Information from Carl Zeiss Documentation.
Manual Optics Cleaning
Contents:
1 Purpose
2 General information of cleaning1
3 Mediums for cleaning
4 Cleaning agents
4.1 Breathing on surface, water,
or water containing tensides
4.2 Ethanol
4.3 Optics cleaning mixture L
4.4 Acetus
4.5 Optics cleaning mixture
(90% acetone + 10% IPA)
4.6 Special cleaning agents for
immersion oils
4.7 Transport regulations
5 Ambient conditions
6 Cleaning technology
7 Procedure with old optics
1 Purpose
This work instruction covers methods for optics cleaning in accordance with today’s environment and
safety aspects.
2 General information of cleaning
In the past, cleaning agents such as ether, chloroform, etc. were considered to be a universal remedy. Though these agents are quite effective for many types of dirt, they can no longer be used for health reasons and reasons of environmental law. Mainly staff having contact with customers should not use these agents. This would create the impression that CZ disregards environmental regulations.
The properties of contamination vary. On account of the chemical and physical behavior of dirt, there is no cleaning agent which could be used universally. If the type of dirt is not known, the cleaning procedure
must be performed systematically. The procedure is described in the following table.
If the type of dirt is known, cleaning can be performed using selected chemicals (see immersion oils, removal of paints and auxiliary cements).
3 Means for cleaning
You may only use such means which do not damage the optical surface. Cleaning agents can cause mechanical damage, but it is also possible that chemical agents, e.g. silicone, negatively affect the optical system.
The following means are used to clean optical surfaces:
Cotton cloth
For the cleaning of optics, only 100% cotton may be used. It is also important that the cloth is not impregnated.
Therefore, new cotton cloths must be washed before they are used. Fiber-protecting agents, e.g. conditioners, should always be dispensed with.
Tweezers
Commercial tweezers, matched to the size of the optics to be cleaned, must be used. To protect the optics, shrinkdown tubing is pulled over the “gripping surfaces.”
In stationary devices, vacuum tweezers or PTFE (Teflon)-coated suction devices are used.
Magnifiers
To check the cleaning results, magnifiers with 3x or 6x magnification are used.
Stereomicroscope
In stationary workstations, a stereomicroscope can be used to check the optical cleanliness. In these cases, a reticle is inserted into the beam path for defect detection.
Light sources:
Halogen illuminator, if available.
4 Cleaning agents
4.1 Breathing on surface, water, or water containing tensides
Many types of dirt can be removed by breathing on the surface and then using a piece of cotton wool or a soft cloth for cleaning. Water containing tensides (commercial cleaners, e.g. Palmolive or Fairy Ultra) can be used to support the process. Cleaning using a standard household cleaner for glass has also proven to be effective.
4.2 Ethanol
Can be used as a mild cleaning agent. It does not attack polymers, cements and paints. It is suitable for minor dirt, e.g. fresh finger prints, minor greasy dirt and the like.
Ethanol is also known under the following synonyms: alcohol, ethyl alcohol and petroleum ether.
Since this is a chemical substance, the following regulations must be observed when using ethanol:
Containers must be marked as follows:
Name of the substance: Ethanol
Symbol: F highly inflammable
R-phrases 11 highly inflammable
S-phrases 7-16 Keep container tightly closed.
Keep away from ignition sources. – No smoking
In the case of continuous and longer use of ethanol, make sure that the industrial safety limit value of 500ml/m3 or 960 mg/m3 is not exceeded.
Hand and eye protection must be chosen for workstations, specifically depending on the substance concentration and quantity. Furthermore, the staff must be instructed every year in the use of this substance in accordance with § 20 of the hazardous substance ordinance.
Purchase:
Through the Göttingen plant, department MG-LAB. Ethanol is available from all suppliers of chemicals and in drugstores. As purity class, absolute ethanol for analysis (p.a.) should be chosen.
4.3 Optics cleaning mixture L
The optics cleaning mixture is also a mild cleaning agent which does not attack surfaces or polymers.
This cleaning mixture is produced of 90 Vol% benzoline and 10 Vol% isopropanol (IPA).
It is ideal for the removal of grease, oils and Immersol 518 F.
