Common Microscope Malfunctions: Diagnosis and Remedies
① Fault 1: The image quality degrades after the microscope has been used for a period of time. The image quality improves significantly after the microscope is powered off for a while and restarted. Diagnosis: The coating technology of the lens is defective. Long‑term operation heats the lens and causes evaporation and diffusion of the coating.
② Fault 2: The image is clear during manual focusing, but becomes blurry after releasing the knob. Diagnosis: Aging of the focusing mechanism.
③ Fault 3: The image seen through the eyepiece is clear, but the captured image is blurry. When the captured image is adjusted to be sharp, the image in the eyepiece becomes out of focus. Diagnosis: Insufficient system parfocality; the viewing path and capture path cannot be synchronized.
④ Fault 4: The stage slips downward or shifts horizontally. Diagnosis: The stage locking mechanism uses star‑shaped gears, whose stability declines after prolonged use.
⑤ Fault 5: The center of the image is sharp while the edges are blurred. Diagnosis: Incomplete spherical aberration correction.
⑥ Fault 6: Why is the center of the microscope field of view clear but the periphery blurred? Diagnosis: This is an objective lens issue. Ordinary achromatic objectives have poor flatness. Usually, the central 60–80% of the field is clear, and the surrounding area appears blurred. Solution: Replace with a plan achromatic objective lens.
⑦ Fault 7: What to do if the background is not dark enough in fluorescence microscopy (viewed through the eyepiece and in captured photos)? Diagnosis: Remove the transmitted‑light condenser during fluorescence imaging; otherwise, a reflected ghost image will appear. Another method: if the fluorescence signal is strong enough, appropriately adjust the fluorescence iris diaphragm to suppress background brightness. In addition, the black balance function in software can darken the background.
