JPH10139474A - Optical glass element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical glass element capable of improving weather resistance, especially durability under a high temperature and high humidity condition, without reducing thermal properties and optical characteristics by forming the glass element comprising a phosphoric acid-based glass and having smaller concentration of phosphoric acid component or a larger concentration of at least one component selected from aluminum oxide, silicone oxide, zinc oxide and magnesium oxide components in the neighborhood of the surface compared to the concentration in the interior, and optionally further forming an antireflection membrane or a protection membrane. SOLUTION: This optical glass element is obtained by dipping the optical glass element comprising a phosphoric acid-based glass into an alkaline treating liquid having an alkali concentration substantially not forming the glass into opaque, performing a washing treatment of the dipped glass element by water to remove the ion component remaining on the surface, and further performing a dripping treatment of the washed glass element for removing the water component remaining on the surface. Further, a protecting membrane is formed by introducing a mixed gas comprising a fluorine based gas such as CF4 and oxygen from an introducing opening 3 into a vacuum chamber 2 having the optical glass element 1 arranged therein, and discharging between the glass element and an opposite electrode 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass element useful for an aspherical lens such as a lens for a VTR camera and a lens for an optical disk pickup, an optical fiber coupling element used for optical communication and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, an optical lens or the like has been manufactured by press molding with high precision without performing a process such as polishing. One of the molding methods is to place a glass material between the upper and lower molds of a molding die made of cemented carbide, cermet, ceramic, etc., raise the temperature to near the softening point of the glass, and press-mold. is there. This press molding is generally performed in a non-oxidizing atmosphere such as nitrogen gas in order to prevent surface deterioration due to oxidation of the mold material. In particular, the surface of the mold where the mold contacts the glass material is coated with a platinum-based alloy to prevent the surface from being roughened due to the fusion with the glass and the reaction with the glass, as well as the antioxidant function. It has been like that.

[0003] Further, in view of the glass material, the optical characteristics have been improved, and a glass having a low softening point has been developed. It has become Above all, phosphate glass is widely used as a glass material for press molding.

[0004] However, phosphate-based glass has insufficient weather resistance, and is not suitable for long-term storage under high temperature and high humidity.
Due to the reaction between the water layer adsorbed on the surface and the phosphoric acid component in the phosphate glass, fogging occurs on the lens surface, and in a remarkable case, a foreign substance is generated, which reduces the optical characteristics, for example, the transmittance. And other problems occur. Improvements are being actively made on this issue.

[0005] For example, providing a coating film on the surface has been performed as a material that is compatible with requirements from the viewpoint of optical characteristics. For example, a multilayer vapor-deposited film of MgF ₂ / ZrO ₂ / CeF ₃ is formed to achieve compatibility with an antireflection function. Further, from the viewpoint of the glass material, an attempt has been proposed to improve the weather resistance of the glass material itself by adding a water-resistant component such as boron oxide or alumina oxide. For example, JP-A-4-8387 and JP-A-4-76938 have made improvements in terms of material composition.

[0006]

However, in the above-mentioned prior art, it is difficult to balance low softening point, optical properties and weather resistance, which have recently been required for high reliability.
There is a problem that a demand for higher-order balance is desired.

[0007] The present invention has been made in view of the above circumstances, and without impairing the thermophysical properties and optical properties, the weather resistance,
In particular, an object of the present invention is to provide an optical glass element having improved durability under high temperature and high humidity and a method for manufacturing the same.

[0008]

In order to achieve the above object, a first optical glass element of the present invention is an optical glass element made of phosphate glass, wherein the composition in the vicinity of the surface is compared with the composition in the inside. And a low phosphoric acid component.

Next, a second optical glass element of the present invention is an optical glass element made of phosphate glass,
The composition near the surface compared to the internal composition, aluminum oxide,
It is characterized in that at least one component selected from silicon oxide, zinc oxide, and magnesium oxide components is large.

Next, a third optical glass element of the present invention is an optical glass element made of phosphate glass,
It is characterized in that the surface includes a vitreous layer altered by a fluorine component.

