JP2009143738A - Optical glass and optical device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical glass having lower autofluorescence intensity than before, and to provide an optical device using the same. <P>SOLUTION: The optical glass contains <5 ppm of Cr per 100% of a base glass composition which contains, on a weight basis, 2-10% of SiO<SB>2</SB>, 5-45% of B<SB>2</SB>O<SB>3</SB>, 0-15% of RO (wherein R=Zn, Sr, Ca, Ba), 30-60% of La<SB>2</SB>O<SB>3</SB>, 0-40% of Ln<SB>2</SB>O<SB>3</SB>(wherein Ln=Y, Gd), and 0-30% of (ZrO<SB>2</SB>+Nb<SB>2</SB>O<SB>5</SB>+Ta<SB>2</SB>O<SB>5</SB>). The optical device comprises an optical system using the optical glass. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical glass, in particular, an optical glass used in an optical system for fluorescence observation and fluorescence intensity measurement, and an optical apparatus using the optical glass. In particular, the content of Cr, which is a component that emits autofluorescence, is reduced as much as possible.

In the use of a fluorescence observation measurement apparatus such as a fluorescence microscope, there is a demand for higher accuracy of an apparatus used for observation measurement such as single-molecule fluorescence observation or fluorescence intensity measurement of a sample having a low fluorescence intensity.
Autofluorescence of glass used for lenses of optical systems is known as one factor that deteriorates the accuracy in image observation and measurement of such an apparatus.

  The autofluorescence is fluorescence that is partially absorbed by the glass that is the material of the lens and emitted when the excitation light passes through the lens to excite the sample. This autofluorescence overlaps with the fluorescence emitted from the sample, and information in the dark part of the fluorescence image is lost, making it difficult to observe with high accuracy. In fluorescence intensity measurement, autofluorescence becomes background noise, making it difficult to accurately measure a sample with low fluorescence intensity. By using glass with reduced intensity of autofluorescence, highly accurate observation and measurement are possible.

  In such fluorescence observation and measurement, when the sample is a living cell or the like, if ultraviolet light is used as excitation light, the living cell may be damaged. For example, visible light having a wavelength of 480 nm is used. There are many.

  As a technique relating to glass with reduced autofluorescence intensity (hereinafter referred to as “low fluorescence glass”), as shown in Patent Document 1 and Patent Document 2, the content of impurities in the glass is reduced. There is. Moreover, as shown in Patent Document 2, there is a manufacturing method in which the mixing of impurities during glass manufacturing is reduced.

In Patent Document 1, as glass having a low impurity content, the content as impurities is 0.05% or less for As ₂ O ₃ , 0.05% or less for Sb ₂ O ₃ , and 10 ppm or less for V ₂ O _5. , Low fluorescent glass with 10 ppm or less CuO and 1 ppm or less CeO ₂ is disclosed.

Further, Patent Document 2 discloses a low-fluorescent glass having a low impurity content of 10 ppm or less of impurities, substantially free of arsenic, and substantially free of antimony. ing. Further, as a manufacturing method, a glass manufacturing method in which the amount of impurities is reduced by preventing the mixing of platinum from the gas phase and the mixing of platinum from the platinum crucible / glass melt interface is disclosed.
JP-A-4-219342 Japanese Patent Laid-Open No. 11-106233

  However, the low fluorescent glass according to the conventional technique has a problem that autofluorescence cannot be sufficiently reduced when visible light is irradiated.

  As described above, the fluorescence microscope is used for observation of fluorescent images and measurement of the amount of fluorescence. In order to correct aberrations satisfactorily, high refractive index and low dispersion optical glass is also used for the lens of the optical system of the fluorescence microscope. However, an optical glass having a high refractive index and low dispersibility tends to generate autofluorescence. Therefore, the fluorescence microscope using the high refractive index and low dispersibility optical glass has a problem that observation of a fluorescent image with high contrast and measurement with high accuracy become difficult.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to use an optical glass with reduced autofluorescence intensity when irradiated with visible light as compared with a conventional one, and this. An object is to provide an optical device.

As a result of intensive studies in order to achieve the above object, in a glass of B ₂ O ₃ -La ₂ O ₃ system, when the content of Cr less than 5 ppm, the auto-fluorescence when irradiated with visible light I found that it can be reduced.

