Glossary of Light Microscope Terms

Abbe Condenser

An advanced illumination system which uses a lens under the stage that would typically move in the vertical direction. It would usually also have an adjustable iris to control the beam diameter of the light prior to entering the lens. By adjusting the iris opening and the lens distance from the target, the user has very good control over the amount of light and its focal point. Usually found on the more advanced microscope systems and very useful at higher magnifications (400X and above).

 

Achromatic Lens

A lens specially designed and coated to correct for the tendency of light to separate into colors when passing through glass. An achromatic lens corrects this such that colors are more accurate after being magnified.

Binocular Microscope

A compound microscope with two eyepieces viewing down a single optical channel and objective. This is different than a stereo microscope, which has a separate optical channel for each eye. 

Coaxial Controls

A configuration where one knob is centered on top of another. For example, coarse and fine focus may have a larger coarse focus knob with a fine focus knob on top of it (so the center of both knobs is on the same axis). Also commonly used for Mechanical Stage X/Y movement knobs.

Compound Microscope

Literally a microscope with multiple lenses such as that pictured above. The compound microscope consist of the ocular or eyepiece lense mounted at one end of a closed tube and the objective lense mounted at the opposite end. Typically the user-selectable objective lenses are of varying magnifications. The image of a compound microscope presents a two-dimensional view.

Digital Microscope

A microscope and video camera combination with a digital output such as USB or firewire. Often includes software to display the image on a PC.

DIN Standard Objectives: (Deutsches Institut fuer Normung)

An international standard which dictates the design compatibility of the objective lens. Therefore DIN standard objectives from one manufacturer can be used in another manufacturer's DIN standard compatible microscope.

Doublet lens

A lens design that is actually two different lenses cemented together (usually one positive magnifier and one negative). This design is used in widefield eyepieces to obtain significantly better color performance than single lens designs.

Dual-view microscope

A monocular microscope with a second, vertical viewing port. The vertical port can be used with an eyepiece for a second person, such as an instructor, to view the specimen, or it can be used with an adapter and a video or still camera. See also: trinocular microscope.

Eyepiece

The lens closest to your eye when looking through a microscope. A binocular or stereo microscope will have two, a monocular microscope will have one. It also plays a critical role in the total system magnification. See also widefield eyepiece.

Interpupillary Distance

Distance between the two eyepieces. Typically it is adjustable to accommodate different users. Some microscopes also have graduated scales to indicate the actual distance between the eyepieces, allowing a user to determine the optimum number and then quickly set it before each use.

Koehler illumination

A highly effective illumination designed by August Köhler that avoids flares and ghosting. For more information, please see Molecular expressions Optical Microscopy Primer.

Mechanical stage

A mechanism mounted on top, or as part, of the stage that allows the operator to move the specimen slide in the X or Y direction by turning a knob. Very useful at higher magnifications as it can be difficult to move the slide by hand otherwise since it must be moved such a small amount. Also, moving by hand can be difficult since you must move it in the opposite direction. Most mechanical stages come with a graduated scale so you can see how far the slide has been moved or keep track of the position of various objects on the slide.

Monocular microscope

A compound microscope with one eyepiece such as that pictured at the top of this page.

Objective Lens

The lens in a microscope closest to the specimen. In a compound microscope there are usually 3, 4 or 5 objective lenses allowing a selection of magnification levels.

Oil Immersion Lens

A lens designed to be immersed in oil. A drop of immersion oil is placed on top of the cover glass and the lens is slowly lowered until it rests in the oil. This allows the light to pass through oil rather than air, and at higher magnifications results in a crisper, higher contrast image. Primarily seen on more advanced systems.

Parcentered

A lens design such that specimens that appear centered in the field of view at one magnification level will also appear centered when the magnification level is changed. See also: parfocal

Parfocal

A lens design such that specimens that appear in focus at one magnification will also appear focused when the magnification level is changed. Keep in mind, however, that depth of field (how much of a specimen's height will appear in focus at one time) changes significantly when magnification is changed. The higher the magnification, the shallower the depth of field. See also: parcentered

Seidentopf

a head design where the interpupillary adjustment (increasing or decreasing the distance between the eyepieces) is achieved by twisting the eyepieces in an up and down arc motion like binoculars.

Stereo or Dissecting Microscope

A microscope with a separate optical channel for each eye (eyepieces and objectives) which allows viewing in three dimensions.

Trinocular Microscope

A binocular microscope with a third, vertical viewing port. The vertical port can be used with an eyepiece for a second person, such as an instructor, to view the specimen, or it can be used with an adapter and a video or still camera. Click for an example trinocular microscope from Microscope Depot. See also: dual-view microscope.

Widefield Eyepiece

an eyepiece with an achromatic doublet lens designed in such a way that it does not have to be limited to viewing only in its center, and the portion of the lens that allows non-distorted viewing is larger than a normal lens. This appears to the user as a bigger aperture or "hole" to look through. It therefore has the advantage of being easier to use and more forgiving of a user's head movements. An eyepiece listed as WF10X/18mm would indicate it has a widefield achromatic doublet lens, 10X magnification and is 18mm in diameter.

Glossary of terms is courtesy of the Microscope Depot. Additional information provided by microscopy.info.

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