Next, a fourth optical glass element of the present invention is an optical glass element made of phosphate glass,
A hard carbon film is formed on the surface. In the first optical glass element of the present invention, it is preferable that the composition in the vicinity of the surface has a phosphoric acid component that is 20% or less in terms of a phosphorus (P) element ratio as compared with the composition in the inside.

In the second optical glass element of the present invention, the composition near the surface is at least one component selected from the group consisting of aluminum oxide, silicon oxide, zinc oxide and magnesium oxide as compared with the internal composition. However, it is preferable that any one of the elements is larger by 50% or more in terms of a ratio of an aluminum (Al) element, a silicon (Si) element, a zinc (Zn) element, and a magnesium (Mg) element.

In the first or second optical glass element of the present invention, it is preferable that a film containing a fluorine component is further formed on the surface of the optical glass element. In the first to third optical glass elements of the present invention,
The thickness of the film containing the fluorine component is preferably in the range of 5 to 20 nm.

In the first to third optical glass elements of the present invention, the vitreous layer altered by a fluorine component is formed by plasma treatment of a mixed gas of a fluorine compound and oxygen. Is preferred.

In the first to third optical glass elements of the present invention, it is preferable that a hard carbon film is formed on the surface of the optical glass element or the surface of the film containing a fluorine component.

In the first to fourth optical glass elements of the present invention, the hardness of the hard carbon film is preferably in the range of 1500 to 2500 as measured by the micro Vickers method.

In the first to fourth optical glass elements of the present invention, the hard carbon film has a thickness of 10 to 30 n.
It is preferably in the range of m. The first aspect of the present invention
In the fourth to fourth optical glass elements, the hard carbon film is
It is preferably a molecular deposition film formed by a plasma CVD method.

Next, in the first method for producing an optical glass element of the present invention, an optical glass element made of a phosphate glass is immersed in an alkaline treatment solution having an alkali concentration not substantially devitrifying. It has a configuration in which a water washing process for removing ionic components remaining on the surface is performed, followed by a draining process for removing moisture remaining on the surface.

Next, in a second method for manufacturing an optical glass element according to the present invention, the optical glass element made of phosphate glass is treated with a plasma of a mixed gas of a fluorine compound and oxygen, and the surface of the optical glass element is treated. To form a vitreous layer containing a fluorine component.

Next, in a third method for manufacturing an optical glass element according to the present invention, an optical glass element made of a phosphate glass is provided in a vacuum chamber, and an electrode is provided on one surface and an opening is provided on an opposite surface. In a sub-chamber provided with a counter electrode having an optical glass element disposed on the surface thereof, a hard carbon film is formed on the surface of the optical glass element by a plasma CVD method.

In the first or third method,
It is preferable that the surface of the optical glass element is further treated with plasma of a mixed gas of a fluorine-based compound and oxygen to form a glassy layer containing a fluorine component.

In the above method, it is preferable that the treatment with the plasma is performed by disposing an optical glass element on the lower electrode surface of a counter electrode arranged vertically. In addition, the first
In the second method, the optical glass element is further provided in a vacuum chamber, and an electrode is provided on one side, and an opening is provided on the opposite side, and a counter electrode on which the optical glass element is arranged is provided. In the sub-chamber, it is preferable to further form a hard carbon film on the surface of the optical glass element by a plasma CVD method.

In the above method, it is preferable that the opposing electrodes are arranged in the vertical direction, the electrode having an opening, and the optical glass element disposed on the surface thereof is a lower electrode.

In the first to third methods,
It is preferable that the alkali concentration of the alkaline processing liquid is in the range of 1 to 10% by weight.

[0025]

Embodiments of the present invention will be described below. The phosphoric acid-based glass of the present invention is not particularly limited, but is generally selected from glasses having the following composition, based on optical characteristics, chemical durability, solubility, moldability, and prevention of devitrification. In consideration of various characteristics such as the above, a combination is used. _{(1) P 2 O 5:} 40~80wt% (2) Al 2 O 3: 8~25wt% (3) B 2 O 3, SiO 2, ZrO 2, TiO 2, La 2
_{O 3: 0.1~20wt% (4)} MgO, ZnO, CaO, BaO, SrO: 0.
1 to 20 wt% The composition near the surface is at least
Low phosphoric acid component or aluminum oxide, silicon oxide,
An optical glass element made of a phosphoric acid glass containing at least one or more components of zinc oxide and magnesium oxide components is immersed in an alkaline treatment solution, and then washed with water to remove ionic components remaining on the surface. It is obtained by removing, followed by a draining treatment to remove water remaining on the surface.

