JPH06230325A - Method for cleaning optical component - Google Patents

Abstract

PURPOSE:To provide the cleaning method for optical components which can clean the optical components with pure water without leaving a stain and a burn on the surface of an optical component in a final dry state and secure a stable yield of products. CONSTITUTION:By this cleaning method for the glass optical component, the glass optical component is dipped in pure water which is warmed up to a necessary temperature, the surface of the glass optical component is cleaned according to the degree of water removing when the component is pull out of the pure water, and then the surface is uniformly dried. When the pulling-up speed (mm/s) of the glass optical component is S1 and the surface tension (dyne/cm) of the pure water on the surface of the glass optical component at this time is A, the glass optical component is pulled up at a speed represented by S1-5814/A-82+ or -2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a method of cleaning optical parts such as lenses, mirrors, prisms, etc., which is devised so that the finished condition of the optical parts can always be kept uniform. Regarding

[0002]

2. Description of the Related Art Conventionally, for cleaning the optical functional surface of an optical component, the optical component is immersed in a CFC vapor or an alcohol vapor heated to a required temperature, and the CFC vapor or an alcohol vapor is heated to the above-mentioned condition. When pulling up an optical component, the dirt adhering to the optical function surface of the optical component is washed away.

However, chlorofluorocarbon is a substance that destroys ozone and has an adverse effect on the ozone layer covering the earth. Therefore, from the viewpoint of environmental protection, it has been shown worldwide that the use of chlorofluorocarbon will be prohibited. Also, when using alcohol,
Its flammability becomes a problem, and therefore, it is necessary to take safety measures such as a fire extinguishing device, so that it is expensive and strict control is required in use.

[0004]

Therefore, recently, by immersing an optical component in pure water heated to a required temperature and pulling it while reducing the water content on the surface,
Although it is dried, if the pulling speed is not proper, then there is a risk that stains or burns will remain on the optical function surface. Here, the [stain] is a stain on the surface due to the cleaning liquid residue remaining on the surface of the optical component that is the object to be cleaned after the cleaning step is finished.
The term “burnt” refers to, for example, when the material to be cleaned is glass, cloudiness or the like generated by a chemical reaction between water and the glass surface. The stains and burns are likely to occur when the object to be cleaned is dipped in a liquid having low volatility, for example, water and then pulled up. Further, burnout is more likely to occur as the contact between water and glass increases. It is considered that this is because when the optical component is pulled up from pure water, a considerable amount of water is raised while adhering to the surface of the optical component, which causes the above-mentioned adverse effect in the drying process.

However, until now, even if it was thought that the state of water adhesion during pulling up depends on the temperature of pure water and the pulling rate, these are only empirically understood. The setting is not accurate and defective products cannot be avoided.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and in the final dry state, it is possible to achieve cleaning of optical components with pure water without leaving spots or burns on the surface of the optical components. An object of the present invention is to provide a method for cleaning an optical component that can secure a stable product yield.

[0007]

Therefore, in the present invention, the glass optical component is dipped in pure water heated to a required temperature, and the surface of the glass optical component is depleted when the glass optical component is drained from the pure water. In a method of cleaning an optical component which is not cleaned and whose surface is dried uniformly, the pulling speed (mm / s) of the glass optical component is set to S ₁ and pure water on the surface of the glass optical component at that time is set. When the surface tension (dyne / cm) of A is A, the glass optical component is pulled up at a speed represented by S ₁ = 5814 / A−82 ± 2.

Further, according to the present invention, at least the optical component whose optical function surface is made of aluminum is immersed in pure water heated to a required temperature, and when the optical component is pulled out from the pure water, the optical component is cut off. A method for cleaning an optical component, in which the optical functional surface of the component is cleaned and the optical functional surface is uniformly dried, a pulling speed of the optical component (mm /
s) is S ₂ and the surface tension (dyne / cm) of pure water on the surface of the optical component at that time is A, S ₂ = 2758 / A−36 ± 2 It will be pulled up.

[0009]

EXAMPLES Examples of the cleaning method of the present invention will be described in detail below with reference to FIGS. 1 and 2. In the figure, reference numeral 1 is a pure water producing apparatus, and the pure water produced by this pure water producing apparatus 1 is:
It is heated to a desired temperature and temporarily stored in the auxiliary tank 3.
Then, it is supplied to the pure water cleaning tank 7 through the filter 5 by the pump 4. The optical components are dipped in the pure water cleaning tank 7 by the elevator 6, and are pulled up at a predetermined pulling speed, and brought to the subsequent drying step. Further, the deionized water cleaning tank 7 has a configuration in which excess deionized water (although dirt such as dust that has been washed away floats due to the cleaning action) is discharged to the drain 8 by the action of overflow. Has become. In this embodiment, the optical components conveyed to the pure water cleaning tank 7 by the elevator 6 are sequentially passed through the cleaning agent tank 9, the pure water tank 10, the cleaning agent tank 11, and the pure water tanks 12 and 13 in advance. , The surface has been chemically cleaned.

