JP2006298743A - Green fluorescent glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent glass capable of being suitably used in optical parts for optical axis alignment or laser beam measuring devices such as a beam profiler, each having an optical system for measuring green fluorescence generated by irradiating a fluorescent glass with laser light in the ultraviolet region, such as an excimer laser, by improving the fluorescent characteristics of the glass by enhancing the excitation efficiency of a fluorescent medium. <P>SOLUTION: The fluorescent glass contains Tb<SP>3+</SP>as the fluorescent medium and exhibits green fluorescence by ultraviolet excitation. The fluorescent glass contains F<SP>-</SP>as the anion and 5-25 mol% Tb<SP>3+</SP>and 0.05-10 mol% Ce<SP>3+</SP>, based on the total cation in the glass. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluorescent glass that generates visible light emission by excitation of ultraviolet light, and more particularly, to a fluorescent glass suitable for performing visible light emission by ultraviolet irradiation such as excimer laser.

In general, phosphors that are put to practical use for displays and lamps are mainly composed of sulfide, oxysulfide, or halophosphate as a base material, and a rare earth element as a luminescent center. As phosphors emitting green light, ZnS: Cu and Al are put into practical use for displays, and LaPO4: Ce ³⁺ and Tb ³⁺ are put into practical use for lamps. However, these phosphors are opaque powders, and are used by applying the powders on a substrate. Therefore, the use is limited to the case of using fluorescence emitted from the surface of the phosphors. (Non-Patent Document 1).

As means for solving this problem, transparent fluorescent glass that emits green light not only from the surface but also from the inside is known (for example, Patent Documents 1 to 3). The fluorescent glass described in these documents is an oxide glass-based or fluorophosphate glass-based fluorescent glass using Tb ³⁺ as a fluorescent medium. These fluorescent glasses are used in optical beam adjusting optical components having an optical system for measuring green fluorescence generated by irradiating fluorescent glass with ultraviolet laser light such as excimer lasers, laser beam measuring devices such as beam profilers, etc. Can be used.

Fluorescent glass exhibiting green fluorescence by excitation with ultraviolet light has an excitation light source in the ultraviolet region. Therefore, if there is light absorption in the ultraviolet wavelength region of the mother glass into which Tb ³⁺ is introduced, when glass is irradiated with ultraviolet light for a long time, Such a problem that the fluorescent efficiency is reduced due to the coloring of the light is likely to occur. Therefore, it is preferable to use a glass having a small light absorption coefficient in the ultraviolet wavelength region as the mother glass used.

As a glass having a small light absorption coefficient in the ultraviolet wavelength region, fluoride glass is known. Although manufactured for a purpose different from that of the present invention, Patent Document 4 and Non-Patent Document 2 disclose glasses in which Tb ³⁺ is introduced using fluoride glass as a base glass.

Japanese Patent Publication No.57-27048 JP-A-8-133780 Japanese Patent Laid-Open No. 10-167755 JP-A-11-302638 Phosphor Handbook, Ohmsha, 1987, 3rd edition: Practical phosphor, 165 Jianrong Qiu et al., “Faradye effect in Tb-containing borate, fluoride and fluorophosphates glasses”, Journal of Non-Crystalline Solids, 213 & 214, (1997), 193-198

The present invention is a fluorescent glass exhibiting green fluorescence by ultraviolet light excitation using Tb ³⁺ as a fluorescent medium, and a glass having a small light absorption coefficient in the ultraviolet wavelength region is used as a base glass, and the excitation efficiency of the fluorescent medium is improved. Laser beam measuring devices such as optical axis adjustment optical components and beam profilers that have an optical system that measures green fluorescence generated by irradiating fluorescent glass with ultraviolet laser light such as excimer lasers by improving fluorescence characteristics It is an object of the present invention to provide a fluorescent glass that can be suitably used for the above.

