Olympus POS Gebrauchsanweisung - Seite 9

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OBSERVATION

METHODS

Standard

In principle,

the polarizer, analyzer, test plate, and Bertrand lens should be slid out of the optical

path since they are not req1.iired for ordinary

microscopic

examinations.

In most cases, however ,

the polarizer

is left in the optical

path.

II.

Orthoscopic

Examination

Strictly speaking, in orthoscopic examinations, only light parallel to the optical axis of the micro-

scope enters the field of view.

In other words, only the parallel optical characteristics

of the

specimen can be examined

through

orthoscopy.

Since, however, parallel light

not only lacks

brightness

but also weakens the resolving power of the lenses, weak aperture lighting

is almost,

always used by sliding the lower condenser lens into the optical path.

For ideal results, weak ,

aperture objectives as the 4x and 10x type should be used.

In this case, better results can be

obtained by adjusting the condenser iris to the aperture of the objectives.

The centering screw

can be used to rotate the specimen so that it will come in line with the center of the view field.

When the polarizer and analyser are clicked into position at 00, the oscillation

direction

of each

coincides with the cross-line

of the eyepiece-Iength,vise

for the polarizer

and widthwise

for

the analyzer.

This

condition

is called crossed Nicols.

When the analyzer is left out, the condition

is called single Nicol or one Nicol.

By using both

methods, the following

characteristics can be examined:

shape, size, and structure of the specimen,

refraction,

double refraction,

interference

color, extinction

angle, optical azimuth and optical poly-

chromism.

IJI.

Conoscopic

Examination

In conoscopic examinations,

optical phenomena are studied by throwing

light from all directions

-with

the exception

of parallel light-on

the specimen.

In other words, the specimen must be illuminated

with circular beams.

Therefore, the numerica~(

aperture is increased by sliding the lower condenser lens out of the optical path;

furthermore,..

large aperturc 40x ohjective is used.

By inserting a Bertrand lens after focusing on the specimen,

an interference image, or conoscopic image, can be observed on the real focal plane of the objective

lens.

If a scaled eyepiece is used, the deflection of the interference fringe can be measured.

The

interference

image can also be observed directly through the tube without

the aid of the Bertrand

lens and the oblective

lens.