Stereo microscopes are also known as stereomicroscopes, inspection microscopes, and dissection microscopes. They look similar to binocular compound microscopes, but they have an essential difference. A binocular compound microscope has one objective and a matching pair of eyepieces. A prism is used to split the beam of light from the image formed by the objective to each eye. This is not the same as a stereo microscope, even though it has two eyepieces.
The key difference in structure between a binocular compound microscope and a stereo microscope is that a stereo microscope has not only two eyepieces but also two objectives. Because of this, the viewer using a stereo microscope views the object from two slightly different angles, making the object appear in three-dimensions. However, two different types of stereo microscopes—fixed and zoom—still offer variations in the magnification and whether one can alter it. Often, stereo microscopes have lower power than compound microscopes. Whether they have fixed or zoom magnification, they are generally below 100x magnification. There is, however, a type of stereo microscope that has a modular design, allowing the user to assemble the stand, lighting device, objectives, and eyepieces that suit the need.
There are other important differences between stereo microscopes and compound microscopes as well. A stereo microscope provides the viewer with an upright and laterally correct image as opposed to the upside-down and backward image that a compound microscope provides. The stereo microscope also has a greater distance in most cases between the stage and the objective, so that the specimen can be worked on or dissected while it is being viewed. In addition, a flex-arm system creates a different type of stereo microscope: one in which the stage is any surface you like and far more working area is available. With this system, the base of the stereo microscope is absent, and the upper part with the eyepieces and objectives is mounted on a flexible arm which can be raised to a height of 2.5 feet (.762 meters). Custom systems can also be designed with the stereo microscope head mounted on a boom stand.
Another difference in types of stereo microscopes is the type of illumination they use—for example, an LED ring light, fluorescent bulb, or fiber-optics, whether they are equipped with a digital camera and/or video capability, and whether they include a video monitor. Various types of stereo microscopes are made for users from children to professionals. Prices range from less than $100 US Dollars (USD) to at least $14,000 USD—this being for a Leica M125 Trinocular Zoom Stereo Microscope with an ergonomic tilted head, a brightfield/darkfield fiber-optic transmitted light base, and a zoom range of 8x to 100x.
By Mary Elizabeth