In order to achieve the above object, the optical glass of the present invention has at least a weight basis,
SiO ₂ 2-10%
B ₂ O ₃ 5~45%
La ₂ O ₃ 30-60%
For 100% of the basic glass composition containing
The Cr content is less than 5 ppm.

Another embodiment of the optical glass of the present invention is based on weight,
SiO ₂ 2-10%
B ₂ O ₃ 5~45%
La ₂ O ₃ 30-60%
RO (R = Zn, Sr, Ca, Ba) 0-15%
Ln ₂ O ₃ (Ln = Y, Gd) 0-40%
ZrO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ 0-30%
For 100% of the basic glass composition containing
The Cr content is less than 5 ppm.

Further, another aspect of the optical glass of the present invention is at least on a weight basis,
SiO ₂ 2-20%
B ₂ O ₃ 5~45%
La ₂ O ₃ 10-29%
For 100% of the basic glass composition containing
The Cr content is less than 5 ppm.

Another embodiment of the optical glass of the present invention is based on weight,
SiO ₂ 2-20%
B ₂ O ₃ 5~45%
La ₂ O ₃ 10-29%
RO (R = Zn, Sr, Ca, Ba) 0-45%
Ln ₂ O ₃ (Ln = Y, Gd) 0 to 10%
ZrO ₂ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ 1-20%
For 100% of the basic glass composition containing
The Cr content is less than 5 ppm.

Another embodiment of the optical glass of the present invention is based on weight,
At least on a weight basis,
SiO ₂ 2-20%
B ₂ O ₃ 5~45%
La ₂ O ₃ 10-29%
Al ₂ O ₃ 0.1-5%
RO (R = Zn, Sr, Ca, Ba) 1-60%
Ln ₂ O ₃ (Ln = Y, Gd) 0 to 10%
ZrO ₂ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ 1-10%
For 100% of the basic glass composition containing
The Cr content is less than 5 ppm.

Moreover, another aspect of the present invention is based on a weight basis, and contains at least one of Sb ₂ O ₃ , chloride, sulfide, and fluoride as a defoaming agent for 100% of the basic glass composition. It contains 0.01 to 1%.

Furthermore, another aspect of the present invention contains 0 to 10% of at least one of Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O on a weight basis. .

  The optical device of the present invention includes an optical system having the optical glass described above.

  According to the optical glass of the present invention, it is possible to realize an optical glass with reduced autofluorescence intensity and an optical device using the same when irradiated with visible light than before.

  In particular, since the optical glass of the present invention has a Cr content of less than 5 ppm, a glass with low autofluorescence can be obtained. And since this glass has a small Cr content, it hardly affects optical properties such as refractive index and dispersion, chemical properties, thermal properties, mechanical properties, etc. at 400 to 700 nm used for fluorescent image observation. .

  Therefore, there is no need to change the design of the optical system, or the process of machining, coating process, etc. that are related to chemical properties, thermal properties, and mechanical properties. Can be easily replaced with glass.

The present invention is a B ₂ O ₃ —La ₂ O ₃ -based optical glass containing the components as described above. Hereinafter, the role of each glass component and the optimum content of each component will be described. The reason for the decision will be explained.

The optical glass of the first embodiment, as base glass composition includes _{SiO 2, B 2 O 3,} La 2 O 3.

SiO ₂ is one of glass network forming components. The optical glass of this embodiment contains ₂ to 10% of SiO ₂ . If it is less than 2%, the chemical durability of the glass deteriorates. On the other hand, in this embodiment, if it exceeds 10%, the stability of the glass is lowered, and the crystallized fluorescence becomes strong.

B ₂ O ₃ is one of the glass network forming components. The optical glass of this embodiment contains 5 to 45% of B ₂ O ₃ . If it is less than 5%, the stability and meltability of the glass deteriorate. If it exceeds 45%, the chemical durability is deteriorated.

La ₂ O ₃ is a component for increasing the refractive index. The optical glass of the present embodiment contains 30 to 60% La ₂ O ₃ . In this embodiment, if it is less than 30%, a desired refractive index cannot be obtained. On the other hand, if it exceeds 60%, the stability of the glass is lowered.

The optical glass of the second embodiment includes, as a basic glass composition, at least one of RO, Ln ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , and Ta ₂ O ₅ in addition to the above three components. Contains.

