JP2002181710A - Fluorescence detecting and measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescence detecting and measuring instreument capable of easily evaluating the internal physical properties of a glass product such as a quartz glass crucible, a photomask or the like, which is difficult to evaluate by a conventional fluorescence detecting and measuring instrument, in a non- destructive manner. SOLUTION: The fluorescence detecting and measuring instreument is equipped with at least a laser oscillator 1 generating laser beam with a wavelength transmittable through a sample, a laser beam source 2 for irradiating the surface of the sample 4 with laser beam, a condenser/detector 3 for condensing fluorescence emitted from the sample irradiated with laser beam to detect the same, and a control unit 6 capable of adjusting and controlling the laser beam source 2 and the condenser/detector 3. Laser beam is allowed to be obliquely incident on the surface of the sample 4, and fluorescence generated from the interior of the sample by incident laser beam is condensed and detected to evaluate the optical physical properties in the depthwise direction of the sample.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescence detection / measurement apparatus, and more particularly to a fluorescence detection / measurement apparatus which can be suitably used for evaluating physical properties and structural analysis of a light-transmitting solid such as a glass product.

[0002]

2. Description of the Related Art Luminescence is a phenomenon in which electrons in a substance change from a ground state to an excited state due to various stimuli, for example, absorption of photons by light irradiation, and emit light when returning to the ground state again. . The emission light having a short decay time (10 ^-9 to 10 ^-3 sec), that is, the luminescence corresponding to the component having a short decay time in the afterglow emitted by the substance after removing the external stimulus. Is called fluorescence.

[0003] In optical materials such as lens materials and photomask materials, it is essential to suppress the generation of fluorescence of a specific wavelength, and thus the evaluation of fluorescence is extremely important. In addition, the quality of a material can be evaluated for a quartz crucible and other glass products by evaluating specific fluorescence. For example, in the case of a photomask material, there is a case where the visible fluorescence intensity is defined so as not to exceed a certain value. In the quartz crucible, the evaluation of the fluorescence can be applied to the evaluation of the generation of harmful bubbles.

[0004] In addition, fluorescence is known to provide important clues about the electronic state in a substance. For this reason, the measurement of fluorescence is also used for qualitative or quantitative analysis as a method for detecting trace substances. Conventionally, the evaluation of fluorescence has been performed by irradiating a sample with an ultraviolet lamp or the like, and the generation of fluorescence has been confirmed visually or by a spectroscope.

FIG. 6 shows an example in which an Ar laser beam or the like is projected onto a sample.
1 shows an example of a conventional fluorescence detection and measurement device that measures generated fluorescence using a spectroscope under a microscope. In FIG. 6, the Ar laser light 20 projected from above in the horizontal direction on the sample 4 is turned 90 degrees downward by the half mirror 21, and is condensed on the sample 4 by the objective lens 22. The fluorescence emitted by the emission center excited by the projected laser light passes through the half mirror 21 and forms an image on a pinhole or slit 24 a provided in the spectroscope 23 via the imaging lens 26. This fluorescence is diffracted by the diffraction grating 25 provided in the spectroscope 23, then guided to the light receiving element 27 via a pinhole or a slit 24b, and distributed on the element according to the frequency distribution. The distribution on the light receiving element 27 is analyzed by the control / analysis device 28. The control / analysis device 28
Controls the two-dimensional movement of the sample stage 7 and displays an image of the fluorescence distribution generated by the sample 4.

With the above-described spectroscope or visual fluorescence evaluation method, information on the surface of the sample can be obtained, but it is difficult to obtain information on the internal state of the sample without destroying the sample. .

[0007]

By the way, in the field of handling quartz materials such as quartz crucibles, there is a demand for a means capable of nondestructively obtaining information on the internal state of the product. However, as described above, the conventional visual fluorescence evaluation method allows nondestructive evaluation, but it has been difficult to measure the wavelength of the fluorescence and to evaluate the depth direction. In addition, in the evaluation using a conventional fluorescence detection and measurement device using a spectroscope as described above, since it is usually necessary to cut a part of the product as a sample and insert it into the sample chamber for measurement, the product must be nondestructively measured. Was difficult to evaluate. Therefore, in any case, it has been difficult to evaluate products in detail in a nondestructive manner by the conventional fluorescence evaluation method.

The present invention has been made in order to solve the above-mentioned technical problems, and it has been proposed that the internal physical properties of glass products such as quartz crucibles and photomasks, which were difficult with a conventional fluorescence detection and measurement apparatus, can be reduced. It is an object of the present invention to provide a fluorescence detection and measurement device that can be easily evaluated by destruction.

[0009]

A fluorescence detection and measurement apparatus according to the present invention generates laser light having a wavelength that can be transmitted through a sample,
A light source / irradiation system that irradiates the surface of the sample with the laser light; a light collection / detection system that collects and detects fluorescence emitted from the sample irradiated with the laser light;
A fluorescence detection and measurement device having at least a control system for adjusting and controlling the detection system, wherein the laser light is obliquely incident on the sample surface, and the fluorescence emitted from the inside of the sample by the incident laser light is collected and detected. It is characterized in that the optical properties of the sample in the depth direction are evaluated. In this way, by using a fluorescence detection and measurement device having a configuration in which laser light is obliquely incident on the sample surface and the fluorescence emitted from the inside of the sample is collected and detected by the incident laser light, glass products such as quartz crucibles can be manufactured. Non-destructive evaluation of the internal structure and the like in the depth direction from the surface can be performed.