By dipping in an alkaline treatment solution, a phosphoric acid component present on the lens surface is eluted, and a relatively hardly eluted component remains on the surface, thereby forming an effective protective film. By such a treatment, the reaction between the water layer adsorbed on the surface under high temperature and high humidity and the phosphoric acid component in the phosphate glass is suppressed, and the durability under high temperature and high humidity is improved.

The alkaline processing liquid is sodium metasilicate,
An aqueous alkali solution of water glass, sodium phosphate, potassium phosphate, caustic soda or the like can be used alone or as a mixture, and a surfactant may be added for the purpose of improving the wettability to the glass surface. The surfactant is desirably a nonionic surfactant having a small residual ionic component on the surface.

The temperature, time, concentration and the like of the immersion of the alkaline treatment liquid can be experimentally determined, but the alkali component is preferably 1 to 10% by weight and the surfactant is preferably 0.01 to 1% by weight. Excessive immersion roughens the lens surface and devitrifies it in a significant case, so it is necessary to adjust it according to the phosphate glass used.
Further, at the time of immersion, efficiency may be improved by mechanically swinging and using ultrasonic vibration together.

Further, after immersion in the alkaline treatment liquid, it is necessary to sufficiently wash with water and perform drainage treatment. Insufficient washing and draining may not only result in fogging of the surface after drying and insufficient effect, but also may lower the weather resistance due to ionic components remaining on the surface.

The water-washing treatment may be performed by immersing in pure water filtered with a 0.2 μm filter, using mechanical vibration and using ultrasonic vibration together, and thereby improving efficiency. Draining treatment, after immersion in a hydrophilic organic solvent such as alcohol, low-boiling solvent heated to near boiling point, for example, acetone, methyl ethyl ketone, ethyl alcohol, isopropyl alcohol, etc. It can be carried out by immersing in a hydrophobic low boiling point solvent such as an organic silicon type or fluorine type and drying.

An optical glass element having a surface on which at least one fluoride of a constituent element is formed can be obtained by treating the optical glass element with a plasma of a mixed gas of a fluorine-based compound and oxygen.

The plasma processing can be performed by the plasma processing apparatus shown in FIG. CF ₄ , C ₂ F ₆ , C ₃ F are placed in a vacuum chamber 2 in which an optical glass element 1 is disposed.
_The discharge is performed between the counter electrodes 4 while introducing a mixed gas of a fluorine compound such as ₈ and an oxygen gas through the inlet 3. The counter electrode 4 is connected to a power supply 6 for plasma generation via an introduction terminal 5. The mixing ratio of the mixed gas of the fluorine compound gas and the oxygen gas is suitably in the range of fluorine compound gas: oxygen gas = 1: 1000 to 1: 1 (volume ratio), and the gas pressure of the vacuum chamber is 0.1. In the range of 01 Torr to 10 Torr, the discharge type may be any of an external electrode type and an internal electrode type,
The discharge frequency can be determined experimentally.
Further, the vacuum chamber 2 is evacuated by a vacuum pump 7.

Also, by arranging the electrodes in the vertical direction as shown in FIG. 1, the sample can be set on the surface of the lower electrode without a holder, and an unprocessed portion by the holder can be eliminated. It is possible to treat the entire surface of the glass element, and it is possible to prevent the generation of foreign substances with an untreated portion as a nucleus, thereby improving environmental preservation.

Next, a hard carbon film is formed by plasma CVD of a mixed gas of a hydrocarbon and an inert gas such as argon.
It can be formed by a method. The method of forming the hard carbon film will be described in more detail with reference to FIG. 2 which is a schematic diagram of a hard carbon film forming apparatus.

