A simple formula for the minimum value is x NA. And for the maximum magnification x NA. Magnifications higher than this value will result in empty magnification, or an image that has a poor resolution. The table below shows some typical NA values with their corresponding objective and provides a range of useful magnification combinations. The blank boxes in the table would provide empty magnification and should be avoided. For example, pairing 20x eyepieces with a x objective would not provide good resolution and would result in empty magnification.
To determine this, we took 1. Microscope Resolution Microscope Magnification and Optical Resolution A microscope's total magnification is a combination of the eyepieces and the objective lens. They include information about the magnification of the image for example, x as well as a scale bar, which acts as a ruler and indicates the true size of the object. These conventions help others to make sense of the images. Explore the worlds within worlds of detail in the microscopic scale.
These articles below explain some of the big science ideas associated with microscopy referenced in this article:. The activity Ferns under the microscope demonstrates how increasing the power of magnification leads to much greater detail. Which microscope is best? Try zooming in on images of famous paintings. The high resolution of the photographs lets you see extraordinary detail. Find our more about how resolution limits affect what can be seen using satellite imaging.
Add to collection. Nature of science Scientists use a series of conventions when labelling microscope images. Related content Explore the worlds within worlds of detail in the microscopic scale.
These articles below explain some of the big science ideas associated with microscopy referenced in this article: Magnification and resolution How microscopes magnify Light microscopes Types of electron microscope Activity ideas The activity Ferns under the microscope demonstrates how increasing the power of magnification leads to much greater detail.
Useful links Try zooming in on images of famous paintings. Both spherical and chromatic aberration are corrected in apochromatic objectives. Curvature of field - causes image to be in focus centrally, but out of focus peripherally or vice versa. This defect is corrected in planar objectives. The type of objective, magnification, numerical aperture, and even the best cover slip thickness to use on your slides is listed on the side of an objective.
There are a number of special types of light microscopy that can enhance certain features of a specimen that is being examined. Some of these are listed below. Phase contrast microscopy - takes advantage of phase differences in the light beam that are caused by different refractive indexes of components within a tissue.
Light travels fastest through air and slowest through glass. Thus, if a light beam encounters at the same time three different spaces of equal thickness that are filled with air, water and glass, the beam will emerge first from the air filled space and last from the glass filled space. The emerging light beams are said to be out of phase with each other.
In the phase contrast microscope, the condenser and objectives are specially made to detect the phase differences of light passing through different components within a tissue specimen. The construction of the condenser and objective lenses is such that these phase differences are made visible by increasing the contrast between light waves of different phase. As a result, components of cells that are normally of low contrast clear or nearly clear , are given higher contrast and, thus, made visible.
Polarizing microscopy - A polarizing filter called the polarizer is placed below the condenser and allows only light vibrating in one plane to reach the condenser.
A second polarizing filter called the analyzer is placed between the objective and ocular. If these two filters are oriented such that their axes of light transmission are perpendicular, no light will pass through the analyser to the ocular.
So nothing will be seen. One use of polarizing light microscopy is related to the fact that certain crystals found in or associated with some cells can bend light waves because of their refractive index. If some of the light waves that have passed through the polarizer are bent into different planes as they pass through crystalline parts of the specimen, then some of these light waves will be able to pass through the analyser even if it is oriented at 90 degrees to the polarizer.
This property of crystals to bend polarized light waves is called birefringency. It is important in identifying certain crystalline structures in or associated with cells.
Interference or Nemarski interference microscopy. It is not the same as phase contrast microscopy. Nemarski interference microscopy requires 2 different light beams that are recombined after passing through the specimen. Differences in phase between the two beams are visualized as depth. The result is an image with depth sort of 3-D.
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