JP2002273358A - Method for cleaning optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a high cleaning quality without generating a latent flaw and also generating a cleaning failure to remove the scum residue of an abrasive or a stain, even when an optical element is less water-resistant and detergent- resistant. SOLUTION: This method for cleaning an optical element comprises an abrasive removing step to sprinkle and run a fluid to which an ultrasonic wave is applied over the optical element to be cleaned, a step to soak the optical element in a semi-water based solvent, a step to soak the optical element in a cleaning solution and perform its finish cleaning process, a step to rinse the optical element with pure water, a step to drain the moisture by means of a hydrophilic alcohol solution, a step to perform a finish cleaning process by the help of a hydrocarbon solvent and a drying step using a hot blast.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cleaning an optical element such as a lens, and more particularly, to a method for cleaning an optical element made of a glass material having low water resistance and low cleaning resistance.

[0002]

2. Description of the Related Art In the production of optical elements such as lenses and prisms, it is necessary to sufficiently wash abrasives and fine glass powder adhered in a polishing step before sending them to the next step. As a general method of this cleaning, there is cleaning by ultrasonic waves immersed in a cleaning liquid. In this method, ultrasonic waves are applied to a cleaning liquid such as an alkaline cleaning liquid, city water, pure water, or a solvent stored in each cleaning tank, and the object to be cleaned is immersed for a certain period of time. It is a method of removing.

As another cleaning method, the surface of glass is slightly eroded by an alkaline cleaning agent to remove abrasives such as cerium oxide which are stuck on the glass surface in a biting manner. .

Further, without using an alkaline cleaning agent,
Cleaning has also been performed using only non-aqueous cleaning agents typified by chlorine-based cleaning agents and hydrocarbon solvents, and quasi-water-based cleaning agents typified by alcohols.

[0005] In general, in order to obtain the required cleaning quality, a method of using a cleaning paper or cloth to impregnate a solvent such as alcohol into the cleaning paper or cloth and wiping it by hand has been used. .

[0006] Japanese Patent Application Laid-Open No. 9-234431 discloses a method of cleaning with a wiping tool while rotating a lens after polishing.

Japanese Patent Application Laid-Open No. 6-262151 describes that productivity is improved by performing a wiping operation using a robot instead of a manual wiping operation.

[0008]

However, the conventional cleaning method as described above has the following problems.

[0009] In an optical element made of a glass material having low water resistance and detergent resistance, the glass surface is easily eroded when immersed in an alkaline cleaning agent. "Latent wounds (washing)" that become apparent
This causes a problem called When ultrasonic cleaning is used in combination to obtain a higher degree of cleaning, there is a problem that the latent wound is further enlarged by the physical force of ultrasonic waves. Further, in this cleaning method, the dirt such as the abrasive material once separated from the optical element is reattached during immersion in the cleaning tank, and the cleaning property is reduced. In order to improve the cleaning performance, the number of cleaning tanks must be increased to ensure the cleanliness of the cleaning liquid, resulting in an increase in the size of the apparatus, a longer cleaning time,
In addition, the lengthening of the cleaning time leads to deterioration of latent scratches.

[0010] It is difficult to remove abrasives, hand grease, and the like that have bitely adhered to the glass surface without using an alkaline cleaning agent.

In a method in which cleaning is performed using only a non-aqueous cleaning agent or a quasi-aqueous cleaning agent represented by alcohols, for example, high cleanliness is required when a vapor deposition film is formed on the surface of an optical element in the next step. Although required, cleaning quality satisfying this cleanliness cannot be obtained. The method of impregnating a solvent such as alcohol into a cleaning paper or cloth and wiping it by hand is cumbersome, time-consuming, and results in poor productivity. Furthermore, in order to wipe the entire surface of the optical element cleanly, a certain level of skill is required by an operator, and there is a problem that unskilled persons may leave unwiped parts.

