JPH07138563A - High-power infrared laser beam detector and its production - Google Patents

Abstract

PURPOSE:To obtain a detector used for high-power infrared laser beams and having excellent durability and emission characteristics. CONSTITUTION:The detector is prepared by binding a powder of a phosphor which converts infrared laser beams into visible light and comprises a fluoride based on lead fluoride in which erbium fluoride and ytterbium fluoride are dissolved to form a solid solution with a glassy substrate. This detector shows a high damage threshold value even with respect to YAG laser beams, does not suffer from damage of phosphor by YAG laser beams, and has high reliability. When compared with conventional detectors, it has a remarkable high emission intensity and can sharply detect YAG laser beams.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared laser light detector for converting infrared laser light into visible light and detecting the presence of the infrared light with the naked eye. The present invention relates to a high-power infrared laser light detector which has a high damage threshold for a high-power infrared laser light, is excellent in durability, and has good emission efficiency.

[0002]

2. Description of the Related Art YAG laser emits high-power infrared light and is used in cutting machines and welding machines. However, since the light beam itself is invisible light, there is a danger in operations such as optical axis adjustment. Therefore, a simple detector that detects the presence of the laser light is required. As such a detecting body, a detecting body is known, in which a phosphor powder that converts infrared light into visible light is applied on a substrate and the presence of the phosphor that receives infrared light can be detected by shining. Has been.

However, many of the detectors currently in use are obtained by adhering a phosphor powder on a heat-resistant glass or a metal substrate with an organic binder such as polyvinyl alcohol, and the infrared light having an output of several watts or more. When the light is received for a long time, there is a problem that the binder deteriorates and volatilizes due to the heat of infrared light. Further, a shape in which a phosphor is sandwiched between transparent resin substrates is also known, but the resin substrate is inferior in heat resistance, and holes are easily formed in the substrate by laser light.

As an example of solving such a drawback, there is known one in which phosphor powder is adhered to the surface of a heat-resistant substrate by an inorganic binder such as water glass, low melting point glass or cement (Practical application No. 3-). 23547). However, this detector also has a limit of use of infrared light having an output of several 150 W / cm ² or less, and it can be used for infrared light having a high energy of lasing output of several KW / cm ² such as YAG laser light. However, there is a drawback that the phosphor layer is volatilized by the heat of the laser beam to form pores. Furthermore, the substrate may be damaged by the volatilization of the phosphor, and if the phosphor layer volatilizes, the volatile substance adheres to the beam irradiation port of the laser light and interferes with the beam irradiation, so the irradiation port must be replaced. Causing serious problems such as
Maintenance of the device becomes very complicated.

In order to avoid damage to the detector, the output of the beam is also reduced at the time of checking the beam shape and adjusting the optical axis. However, the beam shape is affected by the decrease in the output. Such a method is not suitable for processing with a laser beam in a minute area. As described above, the conventional photodetector is easily damaged by high-power light such as YAG laser light, has sufficient durability and stability against YAG laser light, and has high emission intensity. Not currently obtained.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in conventional photodetectors, and provides a photodetector having excellent durability and emission intensity for high-power infrared laser light. Is. In the present invention, a fluoride powder obtained by heating and melting lead fluoride, ytterbium fluoride (hereinafter, Yb) and erbium fluoride (hereinafter, Er) is used as a phosphor powder, and a glass substance is added to the powder. In addition, by solidifying, a photodetector that is not easily damaged by high-power YAG laser light, maintains stable emission characteristics for a long time, and has an emission intensity superior to that of powdered phosphor is obtained. Is.

[0007]

According to the present invention, there is provided a high-power infrared laser light detector having the following structure and a method for manufacturing the same. (1) A phosphor for converting infrared laser light into visible light, which comprises phosphor powder mainly composed of lead fluoride and made of a fluoride containing Er and Yb, which is solidified by a glass substance. Characteristic high power infrared laser light detector. (2) The high-power infrared laser light detector according to (1) above, wherein the phosphor powder is a fluoride powder containing lead fluoride as a main component and Er fluoride and Yb fluoride dissolved in lead fluoride. (3) The photodetector according to (1) above, wherein the phosphor powder is a fluoride powder mainly containing lead fluoride, containing 5 to 30 atom% of Yb and 0.5 to 4.5 atom% of Er. . (4) The photodetector according to (1) above, which is obtained by adding 2 to 30 parts by weight of a glass substance to 100 parts by weight of the phosphor powder, press-molding and sintering. (5) A mixed powder of lead fluoride, Yb fluoride, and Er fluoride is heated and melted at 800 to 1200 ° C. in the air, crushed, added with a glass substance, pressure-molded, and then sintered in the air. A method for manufacturing a high-power infrared laser light detector, comprising:

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below along with examples. The photodetector of the present invention is an infrared-visible light conversion phosphor having excellent durability and emission characteristics for high-power laser light, and is a fluoride containing a small amount of Yb and Er in lead fluoride. The powder is used as a phosphor powder and is solidified by a glass substance.

