JPH11232706A - Three-dimensional optical memory medium and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional(3D) optical memory medium with high read contrast. SOLUTION: Concerning this 3D optical memory medium, a fine grain- dispersed medium 3 such as glass is used as a substrate and single or plural spots, where the dispersing state of fine grains is locally changed by irradiating the inside of the substrate with converged pulse laser beam, are formed inside the substrate. As for fine grain 3, Au, Cu, Ag, Pt, CuCl, CuBr, Cds, CdSe or CdTe is used. At the spot, the absorption coefficient of the fine grain-dispersed medium 3 in an absorption wavelength area is decreased (5). The pulse laser light having the quantity of energy for changing the fine grain dispersing state is converged inside the fine grain-dispersed medium 3 and while relatively moving the convergent point of pulse laser beam inside the fine grain-dispersed medium 3, the single or plural spots obtd. by locally changing the dine grain dispersing state are formed inside the fine grain-dispersed medium 3 so that such a 3D optical memory medium can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional image in which the readout contrast (S / N) is improved by forming one or a plurality of spots in which the state of dispersion of fine particles is locally changed inside the fine particle dispersion medium. The present invention relates to an optical memory medium and a method for manufacturing the same.

[0002]

2. Description of the Related Art Various recording media, such as hard disks, are required to have an improved recording density with an increase in information processing capacity. Above all, the laser beam used for recording / reproduction can be reduced to the diffraction limit of light so that the recordable area can be made as large as the wavelength used, specifically 1 cm.
Since high recording density ² per 10 ^8-bit is obtained, the optical memory studies have made great progress, some have been put into practical use. As the direction of increasing the capacity of optical discs,
Since the writing area can be reduced by shortening the wavelength of the laser used for writing, the wavelength of the laser can be shortened. However, it is not easy to shorten the wavelength of the laser itself, and the absorption coefficient of the material increases with the shortening of the wavelength.
It is about. Even if it is assumed that the problem of shortening the wavelength of the laser and the increase of the absorption coefficient accompanying the shortening of the wavelength can be overcome, it is said that the limit of increasing the recording density to about four times the current level is the limit.

Therefore, instead of increasing the relative recording density by reducing the recording area, it is being studied to increase the recording capacity by increasing the spatial dimension of recording from two to three dimensions. As a member of this system, there are a method of three-dimensionally recording information using a photochromic material whose transmittance changes by light irradiation, and a method of causing a three-dimensional change in refractive index using a photorefractive crystal. . However, in the method having a photochromic material, the photochromic material is an organic material and easily deteriorates due to heat or light. Further, there is a disadvantage that the recording state shows a temporal change, the sensitivity is too high, and the photoreaction proceeds even by the reading light, so that the recording state changes. On the other hand, in the method using a photorefractive crystal, since the photorefractive crystal has optical anisotropy, the recording state differs depending on the axial direction of the crystal when recording.

By multiplexing the wavelengths of light used for reading and writing, the recording density per spot is increased,
Research is also underway to increase capacity. As a member of this system, there is photochemical hole burning (PHB). In photochemical hole burning, the width of the light absorption spectrum by the active center is a medium in which organic dyes, rare earth metal ions, etc. are dispersed as active centers in a transparent solid medium such as glass, polymer, ionic crystal, or metal oxide crystal. Utilizing the fact that it is wider than it originally has (uniform width) due to its non-uniformity. That is,
When a specific wavelength within the non-uniform width is irradiated with a laser beam having a narrow line width, the absorption of the irradiated wavelength is saturated, and a hole is formed in the absorption spectrum. According to this method, in principle, a multiplicity of 10 ³ or more per spot is possible,
It is said that the recording density can be increased to 10 ¹¹ bits / cm ² .

[0005] However, most PHB phenomena are below 200 ° C.
The problem is that it is observed only at the following extremely low temperatures and does not operate at room temperature. In recent years, the PHB phenomenon has been observed even at room temperature (K. Hirao et al., J. Lu.
mi. , 55, 217 (1993)) have problems such as low multiplicity and poor generation efficiency. A novel three-dimensional optical memory glass which solves such a problem is disclosed in
-220688. This three-dimensional optical memory glass is stable to heat and light and has no optical anisotropy. When a pulse laser is condensed and radiated into the glass matrix while scanning the glass matrix three-dimensionally, a light-induced change in refractive index occurs in a minute spot, and information is recorded as a spatial refractive index distribution. This method enables stable recording of information over a long period of time, which is stable against heat and light, has excellent weather resistance, and can increase the recording capacity of an optical disk.

[0006]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No. Hei 8-2
In the case of the optical memory glass introduced in Japanese Patent No. 20688, the change in the refractive index is only induced by the focused irradiation of the pulsed laser beam, and the irradiated material itself is the same. Therefore, there is no large change in composition between the portion where the refractive index change has occurred and the portion where the refractive index change has not occurred, and the amount of the induced refractive index change cannot be so large. Since the change in the transmittance or the reflectance caused by only the change in the refractive index is used for the memory, the contrast (S / N) in reading is reduced due to the small change in the refractive index. I can't make it big. In order to solve such a problem, the present invention forms one or more spots in which the dispersion state of the fine particles is locally changed by condensing irradiation of the pulsed laser light into the inside of the fine particle dispersion medium, thereby improving the read contrast. (S
/ N) is provided.