  RO is R = Zn, Sr, Ca, Ba, and indicates ZnO, SrO, CaO, BaO. RO is a component for adjusting the refractive index and the stability of the glass. In particular, BaO is a component that greatly contributes to increasing the refractive index of glass. The remaining components contribute to the improvement of the stability of the glass as well as the adjustment of the refractive index. The optical glass of this embodiment contains 0 to 15% of RO (R = Zn, Sr, Ca, Ba). If it exceeds 15%, the stability and chemical durability of the glass will decrease. When the optical glass of the present embodiment includes RO, it is sufficient that at least one of ZnO, SrO, CaO, and BaO is included.

Ln ₂ O ₃ is Ln = Y, Gd and represents Y ₂ O ₃ , Gd ₂ O ₃ . Y ₂ O ₃ and Gd ₂ O ₃ are components that increase the refractive index and adjust the dispersion value. The optical glass of this embodiment contains 0 to 40% of Ln ₂ O ₃ (Ln = Y, Gd). If it exceeds 40%, the stability of the glass deteriorates and the crystallization tendency becomes strong. When the optical glass of the present embodiment includes a _{Ln 2 O 3, Y 2 O} 3, may include at least one of Gd ₂ O _3.

ZrO ₂ , Nb ₂ O ₅ , TiO ₂ , and Ta ₂ O ₅ are components that increase the refractive index and adjust the dispersion value. The optical glass of this embodiment contains 0 to 30% of ZrO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ . If it exceeds 30%, the meltability deteriorates and the stability of the glass also deteriorates. When the optical glass of this embodiment contains ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , it suffices if it contains at least one of these.

The optical glass of the third embodiment is different from the optical glass of the first embodiment in the proportion of each component. That, SiO ₂ is 2~20%, B ₂ O ₃ is 5~45%, La ₂ O ₃ has a 10 to 29%. Compared with the first embodiment, SiO ₂ has an upper limit of 20%. On the other hand, La ₂ O ₃ is as low as 10 to 29%.

In addition to the three components of the third embodiment, the optical glass of the fourth embodiment is composed of RO, Ln ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ as a basic glass composition. Of at least one of them. That is, RO (R = Zn, Sr, Ca, Ba) is 0 to 45%, Ln ₂ O ₃ (Ln = Y, Gd) is 0 to 10%, ZrO ₂ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ is 1 to 20%. The optical glass of the fourth embodiment may not contain RO and Ln ₂ O ₃ .

The optical glass of the fifth embodiment, as base glass composition, in addition to the three components of the fourth embodiment includes Al ₂ O _3. Further, at least one of RO, ZrO ₂ , Nb ₂ O ₅ , TiO ₂ , and Ta ₂ O ₅ is included. That is, Al ₂ O ₃ is 0.1 to 5%, RO (R = Zn, Sr, Ca, Ba) is 1 to 60%, ZrO ₂ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ is 1 to 10%. It has become. Further, Ln ₂ O ₃ (Ln = Y, Gd) is 0 to 10% and may not be contained.

Al ₂ O ₃ is a component that adjusts the refractive index and the viscosity and weather resistance of the glass. If it exceeds 5%, the stability and melt life of the glass deteriorate.
The functions of other components are as described in the first and second embodiments.

  Moreover, the optical glass of 1st Embodiment-5th Embodiment has content of Cr less than 5 ppm with respect to said basic glass composition 100%.

  Cr is a component that emits autofluorescence. Cr emits fluorescence having a peak at a wavelength of 545 nm and autofluorescence having a peak near a wavelength of 700 nm. In particular, the latter autofluorescence is observed in a wide range on the longer wavelength side than 650 nm, and is highly sensitive to Cr content. Therefore, it is a component that hinders high-precision fluorescence observation and measurement in the near infrared region. If the Cr content exceeds 5 ppm, the object of the present invention cannot be achieved. Therefore, the Cr content is preferably less than 5 ppm. In particular, the Cr content is preferably 2 ppm or less.

Next, the optical glass of the sixth embodiment will be described. The optical glass of the sixth embodiment is one of at least one of Sb ₂ O ₃ , chloride, sulfide, and fluoride as a defoaming agent in the optical glass of the first to fifth embodiments. Contains 0.01 to 1%. If it does in this way, the bubble which a raw material decomposes | disassembles and reacts at the time of fusion | melting of glass can be reduced. If it is less than 0.01%, the defoaming effect cannot be obtained. On the other hand, if it exceeds 1%, there is a problem that autofluorescence is increased.