[0009] As a light conversion phosphor for converting infrared light into visible light, a phosphorescent sulfide phosphor (ZnS, CaS, etc.) is conventionally known. This type of phosphor utilizes the photostimulation phenomenon in which a phosphor that has been previously excited receives infrared light and emits light, but pre-excitation is indispensable. A phosphor utilizing the energy level of rare earth ions is known as a phosphor that does not require pre-excitation, and a rare earth oxide or a rare earth halide containing a rare earth element such as Er as a light emission participating substance has been proposed.

Of these rare earth oxides and rare earth halides, the substances involved in light emission such as Er and Yb are more easily excited in the halides than the oxides, and among the rare earth halides, chlorides and bromides are converted into fluorides. Compared with the above, the stability and the water resistance are poor, and the fluoride has an advantage that it can contain more rare earth elements than the oxide. Therefore, the present invention uses rare earth fluoride as the phosphor powder.

The rare earth fluoride of the present invention is obtained by using lead fluoride as a base material, adding and mixing Yb fluoride and Er fluoride, and heating and melting. An example of the X-ray diffraction chart of the fluoride powder used as the phosphor in the present invention is shown in FIG. 1 (FIG. 1 (a)). In addition, X-ray diffraction charts of the raw materials lead fluoride, Yb fluoride and Er fluoride are also shown in the same figure (FIGS. 1 (b), (c) and (d)). As shown in the figure, the fluoride of the present invention is approximately 26 degrees, 31 degrees, 44 degrees, 51 degrees.
And has an X-ray diffraction peak similar to the lead fluoride of the base material at each diffraction angle of 70 degrees, but compared to the diffraction peak of lead fluoride (PbF ₂ ) shown by comparison. All the peaks are shifted from the lead fluoride by 1 to 2 degrees on the higher angle side, and a considerable amount of Yb fluoride and E fluoride are contained.
Almost no diffraction peak of r is detected. Judging from this result, it is considered that the fluoride of the present invention is a solid solution of Yb fluoride and Er fluoride in the lead fluoride of the base material.

In the above-mentioned fluoride phosphor, Er is an emission center element and Yb is an excitation energy transfer medium. Yb ions have an energy level excited by YAG laser light (wavelength 1.06 μm), and are excited by being irradiated with YAG laser light and emit energy. This energy is absorbed by the Er ions and raises the energy level of the Er ions to emit light. Thus, Er ions emit light when coexisting with Yb ions, and Er ions alone do not emit light. Er ions absorb infrared light of about 900 to 1100 nm in the coexistence with Yb ions and emit green light (5
It is known to produce red light (around 50 nm) and red light (around 665 nm).

Although lead fluoride is the base material of the phosphor, it has higher emission intensity than the conventionally known base material of Ba fluoride. Further, rare earth elements such as Er and Yb are fluorinated Z
Various kinds of fluorinated glass contained in a glass base material such as r are known, but the phosphor of the present invention is different from these fluorinated glasses and has a crystal having a unique X-ray diffraction peak as described above. Quality fluoride powder is used. Since glass materials can control phonon energy in a fairly wide range, various rare earth fluoride glasses have been studied, but the base material having glass forming ability is limited, and the range of components for vitrification is also limited. There are restrictions. The present invention is an opaque phosphor obtained by consolidating the above-mentioned fluoride powder,
It is superior in light emission intensity to the conventional fluoride glass and does not require heat treatment for vitrification, so that it is easy to manufacture.

The emission intensity depends on Er and Yb, which are substances involved in emission.
As shown in Examples described later, the emission intensity is stronger as the amount of Er is generally larger within a certain range, but when the concentration exceeds a certain level, the emission becomes weak due to concentration quenching. On the other hand, if the Er content is too low, sufficient emission intensity cannot be obtained. That is, the content of Er in the fluoride is 0.5 atom% or more, preferably 1 atom% or more, and 4.5 atom% or less, preferably 2.5 atom% or less. Further, the amount of Er is 1/5 or less of Yb, preferably about 1/10. Er content is Y
When it is more than b, the emission intensity is lowered. On the other hand, the content of Yb is 5 atom% or more, preferably 10 atom% or more,
30 atomic% or less, preferably 20 atomic% or less is suitable. When the content of Yb is less than the above range, the excitation is insufficient and sufficient emission intensity cannot be obtained, and even when it exceeds the above range, the emission intensity is not improved. Further, the total content of Er and Yb is 5 atom% or more, preferably 10 atom% or more, and 30 atom% or less, preferably 20 atom% or less.