That fluorescence glass of the present invention is a fluorescent glass exhibiting green fluorescence by ultraviolet excitation of Tb ³⁺ as the fluorescent medium, the anion of the fluorescent glass F ^- made, Tb ³ relative to the total cations in the glass ⁺ is 5~25mol%, Ce ³⁺ is characterized in that it is a 0.05~10mol%.

As the mother glass into which Tb ³⁺ is introduced, a glass having a small amount of light absorption in the ultraviolet wavelength region can be easily obtained by using a glass whose anion is composed of F ⁻ , that is, a fluoride glass. A fluoride material has a larger band gap energy than an oxide material or a sulfide material, so that the wavelength of the absorption edge on the ultraviolet side is short, so that light absorption is more likely to be reduced in the ultraviolet wavelength region.

  When the light absorption is small, the heat generation of the glass due to the light absorption is small when irradiating with strong ultraviolet light typified by an excimer laser, and the glass is hardly damaged by the heat generation. In addition, since structural defects caused by ultraviolet light absorption are less likely to occur, the glass is less likely to be colored due to structural defects.

Tb ³⁺ is a fluorescent medium that generates green fluorescence by ultraviolet light excitation, and its content needs to be 5 to 25 mol% with respect to all cations in the glass. If it is less than 5 mol%, it is difficult to obtain sufficient fluorescence intensity, and if it exceeds 25 mol%, concentration quenching occurs, resulting in problems such as reduction in fluorescence intensity or difficulty in vitrification. Tb ³⁺ present in the glass of the present invention produces green fluorescence having a wavelength of 470 to 630 nm by irradiating light having a wavelength of 170 to 390 nm as excitation light.

In the present invention, was examined the efficiency of fluorescence generation by ultraviolet excitation of Tb ³⁺ is a fluorescent medium, if the Ce ³⁺ and Tb ³⁺ coexist in the glass, the energy Ce ³⁺ is absorbed Tb ^{3 It} is clear that the excitation efficiency for green fluorescence from Tb ³⁺ is remarkably improved in the wavelength region of wavelengths 220 to 320, particularly in the wavelength range of 230 to 310 nm, and the fluorescence efficiency is improved by passing it efficiently to ⁺ . I made it.

The improvement of the fluorescence efficiency is particularly effective when the amount of Ce ³⁺ is 0.05 to 10 mol% with respect to the total cations in the glass. Although a small amount of Ce ³⁺ is effective, in order to exert a sufficient effect, the amount needs to be 0.05 mol% or more, and preferably 0.5 mol% or more. On the other hand, if the amount exceeds 10 mol%, the tendency to crystallize during glass production increases, the solubility of the glass raw material deteriorates, and the formation of glass becomes extremely difficult. And considering the ease of glass formation during glass production, the amount of Ce ³⁺ is preferably 7 mol% or less with respect to the total cations in the glass.

And it is preferable that the fluorescent glass of this invention has 15-55 mol% of Al3 ⁺ with respect to all the cations. Anions F ^- glass consisting, i.e. the fluoride glass, Al ³⁺ is a component that has a glass-forming ability. Among cations that have glass-forming ability in fluoride glass, Al ³⁺ is a cation for glass formation suitable for the present invention because it has little tendency to increase the absorption coefficient in the ultraviolet wavelength region. And if the crystallization tendency at the time of glass manufacture and the solubility of a glass raw material are considered, the amount is 15-55 mol% with respect to all the cations in glass, Preferably it is 20-50 mol%, More preferably, 30- It is preferable to set it as 40 mol%.

The fluorescent glass of the present invention contains at least one selected from Cl ⁻ , Br ⁻ , and I ^{− as} anions in addition to F ⁻ as anions, in an amount of 0.1 to 15 mol based on the total anions in the glass. % May be included. By introducing these halogen ions into the anion, the electronic state of Ce ³⁺ is affected, and the excitation band is extended to the longer wavelength side. As a result, the excitation efficiency at a wavelength of 300 to 330 nm, particularly at a wavelength of 310 to 330 nm is improved, and it is successful in improving the fluorescence efficiency when excited with light of these wavelengths.