Next, the optical glass of the seventh embodiment will be described. The optical glass of the seventh embodiment is the optical glass of the first to sixth embodiments, and is at least one of Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O, which are alkali metal oxides. It contains 0-10% of 1 or more types. By doing in this way, the meltability of glass can be improved. If it exceeds 10%, chemical durability and glass stability deteriorate. In addition, it is desirable to contain a plurality of alkali metal oxides.

  The optical glass of the present embodiment can contain other components for the purpose of improving defoaming properties, melting properties, and stability.

Next, the fluorescence observation measuring apparatus of the present invention will be described.
The optical device of the present invention is, for example, a fluorescence microscope, a living cell observation device, a gene analysis device, a photoluminescence measurement device, a fluorescence spectrophotometer, a fluorescence lifetime measurement device, a plasma display panel inspection device, an endoscope having a fluorescence observation function Mirror etc. In any case, it is an apparatus for observing or measuring fluorescence.

  These optical devices observe and measure the fluorescence emitted by the sample. In order to emit fluorescence from the sample, the sample is irradiated with excitation light emitted from a light source through an optical system. The sample emits fluorescence by irradiation with the excitation light. This fluorescence is detected by a photodetector (photodiode, photomultiplier tube, CCD, CMOS, etc.) through the optical system.

  The optical system includes optical parts such as lenses made of optical glass or the like, prisms, mirrors, and filters. By using the optical glass of this embodiment for these optical components, the intensity (light quantity) of autofluorescence generated from these components can be reduced. As a result, in fluorescence observation, it is possible to suppress a decrease in the contrast of the fluorescent image. In fluorescence measurement, noise components (autofluorescence) in the fluorescence signal can be reduced.

  Next, the optical glass of Example 1 is shown in Table 1 as Test Examples 1 to 20. In Example 1, 20 types of glass samples were prepared, and the amount of each fluorescence was measured. The composition in Table 1 was expressed as a percentage based on weight.

  For the optical glass of this example, a high-purity glass raw material with less contamination of impurities was used. This glass raw material was mixed so as to have a predetermined ratio, melted at 1100 to 1400 ° C. for 2 to 5 hours in a platinum crucible, and annealed. The glass thus produced was processed into a square column of 11 × 11 × 40 mm, and four surfaces in the longitudinal direction (surface of 11 × 40 mm) were mirror-polished to obtain an optical glass.

Using this optical glass, the fluorescence intensity was measured with a spectrofluorometer (manufactured by JASCO Corporation, FP-6500). In the measurement, the optical glass of each example was irradiated with light of 480 nm, and the fluorescence intensity at 530 nm to 650 nm was measured. Then, the value (arbitrary unit) obtained by integrating the fluorescence intensities at 530 nm to 650 nm is set as the autofluorescence intensity, and the evaluation is performed by comparing with the autofluorescence intensity of the arbitrarily selected commercially available B ₂ O ₃ —La ₂ O ₃ glass. It was. The evaluation was based on the autofluorescence intensity of the commercially available glass, and the ratio with the autofluorescence intensity of each test example in Table 1 was determined, and this ratio was defined as the fluorescence. The fluorescence was less than 0.7 as A, 0.7 to 1.5 as B, and 1.5 or more as C.

Moreover, the evaluation result of the fluorescence based on the measurement result of the autofluorescence intensity performed similarly about 2 types of commercially available optical glass (Cr content is unmeasured) is shown as a comparative example in Table 2. The optical glass of the commercially available glass 1 and the commercially available glass 2 is a commercially available B ₂ O ₃ —La ₂ O ₃ optical glass different from the B ₂ O ₃ —La ₂ O ₃ glass used as the evaluation standard. .

In order to achieve the object of the present invention, it is desirable that the fluorescence index is A.
From this result, it was confirmed that the optical glass of the present example has reduced autofluorescence intensity compared to the optical glass of the comparative example.

