Microscope Equipment Various Types Work

Microscope Equipment for Various Types of Work.

Microscope Equipment for Various Types of Work

A microscope equipment may be very elaborate and some work requires such an outfit, but every microscope to be efficient should be provided with at least two objectives, and preferably two oculars. If but one ocular is bought the 6x (No. 2, or i J") is best. If two are provided, the 4x and 8x (No. I and 3, or 2" and i") are preferable. For ordinary biological, histological and pathological work the most desirable and most universally used objectives are the i6mm (") and 4mm ("). The equivalents of these in European nomenclature are Nos. 3 and 6, or A and D, according to the maker. In some cases where a higher power is desired a 3mm (-J" or No. 7) is used. For counting blood corpuscles a 5mm (3") or a narrow angled 4mm (") with a long working distance for working through the thick cover of the blood counter is used. For entomological work and other low power work a 4Omm (if") is very desirable. If bacteriological work or special cytological work is to be done, an immersion objective is indispensable. The 2mm (yVO 1S m ost used. For extreme work the i.5mm (yVO ls called into use. An immersion objective is one which is so corrected that a drop of oil (water, if it is a water immersion) must be used between the front lens and the cover glass. They are used like any other objective excepting for the placing of this drop of oil and for the fact that their shorter working distance requires greater care in handling. It is best to place the drop of oil upon the front lens of the objective with the little wire or rod which accompanies every immersion oil bottle. Any bubbles or dirt in the oil can be more easily detected in this way. It is a little unhandy to do this where the objective is screwed on the nosepiece. Many workers prefer to put the drop on the cover below the objective. Great care should be taken to exclude dirt or air bubbles. Dirt particles are apt to scratch the lens, and bubbles set up refractions which greatly interfere with the well working of the lens. If the bubbles are present they can be easily seen by removing the ocular and looking down into the objective. They must be removed even though it be necessary to wipe off all the oil and start over. The bubbles are very apt to occur if the oil contact is broken several times in an attempt to focus. If the full aperture of the objective (or any aperture greater than N. A. i. o) is to be used the condenser must also be immersed as described later.

Where the very best possible results are demanded the apochromatic objectives with compensating oculars are used. They are made in the same powers as indicated above and are superior to the achromatic lenses because they have a more perfect chromatic and spherical correction.

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