ABOUT MICROSCOPES
Mechanical Stage
This allows the slide being viewed to be moved in two directions on the main stage, so that the full specimen can be easily viewed.
For farmers doing egg counting, a mechanical stage with large x-y movement is required, so we add a particularly good quality mechanical stage which has horizontal movement of 75mm and vertical movement of 44mm, each by rack and pinion.
Condensers
A condenser is one of the main components of the optical system of many transmitted light compound microscopes. A condenser is a lens that serves to concentrate light from the illumination source that is in turn focused through the object and magnified by the objective lens. It is a basic component of almost all compound light microscopes manufactured since the 19th Century. The main two condensers used are the single lens condenser with disc diaphragm (NA=.65) and the Abbe condenser (NA=1.25).
With a typical two-lens Abbe condenser (NA=1.25), light from the microscope illumination source passes through the condenser aperture diaphragm, located at the base of the condenser, and is concentrated by internal lens elements, which then project light through the specimen in parallel bundles from every azimuth. The size and numerical aperture of the light cone is determined by adjustment of the aperture diaphragm. After passing through the specimen (on the microscope slide), the light diverges into an inverted cone with the proper angle to fill the front lens of the objective.
The NA (Numerical Aperture) value of the condenser needs to be equal or higher than that of the objective lens. With a x100 objective with an NA=1.25, an Abbe condenser is essential for good resolution of the images
EYEPIECE HEAD
THE EYEPIECE HEAD MAY BE MONOCULAR OR BINOCULAR. THE EYEPIECE LENS/LENSES OFFER TYPICALLY X10 MAGNIFICATION. ADDITIONAL LENSES MAY BE INTERCHANGED FOR GREATER MAGNIFICATION. THESE ARE TYPICALLY X15, X16 OR X20. IT SHOULD BE NOTED THAT GREATER MAGNIFICATION GIVES GREATER RESOLUTION BUT SMALLER FIELD OF VIEW. IF YOU WANT TO SEE FINER DETAIL, THEN X15 OR X20 IS GOOD. A BETTER OVERALL VIEW IS ACHIEVED WITH A X10 EYEPIECE.
The advantage of a binocular head is that you can look through two eyes, which is easier on the eyes for prolonged viewing. It is oftern recommended to farmers doing egg counts that they use a binocular system, but it is also a matter of personal, in my opinion. i personally prefer a monocular microscope
2. DISSECTING MICROSCOPE OR STEREO MICROSCOPE
These are always binocular to provide a three-dimensional image.
The stereo or dissecting microscope is designed differently and is for a different purpose. It uses two separate optical paths with two objectives and two eyepieces to provide slightly different viewing angles to the left and right eyes. In this way it produces a three-dimensional view of the sample being examined.
The stereo microscope is often used to study the surfaces of solids or to carry out close work such as sorting, dissection, watch-making, small circuit board manufacture or inspection, insect or specimen observation.
Illumination in a stereo microscope most often uses reflected illumination rather than transmitted illumination, that is, light reflected from the surface of an object rather than light transmitted through an object. Use of reflected light from the object allows examination of specimens that would be too thick or otherwise opaque for compound microscopy. However, stereo microscopes are also capable of transmitted light illumination as well, typically by having a bulb or mirror beneath a transparent stage underneath the object, though unlike a compound microscope, transmitted illumination is not focused through a condenser in most systems. If you want transmitted illumination, you need to purchase a stereo microscope that allows transmitted light
These are typically x4, x10, x40 and x100. You can generally interchange lenses and they are now fairly inexpensive to purcase. To calculate the magnification of what you are viewing, multiply the eyepiece magnification by the objective magnification. eg eyepiece x10 times objective x40 gives a 10x40 = 400 magnification.
Coloured filters can be mounted or unmounted. If unmounted, they are cheaper tp purchase, and are generally the right size to sit on the condenser, so the light passes through the condenser and then through the filter. the reason for filters is that they provide contrast to enhance resolution.
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