between the light source and the specimen you examine. It works to concentrate light into the sample, giving it ample illumination so that you can have a clear view of it through the eyepiece.
The Evolution of the Condenser Microscope
The first microscopes were constructed in the 18th century. Robert Hooke built a salt-water chamber with a plano-convex lens. He observed a piece of cork and discovered that it was made up of small, empty cells.
However, it wasn’t until the 19th century that the condenser was first added to microscopes. In 1827, Joseph Jackson Lister designed a compound microscope with a diaphragm below the stage that could be used to control the amount of light passing through the specimen. It was a significant breakthrough in microscopy as it allowed for much better contrast and resolution.
It wasn’t until 1857 that the first real condenser was added to a microscope. German physicist Carl Zeiss designed a microscope with a concave mirror that could be used to focus light onto the specimen. It resulted in a much brighter and clearer image.
Today’s microscope condensers usually include a variable-aperture diaphragm and one (often more) lens. Whether you have a 110v or battery-powered microscope, the specimen is illuminated from below with a condenser lens when it’s magnified. A contemporary microscope condenser focuses accessible light through its lenses and onto the sample, revealing it from beneath for study.
When the light passes through the sample, it diverges into an inverted cone that fills the objective’s front lens, displaying your specimen correctly.
RELATED: What do you need to know about Compound microscopes?
How does a Microscope Condenser work?
What do you notice about the light that comes out of the light bulb? It goes in various directions, which is not helpful if we want to focus the light through the stage aperture. We need a method for concentrating as much of this light as possible on the sample you are observing.
Without the condenser, the light will be dispersed and not efficiently focused on the specimen. The illumination will be spread in different directions and angles. The image will be blurry and unresolved when this light passes through the microscope slide and into the lens on the other side.
With the condenser at play between the light source and the specimen, it will help to concentrate and focus light on the sample. The condenser is a lens that allows divergent light from the light source and makes it parallel. It means that all light will be efficiently focused on the specimen.
Concentrated lights strike the sample more systematically. As a result, when we look at the specimen with our eyes behind the objective lens on the other side, it will appear more precise and vibrant.
Condensers are most often made up of two lenses, although some low-cost microscope sets only have one. The larger lens aids in the collection and formation of light, while the smaller lens focuses the light down even further.
Generally, there are two controls for the condenser: one knob that adjusts the entire condenser and another knob that adjusts the specimen stage. It is possible to change the resolution of the picture that you see using this tool. The diaphragm regulates how much light reaches the sample.
What Is The Condenser On a Microscope Used For?
There are three main functions of the condenser on a microscope. Here are the essential functions:
Scientists previously observed flaws in the light source that damaged image quality, and before the condenser was developed, it was commonplace. One prevalent problem was that the brilliant filament in a halogen light bulb could be seen beneath the specimen, which severely distorted the image that reached the eye. Ernst Abbe addressed this issue with his Abbe condenser, which features an achromatic lens that captures light from the filament and focuses it precisely into the specimen. The result is a much brighter and clearer image with excellent contrast.
Higher-end condensers correct spherical and chromatic aberration in addition to light distortion. Chromatic aberration is corrected by condensers, which prevents the rainbow effect (also known as ‘color fringing’), where an image appears to be surrounded by a colored outline.
When the light from the edge of a spherical lens does not reach the same focal point as the rest of the lens, images have blurry edges. Spherical aberration condensers correct this by eliminating blurry edges around photos caused by non-coincident focal points.
Light Angle Correction
Conventional microscopes such as compound and inverted microscopes rarely need to be adjusted. You may move the condenser up and down to bring the light cone closer or farther from the sample. It affects how much of the light enters the objective lens above. At 1000x magnification, you want it close to the specimen so that as much light passes through the objective lens. The angle of the light is critical at this point because the narrower the beam, the higher the resolution will be in your image.
Types of Microscope Condensers
There are four major types of condensers for microscopes. Most microscopes available in stores will include an Abbe Condenser (or no condenser at all for kids’ microscopes), but which one you need will depend on your particular application.
Let us discuss each one of these four types.
The Abbe condenser is a standard in the field since it is inexpensive, effective, and mass-produced. You’ll almost certainly have a 1.25 NA Abbe condenser in your microscope.