[0007]

In order to achieve the object, the three-dimensional optical memory medium of the present invention uses a fine particle dispersion medium as a base, and the dispersed state of the fine particles is condensed by irradiating a pulse laser beam inside the base. One or more locally changed spots are present inside the substrate. At the spot, the absorption coefficient in the absorption wavelength region of the fine particle dispersion medium decreases. As fine particles, Au, Cu,
Ag, Pt, CuCl, CuBr, CdS, CdSe,
One or more selected from CdTe are used and dispersed in a fine particle dispersion medium such as glass, polymer, ionic crystal, and metal oxide crystal. This three-dimensional optical memory medium focuses pulsed laser light having an energy amount that changes the state of dispersion of fine particles inside the fine particle dispersion medium, and relatively moves the focal point of the pulse laser light inside the fine particle dispersion medium. It is manufactured by forming one or more spots in which the dispersion state of the fine particles is locally changed, inside the fine particle dispersion medium. As the pulse laser light to be used, a pulse laser light in a wavelength region where the transmittance of the fine particle dispersion medium is 20% or more is preferable.

[0008]

When a pulsed laser beam is condensed and radiated into the fine particle dispersion medium, a change in the refractive index similar to that of the optical memory glass occurs at the converging point, and the dispersion state of the fine particles, which are colored species,
That is, the number of fine particles dispersed in the fine particle dispersion medium, the size of the fine particles, the form of the fine particles, and the like change. Specifically, the number of fine particles is reduced, the size of the fine particles is reduced, and the fine particles disappear due to dissolution or ionization in a medium.
When the particles no longer exist as fine particles due to dissolution or ionization in the medium, the absorption coefficient of that portion becomes the same value as that of the medium in which the fine particles are not dispersed, and decreases as compared to before the irradiation.
When the size of the fine particles changes due to the converging irradiation of the laser beam, the absorption wavelength changes due to the change in the size of the fine particles, and the absorption coefficient at the irradiation wavelength after the converging irradiation is smaller than before the converging irradiation. Therefore, when the wavelength of the laser beam used for reading is set in the absorption wavelength region of the fine particle dispersion medium, the absorption coefficient of the portion other than the focal point is the same as before the irradiation, whereas the absorption coefficient decreases at the focal point. From that
The transmittance or the reflectance is increased only at the focal point, and the read contrast (S / N) is improved as compared with the case where only the change in the refractive index is used.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Fine particles dispersed in a fine particle dispersion medium include metal fine particles such as Au, Cu, Ag, and Pt, and Cd.
There are semiconductor fine particles such as S, CdSe, CdTe, CuCl, and CuBr. These fine particles are dispersed in a medium such as glass, polymer, ionic crystal, and metal oxide crystal. Among them, glass is very suitable as a medium because it is optically isotropic and has excellent heat resistance and light resistance. The dispersion amount of the fine particles dispersed in the fine particle dispersion medium is preferably 0.01 to 50% by weight. The amount of dispersion is 0.
When the content is less than 01% by weight, there is a tendency that the readout contrast cannot be increased because the absorption coefficient is small. Conversely, if the amount of dispersion exceeds 50% by weight, the dispersed fine particles aggregate without being uniformly dispersed, or the aggregates increase the substantial size of the particles, causing light scattering and lowering the read contrast. Show the tendency to do.

[0010] The dispersion state of the fine particles dispersed in the fine particle dispersion medium changes at the light collection point and in the vicinity thereof because the inside of the fine particle dispersion medium is irradiated with the pulsed laser beam whose light collection point is set. In the irradiated portion other than the focal point, the light amount required for changing the dispersion state is not obtained, and the same dispersion state as before the irradiation with the pulsed laser beam is maintained. As a result, only the inside of the fine particle dispersion medium is selectively transformed. The laser light 1 emitted from the light source is condensed by a condensing device 2 such as a lens as shown in FIG. At this time, the focal point of the light collecting device 2 is adjusted so that the light collecting point 4 is located inside the fine particle dispersion medium 3. If the step scan of irradiating the focal point 4 with spots and spots is adopted, a region where the dispersion state of the fine particles has changed is formed in a dot shape. When the focal point 4 is three-dimensionally moved relative to the fine particle dispersion medium 3, a three-dimensionally changed region is formed inside the fine particle dispersion medium material 3. The relative movement of the focal point 4 with respect to the fine particle dispersion medium 3 includes a method of moving the fine particle dispersion medium 3 while fixing the fine focus 4 and a method of moving the focal point 4 while fixing the fine particle dispersion medium 3. Are used in combination.

The peak power of the pulse laser is 1 pulse
Output energy per pulse (J) divided by pulse width (seconds)
Is expressed in watts (W). Peak power density
Is the unit area (cm^Two ) Peak power per W
/ Cm^Two It is represented by Pulsed laser light at the focal point
Has a peak power density of 10⁸ -10¹⁷W / cm^Two Range of
It is desirable to be in the surroundings. 10⁸ W / cm^Two Less than pea
In the power density, the refractive index change and fine particle
The scattering state does not change sufficiently. Conversely 10 ¹⁷W / cm^Two Over
Refraction at the peak power density
Rate change and the dispersion state of fine particles change,
It is difficult to obtain. In addition, excessive amounts of energy
Laser light is practically difficult.

