Magnification | A Level Notes
The resolution of an optical microscope is defined as the shortest distance value in optical microscopy because at high magnification, an image may appear the relationship between numerical aperture, wavelength, and resolution. A distinction is made between Magnification and Resolution: Magnification is how large the Metal Foam in Scanning Electron Microscope, magnification 10x. This article highlights differences in magnification and resolution between the conventional microscopes and the digital pathology systems.
It is the ability of the instrument to produce a detailed image of a subject. It captures more detail which we can see even if the image is magnified, and it can produce an image that can be examined more closely and clearly.
Resolution can be expressed in arcsec or seconds.
Magnification, on the other hand, is the degree which an object is made bigger by using optical instruments such as a telescope or a microscope. They bend light to enlarge an image up to the point when the magnification becomes indistinguishable. But while high magnification would usually signify high resolution, oftentimes the larger an image becomes, the lesser its resolution because as the image is doubled in size, so is its area.
This is due to the irregularity and abnormality in the design of lenses used in optical instruments. When two objects that are held apart and at a distance from the viewer are magnified many times, they will have edges that become blurry, and it becomes impossible to see two separate objects.
To achieve a high magnification and resolution at the same time, a combination of ocular and objective lenses are used with numerical aperture or light range angles that are different.
Resolution | MicroscopyU
The wavelength by which light hits the object will also affect its resolution; the lower it is, the higher the resolution. However, too much diffraction limits the resolution of a microscope. Lens manufacturers work to design lenses with the highest aberration correction possible for a particular class of objective lens.
Mathematical computations have proven that the smallest point of focus for light rays without causing diffraction is nanometers. This is the ideal resolution for an optical microscope. If the light cone is not properly formed diffraction will increase. Light Wavelength and Refractive Index Microscope resolution is also impacted by the wavelength of light being used to illuminate the specimen.
Longer wavelengths of light offer less resolution than short wavelength illumination. Near-ultraviolet light has the shortest usable wavelength and offers the greatest resolution. Following near-ultraviolet in descending order of wavelength are red, orange, yellow, green, blue and violet. The range in nanometers of the wavelength of the visible light is from nm to nm.
Relationship between magnification and resolution in digital pathology systems
Another method of improving microscope resolution is to increase the refractive index between the objective lens and the specimen.
The refractive index is merely a ratio expression of the relative speed of light passing through a substance as a proportion of the speed of light in a vacuum.
As the refractive index increases the speed of the light passing through a medium is slower. As light slows down the wavelength gets shorter and yields better resolution.
Objective lenses are manufactured that allow imaging in immersion oil which has a refractive index of 1. Microscope resolution is the most important determinant of how well a microscope will perform and is determined by the numerical aperture and light wavelength. It is not impacted by magnification but does determine the useful magnification of a microscope.