These microscopes are cheap and adequate for most beginning microscopic investigations. However, they don’t correct for spherical lens imperfection or a chromatic lens error.
Spherical aberration happens when the light rays from a curved lens’ edges do not converge to the same focus as the rest of the lens. It often results in a blurred conclusion, especially at larger aperture values.
Chromatic aberration occurs when all colors are not focused on the same focal point. The consequence of this is color fringing, in which colors appear around the edges of objects.
Aplanatic Condenser (Ideal for Spherical Lens Correction)
An aplanatic condenser corrects for spherical lens aberration. They can compensate for the anomaly from a lens’s surface’s spherical form. The focal points at the lens’ edges will generally be different from those in the middle, resulting in blur.
The aplanatic condenser in the microscope addresses this with several layers of lenses inside. It efficiently flattens the effect and allows light to focus on one location, producing a much crisper image.
An achromatic condenser eliminates color fringing by ensuring that all light rays in the color spectrum converge at one point. It produces a significantly cleaner picture and is popular among photomicrographs.
On the other hand, the majority of them do not correct for spherical aberration, so you may still notice a blurring effect.
Aplanatic-Achromatic Condenser (For Spherical and Chromatic Aberration Correction)
The aplanatic-achromatic condenser is the last and by far the most expensive microscope condenser. It corrects both spherical and chromatic aberration.
Because this condenser accounts for both types of aberration, it is extremely popular among photomicroscopists. However, the high cost is a deterrent to most people.
While you may believe this is the most significant condenser type, it isn’t. It’s challenging to come across a condenser that fits all circumstances. Lower-powered objectives require broader light cones, while higher-powered objectives require very narrow light cones, and it’s challenging to achieve this whole range in one condenser.
This is a pretty broad category! Microscopes come in various forms, and there are hundreds of specialized applications for them. Thus, whether you’re examining transparent (see-through) specimens, dark or light items, using different lighting sources (LED, OLED, or a halogen light source), and so on.
Condensers come in various forms, including darkfield and phase contrast, which aid in producing pictures with more excellent contrast. If you want to image black materials, you’ll need adjustments to consider how light interacts with the specimen. For further information on phase-contrast microscopy, see this article. There are several different specialized condensers, and it’s impossible to go over all of them.
RECOMMENDED: What is Dark Field Microscopy
The condenser of a Microscope FAQs
What are the functions of the condenser and diaphragm?
A condenser and a condenser diaphragm are commonly included in modern course microscopes. The condenser concentrates the light onto the sample while the diaphragm controls resolution, contrast, and depth of field.
RELATED: What Does the Iris Diaphragm do on a Microscope?
What is the function of a condenser Knob in a microscope?
The condenser knob on a microscope controls the amount of light that enters the lens system. By turning the knob, you can increase or decrease the amount of light passing through the condenser, which will, in turn, affect the brightness of your specimen.
What is the condenser lens function in the microscope?
The function of the condenser lens in a microscope is to focus the light onto the specimen. The lens is located between the light source and the specimen, and it helps produce a clear image by concentrating the light onto the sample.
What does condenser focus do in a microscope?
A compound microscope condenser is an optical lens that aids in focusing light onto the objective lens while viewing what you’re studying. If you’re having difficulties inspecting your sample because it’s too dark to see, your microscope condenser is probably misaligned.
What Condenser is Numerical Aperture Proper for Oil Immersion?
Because the condenser is a component of your microscope, it must be selected according to the same criteria that apply to objective lenses. Its NA (Numerical Aperture – a fancy way of assigning a number to determine optical resolution) will vary, just like objectives. If your microscope incorporates an oil immersion element, its maximum numerical aperture should be 1.4; however, a lower NA will work.
A condenser in a microscope is a set of lenses used to regulate the light that falls on the sample. The light issuing from the source is random, and the condenser assists in “organizing” and “focusing” it correctly on the object.
Condensers are used to smooth out imperfections in how light travels through a lens or concerns about the contrast of pictures. Because condensers are comprised of lenses, the numerical aperture of the condenser will ultimately determine how fine the resolution of the final image can be.
Finally, condensers are an essential component of any microscope setup. Their connection to the light and objective lens is the make-or-break factor in determining how effectively it works.