In such a structure, the optical component as the object to be cleaned is immersed in the pure water cleaning tank 7 for the required time, and the optical component is heated to the required temperature by the heat conduction from the pure water. In the stage, when pulling up the optical component at the pulling rate described below, the surface tension of pure water and the relation between the pulling rate indicate that the surface of the optical component is evenly wet with water, and The amount of attached water achieves the lifting of the optical component.

From the experiments conducted so far by the present inventor, the following conclusions have been drawn. In other words, when cleaning optical components with pure water, it has been found that the state of water adhered to the surface of the object to be cleaned (optical components) during pulling up has a great influence on the subsequent drying process, and is as uniform as possible. Therefore, it is important to obtain a small adhesion state in order to avoid the generation of stains and burns. The dominant factors for this are the pulling rate of the optical component and the surface tension of pure water.

In other words, if water forms a lump and adheres to the surface of the optical component, it takes a long time to evaporate the water in that part in the drying process after pulling up, causing burns and adhesion of dust. Therefore, at the time of pulling up, it is necessary that the spread of the moisture adhering to the surface of the optical component is uniform, and this requires consideration of the surface tension of pure water.
On the other hand, since pulling up of the optical component directly affects the operation efficiency of the cleaning process, it is desired to be achieved at a speed as large as possible. However, in order to secure a uniform water film by the surface tension, naturally, The pulling speed will be limited.

Therefore, the present inventor assumes that the pulling speed is inversely proportional to the surface tension, and regarding the pulling speed S,
The following empirical formula was established. S = X / A + Y In the above equation, A is the surface tension of pure water, and X and Y are coefficients and correction coefficients that satisfy the above equation. Here, since the surface tension of pure water changes according to the temperature of the pure water, first of all, the optimum pulling speed of the target optical component (when pulling, a water film as thin as possible and uniform in the optical component is used). It is necessary to experimentally determine the relationship between the maximum pulling speed sufficient to secure the surface) and the temperature of pure water for cleaning, and from this, it is necessary to determine each coefficient of the empirical formula.

As a result of the experiment, the maximum pulling speed under the condition that no stain or burn is generated is as shown in the following table. As for the optical parts, the maximum pulling speed is calculated by dividing the case where the surface is glass (assuming the target is a lens, a prism, etc.) and the case where the surface is aluminum (assuming the target is a polygon mirror). ing.

[0015]

[Table 1] Now, from Table 1, in the case of crows, the surface tension of 60 ° C. is 66.841, and the surface tension of 80 ° C. is 63.
209 is substituted into the empirical formula, and in the case of aluminum, the surface tension of 40 ° C. is 70.224 and 6
Substituting the surface tension of 66.841 at 0 ° C. into the empirical formula to obtain each coefficient, X ₁ = 5814, Y ₁ = −82, X ₂
= 2758, Y ₂ = -36 is obtained. In this case, the allowable width of the correction coefficient was set to ± 2 mm / s, assuming that the surface condition of the object to be cleaned (optical component) differs depending on the cleaning property in the pretreatment process from the experimental results. This allows the glass,
The maximum pulling speeds S ₁ and S ₂ can be obtained from the following empirical formulas for any of aluminum. S ₁ = 5814 / A-82 ± 2 S ₂ = 2758 / A-36 ± 2 The surface tension of water is γ = a in the range of 20 to 100 ° C.
It is known that it is approximated by the formula −bt−ct ² (where, t: liquid temperature (° C.), a: 76.24, b:
0.1379, c: 3.124 × 10 ⁻⁴ by Wilhelmy method). Further, as the above-mentioned pure water, those having a normal water quality are used. For example, it has a specific resistance of 10 MΩ · cm or more, the number of particles of 0.2 μm diameter in pure water is 100 particles / ml or less, and the total organic carbon amount is 1 mg / l or less.