As described above, the fluoride used in the phosphor of the present invention is composed of lead fluoride, Yb fluoride and Er fluoride, but other elements can be added without impairing the above-mentioned emission intensity and damage threshold. A small amount can be added. In addition to Er and Yb, by adding a small amount of rare earth elements such as Y, Gd, and La, the emission persistence is better than that of a conventional photodetector obtained by consolidating phosphor powder with an organic binder.
Moreover, a phosphor having a high damage threshold value can be obtained.

The photodetector of the present invention is obtained by consolidating the above-mentioned fluoride phosphor powder with a small amount of glass substance. Raw materials of lead fluoride, Yb fluoride and Er fluoride are uniformly mixed and heated and melted to obtain the above-mentioned fluoride, which is cooled and pulverized to obtain a phosphor powder. Although the emission intensity for infrared light is almost the same for both the fluoride before pulverization and the fluoride powder after pulverization, the one that is consolidated with a glass substance to increase the denseness emits light more than the powdery one. High strength. Further, the powder state without adding the glass substance volatilizes due to the high output energy of the YAG laser light and has a low emission intensity, so that it is not practical as a YAG laser light detector. The reason why the emission intensity is improved by adding a glass substance to consolidate and increase the denseness is not clear, but in addition to the glass substance acting as a binder, it has some influence on the emission mechanism of the fluoride. It is considered that

The type of glass substance is 650-85.
Those having a softening point of 0 ° C. are suitable, and commercially available powdered glass can be used. Specifically, SiO ₂ -B _{2
O 3 -PbO, SiO 2 -B 2} O 3 -RO, SiO 2 -
Al ₂ O ₃ —RO (R is an alkaline earth element) silicate glass, zinc oxide based glass such as ZnO—B ₂ O ₃ —PbO, or the like can be used. When the softening point is higher than 850 ° C, the fluoride powder is remelted during sintering, which is not preferable. Further, if the softening point is less than 650, the solidification property to high-power infrared rays becomes insufficient.

The glass substance is added in an amount of 2 to 30 parts by weight, preferably 5 to 15 parts by weight, per 100 parts by weight of the phosphor powder. Addition amount is 30 depending on the type of glass
When the amount is more than parts by weight, the amount of the above-mentioned fluoride is relatively decreased and the emission intensity is lowered. If the amount of the glass substance is less than 2 parts by weight, the moldability will be poor and the emission intensity will be low.

Next, a method for manufacturing the above phosphor will be described. The above fluoride raw material powder is charged into a platinum crucible so that the final amount becomes a predetermined amount, and the powder is heated in a temperature range of 800 to 1200 ° C, preferably 950 to 1050 ° C. A fluorinating agent such as ammonium fluoride may be added for the purpose of reducing oxides derived from the fluoride of the raw material during heating. When the heating temperature is 800 ° C. or lower, this melting is insufficient and the emission intensity is reduced. On the other hand, there is no great difference in the emission intensity even if the material is melted at 1200 ° C. or higher. The atmosphere during melting is preferably in the air. When the product is melted in an atmosphere of an inert gas such as argon or nitrogen, the product turns black and the emission characteristics of the phosphor are degraded.

By the above heat treatment, the raw material fluoride is brought into a molten or semi-molten state, and cooled crystalline fluoride is obtained. This fluoride has an X-ray diffraction peak similar to that of the high temperature type lead fluoride (Fig. 1 (b)) of the base material as shown in Fig. 1 (a). Compared to the diffraction peaks, all the peaks are shifted from the lead fluoride by 1 to 2 degrees to the lower angle side, and since the diffraction peaks of Yb fluoride and Er fluoride contained in a considerable amount are hardly detected, Yb fluoride and Er fluoride in lead fluoride of the base material
Is considered to be a solid solution.

