Cytology, General Histology and Embryology - V. K. Napkhanyuk 2002

Microscopes. Microscopy Technique
Microscope
Light Microscope

The Microscope is the primary instrument used by students during Practical Sessions (Fig. 1). It provides an enlarged and inverted image of the object.

Structure OF THE Microscope. A light microscope consists of three main parts:

— optical;

— mechanical;

— illuminating.

The Optical System consists of objective lenses mounted in the revolving nosepiece of the body tube, and an eyepiece located within the upper part of the tube.

The objective lens is a complex system of lenses, an essential component of which is the plano-convex front lens.

The main technical characteristic of an objective lens is its resolving power (the minimum distance at which two adjacent points of an object are perceived as separate). In a light microscope, this is determined primarily by the wavelength of light (equal to half its wavelength).

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Fig. 1. Biological research microscope:

1 — eyepiece; 2 — body tube; 3 — revolving nosepiece; 4 — objective lenses; 5 — stage; 6 — condenser with iris Diaphragm; 7 — mirror; 8 — base; 9 — condenser adjustment knob; 10 — fine adjustment housing; 11 — fine adjustment screw; 12 — coarse adjustment screw; 13 — limb (carrying arm)

Objective lenses can have magnifications of x8, x20, x40, x60, and x90. Based on their design and application, they are divided into dry lenses (x8, x20, x40) and immersion lenses (x60, x90).

The eyepiece consists of an upper lens (eye lens) and a lower lens (field or collective lens). The eye lens magnifies the image produced by the objective, while the collective lens gathers the rays coming from the objective.

The total magnification of an object is determined by multiplying the magnification of the objective by the magnification of the eyepiece. Eyepieces with magnifications of x5, x7, x10, and x15 are most commonly used.

The mechanical part of the microscope consists of the body tube, carrying arm, coarse adjustment screw, fine adjustment screw, revolving nosepiece, stage, and base.

The illumination system consists of a mirror (concave on one side and flat on the other); a condenser, which focuses the light beam onto the specimen; and an iris diaphragm built into the condenser to regulate the level of illumination.

The mirror directs a beam of light into the condenser and through it onto the specimen.

The MBI and Biolam microscopes, which are the most widely used in Ukraine, provide a magnification of up to 2000x.



Last update: 10/08/2026

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