Basic Principles
From middle school students in science class to the biologist who studies cells, the microscope is an important tool in seeing a small object more clearly. A compound microscope, which is the most widely used type of microscope, uses two lens systems, the objective lens and the ocular lens, in combination to magnify a small object or slide. When the image reaches the observer's eye, it appears inverted or upside down. This inversion is a result of the path of the light rays, which ultimately transfer the image to the eye.
How It Works
Most compound microscopes contain an illuminator system built into the base of the microscope. The light generated by the bulb in the illuminator system passes through a blue filter and is collected in the microscope's substage condenser, which is the flat-bottomed panel at the bottom of a microscope.
The substage condenser focuses the light on the object to be viewed, and the image is relayed to the objective lens (the lens closest to the specimen). Because the objective lens is a positive lens, it inverts the image before it projects it to the ocular lens (the lens closest to the eye).
More About Inversion
The image formed by the objective lens is inverted because the rays that are projected through the light cross over, causing the image to appear upside down. Because the ocular lens is a simple magnifying lens, it does not correct the flipped image, and thus the specimen appears inverted when the image reaches the eye.
Tags: objective lens, ocular lens, appears inverted, illuminator system, image reaches