After cooling the melt of the above-mentioned fluoride, it is pulverized to obtain a phosphor powder. The above-mentioned glass material was added to this phosphor powder and molded under a pressure of about 1 ton / cm ² , and then 50
Sinter by heating to a temperature of 0 ° C. or higher. Molding pressure is 50
If it is about 0 Kg / cm ² , the molded body tends to collapse. If the sintering temperature is higher than the softening point of the glass material, the compact will deform. If the sintering temperature is considerably lower than the softening point of the glass and is 450 ° C. or lower, the molded body becomes brittle and handling becomes difficult. The sintering atmosphere is preferably in the air. In an inert gas atmosphere, the fluorescent material turns black and the threshold value of damage to the discolored portion due to the laser light becomes low.

[0022]

EXAMPLES AND COMPARATIVE EXAMPLES Examples of the present invention are shown below together with comparative examples. This example is an illustration and does not limit the scope of the invention.

Example 1 To 155 g of Yb oxide, 250 ml of commercially available special grade hydrochloric acid and 50 parts of distilled water
After adding ml and heating and dissolving, 117 ml of commercial hydrofluoric acid was added to generate a Yb fluoride precipitate. This was filtered, washed, dried at 150 ° C., coarsely pulverized, and fired at 350 ° C. to obtain Yb fluoride. Further, instead of Yb oxide, Er oxide is oxidized
Fluorinated Er was similarly obtained using 150 g. As lead fluoride, a commercially available special grade reagent was used. These fluorinated Er, Yb fluoride and lead fluoride were mixed in an amount ratio of 1.7: 18.3: 81, heated to 980 ° C. to melt, and the melt was cooled and pulverized to obtain a phosphor powder. . An X-ray diffraction chart of this phosphor powder is shown in FIG. The X-ray diffraction charts of the raw materials lead fluoride, Er fluoride and Yb fluoride are also shown in the same figure. A predetermined amount of the commercially available glass material powder shown in Table 1 is mixed with this phosphor powder, molded into pellets under a pressure of 1 ton / cm ² , and baked at the temperature shown in Table 1 to obtain a solid photodetector. It was

The emission intensity and damage threshold of this photodetector were measured. The irradiation test was conducted as follows.
First, after measuring the intensity of YAG laser light with a power meter, the phosphor block was continuously irradiated with YAG laser light for 60 seconds under the same conditions. After the irradiation, the presence or absence of volatile components from the phosphor block layer was confirmed, and the presence or absence of holes at the irradiation position of the phosphor block was visually confirmed. This measurement was performed multiple times while changing the irradiation intensity, and the maximum irradiation intensity at which no holes were formed in the phosphor block was set as the damage threshold. The emission intensity is 3
The sample was irradiated with YAG laser light at an irradiation intensity of 0 W / cm ^{2, and} the intensity of light emission was visually determined, and this was evaluated in three grades of strong, medium and weak. The results are shown in Table 1. As is clear from this result, the phosphor of this example has high emission intensity,
Further, the damage threshold is high with respect to the YAG laser light.

Comparative Example 1 Lead fluoride-fluoride Yb-fluoride E was prepared in the same manner as in Example 1.
A phosphor powder of r (the same quantitative ratio as in Example 1) was obtained. A glass substance was not added to this phosphor powder, and the emission intensity and damage threshold value in the powder state were measured under the same conditions as in Example 1. The results are shown in Table 1. The phosphor of this example is composed of the same amount ratio of fluoride as in Example 1, but has low emission intensity.
The damage threshold is also extremely low.

Example 2 Yb fluoride powder and Er fluoride powder produced in the same manner as in Example 1 and a powder of commercially available special grade lead fluoride were mixed in an amount ratio shown in Table 2, and heated and melted at 980 ° C. After cooling, the mixture was pulverized, 10% by weight of commercially available powdered glass was added thereto, the mixture was molded into pellets under a pressure of 1 ton / cm ² , and fired at 540 ° C. to obtain a fluorescent molded body. Using this phosphor, the emission intensity was measured in the same manner as in Example 1. The results are shown in Table 2. As is clear from the results of this example, the content of Er and Yb in the phosphor powder was Er 0.5 to 4.5 at%, Yb 5
.About.30 atom%, and the total amount thereof is suitably 5.5 to 35 atom%.

Comparative Example 2 Fluorinated Er and Yb powders produced in the same manner as in Example 1 were used, and Er, Yb fluoride and commercially available special grade Ba fluoride powder were added in an amount of 1.6: 18.2: 80.2. Mix to the ratio, heat to 1350 ℃ to melt, cool and pulverize, then add 10 wt% of commercially available silicate glass powder to 1 ton / cm ²
Was molded into pellets under pressure and baked at 570 ° C. to obtain a fluorescent molded body. The results are shown in Table 2. From the results of this example, even when the phosphor contains Er fluoride and Yb fluoride as the substances involved in light emission, the one having Ba fluoride as the base material is inferior in emission intensity to the phosphor powder of the present invention.

