Stereo microscopes also called dissecting microscopes are widely used in educational environments and scientific labs. They are known for relatively low magnifying capacity and are used mainly to view whole objects. These microscopes are particularly useful for obtaining a view with 3-dimensional depth and clear view of the object surface. Technically speaking, stereo microscope consists of two different microscopes offering separate optical paths that are likely to focus on the same objective point from two little different angles. Consequently, the end result we obtain is a 3-dimensional stereo image. This 3-dimensional image of the object has many similarities with the same object depth we experience with our eyes but only with the difference of more clarity due to magnification.
Use of a stereo microscope
The 3-dimensional whole object image or stereo image produced by a stereo microscope is similar to the natural image perceived by our eyes. The same perception of depth can be experienced with such image as with natural viewing with the eyes.
The only difference lies in the enhanced magnifying capacity provided by the stereomicroscope. Because of this natural view, the stereo image is ideal for laboratory applications where coordination between hand and eyes plays an important role. Moreover, as stereo microscopes perform viewing from a relatively larger working distance they offer enough space for manipulating tasks over the viewed objects. For instance, the distance ensured by stereo viewing let tasks like dissection to be performed with great ease.
Magnification in stereo microscopes
As we have already said, stereo microscopes offer relatively low magnification power, in most cases between 20x to 80x magnifying power. Though, some advanced level stereo microscopes can even offer magnification power as big as 300x capacity. The need for magnification depends on the type of object you are going to look at and scrutinize. Stereo microscopes generally come with one or several fixed magnification capacity. Some stereo microscopes also come with zoom magnification system offering zooming capacity to view objects from distance. Each different magnification type and systems have their own advantages and disadvantages and selection of your stereo microscope depend on your specific laboratory need.
The 3-dimensional viewing technology behind stereo microscope design
When seeing an object our brain and eyes function together producing an image with spatial depth. In this way whatever we observe surrounding us are viewed in spatial, three-dimensional images. The stereo microscope is basically designed keeping this natural viewing capacity of our eyes in mind. On an average, both eyes of human beings have a distance of 6.5cm between them. Each of the eyes has a little different viewpoint compared to the other. This makes viewing objects with spatial depth possible when the visual perception transmits the image to the brain. Basically, twin images of two different viewpoints are fused together to produce the single object image of spatial depth. This twin viewpoints and the resulting image is termed as a stereoscopic effect. Stereo microscopes are designed with this viewing logic.
Two types of modern stereomicroscope designs
Modern stereo microscopes can be categorized into two types of designs, namely, Greenough stereo microscopes and Common Main Objective (CMO) microscopes. While the first type utilizes twin body tubes for producing a stereoscopic effect in images, the second type of microscope uses a pair of eyepiece tubes and lens systems to produce a stereoscopic image.
When both these types of stereo microscopes are compared, CMO stereo microscopes come as a better alternative with better light gathering power. But both types have their own respective advantages in certain applications. Greenough stereo microscopes are best utilized for a detailed microscopic view such as inspection of the printed circuit board, dissecting of biological specimens, etc. Greenough stereo microscopes are also smaller in size, less expensive and easy to use. CMO stereo microscopes are used for complex microscopic applications that require higher illumination and resolution for optimum viewing quality.