A microscope is an instrument that is used to magnify small objects. Some microscopes can even be used to observe an object at the cellular level, allowing scientists to see the shape of a cell, its nucleus, mitochondria, and other organelles. While the modern microscope has many parts, the most important pieces are its lenses. It is through the microscope’s lenses that the image of an object can be magnified and observed in detail. A simple light microscope manipulates how light enters the eye using a convex lens, where both sides of the lens are curved outwards. When light reflects off of an object being viewed under the microscope and passes through the lens, it bends towards the eye. This makes the object look bigger than it actually is.

Over the course of the microscope’s history, technological innovations have made the microscope easier to use and have improved the quality of the images produced. The compound microscope, which consists of at least two lenses, was invented in 1590 by Dutch spectacle-makers Zacharias and Hans Jansen. Some of the earliest microscopes were also made by a Dutchman named Antoine Van Leeuwenhoek. Leeuwenhoek’s microscopes consisted of a small glass ball set inside a metal frame. He became known for using his microscopes to observe freshwater, single-celled microorganisms that he called “animalcules.”

While some older microscopes had only one lens, modern microscopes make use of multiple lenses to enlarge an image. There are two sets of lenses in both the compound microscope and the dissecting microscope (also called the stereo microscope). Both of these microscopes have an objective lens, which is closer to the object, and an eyepiece, which is the lens you look through. The eyepiece lens typically magnifies an object to appear ten times its actual size, while the magnification of the objective lens can vary. Compound microscopes can have up to four objective lenses of different magnifications, and the microscope can be adjusted to choose the magnification that best suits the viewer’s needs. The total magnification that a certain combination of lenses provides is determined by multiplying the magnifications of the eyepiece and the objective lens being used. For example, if both the eyepiece and the objective lens magnify an object ten times, the object would appear one hundred times larger.

The dissecting microscope provides a lower magnification than the compound microscope, but produces a three-dimensional image. This makes the dissecting microscope good for viewing objects that are larger than a few cells but too small to see in detail with the human eye. The compound microscope is typically used for observing objects at the cellular level.

 

Microscopes

Though modern microscopes can be high-tech, microscopes have existed for centuries – this brass optical microscope dates to 1870, and was made in Munich, Germany. 

cell
Noun

smallest working part of a living organism.

compound microscope
Noun

microscope that consists of both an eyepiece and an objective lens.

convex
Adjective

curving outward.

dissecting microscope
Noun

low-magnification microscope used for observing and dissecting biological.

eyepiece
Noun

lens or set of lenses through which a person can see an image created by another set of lenses, usually in a telescope or microscope. Also called an ocular.

freshwater
Noun

water that is not salty.

lens
Noun

curved piece of glass or plastic shaped so as to focus or spread light rays that pass through it.

magnification
Noun

measurement of how enlarged an image is

microorganism
Noun

very tiny living thing.

microscope
Noun

instrument used to view very small objects by making them appear larger.

mitochondria
Plural Noun

(singular: mitochondrion) structure (organelle) in the cytoplasm of most cells in which nutrients (sugars, fatty acids, and amino acids) are broken down in the presence of oxygen and converted to energy in the form of ATP.

objective lens
Noun

lens in a microscope that is closer to the object being observed than the observer’s eyes.

organelle
Noun

specialized part of a cell that performs a specific function.