The various components are also known under the following synonyms:
benzoline: medical alcohol, petroleum ether
Isopropanol: 2-propanol, dimethyl carbinol
2-hydroxypropane
Since these are chemical substances, the following regulations must be observed when using the cleaning mixture
:
Containers must be marked as follows:
Name of the substance: Optics cleaning mixture L
(90% benzoline + 10% IPA)
Symbol: F highly inflammable
R-phrases: 11 highly inflammable
S-phrases: 7-16 Keep container tightly closed.
Keep away from ignition sources. – No smoking
In the case of continuous and longer use of the cleaning mixture, make sure that the industrial safety limit value of 500 ml/m3 or 960 mg/m3 is not exceeded. Hand and eye protection must be chosen workstations, specifically depending on the substance concentration and quantity. Furthermore, the staff must be instructed every year in the use of these substances in accordance with § 20 of the hazardous substance ordinance.
Purchase:
Through the Göttingen plant, department MG-LAB. Only the various components of the optics cleaning
mixture L are available from suppliers of chemicals and in drugstores. For analysis (p.a.) should be chosen as purity class.
4.4 Acetus
Acetus is also a cleaning agent which is ideal to remove grease or other organic dirt from glass surfaces.
On account of the high portion of acetone, you should be careful with adjoining polymer-containing or painted surfaces. You should check an inconspicuous area whether it remains unaffected by the solvent.
Acetus is produced of 60 Vol% acetone and 40 Vol% ethanol.
The various components are also known under the following synonyms:
Acetone: dimethyl keton, 2-propanon
Ethanol: alcohol, ethyl alcohol and petroleum ether.
Since these are chemical substances, the following regulations must be observed when using acetus:
Containers must be marked as follows:
Name of the substance:
Acetus (60% acetone + 40% ethanol)
Symbol: F highly inflammable
R-phrases: 11 highly inflammable
S-phrases: 9-16-23-33 Keep container in a well-ventilated place. Keep away away from ignition
sources. No smoking. Do not breathe vapor.
Take precautionary measures against static discharges.
In the case of continuous and longer use of acetus, make sure that the industrial safety limit values of 500
ml/m3 or 1200 mg/m3 for acetone and 500 ml/m3 or 960 mg/m3 for ethanol are not exceeded.
Hand and eye protection must be chosen for workstations, specifically depending on the substance concentration and quantity. Furthermore, the staff must be instructed every year in the use of these substances in accordance with § 20 of the hazardous substance ordinance.
Purchase:
Through the Göttingen plant, department MG-LAB. Only the various components of acetus are available
from suppliers of chemicals and in drugstores. For analysis (p.a.) should be chosen as purity class.
4.5 Optics cleaning mixture
(90% acetone + 10% IPA)
The optics cleaning mixture is also a cleaning agent which is ideal to remove grease or other organic dirt
from glass surfaces. On account of the high portion of acetone, you should be particularly careful with adjoining polymer-containing or painted surfaces. You should check an inconspicuous area whether it remains unaffected by the solvent.
The optics cleaning mixture is produced of 90 Vol% acetone and 10 Vol% isopropanol (IPA).
The various components are also known under the following synonyms:
Acetone: dimethyl keton, 2-propanon
Isopropanol: 2-propanol, dimethyl carbinol
2-hydroxypropane
Since these are chemical substances, the following regulations must be observed when using the optics cleaning mixture:
Containers must be marked as follows:
Name of the substance: Optics cleaning mixture
(90% acetone + 10% IPA)
Symbol: F highly inflammable
R-phrases: 11 highly inflammable
S-phrases: 9-16-23-33 Keep container in a well-ventilated place. Keep away from ignition sources.
No smoking. Do not breathe vapor.
Take precautionary measures against static discharges. In the case of continuous and longer use of the optical cleaning mixture, make sure that the industrial safety limit values of 500 ml/m3 or 1200 mg/m3 for acetone and 200 ml/m3 or 500 mg/m3 for ethanol are not exceeded. Hand and eye protection must be chosen for workstations, specifically depending on the substance concentration and quantity. Furthermore, the staff must be instructed every year in the use of these substances in accordance
with § 20 of the hazardous substance ordinance.
Purchase:
Through the Göttingen plant, department MG-LAB. Only the various components of the optics cleaning
mixture are available from suppliers of chemicals and in drugstores. For analysis (p.a.) should be chosen as purity class.