  If the amount is less than 0.1 mol with respect to the total anions in the glass, the expansion width of the excitation band is small, and the effect of improving the excitation efficiency in the wavelength range is small. Tends to increase, and vitrification tends to be difficult. Considering this, the halogen ion is preferably 1 mol to 12 mol%, more preferably 2 to 10 mol%.

  Since the fluorescent glass of the present invention efficiently generates green fluorescence using light in the ultraviolet wavelength region as excitation light, an optical axis having an optical system for measuring green fluorescence generated by irradiating the fluorescent glass with laser light in the ultraviolet region It is suitable for use in laser beam measuring devices such as optical components for adjustment and beam profilers. And since the fluorescent glass of the present invention efficiently generates fluorescence particularly when the wavelength for excitation is 230 to 320 nm or 230 to 330 nm, when the wavelength of the laser light for excitation is in these wavelength ranges, The use of the fluorescent glass of the present invention is particularly effective.

The fluorescent glass of the present invention is a fluorescent glass that exhibits green fluorescence by ultraviolet light excitation using Tb ³⁺ as a fluorescent medium, and the anion of the fluorescent glass is composed of F ⁻ , and Tb ^{3+ with} respect to all cations in the glass. Is 5 to 25 mol%, and Ce ³⁺ is 0.05 to 10 mol%. Then, various cations and F ^- and fluorides, various cations and F ^- the halides except the melt with a mixture of oxygen amount under less inert atmosphere 1ppm to glass raw material, quenching the this It is vitrified.

In order to obtain the inert atmosphere, the environment in which the mixture is melted is filled with an inert gas such as N ₂ , Ar, He, Ne, Xe, Kr, or a mixed gas thereof. The inert gas includes halogen gases such as F ₂ , Cl ₂ , Br ₂ , and I ₂ , and reactive gases such as CCl ₄ , SF ₆ , and CF ₄ to remove trace amounts of water contained in the glass melt. In order to do this, 0.1 to 5% by volume may be introduced. Then, before the inert gas is introduced into the environment in which the mixture is melted, the environment may be once evacuated, and then the inert gas may be introduced to create an inert atmosphere.

In addition, the mixture contains a fluorinating agent such as acidic ammonium fluoride (NH ₄ F · HF) in order to fluorinate impurities such as oxides and hydroxides in the glass raw material. In contrast, 0.2 to 3% by weight may be introduced.

  The mixture of glass raw materials is melted by heating the mixture at 900 to 1200 ° C. under an inert atmosphere, for example, and rapidly cooled to a temperature lower than the glass transition temperature of the glass obtained. It is preferable to form a supercooled liquid state product obtained in this rapid cooling process into a plate shape. The obtained glass is cut into a desired size and optically polished on at least one surface.

^Examples of cations other than Tb ³⁺ , Ce ³⁺ or Al ³⁺ introduced into the fluorescent glass of the present invention include Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ alkaline earth ion metal ions. Lanthanoid ions of Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ , Lu ³⁺ , Dy ³⁺ , and the like.

Among these cations, it is particularly preferable to use Ca ²⁺ and Ba ²⁺ . These chemical species are components that reduce the crystallization tendency during glass production and improve the solubility of the glass raw material, and preferably improve the glass production efficiency. From this viewpoint, Ca ²⁺ is preferably introduced so as to be 10 to 25 mol% with respect to all cations in the glass, and Ba ²⁺ is introduced with 5 to 27 mol% with respect to all cations in the glass.

Mg ²⁺ and Sr ²⁺ can be introduced in order to improve the solubility of the glass raw material. From this viewpoint, these chemical species are preferably introduced so as to be 5 to 15 mol% with respect to the total cations in the glass.

  Furthermore, the lanthanoid ion may be introduced in order to suppress crystallization during glass formation. From this viewpoint, these chemical species are preferably introduced so as to be 5 to 15 mol% with respect to the total cations in the glass.

  Hereinafter, the present invention will be described in detail with reference to examples. Table 1 shows the glass compositions studied in the examples and comparative examples.