In FIG. 2, reference numeral 8 denotes a vacuum chamber, and the pressure inside the tank is reduced to 10 ⁻⁵ torr by using a vacuum pump 9.
Evacuation is performed so as to attain a high vacuum state of r to 10 ^-4 torr. Generate plasma in the vacuum chamber,
A sub-chamber 10 for forming a hard carbon film on the surface of the optical element is provided, and discharge electrodes 11 and 12 are provided inside the sub-chamber. The discharge electrode is connected to a power supply 13 for plasma generation. Optical glass element 15
Are arranged on the surface of the lower electrode 12. In addition, a slit 16 of 200 μm is provided on the lower electrode and the side wall of the sub-chamber to evacuate the sub-chamber,
A differential pressure is provided between the inside of the vacuum chamber. A source gas composed of a hydrocarbon gas and an inert gas is supplied into the sub-chamber from 14 gas inlets.

To form a hard carbon film, a mixed gas of a hydrocarbon gas and an inert gas is introduced into the sub-chamber,
While maintaining the pressure of 0.001 to 1 Torr, a discharge is generated inside the sub-chamber to generate a plasma of hydrocarbon gas and form a hard carbon film on the surface. As a discharge type, a discharge in which an alternating current is superimposed on a direct current is suitable, and a discharge frequency can be experimentally determined. In addition, by applying a voltage up to -2 KV to the lower electrode on which the sample is placed, the hardness of the film can be improved and the adhesion strength can be improved. As a mixed gas ratio of the hydrocarbon gas and the inert gas, a range of hydrocarbon gas: inert gas = 10: 1 to 1: 3 (capacity ratio) can be used. It can be determined by design.

As the hydrocarbon gas, methane, ethane,
Aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane and octane, and aromatic hydrocarbons such as benzene, toluene and xylene can be used, and argon gas is suitable as the inert gas.

By discharging in the sub-chamber, abnormal discharge due to high voltage can be prevented and stable plasma discharge can be obtained. Further, in order to form a film having a high protective effect, it is desirable to increase discharge energy as much as possible.

The hard carbon film exhibits a protective effect from a thickness of 50 Å (5 nm) or more, and is preferably as thick as possible within a range that satisfies the requirements of optical characteristics. Furthermore, the alkaline treatment liquid immersion method, the plasma treatment of a mixed gas of a fluorine-based compound and oxygen, and the formation of a hard carbon film can also be used in combination.
Improve synergistically.

[0040]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

[0041]

Example 1 A phosphate glass material was placed between an upper mold and a lower mold of a molding die made of a cemented carbide, and a pressure of 100 kg was applied.
Heat molding was performed at a temperature of 420 ° C. to produce an aspherical collimating lens precisely corresponding to a molding die.

Then, this lens was immersed in an alkali treatment solution containing a nonionic surfactant containing 0.5 wt% of polyoxyethylene alkyl ether containing 5 wt% of water glass for 30 minutes while using ultrasonic vibration together. Thereafter, the substrate was immersed in running pure water for 10 minutes while using ultrasonic vibration. Then, after immersing in isopropyl alcohol for 10 minutes while also using ultrasonic vibration, immersing in isopropyl alcohol heated to 90 ° C. for 5 minutes,
It dried and the sample 1 was produced.

Similarly, the processing conditions were changed, and optical lens glasses of Samples 2 to 8 were prepared. When the transmittance was measured, no change was observed in the transmittance of any of the samples before and after the treatment. As comparative samples, optical lens glasses not subjected to the alkali treatment were designated as Samples 9 and 10, Samples 5 to 8, and Sample 10
An antireflection film of magnesium fluoride was formed on the surface of the substrate by a vapor deposition method. The vapor deposition is performed by sandwiching the lens between circular holders. In the lens after the vapor deposition, as shown in FIG. After leaving these samples for three months in an environmental bath at a temperature of 60 ° C. and a relative humidity of 80%, they were observed with an optical microscope at a magnification of 100, and the appearance was evaluated. Calculated.
Table 1 shows the processing conditions and test results. As is clear from Table 1, the lenses of the present invention (Samples 1 to 8) had a cloudy surface,
No foreign matter was observed, and the change in transmittance was within 0.5%. On the other hand, untreated lenses produced white foreign matter on the entire surface, the transmittance decreased by 20% or more, and In the lens having an anti-reflection film made of a magnesium vapor-deposited film, no fogging was observed, but partial fogging was observed on the surface. In addition, a white foreign matter was generated in a non-evaporated part in the peripheral part by the holder at the time of evaporation.