The cleaning method disclosed in JP-A-6-262151 is effective to some extent for cleaning abrasives and grease, but it is difficult to completely remove it due to dirt on a wiping tool, and high cleanliness is required. Can not hope.

In a production process in which optical elements having different shapes frequently flow even when a robot is used, as in the cleaning method disclosed in Japanese Patent Application Laid-Open No. Hei 9-234431, the control of the robot becomes complicated or a dedicated optical element is used. It requires a lot of expense, such as having to prepare many robots. Also,
With a robot, it is difficult to obtain a high degree of cleanliness that can be wiped by a skilled worker's hand.

[0014] In addition to the above, it is a well-known fact that leaving an optical element in the air with polishing material adhered to a lens after polishing may cause burns and spots. As a countermeasure, the polished lens is immersed in an oil-based draining agent.
When the oil-based draining agent is carried into the cleaning liquid in the subsequent process, the deterioration of the cleaning liquid is accelerated. Also,
When the oil taken into the cleaning liquid adheres to the optical element again, poor cleaning occurs.

The present invention has been made in consideration of such conventional problems, and does not cause poor cleaning such as residual stains of abrasives and stains, and has low water resistance and detergent resistance. It is an object of the present invention to provide a cleaning method capable of obtaining high cleaning quality without causing latent scratches on an optical element made of a glass material.

[0016]

Means for Solving the Problems In order to solve the above problems, the invention according to claim 1 provides an optical element to be cleaned with:
An abrasive removal step of flowing a fluid to which ultrasonic waves are applied,
A step of immersing the optical element in a quasi-aqueous solvent, a step of immersing in a cleaning liquid to perform a finish cleaning, a rinsing step with pure water, a draining step with a hydrophilic alcohol solution, and a finish cleaning step with a hydrocarbon solvent. And drying by hot air.

According to the present invention, it is necessary to immerse the optical element in an alkaline cleaning agent to remove the abrasive because the abrasive applied to the optical element is removed by flowing the fluid to which the ultrasonic wave is applied. And the occurrence of latent scratches can be prevented.

Further, by subsequently immersing the optical element in a quasi-aqueous solvent, the optical element is not left in the air. Thereby, the occurrence of burns and spots can be prevented.

Then, a finishing cleaning step, a rinsing step, a draining step, a cleaning step using a hydrocarbon solvent,
After the drying step, the cleaning of the optical element is completed.

In the cleaning by such a procedure, there is no occurrence of poor cleaning such as residual stains of abrasives and stains.
In addition, even if the optical element is made of a glass material having low water resistance and detergent resistance, high cleaning quality can be achieved without causing latent scratches.

According to a second aspect of the present invention, there is provided the method for cleaning an optical element according to the first aspect, wherein a neutral cleaning liquid is used as the cleaning liquid.

By using the neutral cleaning liquid for the final cleaning as described above, the final cleaning can be performed well and the cleaning liquid can be easily removed in the subsequent rinsing step. Thereby, cleaning quality is improved.

According to a third aspect of the present invention, there is provided the method for cleaning an optical element according to the first aspect, wherein a high-frequency ultrasonic wave is used in the rinsing step with the pure water.

By using high-frequency ultrasonic waves in the rinsing step, the rinsing force to the cleaning liquid increases. Therefore, the rinsing of the cleaning liquid can be performed reliably.

[0025]

(Embodiment 1) FIG. 1 shows a flowchart of a cleaning method according to Embodiment 1 of the present invention. In this embodiment, as the optical element to be cleaned, a lens with a diameter of 32 mm and a convex surface on both sides made of a glass material (trade name “FPL51 (manufactured by Ohara Kogaku)”) in which latent scratches easily occur is used.

The first step is an ultrasonic running water washing step.
In this step, the fluid to which the ultrasonic wave is applied is flowed over the lens, so that the abrasive is peeled off from the lens surface by the physical force of the ultrasonic wave and flows down.