Halide raw materials were mixed so that the composition shown in Table 1 was obtained, and a 20 g amount of the mixture was obtained for each example and comparative example. The ammonium acid fluoride of _(NH 4 F · HF) is mixed 0.1g weight was a batch for a glass forming for these mixtures. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a chlorine and nitrogen gas atmosphere having a chlorine concentration of 1%, and then rapidly cooled in a nitrogen atmosphere to obtain glass. It was. The formation of the glass was confirmed by visual observation, and the translucent one was vitrified. This vitrification is described in Table 1 with an example of vitrification (O) and an example of no vitrification (X). The obtained glass was cut into a plate having a size of 20 mm × 20 mm × 3 mm (thickness), and both surfaces were optically polished.

It was visually confirmed that when the glass obtained in Examples 1 to 10 and Comparative Examples 1 to 2 and subjected to optical polishing was excited with ultraviolet light having a wavelength of 248 nm, strong green light was emitted. FIG. 1 shows the fluorescence spectrum of the glass obtained in Example 1. Similar waveforms were obtained with the glasses of Examples 2 to 10 and Comparative Examples 1 and 2. Peak of 542nm regarding green fluorescence solid line in FIG. ^1, Tb ^3+: shows the emission by _{5 D 4} → ⁷ F 5 transition.

Then, to the peak of 542nm in the fluorescence spectrum _{^{(Tb 3+: 5 D 4 →}} 7 F 5 transition) was determined excitation spectrum. The results are shown in FIG. FIG. 2 is for Examples 1 to 5 and Comparative Examples 1 to 2, and in the example in which Ce ³⁺ was added in an amount of 0.5 mol% to 10 mol%, the addition amount of Ce ³⁺ was less than 0.5 mol%. It can be seen that the excitation efficiency in the vicinity of the wavelength of 230 nm to 300 nm is improved as compared with the comparative example.

3, of Example 6 to 10 to the peak of 542nm in the fluorescence spectrum _{^{(Tb 3+: 5 D 4 →}} 7 F 5 transition) is a diagram illustrating an excitation spectrum. In Examples 6 to 9 to which Cl ^- or Br ^- was added, it was confirmed that the excitation efficiency in the vicinity of the wavelength of 310 nm to 330 nm was improved, and the excitation efficiency in this wavelength region was increased as the addition amount of these chemical species was increased. There was a tendency to improve.

It is a figure which shows the fluorescence spectrum when the fluorescent glass of Example 1 is excited with the ultraviolet light with a wavelength of 248 nm. Implementation for a peak of 542nm in fluorescence spectra Examples 1 to 5 and Comparative Examples 1 to _{^{2 (Tb 3+: 5 D 4}} → 7 F 5 transition) is a diagram illustrating an excitation spectrum. Example 6-10 to the peak of 542nm in the fluorescence spectrum _{^{(Tb 3+: 5 D 4 →}} 7 F 5 transition) is a diagram illustrating an excitation spectrum.

Claims (5)

A fluorescent glass exhibiting green fluorescence by ultraviolet light excitation using Tb ³⁺ as a fluorescent medium, the anion of the fluorescent glass is made of F ⁻ , and Tb ³⁺ is 5 to 25 mol% with respect to all cations in the glass, Ce Fluorescent glass characterized in that ³⁺ is 0.05 to 10 mol%. 2. The fluorescent glass according to claim 1, comprising 15 to 55 mol% of Al ³⁺ with respect to all cations. The F ^- in addition, Cl to anion ^-, Br ^-, I ^- at least one selected from and having 0.1～15Mol% relative to the total anions in the glass according to claim 1 or claim Item 3. A fluorescent glass according to Item 2. The fluorescent glass according to any one of claims 1 to 3, which is used in a laser beam measuring apparatus having an optical system for measuring green fluorescence generated by irradiating the fluorescent glass. The fluorescent glass according to claim 4, wherein the wavelength of the irradiated light is 230 to 320 nm.