The correspondence between each test example and the embodiment is as follows.
First Embodiment: Test Example 1 to Test Example 10
Second Embodiment: Test Example 1 to Test Example 10
Third Embodiment: Test Example 11 to Test Example 20
Fourth Embodiment: Test Example 12, Test Example 14 to Test Example 20
Fifth embodiment: Test Example 18 and Test Example 20
Sixth Embodiment: Test Example 3, Test Example 4, Test Example 8 to Test Example 10, Test Example 14 to Test Example 16, Test Example 19, Test Example 20
Seventh Embodiment: Test Example 1 to Test Example 20

Continuation of Table 1

  Next, an embodiment of the optical device of the present invention will be described with reference to FIG. FIG. 1 is an explanatory view showing an outline of a fluorescence microscope 1 which is an optical apparatus of the present invention. The fluorescence microscope 1 includes an excitation light source unit 2, an excitation light optical system 3, a filter unit 4, an eyepiece optical system 5, an image photographing unit 6, a display device 7, an objective lens 8, and a sample stage 10. Reference numeral 9 denotes a sample (specimen).

The excitation light source unit 2 includes a xenon lamp that emits excitation light 11 and a power supply device (not shown). The excitation light optical system 3 is an optical system that guides the excitation light 11 to the sample 9 and is disposed between the excitation light source unit 2 and the filter unit 4. The filter unit 4 is composed of a dielectric multilayer filter. The filter unit 4 includes a band pass filter and a dichroic mirror. The dichroic mirror has a characteristic of reflecting the excitation light 11 and transmitting the fluorescence 12.

The eyepiece optical system 5 is an optical system for observing an image (fluorescent image) of the sample 9 with the naked eye. The image capturing unit 6 is a CCD camera that captures an image of the fluorescence 12. The display device 7 displays the captured image of the fluorescence 12. The objective lens 8 condenses the excitation light 11 on the sample and condenses the fluorescence 12 at a predetermined position to form an image. The sample stage 10 is for installing the sample 9.

  The light emitted from the excitation light source unit 2 passes through the excitation light optical system 3 and enters the filter unit 4. The filter unit 4 is provided with a bandpass filter that transmits 460 to 495 nm. Therefore, when the light emitted from the excitation light source unit 2 passes through the filter unit 4, light having a wavelength of 460 to 495 nm, that is, excitation light 11 is obtained.

  Next, the excitation light 11 enters the dichroic mirror. The dichroic mirror has an optical characteristic of reflecting light having a wavelength shorter than 505 nm and transmitting light having a wavelength longer than 505 nm. This dichroic mirror is provided at an angle of 45 degrees with respect to the traveling direction of the excitation light 11. Therefore, the excitation light 11 incident on the dichroic mirror is bent 90 degrees and guided to the objective lens 8.

  The excitation light 11 is collected by the objective lens 8 and irradiated to the sample 9 provided on the sample stage 10. The excitation light 11 is absorbed by the sample 9 (fluorescent substance), and the fluorescence 12 is emitted from the sample 9.

  The fluorescence 12 is collected by the objective lens 8. The condensed fluorescence 12 enters the dichroic mirror of the filter unit 4. Here, the wavelength of the fluorescence 12 is longer than 505 nm. Therefore, the fluorescence 12 is transmitted through the dichroic mirror. The fluorescence 12 further passes through a filter that transmits light having a wavelength longer than 510 nm, and then is condensed at a predetermined position to form a fluorescence image. This fluorescent image is observed by the eyepiece optical system 5.

  Further, the fluorescence microscope 1 may include an optical path switching mechanism (not shown). The fluorescence 12 can be guided to the image capturing unit 6 by switching the optical path by the optical path switching mechanism. In this way, a fluorescent image can be taken by the image taking unit 6. The captured fluorescent image is displayed on the display device 7.

  In this embodiment, autofluorescence that becomes noise occurs in the filter unit 4 and the objective lens 8. In this example, the optical glass of Example 1 (any one of Test Examples 1 to 20) is used as a part of the optical lens used for the objective lens 8. Thereby, autofluorescence generated in the objective lens 8 could be reduced. As a result, the contrast of the fluorescent image increased and a clear fluorescent image could be obtained.

  Next, another embodiment of the optical device of the present invention will be described with reference to FIG. FIG. 2 is an explanatory view showing an outline of a fluorescence microscope 13 which is an optical apparatus of the present invention. The fluorescence microscope 13 is not different from the fluorescence microscope 1 shown in FIG. 1 except that the image capturing unit 6 is a light detection unit 14, and thus detailed description thereof is omitted. The light detection unit 14 includes a photomultiplier tube that measures the intensity of the fluorescence 12 and a power supply device (not shown).