When irradiating with a laser beam having the same peak power density, a laser beam having a smaller pulse width is more likely to cause a change in the refractive index and a change in the state of dispersion of fine particles. In this regard, laser light having a pulse width of 10 ^-10 seconds or less is preferable. In the case of a laser beam having an excessively wide pulse width, it is necessary to irradiate a laser beam having a very large energy for a change in the refractive index and a change in the state of dispersion of the particles, which may destroy the material of the particle dispersion medium. The irradiation amount is set to an amount necessary for a change in the refractive index and a change in the dispersion state of the fine particles. The repetition period (interval between pulses) of the pulse laser is not particularly limited, but is an extremely short period (for example, 100 MHz).
In such a case, a change in the refractive index and a change in the state of dispersion of the fine particles begin to occur even in portions other than the condensing portion.

[0013]

Example 1 Au fine particle dispersed glass An aqueous solution of chloroauric acid was added to a compounding raw material of SiO ₂ , B ₂ O ₃ , Na ₂ CO ₃ and Sb ₂ O ₃ , and SiO ₂ : 72% by weight, B ₂ O _3: 18 wt%, 10Na ₂ O: 10 wt%, Sb ₂ O _3: 4 wt%, Au: is prepared to have a 0.02 weight% of the composition. 400g of raw material powder to 300c
c After being charged into a platinum crucible, the mixture was heated and dissolved at 1450 ° C. in the atmosphere with stirring for 2 hours. The uniformly melted glass was poured into a brass mold, formed into a plate having a thickness of 5 mm, and cooled. The obtained glass was annealed at 450 ° C. to remove the distortion. In order to precipitate Au fine particles in the glass, the temperature of the glass was raised at a rate of 5 ° C./min using an electric furnace, and the temperature was raised to 650.
After holding at 4 ° C. for 4 hours, it was allowed to cool in the furnace. Then, the sample was cut and polished to obtain a sample having a thickness of 4 mm. The obtained glass sample was colored red due to the precipitation of gold fine particles. When the size of the Au fine particles dispersed in the glass was observed using a transmission electron microscope (TEM), fine particles having an average particle diameter of 10 nm were dispersed.

The glass sample was irradiated with a pulse laser focused so that the focal point was located inside the glass sample.
That is, the pulsed laser beam 1 is collected inside the glass sample 3 as shown in FIG. 1 with the glass sample 3 placed on an electric stage capable of scanning in the XYZ directions and the Z-axis (optical axis) direction fixed. The light was focused by the lens 2 so that the light spot 4 was positioned, and the glass sample 3 was irradiated. As the pulse racer light, light having a pulse width of 1.5 × 10 ^-13 seconds, a repetition period of 50 Hz, and a wavelength of 800 nm emitted from an argon laser-excited Ti-sapphire laser was used. Focus point 4
The spot formed in the sample had a diameter of about 1 μm. The diameter of the spot is determined by the magnification of the lens 2 and the pulse laser beam 1
Can be further reduced by increasing the beam diameter.
The Au particle-dispersed glass of this example had a transmittance of 89% at a wavelength of 800 nm. After irradiating the focal point 4 with a peak energy density of 10 ¹³ W / cm ² for 3 seconds, the laser beam 1 is stopped from entering the glass sample 3, the glass sample 3 is scanned in the X and Y directions, and collected again under the same conditions. Light irradiation was performed. After repeating the focusing irradiation, stopping the focusing irradiation, and moving the glass sample 3, the motorized stage in the Z-axis direction
The laser beam was moved by μm, and focused and irradiated similarly in the XY directions.

When the glass sample 3 subjected to the condensing irradiation treatment was observed with an optical microscope, as shown in FIG. 2, in the condensing irradiation part, the absorption in the wavelength band (about 400 to 580 nm) absorbed by the Au fine particles was observed. The region 5 in which the coefficient was reduced and the red coloring disappeared was formed. On the other hand, no color change was observed in the non-condensed irradiation part. Wavelength 530n
When the recorded information was read using light of m, the difference between the refractive index change and the transmittance, which is thought to be due to the phenomenon of the absorption coefficient, was detected between the condensing irradiation part and the non-condensing irradiation part. The contrast was significantly higher than that of Comparative Example 1 using only There was no reading error between the upper and lower spots at intervals of 5 μm, and information could be recorded three-dimensionally in the X, Y, and Z directions.

Example 2: Cu fine particle dispersed glass SiO_Two , B_Two O_Three , Na_Two CO_Three , Cu_Two O, SnO
The raw material powder of SiO _Two : 72% by weight, B_Two O_Three : 20
Wt%, Na_Two O: 8% by weight, Cu: 0.5% by weight, S
nO: It was blended in a composition of 0.25% by weight. Raw material powder 40
After charging 0g into a 300cc platinum crucible,
The mixture was heated and dissolved at 450 ° C. with stirring for 2 hours. Uniform dissolution
Pour the glass into a brass mold and form a 5mm thick plate.
Molded and cooled. Anneal the obtained glass at 450 ° C
Then, the distortion was removed. Precipitating Cu fine particles in glass
The temperature of the glass at a rate of 5 ° C / min using an electric furnace
Then, after maintaining the temperature at 650 ° C. for 4 hours, it was cooled in a furnace. Analysis
The glass that has been exposed is cut and polished, and a 4 mm thick sample is
Produced. This glass sample is obtained by the precipitation of Cu fine particles.
It is colored yellow and can be observed with a transmission electron microscope (TEM).
It was observed that Cu fine particles with an average particle size of 20 nm
It was dispersed in the matrix.

