- see condenser
- numerical, a measure of the resolving power of the power of an objective respectively.
- see chromatic and spherical
- term referring to the lens. A lens which brings in light from two parts of the spectrum (red and blue wavelengths) to the same focus, reducing Chromatic Aberration. This is the most common lens on a microscope. Color fringes may appear when viewing under bright white light because not all wave lengths are brought within an acceptable focus range. If you use filtered light (monochromatic) as in phase contrast the image will be sharper.
- see polarizer
- the body tube of the microscope moves to focus the objective lenses and the stage is fixed.
- in polarizing microscopes a special lens used to view interfaced figures.
- bright white light which illuminates a transparent or translucent specimen which appears dark against a bright or white background.
Body Tube Length
- the distance between the objective and the top of the body tube, usually 160mm. Objectives are designed for a specific length, if mis-matched, spherical aberration will occur.
- focusing system where the coarse and fine focus are mounted together on a common axis.
- provides an even cone of light that illuminates the specimen. Light from the condenser converges on the specimen, passes through it, and diverges to from an inverted illumination cone that is captured by the objective lens. The Abbe condenser is the most common. The condenser numerical aperture (NA) should be equal to or greater than the highest objective NA., usually 1.25 to 1.32 for a 100x oil objective. The resolving power of the optical system composed of condenser, objective ocular lens is limited to the lowest NA of its individual components.
- failure of lens to bring light of different wavelengths to a common focus . This can be compensated by using an achromatic lens.
- An optical technique where the specimen is seen as a bright object against a dark background.
Depth of Field
- the distance along the optical axis throughout which the object can be located and yet be imaged with satisfactory clarity. This is used in stereo microscopy.
- adjustment ring of the eyepiece that fine focuses the eye lens element.
- a circular disc, located under the stage platform containing five or six apertures of various sizes which controls the size of illumination cone converging on the specimen.
- a term referring to optics which is the abbreviation for Deutsche Industrie Normen, an industry standard for optics.
- also known as ocular, it produces the second stage of magnification enlarging the image magnified by the objective lens. Eyepieces vary in magnification from 5x to 30x. The standard is 10x.
- the piece inside the eyepiece which holds gracticules and reticules. It also defines the round field of view that is seen through the microscope.
- These are placed at a focal plane of the eyepiece coincident with the primary image plane of the objective. When the microscope is focused the image of the specimen and graticule will be seen togethe
- the visible area through the eyepiece when the microscope is in focus.
Flat Field Objectives or Optics
- lenses which are corrected to eliminate curvature. Flat field optics are a higher grade then achromatic.
- a type of eyepiece that has two planoconvex lens elements with the eyepiece diaphragm between them. Usually with a narrow field of view.
- most common is the 100x oil objective. Oil is placed on the cover glass of the slide which (and sometimes on the top element of the condenser) to produce a high magnification and high resolving power of the objective when immersed in the oil. This produces the full NA of objective lens.
- usually mounted under the condenser this controls the amount of light converging on the specimen by opening or closing the leaf diaphragm.
- a technique for uniformly illuminating a field from non-uniform light such as a coiled filament lamp.
- the enlargement of an object through the lens system. This is determined by multiplying the magnifying power of the objective by the eyepiece.
- magnification, which is the ability of the lens to make an object appear larger. It is the number of times the image is seen through the microscope is larger than the item appears to the unaided eye.
- a device on the platform for holding and moving the slide (or specimen) on an X or Y axis.
- a glass disc with a scale or grid mounted to the eyepiece diaphragm used for measurement.
- (N.A.) a term representative of the angle included by a cone of light accepted by the objective of a microscope. The higher the N.A., the greater the resolving power.
- forms the primary image of the microscope which is seen through the eyepiece. The markings on the objective lens are the magnifying power (such as 10x), followed by the NA (0.25) and the tube length. Other numbers which appear on the objective lens may refer to the manufactures catalog number of the particular item.
- a high aperture objective requiring immersion oil between objective front lens and specimen surface.
- the optical system of the microscope near the specimen. The objective projects the specimen image into the intermediate image plane of the microscope tube.
- When all the elements of the optical system are aligned on a single axis thus reducing aberration.
- a term used describing the property of a microscope where the subject stays in focus when the objective lenses are changed. Less then 1/2 of a revolution from the fine adjustment is usually acceptable.
- an achromat lens which has been corrected for a flat field.
- a two sided mirror 50mm in diam., with one side flat (plano) and the other curved, (concave). The concave side is used for low NA when no condenser is used, the plano surface is used with a substage condenser.
- the optical technique used to view the structure of transparent objects whose varying but invisible differences in thickness result in differences in the phase of transmitted light. This is done when the transmitted light changes its optical path by about 1/3 wavelength.
- transparent material which can absorb all vibrations of light passing through it except those in a single plane.
Rack and Pinion
- term used to describe the gear system for lowering and raising the stage or barrel when focusing. The coarse adjustment control (knob), usually moves the barrel or stage.
Refractive Index (R I )
- the ratio of the speed of light in a vacuum to its speed in some other medium. This will determine how much light rays are bent. When using immersion objectives it is important to keep the values as close together as possible.
- a measure of the ability of a lens to image closely spaced objects so they are recognized as separate objets.
- the capacity of any optical system to distinguish and separate details in a specimen.
Retractable Objective (XR)
- usually on the 40x and 100x objectives, a spring is loaded inside the objective so that minimal damage is done to the slide and the top element of the lens should it be racked down beyond its normal stop.
- the failure of a lens system to image the central and peripheral rays at the same focal point.
- the platform on the microscope where the slide or specimen is placed. The stage may be square, circular, fixed, rotating or even interchanged.
- a specific type of focus where the stage moves and the body tube is stationary when focusing.
- resilient mount of objectives of medium and high powers, avoids damage to specimen and objective.
- a microscopefor three-dimensional vision with long working distance and favorable depth of field.
- the final magnification of the microscope is the result of objective magnification x eyepiece magnification with consideration of the tube factor.
- the connection between objective and eyepiece. According to DIN the mechanical tube lenght is 160mm. Meiji objectives are computed for this tube lenght.
- is given if its value is other than 1.0 and must be added to the eyepiece magnification. It is due to optical systems between objective and eyepiece or to a change in the tube lenght.
- with several objectives, a precision-engineered part of the microscope. turret (Zernike) condenser
Widefield Oculars (eyepieces)
- a term referring to the size of the field of view on the ocular. A wide field ocular may be 19
-21mm compared to a lower measure.
- the distance between the cover glass or object and the tip of the objective.
This governs the allowable movement of the objective in obtaining critical focus of the specimen.
- a lens system that provides for variable magnification capability while keeping the specimen in focus.
- used in reference to phase microscopes, after its Dutch inventor Frits Zernike (July 16, 1888 – March 10, 1966)
Zernike (turret) condenser
- special condenser used in phase contrast microscope.
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