What are the factors that have an impact on the resolution of a microscope?
Factors that affect the resolution of the microscope are:
1, chromatic aberration
Chromatic aberration is a serious defect in lens imaging, occurring in the case of multi-coloured 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, various wavelengths 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 colour spot.
Chromatic aberration generally have position chromatic aberration, magnification chromatic aberration. Positional chromatic aberration makes the image observed at any position with a colour spot or halo, making the image blurred. And magnification chromatic aberration makes the image with coloured edges.
2,Spherical aberration
Spherical aberration is the monochromatic phase difference of the points on the axis, which is 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 middle bright, the edge of the gradual blurring of the 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, such as the type of comet, so it is called "coma".
4, like scattering
Like dispersion is also affecting the clarity of the off-axis point monochromatic phase difference. When the field of view is very large, the edge of the object point away from the optical axis is far, the beam tilted large, by the lens is caused by the image of dispersion. 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 of the plane of 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.
(1) When the object is located outside the focal length of two times the object side of the lens, a reduced inverted solid image is formed within the focal length of two times the image side and outside the focal point;
(2) When the object is located on the object side of the lens at twice the focal length, an inverted solid image of the same size is formed on the image side at twice the focal length;
(3) When the object is located within the focal length of the object side of the lens and outside the focal length, it forms a magnified inverted solid image outside the focal length of the image side two times;
(4) When the object is located on the focal point of the object side of the lens, the image cannot be imaged on the image side;
(5) When the object is located within the focal point of the object side of the lens, there is no image formation in the image side, but in the same side of the object side of the lens than the object far away from the position of the formation of a magnified upright virtual image.