Next, the manufactured glass sample 3 was irradiated with pulsed laser light in the same manner as in Example 1. As the pulse laser light, light having a pulse width of 1.5 × 10 ^-13 seconds, a repetition period of 100 Hz, and a wavelength of 1.0 μm, emitted from a Ti-sapphire laser excited by an argon laser, was used.
The spot formed at the focal point 4 had a diameter of about 2 μm. The Cu fine particle dispersed glass of this example is 1.0 μm
At a wavelength of 90%. After irradiating the focal point 4 with a peak energy density of 10 ¹¹ W / cm ² for 5 seconds, the laser beam 1 is stopped from entering the glass sample 3, the glass sample 3 is scanned in the X and Y directions, and collected again under the same conditions. Light irradiation was performed. The focusing irradiation, stopping the focusing irradiation, and moving the glass sample were repeated. Next, the electric stage was moved to 15 μm in the Z-axis direction, and the light was similarly irradiated in the XY directions.

Observation of the condensed and irradiated glass sample 3 by an optical microscope revealed that, as shown in FIG. 2, an absorption coefficient of a wavelength band (about 400 to 580 nm) absorbed by the Cu fine particles in the condensed and irradiated portion. Was reduced, and the colorless region 5 was formed without yellowing.
On the other hand, no color change was observed in the non-condensed irradiation part. When the recorded information was read using light having a wavelength of 530 nm, a difference in the transmittance, which is considered to be caused by the change in the refractive index and the phenomenon of the absorption coefficient, was detected between the converging irradiation part and the non-condensing irradiation part, which will be described later. The contrast was significantly higher than that of Comparative Example 1 using only the change in the refractive index of Comparative Example 1. In addition, there was no reading error of the upper and lower spots at an interval of 15 μm, and information could be recorded three-dimensionally in the X, Y, and Z directions.

Example 3: Ag fine particle dispersed glass SiO ₂ , CaCO ₃ , Na ₂ CO ₃ , Ag ₂ O, Sn
O as raw material powder, SiO ₂ : 72% by weight, CaO: 2
0 wt%, Na ₂ O: 8% by weight, Ag: 0.4% by weight,
SnO: It was blended so as to have a composition of 0.2% by weight. After 400 g of the raw material powder was put into a 300 cc platinum crucible, the mixture was heated and dissolved in the atmosphere at 1450 ° C. for 2 hours while stirring. The uniformly melted glass was poured into a brass mold to form a plate having a thickness of 5 mm. After cooling, the strain was removed by annealing at 450 ° C. In order to precipitate Ag fine particles in the glass, the glass was heated at a rate of 5 ° C./min using an electric furnace, kept at 550 ° C. for 4 hours, and then allowed to cool in the furnace. Thereafter, the sample was cut and polished to produce a sample having a thickness of 4 mm. The glass subjected to the precipitation treatment is colored yellow by precipitation of Ag fine particles, and is observed by a transmission electron microscope (TEM).
As a result, Ag fine particles having an average particle size of 8 nm were dispersed in the glass matrix.

The glass sample 3 subjected to the deposition treatment was irradiated with pulsed laser light in the same manner as in Example 1. As the pulse laser light, light having a pulse width of 1.5 × 10 ^-13 seconds, a repetition period of 1 kHz, and a wavelength of 600 nm, emitted from a Ti-sapphire laser excited by an argon laser, was used. The spot formed at the focal point 4 had a diameter of about 0.8 μm. The Ag particle dispersed glass of this example had a transmittance of 91% at a wavelength of 600 nm. After irradiating the focal point 4 with a peak energy density of 10 ¹⁴ W / cm ² for 3 seconds, the laser beam 1 is stopped from entering the glass sample 3, the glass sample 3 is scanned in the X and Y directions, and collected again under the same conditions. Light irradiation was performed. After repeating the condensing irradiation, stopping the condensing irradiation, and moving the glass sample, the electric stage was moved by 5 μm in the Z-axis direction, and the condensing irradiation was similarly performed in the XY directions.

When the glass sample 3 subjected to the condensing irradiation treatment was observed with an optical microscope, as shown in FIG. 2, the wavelength band (about 3
The absorption coefficient (60 to 480 nm) was reduced, and the colorless region 5 was formed without yellowing. on the other hand,
No color change was observed in the non-condensed irradiation part. When the recorded information was read using light having a wavelength of 420 nm, a difference in the transmittance, which is considered to be due to a change in the refractive index and a decrease in the absorption coefficient, was detected between the converging irradiation part and the non-condensing irradiation part. The contrast was significantly higher than that of Comparative Example 2 using only the change. In addition, there was no reading error of the upper and lower spots at 5 μm intervals.
Information could be recorded three-dimensionally in the Y and Z directions.

Example 4: Pt fine particle-dispersed glass An aqueous solution of chloroplatinic acid was added to raw material powders of SiO ₂ , B ₂ O ₃ , Na ₂ CO ₃ and Sb ₂ O ₃ , and SiO ₂ : 72% by weight, B ₂ O ₃ : 18% by weight, Na ₂ O: 10% by weight, S
The composition was prepared to have a composition of b ₂ O ₃ : 2% by weight and Pt: 0.05% by weight. After 400 g of the raw material powder was charged into a 300 cc platinum crucible, the mixture was heated and dissolved at 1450 ° C. in the atmosphere for 2 hours. The uniformly melted glass was poured into a brass mold to form a plate having a thickness of 5 mm, cooled, and annealed at 450 ° C. to remove distortion. Pt in glass
Use an electric furnace to raise the temperature at 5 ° C to precipitate the fine particles.
/ Min, and hold the glass at 600 ° C for 4 hours.
It was left to cool in the furnace. Next, the glass sample was cut and polished to produce a glass sample having a thickness of 4 mm. This glass sample was colored gray due to precipitation of Pt fine particles, and when observed by a transmission electron microscope (TEM), Pt fine particles having an average particle size of 15 nm were dispersed in the glass matrix.