  The fluorescence 12 passes through a filter that passes through the dichroic mirror of the filter unit 4 and further transmits light having a wavelength longer than 420 nm. Then, the fluorescence 12 enters the light detection unit 14. In the light detection unit 14, the light intensity (fluorescence intensity) is measured as a current value, and the value is displayed on the display device 15.

  At this time, auto-fluorescence that becomes noise occurs in the filter unit 4 and the objective lens 8. Here, when the fluorescence intensity is measured without installing the sample 9 on the sample stage 10, the autofluorescence generated in the filter unit 4 and the objective lens 8 is measured.

  In this example, the optical glass of Example 1 is used as part of the glass used for the objective lens 8. The fluorescence intensity was measured without placing the sample on the sample stage 10. Moreover, the fluorescence intensity measurement was performed using the objective lens 8 which used the conventional optical glass.

  As a result, in the case of the objective lens 8 using the optical glass of Example 1, the measured fluorescence intensity (arbitrary unit) was 63. On the other hand, the fluorescence intensity measurement value (arbitrary unit) in the case of the objective lens 8 using the conventional optical glass was 260. Thus, the intensity of autofluorescence in the optical glass of Example 1 is about ¼ compared to the conventional case. Therefore, the background noise could be reduced as compared with the fluorescence microscope according to the prior art.

  Next, another embodiment of the optical device of the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram showing the configuration of the spectrofluorometer 20 which is the optical apparatus of the present invention. The spectrofluorometer 20 includes a photometer main body 21, a control / analysis unit 22, and a power source (not shown).

  The photometer body 21 irradiates the sample with the excitation light 34 and converts the fluorescence 35 emitted from the sample into an intensity signal. The control / analysis unit 22 controls the photometer main body 21 and displays / analyzes the measured fluorescence intensity.

  The photometer main body 21 includes an excitation light optical system 23, a sample chamber 24, and a fluorescence optical system 25. The excitation light optical system 23 includes a xenon lamp 26 that emits excitation light 34, a diffraction grating 27 for excitation light that splits the excitation light 34, a mirror 28 that changes the direction of the excitation light 34 toward the sample, and a sample chamber. 24 and an excitation light exit window 29 that divides the space. The excitation light exit window 29 uses the low fluorescent glass of the first embodiment.

  The reason why the space between the sample chamber 24 and the excitation light optical system 23 is divided is to prevent contamination of the excitation light optical system 23 due to entry of foreign matter from the sample chamber 24 or the like. For the same reason, a later-described fluorescence optical system 25 also divides the space by the sample chamber 24 and the fluorescence incident window 31.

  The fluorescence optical system 25 includes a light incident window 31, a fluorescence diffraction grating 32, and a photomultiplier tube 33. The light incident window 31 is provided at a position where the fluorescence 35 emitted from the sample 30 enters the fluorescence optical system 25. The fluorescence diffraction grating 32 separates the incident fluorescence 35. The photomultiplier tube 33 converts the light intensity of the separated fluorescence into an electric current. Here, the optical glass of Example 1 is used for the fluorescence incident window 31.

  Next, fluorescence measurement using the spectrofluorometer 20 will be described. A sample 30 for fluorescence measurement is installed in the sample chamber 24. The excitation light 34 emitted from the xenon lamp 26 is split into, for example, light having a center wavelength of 480 nm and a wavelength width of 10 nm by the excitation light diffraction grating 27. This excitation light is reflected by the mirror 28, passes through the excitation light exit window 29, enters the sample chamber 24, and irradiates the sample 30.

  A part of the excitation light 34 irradiated to the sample 30 is absorbed by the sample 30, and fluorescence is emitted from the sample 30 by the energy of the absorbed excitation light 34. The fluorescence 35 emitted from the sample 30 enters the fluorescence optical system 25 through the fluorescence incident window 31. The fluorescence 35 is dispersed by the fluorescence diffraction grating 32 (for example, wavelength 600 nm). At the time of spectroscopy, the fluorescence diffraction grating 32 is operated to change the incident angle of the fluorescence 35 with respect to the fluorescence diffraction grating 32. By doing so, the wavelength of light incident on the photomultiplier tube 33 is changed.