Comparative Example 3 10% by weight of commercially available silicate glass glass powder was mixed with the phosphor powder obtained in Example 1 to obtain 0.1, 0.3, 0.5 ton /
A fluorescent molded body manufactured in the same manner as in Example 1 except that the molding was carried out at a pressure of cm ² was subjected to the same light emission test as in Example 1. As a result, as shown in Table 1, the phosphors of this example had almost the same emission intensity as that of the powder, and the damage threshold value was also significantly low.

Example 3 Fluoride powder of the elements shown in Table 3 was used as a raw material together with lead fluoride, Yb fluoride and Er fluoride, and these were mixed in the ratios shown in the table, and the same method as in Example 1 was performed. When a molded article of the phosphor was manufactured with, and the emission intensity and the damage threshold were measured,
As shown in the same table, the fluorescent molded article of this example had a better sustainability of light emission and a higher damage threshold than the photodetector obtained by consolidating the phosphor powder with the conventional organic binder.

Comparative Example 4 A fluoride powder was produced in the same manner as in Example 1 except that the heat treatment temperature for obtaining the phosphor powder was 400 ° C.
In the X-ray diffraction chart of this fluoride powder, raw material lead fluoride, Yb fluoride, and Er fluoride diffraction peaks coexist, so that the raw material fluoride particles coexist and are sintered. Therefore, Yb fluoride and Er fluoride are not solid solutions in lead fluoride. Using this fluoride powder, a glass material was added in the same manner as in Example 1, followed by pressure molding and firing to obtain a molded body. When a luminescence test was conducted on this molded product, no luminescence was observed.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

INDUSTRIAL APPLICABILITY The photodetector of the present invention has a high damage threshold even for high-output YAG laser light, and the phosphor is not damaged by YAG laser light even after repeated use for a long time. It is highly likely. Further, the emission intensity is remarkably higher than that of the conventional detector, and the detection of the YAG laser light is clear.

[Brief description of drawings]

1 (a) is an X-ray diffraction chart of the fluoride phosphor powder manufactured in Example 1, and FIG. 1 (b) (c).
(D) is an X-ray diffraction chart of raw material powders of lead fluoride, Yb fluoride, and Er fluoride.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shoji Ishiwata, 1-297 Kitabukuro-cho, Omiya-shi, Saitama, Central Research Laboratory, Mitsubishi Materials Corporation (72) Keitaro Okawa 1-1-5, Otemachi, Chiyoda-ku, Tokyo Sanryo Materials Co., Ltd. (72) Inventor Wu Uko 1-28 Kandasudacho, Chiyoda-ku, Tokyo Sumita Optical Glass Co., Ltd. (72) Inventor Masaaki Otsuka 1-28 Kandasuda-cho, Chiyoda-ku, Tokyo Shares Company Sumita Optical Glass (72) Inventor Sawa Noboru 1-228 Kandasudacho, Chiyoda-ku, Tokyo Sumita Optical Glass Co., Ltd. (72) Shinobu Nagahama 1-28 Kandasudacho, Chiyoda-ku, Tokyo Sumita Co., Ltd. In optical glass

Claims (5)

[Claims] 1. A phosphor for converting infrared laser light into visible light, which comprises lead fluoride as a main component and a phosphor powder made of a fluoride containing erbium and ytterbium, which is solidified by a glass substance. A high-power infrared laser light detector characterized by the above. 2. The high-power infrared laser photodetector according to claim 1, wherein the phosphor powder is a fluoride powder containing lead fluoride as a main component and erbium fluoride and ytterbium fluoride as a solid solution in lead fluoride. . 3. The phosphor powder is mainly composed of lead fluoride, and 5
~ 30 atom% ytterbium, 0.5-4.5 atom%
2. The photodetector according to claim 1, which is a fluoride powder containing erbium. 4. The glass substance 2 in 100 parts by weight of the phosphor powder.
The photodetector according to claim 1, which is obtained by adding -30 parts by weight, press-molding, and sintering. 5. A mixed powder of lead fluoride, ytterbium fluoride and erbium fluoride in air at 800 to 120.
A method for producing a high-power infrared laser light detector, which comprises heating and melting at 0 ° C., crushing, adding a glass substance, press-molding, and sintering in the air.