What are some of the factors that can affect the resolution of a microscope?
1. Chromatic aberration
Chromatic aberration is a serious defect in lens imaging, occurs in the case of multi-color light as a light source, monochromatic light does not produce chromatic aberration. White light from the red, orange, yellow, green, blue, blue and purple seven kinds of composition, the wavelength of various kinds of light is different, so in the refractive index through the lens is also different, so that the object side of a point, in the image of the side may form a color spot.
Chromatic aberration generally have positional chromatic aberration, magnification chromatic aberration. Positional chromatic aberration makes the image observed in any position with a color spot or halo, making the image blurred. And magnification chromatic aberration makes the image with colored edges.
2、Spherical aberration
Spherical aberration is a monochromatic phase difference of points on an axis, caused by the spherical surface of the lens. Spherical aberration caused by the result is that a point after imaging, not a bright spot, but a bright center, the edge of the gradually fuzzy bright spot. This affects the quality of the image.
Correction of spherical aberration is often used to eliminate the combination of lenses, due to the convex and concave lens spherical aberration is opposite, can be selected from different materials of convex and concave lenses glued together to give the elimination. The spherical aberration of the objective lens is not fully corrected in old microscopes, and should be matched with the corresponding compensating eyepieces in order to achieve the corrective effect. Generally, the spherical aberration of new microscope is completely eliminated by the objective lens.
3、Hysteresis
Wisdom aberration is the monochromatic phase difference of off-axis point. When the off-axis object point is imaged with a large-aperture beam, the light beam emitted through the lens no longer intersects a point, then the image of a point of light will get a comma shape, such as a comet, so it is called "coma".
4, like scattering
Like dispersion is also affecting the clarity of the off-axis point of monochromatic phase difference. When the field of view is very large, the edge of the object point away from the optical axis, the beam tilted large, after the lens is caused by like scatter. Scattering makes the original object point in the imaging into two separate and perpendicular to each other after the short line, in the ideal image plane after the synthesis, the formation of an oval-shaped spot. Image dispersion is eliminated by a complex combination of lenses.
5, field curvature
Field curvature is also known as "image field bending". When there is field curvature of the lens, the intersection of the entire beam does not coincide with the ideal image point, although in each specific point can get a clear image point, but the entire image plane is a curved surface. In this way, the entire phase plane cannot be seen at the same time during microscopic examination, causing difficulties in observation and photography. Therefore, the objective lens of the research microscope is generally flat field objective lens, this objective lens has been corrected for field curvature.
6, aberration
Previously mentioned a variety of phase differences in addition to field curvature, all affect the clarity of the image. Aberration is another nature of the phase difference, the concentricity of the beam is not damaged. Therefore, does not affect the clarity of the image, but make the image and the original object than in the shape of the distortion.