The second step is a quasi-aqueous solvent stock step. In this process, before pouring the lens into the next cleaning agent, the lens is temporarily immersed in a semi-aqueous solvent and the quality of burns, stains, etc. due to leaving the lens that has been washed with ultrasonic running water in the air is considered. Prevent the occurrence of defects.

The third step is a cleaning agent cleaning step. In this step, cleaning with a neutral detergent is performed to remove oils and fats attached to the lens.

The fourth step is a pure water rinsing step. In this step, the neutral detergent is rinsed and removed with pure water.

The fifth step is a draining step using a hydrophilic alcohol solution. In this step, water adhering to the lens surface is replaced with a hydrophilic alcohol solution that is soluble in the hydrocarbon solvent used in the next step. As a hydrophilic alcohol solution to be used, isopropyl alcohol (IPA) is preferable.

The sixth step is a hydrocarbon solvent cleaning step. In this step, by dipping in a hydrocarbon-based solvent having good drying properties, the drying time in the subsequent step is reduced, and the occurrence of dry spots is suppressed.

The seventh step is a drying step using hot air.

FIG. 2 shows a cleaning apparatus 1 used in the first ultrasonic cleaning step. A first ultrasonic flowing water generator 2 for generating ultrasonic flowing water to which ultrasonic waves are applied;
Are attached to the holder 4 so as to face each other at the vertical position.

These ultrasonic flowing water generators 2 and 3 have ultrasonic oscillators 2a and 3a respectively disposed therein. In addition, the nozzles 2 b and 3 b that discharge the ultrasonic flowing water face the lens 6. Thereby, the ultrasonic flowing water is discharged so as to collide with each other.

A holder 4 for holding the ultrasonic flowing water generators 2 and 3 is attached to a movable device 5. The movable device 5 performs an amplitude motion, whereby the ultrasonic flowing water generators 2 and 3 can perform an amplitude motion.

The lens 5 to be cleaned is held at the lens holder 7 and is arranged at a central position between the nozzles 2b and 3b of the first ultrasonic flowing water generator 2 and the second ultrasonic flowing water generator 3. Have been.

In the cleaning device 1, the ultrasonic flowing water generators 2 and 3 make amplitude movements by the driving of the movable device 3 to peel off the abrasives attached to both surfaces and end surfaces of the lens 5, and to remove the abrasives removed. Free fall the washing water containing. This can prevent the abrasive from re-adhering and enhance the cleaning effect.

FIG. 3 shows a cleaning apparatus used in the quasi-aqueous solvent immersion step of the second step. When cleaning of the lens 6 with the ultrasonic flowing water is completed, the lens 6 is transferred to the stock tank 11 of the cleaning device. The quasi-aqueous solvent 12 is stored in the stock tank 11.

In the quasi-aqueous solvent immersion step, the lenses 6 that have been washed with ultrasonic flowing water are arranged in a washing basket 13. The washing basket 13 is provided with mesh-like partition plates 13a at appropriate intervals, and the lenses 6 are arranged by inserting between the partition plates 13a. By having the partition plate 13a in this manner, the lenses 6 do not contact each other,
The whole can be immersed in the semi-aqueous solvent 12. The lens 6 is immersed in the semi-aqueous solvent 12 by submerging the cleaning basket 13 in the semi-aqueous solvent 12 of the stock tank 11.
As a result, the lens 6 that has been cleaned by the ultrasonic flowing water is completed.
Minimizes exposure to air,
The occurrence of spots can be prevented.

In such an embodiment, since the fluid to which the ultrasonic wave is applied is flowed to remove the abrasive attached to the optical element, it is not necessary to immerse the optical element in an alkaline cleaning agent. The occurrence of scratches can be prevented. Further, since the optical element is not immersed in the air by subsequently immersing it in a semi-aqueous solvent, the occurrence of burns and spots can be prevented.

Therefore, in this embodiment, there is no occurrence of poor cleaning such as residual stains of abrasives and stains, and even if the optical element is made of a glass material having low water resistance and small detergent resistance, latent scratches may occur. High cleaning quality can be achieved without generation of odor.