[0044]

[Table 1]

The surface of Sample 1 was analyzed before and after the treatment. The analysis was performed by measuring a depth profile by Auger spectroscopy. In the sample before treatment, the depth from the outermost surface is 1
In the vicinity of the surface up to 0 nm, the phosphoric acid component exhibited a substantially constant intensity, gradually decreased from 10 nm to 20 nm, and thereafter exhibited a substantially constant intensity. On the other hand, the strength of each component of aluminum oxide, silicon oxide, zinc oxide, and magnesium oxide gradually increased in the vicinity of the surface from the outermost surface to a depth of 20 nm, and showed a substantially constant strength thereafter. As described above, in the press-molded lens, the surface has many phosphoric acid components having low weather resistance, and the components of aluminum oxide, silicon oxide, zinc oxide, and magnesium oxide that improve moisture resistance are small. In the sample after the treatment, the opposite tendency was exhibited, and in the vicinity of the surface from the outermost surface to a depth of 10 nm, each component of aluminum oxide, silicon oxide, zinc oxide, and magnesium oxide exhibited a constant strength, and showed a strength of 10 nm to 20 n.
m, the strength gradually decreased, and thereafter, the strength was almost constant. Conversely, the strength of the phosphoric acid component gradually increased near the surface from the outermost surface to a depth of 20 nm, and thereafter showed a substantially constant strength. By immersion in alkali treatment solution, phosphoric acid component with low weather resistance on the surface decreased, indicating that aluminum oxide, silicon oxide, zinc oxide, magnesium oxide, which improve moisture resistance, were increased. . The analysis results of the same tendency were obtained in Samples 2 to 8.

[0046]

Embodiment 2 An aspherical collimating lens manufactured in the same manner as in Embodiment 1 was placed on the lower electrode surface in a vacuum chamber of the plasma processing apparatus shown in FIG. 1, and carbon tetrafluoride / oxygen (1) was supplied at a flow rate of 60 SCCM. / 10, volume ratio) while introducing a mixed gas of 300 W under a gas pressure of 0.2 Torr.
Microwave discharge was performed at a power of 30 minutes to perform a plasma treatment, and the sample was manufactured by performing the plasma treatment under the same conditions from the opposite side, with the sample being turned upside down. Similarly, the processing conditions were changed, and optical lens glasses of samples 12 to 18 were prepared. When the transmittance was measured, no change was observed in the transmittance before and after the treatment. An anti-reflection film made of a magnesium fluoride vapor-deposited film was formed on a part of the sample as in Example 1. After leaving these samples for 3 months in an environmental bath at a temperature of 60 ° C. and a relative humidity of 80%, they were observed with an optical microscope at a magnification of 100 ×, and the appearance was evaluated.
The transmittance was measured and the rate of change was calculated. Table 2 shows the processing conditions and test results. Table 2 shows the processing conditions and test results.
As is clear from Table 2, the lenses of the present invention (samples 11 to 11)
18) is cloudy on the surface, no generation of foreign matter is observed, and the change in transmittance is within 0.5%. On the other hand, the lens which is not treated at the same time produces white foreign matter on the entire surface, and the transmittance is Also, in the lens on which the antireflection film made of the magnesium fluoride vapor-deposited film was formed, although the generation of foreign matter was not observed, partial fogging was observed on the surface.

[0047]

[Table 2]

The depth profiles of the samples 11 to 18 were measured by X-ray photoelectron spectroscopy (ESCA). In all samples, fluorine was detected in the vicinity of the surface from the outermost surface to a depth of 20 nm, indicating the formation of fluoride.