Next, the results obtained when the cleaning method of the present invention is carried out at the maximum pulling rate based on the above empirical formula will be verified in the following examples. Example 1 In a cleaning process as shown in FIG. 2, a diameter of 30 m
m, thickness center part 5 mm, end part 1 mm, 10 optical lenses were immersed in each tank for 1 minute, frequency 28 kHz, output 1
After performing ultrasonic cleaning at 200 W, immerse in a pure water cleaning tank at 60 ° C. for 1 minute as shown in FIG.
The optical lens is pulled up at a pulling rate of m / s, and hot air at 80 ° C. is blown onto the surface of the optical lens for 3 minutes. The optical lens that had been washed and dried was visually inspected with the transmitted light of a light of 150 W, and the presence or absence of stains and burns on this surface was evaluated. The results are shown in Table 2 and the surface of the optical lens After coating the MgF ₂ film with a thickness of about 200 nm on the substrate, 100
A durability test was performed for 0 hours, and thereafter, the same visual evaluation as described above was performed. The results are shown in Table 3.

Example 2 In the same manner as in Example 1, ten optical lenses having a diameter of 150 mm, a thickness center portion of 20 mm, and an end portion of 5 mm were washed and dried. The results of visual evaluation similar to those described above are also shown in Tables 2 and 3.

Example 3 In the same manner as in Example 1, ten optical lenses each having a diameter of 300 mm, a thickness of 50 mm, and an edge of 10 mm were washed.
It was dried. The results of visual evaluation similar to those described above are also shown in Tables 2 and 3.

Example 4 In the same manner as in Example 1, ten optical lenses having a diameter of 300 mm, a thickness center of 50 mm and an edge of 10 mm were washed and immersed in a pure water washing bath at 80 ° C. for 1 minute. , Then 1
Pull up the optical lens at a pulling speed of 0 mm / s,
Blow hot air at 80 ° C. for 3 minutes. Then, the same visual evaluation results as described above are also shown in Tables 2 and 3.

Example 5 In the same manner as in Example 1, the central portion 5 having a diameter of 30 mm and a thickness of 5
mm, edge 10mm optical lens was washed, 80 ℃
Immerse in pure water cleaning tank for 1 minute, then 10mm / s
Pull up the optical lens at a pulling speed of
Blow hot air at 0 ° C. Then, the same visual evaluation results as described above are also shown in Tables 2 and 3.

Example 6 In a cleaning process as shown in FIG. 2, a diameter of 30 m
10 pieces of optical aluminum with m and thickness of 5 mm
Immerse in each tank for 1 minute, frequency 200 kHz, output 60
After performing ultrasonic cleaning at 0 W, 4 as shown in FIG.
Immerse in pure water cleaning tank at 0 ° C for 1 minute, then 3mm /
The optical aluminum is pulled up at a pulling rate of s, and hot air at 80 ° C. is blown onto the surface of the optical aluminum for 3 minutes. Table 4 shows the results of measuring the 600 nm reflectance of optical aluminum after the completion of washing and drying.

Example 7 In the same manner as in Example 6, 10 pieces of mirror-polished optical aluminum having a diameter of 30 mm and a thickness of 5 mm were immersed in a pure water cleaning tank at 50 ° C. for 1 minute as shown in FIG. , Then 4 mm /
The optical aluminum is pulled up at a pulling rate of s, and hot air at 80 ° C. is blown onto the surface of the optical aluminum for 3 minutes. Washing·
Table 4 shows the results of measuring the 600-nm reflectance of the optical aluminum after the drying was completed.

Example 8 In the same manner as in Example 6, 10 pieces of mirror-polished optical aluminum having a diameter of 30 mm and a thickness of 5 mm were immersed in a pure water cleaning tank at 60 ° C. for 1 minute as shown in FIG. , Then 5 mm /
The optical aluminum is pulled up at a pulling rate of s, and hot air at 80 ° C. is blown onto the surface of the optical aluminum for 3 minutes. Washing·
Table 4 shows the results of measuring the 600-nm reflectance of the optical aluminum after the drying was completed.

In order to show the superiority of the cleaning method of the present invention,
An experimental comparison example set outside the technical scope of the present invention is shown below. Comparative Example 1 In the same manner as in Example 4, ten optical lenses each having a diameter of 300 mm, a thickness of 50 mm and a thickness of 50 mm and an edge of 10 mm were washed and immersed in a pure water washing tank at 80 ° C. for 1 minute, and then, Two
The optical lens is pulled up at a pulling rate of 0 mm / s (this point is different), and hot air of 80 ° C. is blown for 3 minutes. Then, the same visual evaluation results as described above are also shown in Tables 2 and 3.

