1.Difficulty in observing minute structures: Some tiny structures in cells and tissues, such as organelles and biological macromolecular complexes, are often near or below the resolution limit of optical microscopes.
2.Contrast issues: Low contrast in some samples makes it difficult to distinguish the fine structures of cells and tissues.
3.Optical aberrations: Optical aberrations including spherical aberration, chromatic aberration, and astigmatism can degrade the clarity and accuracy of images.