  The light split by the fluorescence diffraction grating 32 enters the photomultiplier tube 33, and the light intensity is converted into an electric current. The light intensity converted into current by the photomultiplier tube 33 is displayed and analyzed by the control / analysis unit 22. When fluorescence intensity data is collected for each wavelength, a fluorescence spectrum representing the fluorescence intensity with respect to the fluorescence wavelength is obtained.

  In the spectrofluorometer according to the prior art, autofluorescence is generated from the excitation light exit window 29 irradiated with the excitation light 34. In addition, the scattered light of the excitation light 34 applied to the sample 30 enters the excitation light exit window 29 and the fluorescence entrance window 31, and autofluorescence is generated. Such autofluorescence increases the background value in the measurement, making it difficult to perform measurements that require high accuracy such as measurement of weak fluorescence intensity.

  On the other hand, in the spectrofluorometer 20 according to the present embodiment, the optical glass of the first embodiment is used for the excitation light exit window 29 and the fluorescence entrance window 31. Thereby, the intensity of autofluorescence generated from these windows can be reduced. Therefore, the measurement background value can be lowered. As a result, it was possible to measure with high accuracy even if the fluorescence was weak.

  The optical device of the present invention is not limited to the above-described embodiment, and the same effect can be obtained in other optical devices using the optical glass of this embodiment.

It is a schematic explanatory drawing of the fluorescence microscope which is Example 1 of the optical apparatus of this invention. It is a schematic explanatory drawing of the fluorescence microscope of this invention. It is a structure explanatory drawing of the spectrofluorometer of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluorescence microscope 2 Excitation light source part 3 Excitation light optical system 4 Filter part 5 Eyepiece optical system 6 Image pick-up part 7 Display apparatus 8 Objective lens 9 Sample 10 Sample stand 11 Excitation light 12 Fluorescence 13 Fluorescence microscope 14 Light detection part 15 Display part 20 Spectrofluorometer 21 Photometer body 22 Control / analysis section 23 Excitation light optical system 24 Sample chamber 25 Fluorescence optical system 26 Xenon lamp 27 Excitation light diffraction grating 28 Mirror 29 Excitation light exit window 30 Sample 31 Fluorescence entrance window 32 Diffraction grating for fluorescence 33 Photomultiplier tube 34 Excitation light 35 Fluorescence

Claims (8)

At least on a weight basis,
SiO ₂ 2-10%
B ₂ O ₃ 5~45%
La ₂ O ₃ 30-60%
For 100% of the basic glass composition containing
An optical glass having a Cr content of less than 5 ppm. On a weight basis,
SiO ₂ 2-10%
B ₂ O ₃ 5~45%
La ₂ O ₃ 30-60%
RO (R = Zn, Sr, Ca, Ba) 0-15%
Ln ₂ O ₃ (Ln = Y, Gd) 0-40%
ZrO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ 0-30%
For 100% of the basic glass composition containing
An optical glass having a Cr content of less than 5 ppm. At least on a weight basis,
SiO ₂ 2-20%
B ₂ O ₃ 5~45%
La ₂ O ₃ 10-29%
For 100% of the basic glass composition containing
An optical glass having a Cr content of less than 5 ppm. On a weight basis,
SiO ₂ 2-20%
B ₂ O ₃ 5~45%
La ₂ O ₃ 10-29%
RO (R = Zn, Sr, Ca, Ba) 0-45%
Ln ₂ O ₃ (Ln = Y, Gd) 0 to 10%
ZrO ₂ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ 1-20%
For 100% of the basic glass composition containing
An optical glass having a Cr content of less than 5 ppm. On a weight basis,
SiO ₂ 2-20%
B ₂ O ₃ 5~45%
La ₂ O ₃ 10-29%
Al ₂ O ₃ 0.1-5%
RO (R = Zn, Sr, Ca, Ba 1-60%
Ln ₂ O ₃ (Ln = Y, Gd) 0 to 10%
ZrO ₂ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ 1-10%
For 100% of the basic glass composition containing
An optical glass having a Cr content of less than 5 ppm. It contains 0.01 to 1% of any one or more of Sb ₂ O ₃ , chloride, sulfide and fluoride as a defoaming agent with respect to 100% of the basic glass composition on a weight basis. The optical glass according to claim 1, wherein the optical glass is characterized in that 7. The composition according to claim 1, wherein at least one of Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O is contained in an amount of 0 to 10% on a weight basis. The optical glass described in 1.   An optical apparatus comprising an optical system having the optical glass according to any one of claims 1 to 7.

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