Comparative Example 2 In the same manner as in Example 3, ten optical lenses having a diameter of 300 mm, a thickness center of 50 mm and an end of 10 mm were washed and immersed in a pure water washing tank at 60 ° C. for 1 minute. , Then 1
The optical lens is pulled up at a pulling rate of 0 mm / s (this point is different), and hot air of 80 ° C. is blown for 3 minutes. Then, the same visual evaluation results as described above are also shown in Tables 2 and 3.

Comparative Example 3 In the same manner as in Example 1, the central portion 5 having a diameter of 30 mm and a thickness of 5
mm, edge 10mm optical lens was washed, 60 ℃
Immerse in pure water cleaning tank for 1 minute, then 10mm / s
The optical lens is pulled up at the pulling rate (different in this point), and hot air at 80 ° C. is blown for 3 minutes. Thereafter, the same visual evaluation results as described above are also shown in Tables 2 and 3.

Comparative Example 4 In the same manner as in Example 7, 10 pieces of mirror-polished optical aluminum having a diameter of 30 mm and a thickness of 5 mm were immersed in a pure water cleaning tank at 50 ° C. for 1 minute as shown in FIG. , Then 7 mm /
The optical aluminum is pulled up at a pulling rate of s (this point is different), and hot air of 80 ° C. is blown onto the surface of the optical aluminum for 3 minutes. After cleaning and drying, the optical aluminum 6
The results of measuring the 00 nm reflectance are shown in Table 4.

Comparative Example 5 In the same manner as in Example 8, 10 pieces of mirror-polished optical aluminum having a diameter of 30 mm and a thickness of 5 mm were immersed in a pure water cleaning tank at 60 ° C. for 1 minute as shown in FIG. , Then 8 mm /
The optical aluminum is pulled up at a pulling rate of s (this point is different), and hot air of 80 ° C. is blown onto the surface of the optical aluminum for 3 minutes. After cleaning and drying, the optical aluminum 6
The results of measuring the 00 nm reflectance are shown in Table 4.

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

INDUSTRIAL APPLICABILITY As described above, the present invention immerses a glass optical component in pure water heated to a required temperature, and when the glass optical component is drained from the pure water, the surface of the glass optical component is removed. In a method of cleaning an optical component which is not cleaned and whose surface is dried uniformly, the pulling speed (mm / s) of the glass optical component is set to S ₁ and pure water on the surface of the glass optical component at that time is set. Surface tension (dy
ne / cm) is A, S ₁ = 5814 / A-82
The glass optical component is pulled up at a speed represented by ± 2.

Further, according to the present invention, at least an optical component whose optical function surface is made of aluminum is immersed in pure water heated to a required temperature, and when the optical component is pulled out from the pure water, the optical component is drained. A method for cleaning an optical component, in which the optical functional surface of the component is cleaned and the optical functional surface is uniformly dried, a pulling speed (mm / s) of the optical component
Is S ₂ and the pure water surface tension (dyne / cm) on the optical functional surface of the optical component at that time is A, S ₂ = 2
The optical component is pulled up at a speed represented by 758 / A-36 ± 2.

Therefore, in the final dry state, the optical components can be washed with pure water without leaving stains or burns on the surface of the optical components, and a stable product yield can be secured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a first-stage cleaning step in the cleaning method of the present invention.

[Explanation of symbols]

 1 Pure Water Production Device 2 Heater 3 Auxiliary Tank 4 Pump 5 Filter 6 Elevator 7 Pure Water Cleaning Tank

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Susumu Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A glass optical component is immersed in pure water heated to a required temperature, and when the glass optical component is drained from the pure water, the surface of the glass optical component is washed and the surface is dried. In a method of cleaning an optical component in which the temperature is made uniform, the pulling speed of the glass optical component (mm /
s) is S ₁ and the surface tension (dyne / cm) of pure water on the surface of the glass optical component at that time is A, S ₁ = 5814 / A−82 ± 2 A method for cleaning an optical component, which comprises pulling up the component. 2. An optical function of the optical component at least when the optical component whose optical functional surface is made of aluminum is immersed in pure water heated to a required temperature and drained when the optical component is pulled up from the pure water. In the method of cleaning an optical component in which the surface is cleaned and the optical functional surface is dried uniformly, the pulling speed (mm / s) of the optical component is set to S ₂ and the optical functional surface of the optical component at that time is set. Surface tension of pure water (d
Y / cm) is A, the method for cleaning an optical component is characterized in that the optical component is pulled up at a speed represented by S ₂ = 2758 / A-36 ± 2. 3. The method for cleaning an optical component according to claim 1, wherein the temperature of pure water is set in a range of 40 to 100 ° C.