[0049]

Embodiment 3 An aspherical collimating lens manufactured in the same manner as in Embodiment 1 was placed on the lower electrode surface in a sub-chamber of the hard carbon film forming apparatus shown in FIG. 2, and methane and argon (3: 1) were mixed. A gas was introduced under the conditions of 400 SCCM, high-frequency (10 KHz) plasma was generated, a DC voltage of -1.0 KV was applied to the lower electrode, and discharge was performed.
A hard carbon film having a thickness of nm was formed. Further, a hard carbon film was formed under the same conditions from the opposite side, with the front and back of the sample reversed. This lens is referred to as a sample 19. Similarly, the processing conditions were changed, and optical lens glasses of Samples 20 to 26 were prepared. As a comparative example, samples 27 and 28 in which the ends of the lens were held in such a manner as to be held down from both sides, and carbon films were formed on both sides by sputtering using graphite as a target.
It was created. An anti-reflection film made of a magnesium fluoride vapor-deposited film was formed on a part of the sample as in Example 1.

After leaving these samples in an environmental bath at a temperature of 60 ° C. and a relative humidity of 80% for 3 months, they were observed with an optical microscope at a magnification of 100, and the appearance was evaluated and the transmittance was measured. Then the rate of change was calculated. Table 3 shows the processing conditions and test results. As is clear from Table 3, the lenses of the present invention (samples 20 to 26) were clouded on the surface, no foreign matter was observed, and the change in transmittance was within 0.5%. In the lens (sample 27) on which the sputtered carbon was formed, fogging occurred in spots. Also, a lens (sample 28) in which an antireflection film made of a vapor-deposited magnesium fluoride film was formed on sputtered carbon was formed.
Partial clouding was observed, white foreign matter was generated from the untreated portion of the lens at the periphery of the holder, and a decrease in transmittance was measured.

[0051]

[Table 3]

As is apparent from Tables 1, 2 and 3, the optical glass lens of the present invention can be applied to the surface of the optical glass lens even when left in a high-temperature and high-humidity environment for a long time. No fogging or microscopic foreign matter was generated, and the change in transmittance was 0.5% or less, indicating excellent durability.

Sample 1 immersed in the alkali treatment liquid of Example 1 was replaced with Sample 29 subjected to plasma treatment under the same conditions as Sample 11 of Example 2, or Sample 1 was replaced with hard carbon under the same conditions as Sample 19 of Example 3. A sample 30 having a film formed thereon, and a sample 31 having a hard carbon film formed thereon under the same conditions as the sample 19 of Example 3 were formed on a sample 29 subjected to plasma treatment after being immersed in an alkali treatment solution. These samples were then
An environmental test was conducted by leaving the sample in an environmental bath at a temperature of 60 ° C. and a relative humidity of 80%. In any of the samples, no generation of foreign matter was observed, and a reduction in transmittance was within 1%. It showed durability.

As described above, the combination of the alkali treatment, the plasma treatment, and the formation of the hard carbon film showed excellent durability.

[0055]

As described above, according to the present invention, thermophysical properties,
An optical glass element with improved weather resistance, especially durability under high temperature and high humidity, without impairing optical characteristics, and a method for producing the same can be provided. Further, an effective protection effect can be given to the optical glass element, and a remarkable effect of preventing deterioration of optical characteristics can be obtained in long-term use in a high temperature and high humidity environment.

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view of a plasma processing apparatus according to a second embodiment of the present invention.

FIG. 2 is a conceptual sectional view of a hard carbon film forming apparatus according to a third embodiment of the present invention.

