More than 400 years ago, the first microscopes were invented. While they helped magnify items the human eye couldn’t see, they had limited capabilities.
The opticians that invented the microscope understood the importance of the lenses; the light source was later found to be just as important to viewing images that were considered microscopic. This is why it’s important to understand what the condenser does on a microscope.
Why Is Light Important for Microscopes
The lens portion of a compound microscope is incredibly important, but the illumination system also plays a vital role in magnification. The light must bounce off or shine through the specimen to get a good image. In a standard microscope, the light passes through a translucent object. In modern microscopes, a light source and a lens system are used to form the condenser.
What Does a Condenser Do on a Microscope
A microscope condenser is a lens that takes a beam of light from the source and concentrates it onto the specimen. This enhances the view you see through the eyepiece and gives you greater illumination and clarity.
On upright microscopes, the condenser is located beneath the stage or the platform which holds the specimen. The condenser gathers light and concentrates it into a cone of light that shines up through a hole in the stage and through the specimen. The result is a light source that comes through with uniform intensity.
Inverted microscopes mount the condenser above the stage, and the specimen rests below. Otherwise, a condenser works in the same manner in inverted microscopes as it does in an upright microscope.
To get a condenser to work properly, an adjustment must be made to account for each new objective. This requires aperture adjustments and focusing of the condenser. The condenser’s height can also be adjusted to manipulate the illumination of the specimen.
The Abbe Condenser
No discussion of microscope condensers is complete without mentioning the Abbe Condenser. The inventor, Ernst Abbe, developed a specialized condenser that uses an iris diaphragm to control the diameter of the beam of light being projected through the specimen, allowing for more accurate focus.
An Abbe condenser is a component of a microscope. It was invented by Ernst Karl Abbe in 1870. The Abbe condenser is mounted below the stage of the microscope and concentrates and controls the light that passes through the specimen and enters the objective. It has two controls, one which moves the Abbe condenser closer to or further from the stage, and another, the iris diaphragm, which controls the diameter of the beam of light. The controls can be used to optimize brightness, evenness of illumination, and contrast.
The Abbe condenser was developed in 1870 and is still used in many modern microscopes. It does have its limitations and is not practical for magnification levels above 400x. Abbe condensers are used up to 1000x magnification
Types of Microscope Condenser
- Chromatic condenser: The Abbe condenser is a chromatic condenser that uses two special lenses to produce the light source. These condensers do not correct for spherical or chromatic aberrations.
- Aplanatic condenser: An aplanatic condenser corrects for spherical aberration, which is what happens when light is focused through a curved lens and the light rays spread along an optical axis instead of coming together at one point.
- Compound achromatic condenser: The compound achromatic condenser corrects for both spherical and chromatic aberrations and provides the highest level of correction.
What Are Darkfield Condensers
There are some specialized microscope condensers; one common one is a darkfield condenser. Darkfield microscopy is used to illuminate unstained samples with a darkfield condenser. This condenser scatters light, and it reflects off the specimen at an angle, causing the image to appear brightly illuminated on a dark background.
Answering the question, what is the function of the condenser on a microscope can become very complicated. To simplify the answer, the condenser brings and focuses light on the subject.