Introduction to Factors Affecting Microscope Resolution
1. Color difference
Color difference is a serious defect in lens imaging, which occurs when multiple colored light sources are used, and monochromatic light does not produce color difference. White light is composed of seven types: red, orange, yellow, green, cyan, blue, and purple. Each type of light has a different wavelength, so the refractive index when passing through a lens is also different. In this way, a point on the object side may form a color spot on the image side.
Color difference generally includes positional color difference and magnification color difference. The positional color difference causes the image to have color spots or halos when observed at any position, making the image blurry. And the magnification chromatic aberration causes the image to have colored edges.
2. Ball difference
Spherical aberration is the monochromatic phase difference of points on the axis, caused by the spherical surface of the lens. The result of spherical aberration is that when a point is imaged, it is no longer a bright spot, but a bright spot with a bright center and gradually blurred edges. Thereby affecting the imaging quality.
The correction of spherical aberration is often achieved through lens combinations. Since the spherical aberration of convex and concave lenses is opposite, different materials of convex and concave lenses can be selected and glued together to eliminate it. The spherical aberration of the objective lens of the old model microscope has not been completely corrected, and it should be matched with the corresponding compensating eyepiece to achieve the correction effect. The spherical aberration of typical new microscopes is completely eliminated by the objective lens.
3. Huicha
Huicha is a monochromatic difference of points outside the axis. When an off-axis object point is imaged with a large aperture beam, the emitted beam passes through a lens and no longer intersects at any point, resulting in a point like image of a single light spot, resembling a comet, hence the name "Huixia".
4. Astigmatism
Astigmatism is also an off-axis point monochromatic phase difference that affects clarity. When the field of view is large, the object points on the edge are far away from the optical axis, and the beam tilt is large, causing astigmatism after passing through the lens. Astigmatism causes the original object point to become two separate and perpendicular short lines after imaging, which combine on the ideal image plane to form an elliptical spot. Astigmatism is eliminated through complex lens combinations.
5. Field tune
Field curvature, also known as' like field curvature '. When the lens has a field curvature, the intersection point of the entire beam does not coincide with the ideal image point. Although clear image points can be obtained at each specific point, the entire image plane is a curved surface. This makes it difficult to see the entire image at the same time during microscopic examination, which poses challenges for observation and photography. Therefore, the objective of microscopes used in research is generally a flat field objective, which has already corrected the field curvature.
6. Distortion
All the differences mentioned earlier, except for the field curvature, affect the clarity of the image. Distortion is another property of phase difference, where the concentricity of the beam is not compromised. Therefore, it does not affect the clarity of the image, but causes distortion in shape compared to the original object.