(Embodiments 2 and 3) FIG. 4 shows a cleaning line used in Embodiments 2 and 3, and the cleaning using this cleaning line will be described below.

Using the polished lens, the lens is immersed in a quasi-aqueous solvent after washing with ultrasonic running water and then washed with a neutral detergent. A comparison was made between the cleaning performance and the latent scratching performance by the conventional cleaning (comparative example) in which the cleaning was performed with a system cleaning agent.

As the optical element, a glass lens to which an abrasive made of cerium oxide was adhered was used. The ultrasonic running water device is a product name "Ultrasonic line shower (Shimada Rika Corporation)
)) Was used. This ultrasonic water flowing device is a USG-30 as an ultrasonic oscillator.
1H-3AS ”and the main unit is“ UST-301 ”
P-85-1A ".

City water as an ultrasonic running water cleaning solution, and a stock solution of “Fine Top S110 (manufactured by Kuraray Co., Ltd.)” as a semi-aqueous solvent for stocking a polished lens,
"EE11" as a cleaning agent after stocking of semi-aqueous solvent
10 (manufactured by Olympus Optical Co., Ltd.), IPA as a draining agent, and a hydrocarbon-based solvent for finishing washing, "Kyowasol C-900 (manufactured by Kyowa Hakko Co., Ltd.)" Was used.

The cleaning liquid was all at room temperature, and the cleaning agent "EE11
10 ”cleaning tank, rinsing cleaning tank and IPA tank have 4
A 0 kHz ultrasonic oscillator was installed. Further, in the comparative example, a trade name “WRS (produced by Yushiro Chemical Co., Ltd.)” is used as an oil-based draining agent for stocking the polished lens.
Was used as an alkaline cleaning solution, a 3% dilution of the brand name "N Cool (National Trading Co., Ltd.)".

At the time of cleaning with ultrasonic flowing water, the lens 6 is moved from the nozzles 2b, 3b to
It was fixed at a position of 0 mm and washed with ultrasonic flowing water for 5 to 20 seconds. The ultrasonic water flowing device 1 was caused to perform an amplitude motion by the movable device 5 at a speed of 100 to 200 mm / sec. All handling of the lens 6 is performed with tweezers.
Dirt such as hand grease is prevented from adhering.

The stock tank 11 filled with "Fine Top S110" was used as stock of the lens after the ultrasonic running water washing. The liquid temperature was room temperature, and the immersion time was 1 hour. As a cleaning step using a cleaning agent, the substrate was immersed in an “EE1110” cleaning solution adjusted to a concentration of 3% for 30 seconds to 3 minutes, and then rinsed in a pure water tank composed of four tanks. "EE111
0 ”Ultrasonic wave of 40 kHz was used in combination only in the washing tank and the first tank of pure water. The rinsing time with pure water was 1 minute per tank, and the rinsing was performed for a total of 4 minutes.

Draining by IPA was performed in an IPA tank comprising four tanks equipped with 40 kHz ultrasonic waves. The washing time was 1 minute per tank, and draining was performed for a total of 4 minutes.

The finish cleaning with the hydrocarbon solvent was performed in a “C900” tank composed of two tanks. Finishing cleaning was performed for one minute per tank, for a total of two minutes.

Drying after washing is performed in a hot air drying oven at 75 ° C. for 3 hours.
Minutes.

As a comparative example, the polished lens is referred to as “WR”.
After immersion in "S" for 1 hour, washing was performed for 10 seconds to 3 minutes in an "N-cool" tank equipped with 40 kHz ultrasonic waves. The steps after the rinsing with pure water are the same as the steps of the above embodiment.

Table 1 shows the results of the embodiment, and Table 2 shows the results of the comparative example.

[0054]

[Table 1]

[0055]

[Table 2]

In the comparative example, the latent damage is improved by shortening the cleaning time of “N cool”, but at the same time, the abrasive cannot be dropped. On the other hand, in the embodiment, the abrasive could be removed, and the cleaning could be performed without generating latent scratches.

