JP2002128539A - Low fluorescent optical glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low fluorescent optical glass having optical constant ranging in refractive index (nd) of 1.70< and <=1.81 and in Abbe's number (νd) of 48< and <= 55 and exhibiting excellent light transmissiveness in an infrared region and low in strength of fluorescence generated when an ultraviolet-ray or the like is radiated. SOLUTION: The optical glass comprises a B2O3-Ln2O3 (Ln is one or more selected from Y, La, and Gd)-based composition, and has the content of Nb2O5 component of 0.01<= and <1 mass % and the optical constant ranging in refractive index (nd) of 1.70< and <= 1.81 and in Abbe's number (νd) of 48< and <=55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a polymer having a refractive index (nd) of more than 1.70 to 1.81 and an Abbe number (νd) of 48.
The present invention relates to a low-fluorescent optical glass having an optical constant in the range of over to 55, exhibiting excellent light transmittance in the infrared region, and having low intensity of fluorescence generated by irradiating the glass with ultraviolet rays.

[0002]

2. Description of the Related Art In the fields of biology and medicine, fluorescence is emitted from an observation object by irradiating the observation object with excitation light such as ultraviolet light for observing biological tissues, cells, genes, bacteria, and the like. Techniques for observing and measuring are widely used, and in recent years, techniques for detecting weak fluorescence emitted from a phosphor adsorbed to a specific site such as a very small amount of bacteria or cells have been actively studied. . However, the optical glass used for the objective lens of the microscope used for such observation and measurement is also excited by ultraviolet rays to generate fluorescence. When observing the fluorescence emitted from the observation object, the fluorescence from the glass becomes a noise, and thus has been regarded as a problem. Therefore, there is a demand for an optical glass having a small intensity of fluorescence generated by excitation of ultraviolet light or the like.
In particular, almost no high refractive index low dispersion optical glass is considered so that the fluorescence intensity due to excitation of ultraviolet light or the like becomes small. It cannot be used for an optical instrument for observing or measuring weak fluorescence generated from the observation target by irradiating the observation target with the excitation light. Also, JP-A-2000-128569 discloses that
Although a low-fluorescence optical glass having a high refractive index and a low dispersion is disclosed, the glass having the composition specifically disclosed in the above publication has a low fluorescence intensity due to ultraviolet excitation, but all have a large amount of Yb ₂ O. ₃ has a drawback that the light transmittance in the infrared region around 970 nm is extremely poor.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device having a refractive index (nd) of more than 1.70 to 1.81 and an Abbe number (νd) of more than 48 to 55 in view of the above-mentioned prior art. It is an object of the present invention to provide a low-fluorescence optical glass which has an optical constant in the range described above, exhibits excellent light transmittance in the infrared region, and has a small intensity of fluorescence generated upon irradiation with ultraviolet rays or the like.

[0004]

Means for Solving the Problems As a result of intensive studies and studies, the present inventors have found that a small amount of Nb ₂ O ₅ in a specific range is added to a glass having a B ₂ O ₃ -Ln ₂ O ₃ composition. The present inventors have found that a glass having an optical constant in the above-described range, exhibiting excellent light transmittance in the infrared region, and having a desired low fluorescence intensity can be obtained.

[0005] That is, the feature of low fluorescence optical glass of the present invention as set forth in claim _{1, B 2 O 3 -Ln 2 O} 3 (Ln is one or more members selected Y, from La and Gd)
In the optical glass having the system composition, the content of the Nb ₂ O ₅ component is 0.01 to less than 1% by mass%, the refractive index (nd) exceeds 1.70 to 1.81, and the Abbe number (νd). Has an optical constant in the range of more than 48 to 55.

The low-fluorescent optical glass of the present invention according to claim 2 is characterized in that, in the low-fluorescent optical glass according to claim 1, 0.5 to 8% by mass of SiO ₂ , _Two
O ₃ up to 45% greater than the 24%, Y ₂ O ₃ 0.5~20
_{%, La 2 O 3 25~46%} , Gd 2 O 3 10~30
%, Nb ₂ O ₅ less than 0.01~1%, ZrO ₂ 0.5
~10%, Ta ₂ O ₅ less than 0~2%, Sb ₂ O ₃ 0~
0.2%.

The low-fluorescence optical glass of the present invention according to claim 3 is characterized in that, in the low-fluorescence optical glass according to claim 2, MgO is 0 to 5% by mass%.
CaO 0-10%, SrO 0-10%, BaO 0
-10%, ZnO 0-8%, provided that MgO, Ca
O, SrO, BaO and one component or two or more components of the total amount 0-10% selected from ZnO, Li ₂ O 0 to
Less than 0.5%, there is to containing Yb ₂ O ₃ 0~5%.

[0008]

The reasons for limiting the range of each component as described above are as follows. That is, the SiO ₂ component is a glass-forming oxide, increasing the viscosity of the glass,
This has the effect of reducing the tendency to devitrify. However, if the amount is less than 0.5%, the effect is not sufficient and the glass tends to rapidly devitrify. On the other hand, if the amount exceeds 8%, the melting property of the glass deteriorates, making it difficult to obtain a homogeneous glass.