The glass sample 3 subjected to the precipitation treatment was irradiated with pulsed laser light in the same manner as in Example 1. As the pulse laser light, light having a pulse width of 1.5 × 10 ^-13 seconds, a repetition period of 1 kHz, and a wavelength of 1.0 μm, emitted from a Ti-sapphire laser excited by an argon laser, was used. The spot diameter at the focal point 4 was about 2 μm. The Pt fine particle dispersed glass of this example had a transmittance of 89% at a wavelength of 1.0 μm. Peak energy density 10
After irradiating the focusing point 4 with ¹³ W / cm ² for 5 seconds, the laser beam 1 was stopped from entering the glass sample 3 and the glass sample 3
Scanning was performed in the Y-axis direction, and irradiation was again performed under the same conditions. After repeating the condensing irradiation, stopping the condensing irradiation, and moving the glass sample, the electric stage is set to 20 μm in the Z-axis direction.
It was moved and irradiated similarly in the XY directions.

When the condensed and irradiated glass sample 3 was observed with an optical microscope, as shown in FIG. 2, the wavelength band (about 400 to 750 nm) absorbed by the Pt fine particles was observed.
The region 5 in which the absorption coefficient was decreased, the gray coloration was lost, and the color changed to colorless was formed in the condensed irradiation part. No color change was observed in the non-condensed irradiation part. 600n wavelength
When the recorded information was read using the light of m, the difference in the refractive index between the condensed irradiation part and the non-condensed irradiation part, which was considered to be due to the change in the refractive index and the decrease in the absorption coefficient, was detected. The contrast was remarkably higher than that of Comparative Example 1 using only In addition, there was no reading error of the upper and lower spots at intervals of 20 μm, and information could be recorded three-dimensionally in the X, Y, and Z directions.

Example 5: CuCl fine particle dispersed glass SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Li ₂ CO ₃ , Na
_{Using 2} CO ₃ , K ₂ CO ₃ , CuCl and SnO as raw material powder, SiO ₂ : 65 wt%, Al ₂ O ₃ : 6 wt%, B ₂ O ₃ : 17 wt%, Li ₂ O: 4 wt% , Na
₂ O: 4% by weight, K ₂ O: 4% by weight, CuCl: 0.5% by weight, SnO: 0.2% by weight. After 400 g of the raw material powder was put into a 300 cc platinum crucible, the mixture was heated and dissolved in the atmosphere at 1450 ° C. for 2 hours while stirring. The uniformly melted glass was poured into a brass mold to form a 5 mm-thick plate. After cooling, the strain was removed by annealing at 450 ° C.

In order to precipitate CuCl fine particles in the glass, the glass was heated at a rate of 5 ° C./min using an electric furnace, kept at 550 ° C. for 4 hours, and allowed to cool in the furnace. Next, the glass sample was cut and polished to produce a glass sample having a thickness of 4 mm. The obtained glass sample is subjected to a transmission electron microscope (TEM).
As a result, it was found that CuCl fine particles having an average particle diameter of 8 nm were dispersed in the glass matrix. The glass sample 3 subjected to the precipitation treatment was irradiated with a pulse laser in the same manner as in Example 1. The pulsed laser light includes argon laser-excited T
Pulse width 1.5 oscillated from i-sapphire laser
Light having a wavelength of 500 nm and a repetition period of 1 kHz and a wavelength of ^10-13 seconds was used. The spot formed at the focal point 4 had a diameter of about 0.7 μm.

The CuCl fine particle dispersed glass of this embodiment is
The transmittance at a wavelength of 500 nm was 92%. After irradiating the focal point 3 with a peak energy density of 10 ¹⁵ W / cm ² for 3 seconds, the laser beam 1 is stopped from entering the glass sample 3 and the glass sample 3 is scanned in the X and Y directions, and collected again under the same conditions. Light irradiation was performed. This focusing irradiation, stopping the focusing irradiation,
After repeating the operation of moving the glass sample, the motorized stage was moved by 3 μm in the Z-axis direction, and focused and irradiated similarly in the XY-axis directions. When the glass sample subjected to the condensing irradiation treatment was observed with an optical microscope, as shown in FIG. 2, the wavelength band (about 30 nm) absorbed by the CuCl fine particles in the condensing irradiation part was observed.
(0 to 385 nm), a region 5 having a reduced absorption coefficient was formed. On the other hand, no color change was observed in the non-condensed irradiation part. When the recorded information was read using light having a wavelength of 375 nm, a difference in the transmittance, which is considered to be due to a change in the refractive index and a decrease in the absorption coefficient, was detected between the condensing irradiation part and the non-condensing irradiation part. The contrast was significantly higher than that of Comparative Example 3 using only the rate change.
In addition, there was no reading error of the spots of the upper layer and the lower layer at an interval of 3 μm, and information could be recorded three-dimensionally in the X, Y, and Z directions.

