How to Prevent Microscope Fogging?

Microscope is a relatively expensive instrument among optical instruments, so how to protect it relatively becomes the focus of customers.

Fog is a common problem with optical microscopes.

No matter what the cause of the fog is, because the fog droplets are spherically distributed on the surface of the optical parts with a very small radius of curvature, the incident light is scattered, which not only reduces the effective light transmittance of the instrument, but also causes the poor imaging quality to affect the observation. . Due to long-term fogging of some optical parts, many micropores are formed on the corroded glass surface, which will seriously make the glass parts scrapped.

In this article, we will explain the knowledge about fogging and provide you with a way to prevent fogging of optical microscopes.

 

There are many factors that generate fog, and fog can be divided into:

• Water-based fog
• Oily fog
• Oil-water mixed fog

The formation of fog is related to instrument structure, sealing performance, chemical stability of glass, temperature, humidity, stability of grease, etc., especially related to assembly operations.

 

Water-Based Fog

1. The glass is not cleaned or the auxiliary materials are not clean. After a long time, in the presence of humid air, the traces along the wiping direction will form a fog like wiping the table with a wet towel.
2. The dust in the air enters the instrument and falls on the glass, forming a crystalline core and forming fog beads.
3. The sealing of the instrument is poor, or the instrument shell has air leakage blisters, so that after the humid air enters the optical instrument, fog beads appear on the glass surface.
4. The chemical stability of glass materials is poor, and inorganic salts are easily precipitated after being damp, and then absorb moisture to form fog.
5. Due to the growth of mold on the optical glass, the secretion of the mold will also form a water-based fog.
6. Water mist is formed due to the humid environment in which the instrument is placed.

Oily Fog

After the optical parts are contaminated with oil (gasoline, engine oil, grease, animal oil, vegetable oil, etc.), if they are degreased or not wiped cleanly, oily fog will appear over time, and even large fog beads will appear. The specific forming factors are as follows:

1. The accessories used for wiping optical parts have high fat content, or the tools used have grease, and the optical parts are directly picked up and touched with fingers, etc., which will cause oily fog.
2. The chemical stability of the grease used in optical instruments is not good, and the grease splashes on the optical parts to form oily fog.
3. When assembling the metalworking parts by rolling edge, the oily fog caused by the contamination of the optical parts by the oil on the tool or the hand is not wiped off and degreased.
4. Oil mist is formed due to the diffusion of various grease molecules onto the surface of optical parts. The volatilization of various grease vapors will also condense into oily mist when encountering the surface of optical parts. Sometimes the oil is segregated and deteriorated, resulting in the phenomenon of oil volatilization, diffusion and oil flow, thus forming an oily mist.
5. Due to the poor sealing performance of the product structure or excessive filling of grease, oil mist or oil mist will be generated due to improper use and storage.

Oil-water Mixed Fog

Intuitively, there are obvious differences between oil-based fog and water-based fog, but some fogs are both oil-based fog and water-based fog, which are called mixed fog. It is produced under the conditions that both oily mist and water-based mist are formed.

 

Below we also provide you with some measures to prevent fogging:

• The workshop for assembly and maintenance must be clean, and the operating procedures must be strictly followed, and the optical parts should be carefully wiped.

 

• It is strictly forbidden to directly touch and take optical parts with hands. The tools that hold optical parts must be degreased, and the accessories used for optical parts, such as cotton light, cloth, ethanol, ether, iodine and organic pads in contact with optical parts The film must be strictly degreased to control the fat content. The utensils for optical parts and the bottles containing ethanol and ether must be cleaned frequently and kept clean. These are the ways to reduce oily mist.

 

• When applying grease to the metal parts of the optical instrument, first clean the parts, let the gasoline evaporate and then apply the grease, and it should be even and not too much. Dust-proof grease to prevent oily mist from spreading.

• Chemical cleaning, which uses chemicals to kill or Inhibit mold

1. Use mercuric acetate or 8-copper or dimethyl sialidin to add dustproof grease, moisturizing grease, sealing wax, or soak into the organic solvent to soak the pressure ring and other parts.
2. Nitrobenzaldehyde, which is harmless to people, has a long effective time and is easy to process. When in use, press it into a tablet, wrap it with plastic film, tie several air holes, and paste it in the place where the light path will not be affected, that is, it can prevent mildew, but the structure of the instrument is required to be well sealed.