The B ₂ O ₃ component, like the SiO ₂ component, is a glass-forming oxide, but if its amount is less than 24%, the tendency of the glass to devitrify will increase, and if its amount exceeds 45%, it will increase. The target optical constant cannot be maintained. In addition, in order to easily maintain the target optical constant, the total amount of the SiO ₂ and B ₂ O ₃ components is preferably set to 45% or less.

The La ₂ O ₃ component gives the glass a high refractive index and low dispersion, and is an important component in a glass having a high refractive index such as the glass of the present invention.
If it is less than 1, the effect is not sufficient, and it is difficult to obtain a target optical constant. On the other hand, if the amount exceeds 46%, the glass tends to have a devitrification tendency.

[0011] Gd ₂ O ₃ and Y ₂ O ₃ component, with a component to provide a high refractive index and low dispersion to the glass like the La ₂ O ₃ component, a relatively high content of La ₂ O ₃ component By adding these two components to the glass, the devitrification resistance of the glass is improved, so that a stable glass can be produced. Further, the Gd ₂ O ₃ component is also effective for improving the chemical durability of glass. However, their quantity is G
If the content is less than 10% for the d ₂ O ₃ component and less than 0.5% for the Y ₂ O ₃ component, the above effect is insufficient.
Conversely, when the amounts of the Gd ₂ O ₃ and Y ₂ O ₃ components exceed 30% and 20%, respectively, the tendency to devitrify significantly increases.

The Nb ₂ O ₅ component is a component effective for imparting high refractive index and high dispersibility to glass and preventing devitrification. In the present invention, B ₂ O ₃ -Ln ₂ This is a very important component which has been found to have an effect of significantly reducing the intensity of the fluorescence generated when the glass is irradiated with light such as ultraviolet rays by adding the Nb ₂ O ₅ component to the glass having an O ₃ composition. is there. However, the amount of the Nb ₂ O ₅ component is 0.01%.
When the amount is less than the above range, the above effect is not sufficiently exhibited. When the amount is 1% or more, the light transmittance in a short wavelength region is adversely affected. Furthermore, in order to obtain a glass that light transmittance is particularly excellent, it is more preferable that the amount of Nb ₂ O ₅ component to 0.01-0.5%.

The ZrO ₂ component is an effective component for improving the chemical durability of glass and increasing the refractive index. However, if the amount is less than 0.5%, the above effect is not sufficient, When the amount exceeds 10%, the devitrification resistance of the glass deteriorates.

The Ta ₂ O ₅ component is contained in the glass of the present invention to maintain a desired range of optical constants,
It has the effect of increasing the light transmittance and the chemical refractive index and improving the devitrification resistance, and may be added arbitrarily as needed. However, to obtain the above effect, less than 2% is sufficient.

The Sb ₂ O ₃ component can be contained for fining the molten glass. However, to exert its effect, the amount is sufficient to be 0.2% or less.

Further, the following components may be added to the low fluorescent optical glass of the present invention. That is, MgO,
The CaO, SrO, BaO and ZnO components are effective for producing a homogeneous glass because the glass materials are easily melted, but the MgO component exceeds 5% and the CaO, SrO and BaO components each account for 10%. Exceeding the ZnO component in excess of 8% is not preferred because the glass tends to be devitrified. If the total amount of these five components exceeds 10%, it becomes difficult to maintain a target optical constant.

The Li ₂ O component is effective for accelerating the melting of the glass raw material.
Less than is sufficient.

The Yb ₂ O ₃ component comprises a Gd ₂ O ₃ component and Y ₂
Like the O ₃ component, by introducing into a glass having a B ₂ O ₃ -Ln ₂ O ₃ composition, it imparts a high refractive index and low dispersion to the glass and improves the devitrification resistance of the glass. be able to. However, since the Yb ₂ O ₃ component has strong absorption specific to a wavelength of about 970 nm, there is a problem that information in this wavelength range cannot be obtained. B ₂ O ₃ -Ln ₂ O ₃ system if the Yb ₂ O ₃ component is contained 6% glass composition, thickness 10mm
Has a light transmittance of 4% at a wavelength of about 970 nm.
The use of glass having such strong absorption in the infrared region for optical systems must be greatly restricted in terms of application. Therefore, the amount of the Yb ₂ O ₃ component should be 5% or less, preferably 2% or less.
In particular, in order to obtain glass having excellent light transmittance in the infrared region, the amount is more preferably less than 1%.

The low-fluorescence optical glass of the present invention contains components other than those described above, for example, components such as cation fluoride and GeO ₂ of each component up to a total of about 5%, such as optical constant and light transmittance. May be added as needed for the adjustment of.

