Please note, you must be an educator in higher ed or maybe high school to qualify to recieve the MCI
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|Below we describe detailed directions for the use of a microscope. This will give you an appreciation of their operation. These directions have been written as generally as possible, but it may be necessary for your instructor to make modifications for the exact microscopes you are using. Light microscopes used in teaching laboratories are designed for ease of use and with some practice should become automatic.
Raise the nosepiece using the course adjustment knob. This provides greater access for positioning the slide on the stage.
Rotate the nosepiece so that the 10X objective lens is in operating position.
Open the iris diaphragm approximately half way.
Turn on the in-base illuminator by depressing the push-type switch.
Place a stained specimen slide on the stage and with the naked eye position the specimen directly above the center of the condenser.
Use the thumbwheel below the eyepieces to adjust the interpupillary distance between the two eyepieces. This is important to be able to view specimens with both eyes, maximizing the quality of the image and preventing fatigue from prolonged use of one eye.
Move the microscope condenser by means of the condenser adjustment knob until the top of the condenser is almost at the highest position. There should be enough room to slide a piece of paper between the stage and the condenser, but no more. This will focus the light onto the slide.
Rotate the coarse adjustment knob in a clockwise direction to bring the 10X objective closer to the slide. View through the eyepieces and, without disturbing the coarse adjustment setting, slowly rotate the fine adjustment knob until the specimen is in the sharpest possible focus.
The left eyepiece tube is focusable to compensate for refraction differences of the eyes. The correct procedure is to bring the specimen into sharp focus looking though the right eyepiece only. Then focus for the left eye by turning the left eye tube collar fully counter-clockwise. Next, while viewing the specimen with the left eye only turn the knurled collar clockwise until the specimen is in sharp focus. Do not adjust the fine adjustment knob during this procedure.
Remove an eyepiece to view the back aperture of the objective lens. Close the condenser iris diaphragm, then re-open until the leaves of the diaphragm just disappear from view. Replace the eyepiece and view the specimen. The iris diaphragm may be closed slightly to enhance contrast, especially when viewing unstained specimens.
Unstained specimens have only minimal contrast with their surrounding environments. As a result they can usually be viewed more effectively by setting the diaphragm at or near minimum opening. Reducing the diaphragm setting increases definition, contrast, and depth of focus but introduces diffraction problems and sacrifices resolution. Play with the diaphragm setting and select the best compromise by trial and error.
Once the specimen is in sharp focus using the 10X objective lens, it is then possible to rotate the nosepiece to the 40X objective lens without changing the position of the coarse adjustment knob. Very little refocusing with the fine adjustment knob is required since most light microscope objective lenses are parfocal. Remember that the iris diaphragm setting must be changed to allow more light to pass though the sample as the magnification increases.
If the specimen is to be viewed using the 100X oil immersion lens, immersion oil must be applied to the slide.
Rotate the 40X objective lens slightly to the side so that a drop of immersion oil may be placed on the specimen without getting it on the 40X lens.
Place a drop of immersion oil in the center of the circle of light formed on the specimen slide.
Carefully turn the nosepiece until the 100X objective lens snaps into place. The objective lens should be in the oil but must not touch the slide.
Increase the light intensity as required and rotate the fine adjustment knob to obtain a sharp focus of the specimen. If necessary make further adjustments to obtain optimal illumination.
If the microscope is not parfocal, it will be necessary to lower the objective lens as close to the slide as possible without touching it. This is done only while looking at the lens and slide from the side of the microscope. Bring the specimen into view by slowly raising the objective lens with the coarse adjustment knob. Next, focus with the fine adjustment knob and adjust the illumination as necessary. If this is not successful the first time, repeat the entire procedure.
In many cases, a preparation needs to be observed only under the oil immersion lens. In this case, first locate the specimen and center it in the field with the low power objective lens. Then add oil and rotate the oil immersion objective lens into position.