The familiar, traditional microscope has an objective lens (the lens positioned closest to the object to be viewed) and a single eyepiece for the user. A stereo microscope is one which has two separate objective lenses, and two eyepieces. A stereo microscope is actually two complete microscopes – one for each of the viewer’s eyes. Both objective lenses focus at the same point, but from slightly different angles. When the viewer looks through the stereo eyepieces and the two resulting images are processed by the brain, the result is a three-dimensional image – one where depth can be perceived.
This stereo (3-D) effect makes stereo microscopes particularly well suited for viewing very small objects while working on them – repairing or even building a watch or electronic circuit, doing very fine engraving, or dissecting biological or medical specimens, for example. The depth effect of the microscope’s stereo view allows the user to accurately perceive relative positions and distances, and to make fine movements and manipulations with tools or instruments.
Because of their many uses, stereo microscopes are also commonly known by a number of different names, the most common of which are “stereoscope,” and “dissecting microscope.” When a stereo microscope is equipped with a zoom lens system (allowing the user to smoothly and easily change the instrument’s magnification while viewing) it is known as a “stereo zoom microscope.”
An Instrument of Many Uses
Stereo microscopes are used in a wide range of fields and applications. In addition to those mentioned earlier, other uses include examination of stamps and coins by hobbyists and dealers; inspection of small devices, circuits and components for quality control, repair and other purposes; forensic examinations; inspection and grading of gemstones; creating or repairing jewelery, and examination or restoration of documents, artifacts or works of art.
Different Types of Stereo Microscopes
Because of their widely varied applications, stereo microscopes are available in a similarly wide variety of types and configurations.
One such variable is the microscope’s mounting. The most basic type of mounting is also perhaps the most familiar an upright stand, most often used at a lab table or desk. Of course, some such stands are more elaborate than others, allowing the user greater flexibility in how the instrument is positioned, how objects to be viewed are held in place and so on.
Another common mounting for the stereo microscope’s “head” is the boom stand. The most simple boom stand consists of a simple base, with a vertical rod or pole (boom) attached, to which the head is fastened. The head can be positioned higher or lower on the boom. Much more elaborate boom stands are also available, including complex systems of articulated arms which allow the optical head to be moved easily into and out of a working area, or shifted about within the working/viewing field in order to view an object from different angles.
Optical Options
A wide variety of optical options are also available for stereo microscopes. The most familiar optical variable is magnification. Some stereo microscopes offer magnification from 6.5X, up to as high as 80X. Using supplemental lenses, magnifications can be boosted even higher – but for truly high magnification, completely different types of microscopes are most often used.
A stereo microscope may also offer either fixed magnification, or zoom magnification.
In fixed magnification, a single lens-and-eyepiece arrangement is used, to produce a specific degree of magnification. Some fixed-magnification instruments are fitted with a lens “turret” – a device which holds two or more fixed-magnification objective lenses; the turret allows the user to rotate the desired lens into position for viewing, and to switch between lenses to observe an object at different magnifications, standard fixed magnification sterescopes are usually either 10x & 30x fixed or 20x & 40x fixed.
Zoom magnification is achieved with a set of lenses arranged in such a way that the user can “zoom” smoothly from one degree of magnification to another, usually by simply turning a knob. Zoom lenses are more complex and difficult to manufacture than fixed-magnification lenses, and so are generally more expensive.
Stereo microscopes have binocular optical heads, they may also have an additional optical port (making them trinocular) included, to accommodate attachment of digital imaging equipment, for still photos or video. Such imaging equipment may also be connected to a video monitor or other display – either eliminating the need to use the instrument’s eyepieces, or for simultaneous viewing by others than the user at the eyepieces.
Specialized eyepieces are also available, with options such as reticles for making through-the-lens measurements of objects being viewed.
For assistance in selecting the right stereo microscope for your applications, needs and budget, please contact one of our instrumentation specialists. They’ll be happy to work with you to select the ideal instrument, and make all the arrangements to send it on its way to you.
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