4.6 Special cleaning agents for immersion
oils
The following cleaning agents are recommended for immersion oils marketed by CZ:
– Immersion oil 518 C (no longer included in the current line): Acetus
– 518 N immersion oil: Optics cleaning mixture L
– Immersol 518 F: Optics cleaning mixture L
Fungus cleaner:
Fungus settles on all surfaces. High air humidity and temperatures around 37°C are ideal for the growth of fungus. Therefore, it is absolutely necessary to store optical systems in a dry place. If fungus has settled on a surface and spread its mycelium, the optical system is past remedy in most cases, since the mycelium and the metabolic products of the fungus damage the glass surfaces. Therefore, the fungus cleaner must be used prophylactcally. The frequency of its use depends on the ambient conditions.
4.7 Transport regulations
All the above cleaning agents (solvents) are subject to the transport regulations (GGVS or ADR) which must be observed in any case. If these regulations are not observed, the transport company or the forwarder (the one who handed over the hazardous substance) must expect severe penalties.
Therefore, it is important to observe the following during transport:
– The containers must be properly labeled.
– Only leak-proof glass or aluminum bottles may be used for packaging.
– The inside packing (bottle) must not exceed the volume of 1 liter.
– The delivery package (outside packing) must not exceed the volume of 12 liters or 20 kg.
– The outside packing consists of a standard cardboard box with UN sticker.
– Furthermore, the relevant information must be included in the delivery documents.
– Detailed information about this subject can be obtained from the person in charge of hazardous goods.
5 Ambient conditions
The cleaning results strongly depend on the ambient conditions. It is important to ensure that contamination from the outside is avoided as far as possible. Therefore, the work environment must be carefully cleaned first. This cleaning should be performed with a damp cloth. Eating, drinking and smoking during the cleaning procedure is not allowed, not at least because of safety reasons. In stationary workstations, the use of a Laminar Flow Box is recommended. If this is not possible, make sure
that cleaning is performed in a place which is not affected by draught.
6 Cleaning technology
General
For the cleaning of optical surfaces, only the agents (or comparable ones) described in this manual may be used, since otherwise major damage may occur. The optics to be cleaned should never be held with your bare hands. Contact with the skin should be avoided, since otherwise the cleaning results may be affected. Coated surfaces must always be cleaned with a wet cloth.
Producing cotton wad:
To produce a cotton wad, one end of the matchwood is moistened with the cleaning solution. To make it easier to wind up the cotton, it may be necessary to roughen the matchwood on one side. The cotton is then wound up by turning the moistened matchwood. Again, you must be careful to avoid contact between the skin and the cotton, since sweat will considerably affect the cleaning results. The cotton
wad can be made more compact by turning it inside a cotton cloth. The length of the cotton wad depends on the size of the surface to be cleaned. Standard value: the cotton wad should cover half the surface to be cleaned. The cotton wad produced in this way is dipped into the cleaning solution. Ensure that the entire cotton wad is wetted with the solution. Avoid pressing it out at the vessel wall so that the cleaning solution is not contaminated. Furthermore, the cleaning solution should be replaced in regular intervals, since small particles from the cotton wad gather in it because the cotton wad should not be too wet and not too dry for cleaning. Optimum humidity is achieved by dabbing the cotton wad on a cotton cloth.
Always clean the optical surface by moving in circles starting in the middle. Slight pressure should be exerted on the optics during cleaning.
Cleaning through rotation
When cleaning through rotation (motorized mounts), the cotton ball must also be moved from the center to the edge. However, the rotation direction of the optics is also important. In the case of right-handed rotation, cleaning is performed from the center to the right, and from the center to the left in the case of left-handed rotation.
Checking the cleaning results
The cleaning results should always be checked under a good light source. Halogen lamps have proven to be suitable for this purpose. The light should be obliquely incident (the surfaces are reflected). If such lamps are not available, reflection of the optics can be achieved by holding it against a bright illuminated window. When viewing the optics with a magnifier, any available dirt is particularly visible near the bright/dark border (edge of the window). In the case of strongly curved lenses, checking should be performed in transmitted light. Further checking is possible by breathing on the surface. The formed fogging must be homogeneous. There must be no formation of spots or “islands”. The fogging must also homogeneously disappear from the cleaned surface in a single front.
7 Procedure with old optics
In general, old optics must be treated in the same way as the current line. However, the cement of some old objectives may contain Canada balm. This is recognized by the amber color of the cement. In this case, watery cleaning agents are always recommended.