Example 6: Cd (S, Se) fine particle dispersion gas
Las SiO_Two , Al_Two O_Three , B_Two O_Three , Na_Two CO_Three , Zn
O, CdS, CdSe as raw material powder, SiO
_Two : 69% by weight, Al_Two O_Three : 1% by weight, B_Two O _Three : 1
2% by weight, Na_Two O: 6% by weight, ZnO: 11% by weight,
Composition of CdS: 0.3% by weight and CdSe: 0.2% by weight
Was prepared. 400g of raw material powder is 300cc platinum ruth
After being charged into the bottle, stir at 1450 ° C for 2 hours in the atmosphere.
And dissolved by heating. Pour the uniformly melted glass into a brass mold
And molded into a 5 mm thick plate. After cooling, 450 ° C
The strain was removed by annealing. Cd in glass
(S, Se) Using an electric furnace to precipitate fine particles
The temperature of the glass is raised at a rate of 5 ° C./min, and the temperature is raised to 650 ° C. for 4 hours.
After holding, it was allowed to cool in the furnace. Then, cutting and polishing,
A glass sample having a thickness of 4 mm was prepared. This glass sample
Is colored red by precipitation of Cd (S, Se) fine particles.
And observed with a transmission electron microscope (TEM)
Cd (S, Se) fine particles having an average particle size of 10 nm
The tricks were dispersed.

The glass sample 3 subjected to the precipitation treatment was irradiated with a pulse laser in the same manner as in Example 1. As the pulse laser light, light having a pulse width of 1.5 × 10 ^-13 seconds, a repetition period of 1 kHz, and a wavelength of 650 nm, emitted from a Ti-sapphire laser excited by an argon Ar laser, was used. The spot formed at the focal point 4 had a diameter of about 0.9 μm. The Cd (S, Se) fine particle-dispersed glass of this example had a transmittance of 85% at a wavelength of 650 nm. Focus point 3 with peak energy density 10 ¹⁵ W / cm ²
After 3 seconds, the laser beam 1 was stopped from being incident on the glass sample 3, and the glass sample 3 was scanned in the X and Y directions, and again focused and irradiated under the same conditions. After repeating the condensing irradiation, stopping the condensing irradiation, and moving the glass sample, the electric stage was moved by 10 μm in the Z-axis direction, and the condensing irradiation was similarly performed in the XY-axis directions.

When the glass sample 3 subjected to the condensing irradiation treatment was observed with an optical microscope, as shown in FIG. 2, in the condensing irradiation part, the wavelength band (about 450 to 450) absorbed by the Cd (S, Se) fine particles was observed. 580 nm),
The red-colored region 5 was changed to a colorless state. On the other hand, no color change was observed in the non-condensed irradiation part. When the recorded information was read out using light having a wavelength of 480 nm, a difference in transmittance between the condensed irradiating portion and the non-condensing irradiating portion, which is considered to be caused by a change in refractive index and a phenomenon of an absorption coefficient, was detected. The contrast was significantly higher than that of Comparative Example 4 using only the change. Also, 10μ
There is no reading error of the upper and lower spots at m intervals,
Information could be recorded three-dimensionally in the X, Y, and Z directions.

Example 7: Cd (Se, Te) fine particle dispersed glass SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Na ₂ CO ₃ , Zn
O, CdSe, CdTe as raw material powder, SiO
₂ : 69% by weight, Al ₂ O ₃ : 1% by weight, B ₂ O ₃ : 1
2% by weight, Na ₂ O: 3% by weight, ZnO: 11% by weight,
The composition was prepared to have a composition of CdSe: 0.3% by weight and CdTe: 0.2% by weight. After 400 g of the raw material powder was put into a 300 cc platinum crucible, the mixture was heated and dissolved in the atmosphere at 1450 ° C. for 2 hours while stirring. The uniformly melted glass was poured into a brass mold to form a 5 mm-thick plate, and after cooling, 450 g
The strain was removed by annealing at ° C. Cd in glass
In order to precipitate (Se, Te) fine particles, the glass was heated at a heating rate of 5 ° C./min using an electric furnace, kept at 650 ° C. for 4 hours, and then allowed to cool in the furnace. Next, the glass sample was cut and polished to produce a glass sample having a thickness of 4 mm. The obtained glass sample was colored red by precipitation of Cd (Se, Te) fine particles, and when observed with a transmission electron microscope (TEM), the Cd (Se, Te) fine particles having an average particle size of 10 nm were glass. The matrix was dispersed.

The glass sample 3 subjected to the precipitation treatment was irradiated with a pulse laser in the same manner as in Example 1. As the pulsed laser light, light emitted from a Ti-sapphire laser excited by an argon laser, having a pulse width of 1.5 × 10 ⁻¹³ seconds, a repetition period of 1 kHz, and a wavelength of 1.2 μm was used. The spot formed at the focal point 4 had a diameter of about 2 μm.
The Cd (Se, Te) fine particle dispersed glass of the present embodiment is
The transmittance at a wavelength of 1.2 μm was 85%. 10 at the focal point 3 with a peak energy density of 10 ¹⁵ W / cm ²
After irradiation for 2 seconds, the laser beam 1 was stopped from being incident on the glass sample 3, the glass sample 3 was scanned in the X and Y directions, and the light was again irradiated under the same conditions. After repeating the condensing irradiation, stopping the condensing irradiation, and moving the glass sample, the electric stage was moved by 20 μm in the Z-axis direction, and the condensing irradiation was similarly performed in the XY directions.