FIG. 3 is an external view of a lens having an antireflection film formed on a surface by a vapor deposition method according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical glass element 2 Vacuum chamber 3 Gas inlet 4 Counter electrode 5 Introducing terminal 6 Power supply for plasma generation 7 Vacuum pump 8 Vacuum chamber 9 Vacuum pump 10 Subchamber 11 Upper electrode 12 Lower electrode 13 Power supply for plasma generation 14 Gas inlet 15 Optical glass element 16 Slit 17 Evaporated part 18 Non-evaporated part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02B 1/02 G02B 1/02 1/10 1/10 Z

Claims (21)

[Claims] 1. An optical glass element comprising a phosphate glass, wherein the composition near the surface has less phosphoric acid components than the composition inside the optical glass element. 2. In an optical glass element made of a phosphate glass, at least one component selected from the group consisting of aluminum oxide, silicon oxide, zinc oxide and magnesium oxide has a greater composition in the vicinity of the surface than in the interior. An optical glass element, characterized in that: 3. An optical glass element made of a phosphate glass, comprising a vitreous layer whose surface is altered by a fluorine component. 4. An optical glass element comprising a phosphate glass, wherein a hard carbon film is formed on the surface. 5. The optical glass element according to claim 1, wherein the composition in the vicinity of the surface has a phosphoric acid component that is at least 20% less in terms of the elemental ratio of phosphorus (P) than the composition in the interior. 6. A composition in which at least one component selected from the group consisting of aluminum oxide, silicon oxide, zinc oxide and magnesium oxide has an aluminum (Al) element and a silicon (Si) element as compared with the inner composition. 3. The optical glass element according to claim 2, wherein the content of any one of the elements is 50% or more in terms of a ratio of element, zinc (Zn) and magnesium (Mg). 7. The optical glass element according to claim 1, wherein a glassy layer further modified by a fluorine component is formed on the surface of the optical glass element. 8. The optical glass element according to claim 3, wherein the thickness of the vitreous layer altered by the fluorine component is in the range of 5 to 20 nm. 9. The optical glass element according to claim 3, wherein the glassy layer altered by the fluorine component is formed by plasma treatment of a mixed gas of a fluorine-based compound and oxygen. 10. A hard carbon film formed on an optical glass element surface or a film containing a fluorine component.
8. The optical glass element according to 2, 3, or 7. 11. The optical glass element according to claim 4, wherein the hardness of the hard carbon film is in a range from 1500 to 2500 as measured by a micro Vickers method. 12. The hard carbon film has a thickness of 10 to 30 nm.
The optical glass element according to claim 11, wherein 13. The optical glass element according to claim 4, wherein the hard carbon film is a molecular deposition film formed by a plasma CVD method. 14. An optical glass element made of a phosphoric acid-based glass is immersed in an alkaline treatment solution having an alkali concentration not substantially devitrifying, and then subjected to a water washing treatment for removing ionic components remaining on the surface. A method for producing an optical glass element, which performs a water removal treatment for removing water remaining on the surface. 15. An optical glass element comprising an optical glass element made of a phosphoric acid-based glass and treated with plasma of a mixed gas of a fluorine-based compound and oxygen to form a glassy layer containing a fluorine component on the surface of the optical glass element. Production method. 16. An opposing electrode having an optical glass element made of a phosphoric acid-based glass in a vacuum chamber, having an electrode on one surface and an opening on an opposing surface, and arranging the optical glass element on the surface. A method for manufacturing an optical glass element, wherein a hard carbon film is formed on the surface of the optical glass element by a plasma CVD method in a sub-chamber provided with. 17. The method for producing an optical glass element according to claim 14, wherein the surface of the optical glass element is further treated with plasma of a mixed gas of a fluorine compound and oxygen to form a glassy layer containing a fluorine component. 18. The method of manufacturing an optical glass element according to claim 17, wherein the plasma processing is performed by arranging the optical glass element on a lower electrode surface of a counter electrode arranged vertically. 19. A sub-chamber in which an optical glass element is further provided in a vacuum chamber, an electrode is provided on one surface, and an opening is provided on an opposite surface, and a counter electrode having an optical glass element disposed on the surface is provided. In the plasma CV
The method for manufacturing an optical glass element according to claim 14, 15, or 17, further comprising forming a hard carbon film on the surface of the optical glass element by a D method. 20. The method of manufacturing an optical glass element according to claim 19, wherein the opposing electrodes are arranged in the up-down direction, the opening has an opening, and the electrode on which the optical glass element is arranged is a lower electrode. Method. 21. The alkaline processing liquid having an alkali concentration of:
The method for producing an optical glass element according to claim 14, wherein the content is in a range of 1 to 10% by weight.