As shown in Table 1, in the second embodiment, the ultrasonic cleaning time was 20 seconds, the cleaning with "EE1110" was 1 minute, and the abrasive material could be removed, and no latent scratch was generated.
In the third embodiment, the cleaning time of “EE1110” is set to 30.
Even if it was reduced to seconds, there was no change in the removability of the abrasive.

As shown in Table 2, in Comparative Examples 1 to 3,
Even if the cleaning time by "N Cool" was shortened from 3 minutes to 10 seconds, latent scratches occurred. Also, by shortening the cleaning time by "N Cool", the abrasive could not be removed.

(Embodiments 4 to 8) In these embodiments, the same cleaning lines as those in Embodiments 2 and 3 were used. Further, in these embodiments, the frequency of the ultrasonic wave in the pure water rinsing tank 1 in FIG.
The cleaning was performed by changing to z and 200 kHz. The conditions of each step other than the pure water rinsing step are the same as those in the second and third embodiments. Rinsing was performed in one tank with pure water rinsing using ultrasonic waves, and then in three tanks using pure water rinsing without using ultrasonic waves.

Table 3 shows the results of Embodiments 4 to 8, and Table 4 shows the results of Comparative Examples 4 and 5.

[0061]

[Table 3]

[0062]

[Table 4]

In Comparative Examples 4 and 5, the latent wound was improved by shortening the pure water rinse time using ultrasonic waves.
Latent wound has occurred even for one minute. On the other hand, Embodiments 4 to 8
In the above, the abrasive could be removed, and cleaning could be performed without causing latent scratches.

As shown in Table 3, in Embodiments 4 and 5, when rinsing was performed using 100 kHz ultrasonic waves, the abrasive was easily removed and no latent scratch was generated. In Embodiments 6 to 8, rinsing was performed using ultrasonic waves of 200 kHz. However, the abrasive was easily removed, and no latent scratch was generated.

As shown in Table 4, in Comparative Examples 4 and 5, 40
Rinsing was performed using ultrasonic waves of kHz, but latent scratches occurred.

[0066]

According to the first aspect of the present invention, even if the optical element is made of a glass material having low water resistance and small detergent resistance, there is no occurrence of poor cleaning such as residual stains and stains of abrasives and the like. High cleaning quality can be achieved without causing latent scratches.

According to the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, the finish cleaning can be performed well,
In addition, the finishing cleaning liquid can be easily removed in a later step, and the cleaning quality is improved.

According to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, the rinsing force for the cleaning liquid is increased.
Rinsing of the cleaning liquid can be performed reliably.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a cleaning flow according to a first embodiment.

FIGS. 2A and 2B are a side view and a front view of a cleaning apparatus that performs an ultrasonic flowing water process.

FIG. 3 is a cross-sectional view of a cleaning device that performs an immersion step.

FIG. 4 is a block diagram of a cleaning line according to Embodiments 2 to 8;

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kunihisa Obi 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Co., Ltd. 3B201 AA01 AB45 BB02 BB21 BB83 BB92 BB93 BB94 BB95 CB15 CC01 CC12

Claims (3)

[Claims] An optical element to be cleaned is washed with a fluid to which an ultrasonic wave is applied, a polishing agent is removed, an optical element is immersed in a semi-aqueous solvent, and a final cleaning is performed by immersing the optical element in a cleaning liquid. A method for cleaning an optical element, comprising: a step; a rinsing step with pure water; a draining step with a hydrophilic alcohol solution; a finishing cleaning step with a hydrocarbon solvent; and a drying step with hot air. 2. The method for cleaning an optical element according to claim 1, wherein a neutral cleaning liquid is used as said cleaning liquid. 3. The method for cleaning an optical element according to claim 1, wherein a high frequency ultrasonic wave is used in the rinsing step with the pure water.