100XRD Objective
Immersion Oil
Slide
OPERATION OF THE BIOLOGICAL MICROSCOPE
Interpupillary distance adjustment
1. While looking through the microscope, grasp the eyetubes and move them on their hinges
until the two circular fields in the observation field coincide with each other.
2. If several people will be using the same microscope, each user can record the correct
interpupillary distance for them from the scale. The microscope can then be quickly reset to
the correct distance.
Setting bright field illumination
The SILVER250 Series biological microscope with adjustable condenser can do as
follow:
• Raise the stage by turning the coarse focus knob.
• Completely lower the condenser carrier by turning the condenser focus knob.
• Turn the condenser focus knob to raise the condenser up to the working position.
SILVER
250
SERIES
| 06
FIRST TIME TO USE & OPERATION
SILVER
LINE
OIL IMMERSION
When light rays pass through air from the specimen to the objective lens, they are distorted
slightly, a phenomenon known as refraction. This is usually not a problem at a magnification
of 400X or lower. However, at a magnification of 1,000X and above, refraction becomes
problematic. This problem is reduced significantly by placing a thin layer of very clear,
viscous oil between the slide and tip of the objective lens. The result is a much clearer image
at 1,000X because the oil has the same light transmitting properties as glass. Using oil slight-
ly increases the resolution and brightness of the image. Usually a very thin slide (size #1) is
used for oil immersion because at this magnification, the working distance is very small and
is critical to focusing the specimen. Good quality glass (not plastic) cover slips should be
used. If their thickness is over 0.17mm, the objective will not resolve properly, because the
specimen cannot be moved close enough to the objective lens to be in focus. Place a tiny
amount of oil (only 1 drop should be sufficient) onto the slide prior to rotating the 100XRD
objective into position. It is essential to thoroughly clean the objective tip after use to prevent
damage and to ensure that an image can be seen clearly the next time the objective is used.
Please contact Motic Optical or your authorized Motic dealer for the appropriate immersion
oil to use.
IMPORTANT:
The working distances of the 40XRD and 100XRD objectives to the slide
surface are very small and although these objectives are sealed to prevent oil contamination,
it is a good practice to avoid dragging these objectives through an oiled slide. The 100XRD
oil immersion lens on Motic microscopes has a spring-loaded end to prevent cracking the
cover slip upon its initial contact. Once this zone of safety is exceeded by moving the slide
further toward the lens, a point can be reached where damage will occur. Always make a
practice of frequently checking the position of the lens on the slide. Note that a 100XRD
objective requires an iris diaphragm for brightfield oil immersion microscopy.