When the glass sample subjected to the condensing irradiation treatment was observed with an optical microscope, as shown in FIG. 2, in the condensing irradiation part, the wavelength band (about 700 to 900 nm) absorbed by the Cd (Se, Te) fine particles was observed. ) Has a reduced absorption coefficient,
The region 5 changed to colorless was formed. On the other hand, no color change was observed in the non-condensed irradiation part. Wavelength 75
When the recorded information was read using light of 0 nm, the difference in the transmittance, which is considered to be due to the change in the refractive index and the phenomenon of the absorption coefficient, was detected between the converging irradiation part and the non-condensing irradiation part,
The contrast was significantly higher than that of Comparative Example 4 using only the change in the refractive index. In addition, there was no reading error of the upper and lower spots at intervals of 20 μm, and information could be recorded three-dimensionally in the X, Y, and Z directions.

Example 8: Cd (S, Te) fine particle dispersion gas
Las SiO_Two , Al_Two O_Three , B_Two O_Three , Na_Two CO_Three , Zn
O, CdS, CdTe as raw material powder, SiO
_Two : 69% by weight, Al_Two O_Three : 1% by weight, B_Two O _Three : 1
21 weight, Na_Two O: 61 weight, ZnO: 111 weight,
Composition of CdS: 0.31 weight, CdTe: 0.21 weight
Was prepared. 400g of raw material powder is 300cc platinum ruth
After being put in the bottle, stir in the atmosphere at 1450 ° C for 2 hours.
And dissolved by heating. Pour uniformly melted glass into a brass mold
After shaping into a 5 mm thick plate and cooling, 450
The strain was removed by annealing at ℃. Cd (S,
Te) In order to precipitate fine particles, the heating rate is increased using an electric furnace.
The temperature of the glass is raised at a rate of 5 ° C./min and held at 650 ° C. for 4 hours.
After that, it was allowed to cool in the furnace. Then, cut and polished to a thickness of 4
mm glass samples were prepared. The obtained glass sample is
Colored red by precipitation of Cd (S, Te) fine particles
When observed with a transmission electron microscope (TEM),
Cd (S, Te) with an average particle size of 10 nm
Was dispersed in the box.

The glass sample 3 subjected to the precipitation treatment was irradiated with a pulse laser in the same manner as in Example 1. As the pulse laser light, light having a pulse width of 1.5 × 10 ^-13 seconds, a repetition period of 200 kHz, and a wavelength of 800 nm emitted from an argon laser-excited Ti-sapphire laser was used. The spot formed at the focal point 4 had a diameter of about 1.5 μm. The Cd (S, Te) fine particle-dispersed glass of this example had a transmittance of 80% at a wavelength of 800 nm. Focus point 3 with peak energy density 10 ¹⁵ W / cm ²
After irradiating the glass sample 3 for 10 seconds, the laser beam 1 was stopped from being incident on the glass sample 3, the glass sample 3 was scanned in the XY-axis directions, and the light was again irradiated under the same conditions. After repeating the condensing irradiation, stopping the condensing irradiation, and moving the glass sample, the electric stage was moved by 15 μm in the Z-axis direction, and the condensing irradiation was similarly performed in the XY directions.

When the glass sample 3 subjected to the condensing irradiation treatment was observed with an optical microscope, as shown in FIG. 2, in the condensing irradiation part, the wavelength band (about 500 to 500) absorbed by the Cd (S, Te) fine particles was observed. 750 nm),
The red-colored region 5 was changed to a colorless state. On the other hand, no color change was observed in the non-condensed irradiation part. When the recorded information was read using light having a wavelength of 580 nm, a difference in transmittance between the condensed irradiating portion and the non-condensing irradiating portion, which is considered to be due to a change in the refractive index and a decrease in the absorption coefficient, was detected. Comparative Example 4 using only change
A remarkably large contrast was obtained as compared with. Also, 1
There was no reading error of the upper and lower layer spots at 5 μm intervals, and information could be recorded three-dimensionally in the X, Y, and Z directions.

Comparative Example 1 Same as Example 1 except that no aqueous solution of chloroauric acid was added.
Using raw materials, SiO _Two : 72% by weight, B_Two O_Three : 18
Wt%, Na_Two O: 10% by weight, Sb_Two O_Three : 4% by weight
A glass having the following composition was produced. The resulting thickness of 4mm
Glass was used as the recording material, and the
It was focused and irradiated with laser light. Concentrated irradiation treated glass
Was observed with an optical microscope. As shown in FIG.
The area 6 where the rate has changed is formed in the condensed irradiation part,
No change in the refractive index was observed in the non-light-collected irradiation part.
The recorded information was read using light with a wavelength of 530 nm.
Of course, depending on the change in the refractive index between
The difference in transmittance (contrast)
I found out. However, contrast (S / N)
Is very small compared to Examples 1, 2, and 4.
Was.

Comparative Example 2 Using the same raw materials as in Example 3 except that Ag ₂ O was not blended, SiO ₂ : 72% by weight, CaO: 20% by weight,
A glass having a composition of Na ₂ O: 8% by weight and SnO: 0.2% by weight was prepared. The obtained glass having a thickness of 4 mm was used as a recording material, and focused and irradiated with pulsed laser light in the same manner as in Example 3. Observation of the condensed and irradiated glass by an optical microscope revealed that a refractive index change region 6 was formed in the condensed and irradiated portion as shown in FIG. No change in the refractive index was observed in the non-condensed irradiation part. Wavelength 420nm
When the recorded information was read using this light, it was found that there was a difference (contrast) in the transmittance between the condensed light irradiating part and the non-condensing light irradiating part, presumably due to the change in the refractive index. However, the contrast (S / N) was much smaller than that of Example 3.