[0020]

EXAMPLES Next, preferred examples (No. 1 to No. 22) of the low fluorescent optical glass according to the present invention and comparative examples (No. A and No. B) of the conventional optical glass will be described. Index, Abbe number and fluorescence spectrophotometer (Spectrofluorometer JASCO)
Co. The results are shown in Tables 1 to 4 together with the results of measuring the fluorescence intensity using FP-750 (manufactured by FP-750). Here, the fluorescence intensity is the maximum output of the fluorescence generated in the wavelength range of 300 nm to 700 nm when the glass sample was irradiated with light having a wavelength of 254 nm. The peak height of the fluorescence generated from the glass of A is 1.00, and the relative value is shown.

[0021]

[Table 1] (% by mass)

[0022]

[Table 2] (% by mass)

[0023]

[Table 3] (% by mass)

[0024]

[Table 4] (% by mass)

As can be seen from Tables 1 to 4, all of the glasses of Examples of the present invention have a refractive index and Abbe number within desired ranges, and the fluorescence intensity is the same as that of the conventional Comparative Example No. . In each case, the value is much lower than that of the glass of A. In addition, Example Composition No. 1 of the present invention shown in Table 4 was used. 2
2 and the comparative example No. 2 of the prior art. From the glass of B,
Each of the glass samples having a thickness of 10 mm was polished face-to-face, and the spectral transmittances of these samples including reflection loss in the infrared region in the wavelength range of 700 to 1100 nm were measured. Although the glass B has a low fluorescence intensity, a very large absorption is observed around a wavelength of 970 nm.
While the spectral transmittance at a wavelength of 970 nm where the absorption is the largest is only 4%, the composition of the working example No. In the glass of No. 22, although the absorption was observed around the wavelength of 970 nm, the spectral transmittance at the wavelength of 970 nm where the absorption was the largest was 58%. You can see that it is done. In addition, the said Example composition example (No. 1-No. 1) of this invention.
Each of the glasses of 22) is prepared by weighing and mixing ordinary optical glass materials such as oxides, carbonates, nitrates, and hydroxides at a predetermined ratio, and then throwing them into a container such as a platinum crucible.
After melting at 00 to 1400 ° C. for about 2 to 4 hours and homogenizing by stirring, it can be easily obtained by casting into a mold or the like and gradually cooling.

[0026]

As described above, according to the present invention, low fluorescence optical glass according to the present _{invention, B 2 O 3 -Ln 2 O} 3 based composition which contains a small amount of Nb ₂ O ₅ component in a specific composition range to the glass composition Since it is a system glass, the refractive index (nd) exceeds 1.70 to 1.81 and the Abbe number (νd) exceeds 48 to 55
In addition to having an optical constant in the range described above, in addition to having a low fluorescence intensity upon excitation with ultraviolet light or the like, it exhibits excellent light transmittance in the infrared region and has excellent melting properties, and thus has excellent mass productivity. Therefore, it is particularly suitable for use as a lens or the like in an optical system such as a biological microscope in which noise due to fluorescence is a problem, and has a low fluorescence property such as a solution cell for fluorescence measurement or a cover glass of a solid-state imaging device. It is also suitable for use as required optical members and the like.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4G062 AA04 BB05 BB08 DA02 DA03 DB01 DC04 DC05 DD01 DE01 DE02 DE03 DF01 EA01 EA02 EA10 EB01 EC01 ED01 ED02 ED03 EE01 EE02 EE03 EF01 EF02 EF03 EG01 FC03 EG01 FG02 FH01 FH02 FH03 FJ02 FJ03 FJ04 FK04 FK05 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ04 JJ05 JJ07 JJ10 KK01 NN01 KK01 KK01 NN03

Claims (3)

[Claims] 1. An optical glass having a composition of B ₂ O ₃ -Ln ₂ O ₃ (Ln is one or more selected from Y, La and Gd), wherein the content of the Nb ₂ O ₅ component is% by mass. At 0.0
1 to less than 1%, a refractive index (nd) of more than 1.70 to 1.81 and an Abbe number (νd) of more than 48 to 55
A low-fluorescence optical glass characterized by having an optical constant in the range of: 2. The composition according to claim 1, wherein said SiO _{2 is} 0.5 to 8% by mass% and B ₂ O
_{3 More} than 24% to 45%, Y ₂ O ₃ 0.5 to 20
_{%, La 2 O 3 25~46%} , Gd 2 O 3 10~30
%, Nb ₂ O ₅ less than 0.01~1%, ZrO ₂ 0.5
~10%, Ta ₂ O ₅ less than 0~2%, Sb ₂ O ₃ 0~
The low-fluorescent optical glass according to claim 1, which contains 0.2%. 3. The composition according to claim 1, further comprising 0 to 5% of MgO,
aO 0-10%, SrO 0-10%, BaO 0
10%, ZnO 0-8%, provided that MgO, CaO,
Total amount of one or more components selected from SrO, BaO and ZnO 0 to 10%, Li ₂ O 0 to 0.
Less than 5%, a low fluorescent optical glass according to claim 2, characterized by containing Yb ₂ O ₃ 0~5%.