Comparative Example 3 The same raw materials as in Example 5 were used except that CuCl was not blended. SiO ₂ : 65% by weight, Al ₂ O ₃ : 6% by weight,
B ₂ O ₃ : 14% by weight, Li ₂ O: 4% by weight, Na ₂
O: 4 wt%, K ₂ O: 4 wt%, SnO: to produce a glass having a composition of 0.2 wt%. Obtained thickness 4mm
Was used as a recording material, and focused and irradiated with pulsed laser light in the same manner as in Example 5. Observation of the condensed and irradiated glass sample with an optical microscope revealed that the refractive index change region 6 was formed in the condensed and irradiated portion as shown in FIG. No change in the refractive index was observed in the non-condensed irradiation part. When the recorded information was read using light having a wavelength of 375 nm, the difference (contrast) in the transmittance between the converging and irradiating portions and the non-condensing irradiating portion, which is considered to be due to a change in the refractive index.
It turned out that it was attached. However, the contrast (S
/ N) was much smaller than that of Example 5.

Comparative Example 4 The same raw materials as in Examples 6 to 8 were used except that the Cd compound was not blended. SiO ₂ : 69% by weight, Al ₂ O ₃ : 1% by weight, B ₂ O ₃ : 12% by weight, Na ₂ O: 6% by weight, Z
A glass having a composition of nO: 11% by weight was produced. The obtained glass having a thickness of 4 mm was used as a recording material, and was irradiated with condensed laser light in the same manner as in Example 6. Observation of the glass sample subjected to the condensing irradiation treatment with an optical microscope,
As shown in FIG. 3, the refractive index changing region 6 was formed in the condensed irradiation part. On the other hand, no change in the refractive index was observed in the non-condensed irradiation part. When the recorded information was read out using light having a wavelength of 480 nm, it was found that a difference (contrast) in transmittance between the converging and irradiating portions and the non-concentrating irradiating portions was considered to be due to a change in refractive index. But,
The contrast (S / N) was very small as compared with Examples 6 to 8.

Table 1 shows changes in transmittance in Examples 1 to 8 and Comparative Examples 1 to 4. As is clear from the comparison between the example and the comparative example, in the glass according to the present invention, the region 5 in which the precipitated fine particles are changed by the irradiation of the laser beam condensed, the refractive index is changed, or the absorption coefficient is reduced. It is formed. Due to this region 5, an extremely large contrast (S / N) is obtained as compared with a glass having a conventional refractive index changing region 6.
Is obtained, and it can be seen that this is an excellent three-dimensional optical memory medium.

[0042]

[0043]

As described above, in the three-dimensional optical memory medium of the present invention, the inside of the fine particle dispersion medium is condensed and irradiated with the pulsed laser light, so that the fine particles precipitated in the fine particle dispersion medium are altered. Thus, a region where the refractive index changes or the absorption coefficient decreases is formed. Since a large number of such regions are formed three-dimensionally in the fine particle dispersion medium in accordance with the focal point of the pulsed laser beam, they can be used for high-density recording. In addition, the contrast is very high and the reading error is small as compared with the optical memory medium using only the change in the refractive index.

[Brief description of the drawings]

FIG. 1 A state in which a fine particle-dispersed medium is irradiated inside a fine-particle-dispersed glass material with a laser beam whose focal point is adjusted.

FIG. 2 shows a three-dimensional optical memory medium in which a spot-like refractive index change / absorption coefficient reduction region is formed inside a fine particle dispersion medium.

FIG. 3 shows a three-dimensional optical memory medium in which a spot-like refractive index change region is formed inside a fine particle dispersion medium.

[Explanation of symbols]

1: pulsed laser light 2: focusing device (lens)
3: Fine particle dispersion medium (glass sample) 4: Focus point
5: a region where the refractive index has changed or the absorption coefficient has decreased 6: a refractive index change region

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyotaka Miura 1-13-22 Suzaku, Nara City, Nara Prefecture

Claims (5)

[Claims] 1. A three-dimensional light in which one or a plurality of spots in which a dispersion state of fine particles is locally changed by condensing irradiation of a pulsed laser beam on the inside of a base and a fine particle dispersion medium is present in the base. Memory medium. 2. The three-dimensional optical memory medium according to claim 1, wherein one or more spots having a reduced absorption coefficient in an absorption wavelength region of the fine particle dispersion medium are formed. 3. The three-dimensional optical memory medium according to claim 1, wherein the fine particle dispersion medium is a fine particle dispersion glass. 4. The method according to claim 1, wherein the fine particles of the fine particle dispersion medium are Au, C
u, Ag, Pt, CuCl, CuBr, CdS, CdS
The three-dimensional optical memory medium according to any one of claims 1 to 3, wherein one or two or more kinds of fine particles selected from e and CdTe are dispersed. 5. A method in which a pulsed laser beam having an amount of energy that changes the state of dispersion of fine particles is focused inside the fine particle dispersion medium, and while the focal point of the pulse laser light is relatively moved inside the fine particle dispersion medium, the fine particles are dispersed. A method for manufacturing a three-dimensional optical memory medium, wherein one or more spots whose states have locally changed are formed inside a fine particle dispersion medium.