In the fluorescence detection and measurement apparatus, the irradiation light source in the light source / irradiation system and the light collection / detection system are housed in the same housing, and the housing is vertically moved with respect to the sample surface. Therefore, it is preferable to change the depth of penetration of the laser light from the sample surface into the inside. As described above, in the measuring device in which the laser light source and the respective devices of the light collection / detection system are housed and arranged in the same housing,
Even in the case of a large object in which it is difficult to move the sample freely for transport or inspection, the device itself can be easily non-destructively disposed by arranging it on the surface of the sample. Can be evaluated.

[0011] The fluorescence detection and measurement apparatus according to the present invention comprises:
The condensing / detecting system includes a zoom lens and a two-dimensional detector, and the control system has a function of controlling a zoom operation in the condensing / detecting system and a fluorescence detection area of the two-dimensional detector. Preferably, it is provided. As described above, the apparatus according to the aspect including the zoom lens capable of externally controlling the light collection / detection system and the two-dimensional detector such as a CCD (Charge Coupled Device) detector has an arbitrary depth inside the sample. Fluorescence emitted from the position can be detected with high accuracy, and
The amount of light can be quantitatively measured together with the imaging.

Further, it is preferable that the condensing / detecting system includes a two-stage color filter and is configured to selectively detect fluorescence in a specific wavelength region. As described above, the apparatus of the embodiment including the two-stage color filter in which the color filters each having a different wavelength region to be cut are combined in two stages in the light collection / detection system selectively detects the fluorescence of the specific wavelength and performs measurement. This method is suitable for detecting and quantifying a specific impurity present in a sample, and for measuring and evaluating its distribution in the depth direction.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and features of a fluorescence detection and measurement apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of the fluorescence detection and measurement device according to the present invention. As shown in FIG. 1, a laser light source 2 connected to a laser oscillator 1
Fixed to. The laser light source 2 is configured to be able to move in the XYZ axis (vertical / horizontal / height) direction and change the incident angle of the laser light on the sample by the condensing / detecting device 3. Thus, the irradiation position and the irradiation angle on the surface of the sample 4 can be adjusted.

A filter 5 is provided between the sample 4 to be measured and the condenser / detector 3. The filter 5 is composed of two-stage color filters, and a wavelength region to be measured can be selected by combining color filters having different wavelength regions to be cut.

The condenser 3a is a zoom lens, and the zoom operation can be controlled from the outside. The detector 3b is a two-dimensional detector such as a CCD (Charge Coupled Device) detector, and has a mechanism capable of performing light quantity measurement together with imaging. The condensing / detecting device 3
Is connected to a control device 6 for performing the vertical movement, the zoom operation of the condenser 3a, the setting of the detection wavelength region, and the measurement of the amount of light emission / fluorescence. The control device 6 has a function of controlling the zoom operation of the condenser and the fluorescence detection area of the two-dimensional detector, and is configured to be able to automatically control the narrowing of the fluorescence detection area of the sample 4. Is preferred.

For example, as shown in FIGS.
The condenser / detector 3 is configured to be vertically movable with respect to a stand 8 (FIGS. 2 and 3) or an enclosure (housing) 12 (FIG. 4) via a gear 9a. Further, by adding a mechanism such as a stepping motor (not shown) for automatically moving up and down from the outside, it is possible to focus on an arbitrary position inside the sample 4.

In the present invention, the detector 3b is not particularly limited, but is preferably a two-dimensional detector. Suitable two-dimensional detectors include detectors such as photomultiplier tubes, photodiode arrays, and CCDs, among which CCD is the most preferable. By using a two-dimensional detector as a detector, not only imaging, light quantity measurement and the like can be performed, but also a luminescence / fluorescence distribution image from a sample to be measured can be more accurately captured.

In the present invention, the sample 4 to be measured is
Is mainly, but not exclusively, intended for glass products including quartz glass materials such as lens materials, photomasks and quartz crucibles.

As the irradiation laser light emitted from the laser oscillator 1, any oscillator that emits laser light having a wavelength corresponding to the sample can be arbitrarily selected and used. A laser oscillator is used.

The fluorescence detection / measurement apparatus according to the present invention is basically used by a method having the same structure as a microscope, as shown in FIG. That is, fluorescence detection is performed in a state where the condenser / detector 3 and the sample stage 7 are attached to the stand 8 via the gears 9a and 9b so that they can move up and down independently.

In a test in a manufacturing process or a measurement of a large sample, for example, as shown in FIG.
Is attached to the arm 11 extended from the stand 8,
It is also possible to perform detection and measurement in a state where it is mounted above the sample 4 and is located above the sample 4 placed on the table 10.

Further, in the fluorescence detection and measurement apparatus according to the present invention, as shown in FIG. 4, the devices of each system are formed in a small size, and these are compactly housed in a casing-shaped envelope 12. By arranging and housing, a mode that is small and lightweight and easy to carry can also be provided. The device of this embodiment has a sample 4
Is large, it can be used mounted on the sample 4 as shown in FIG. 4, and is particularly suitable for measuring a large sample that is not easily moved.

Next, a method for measuring the fluorescence in the depth direction from the surface of the sample using the above-described apparatus according to the present invention will be described. First, the positions of the condenser / detector 3 and the laser light source 2 and the laser irradiation angle are adjusted so that the position of the surface of the sample 4 where the laser light is irradiated is captured by the detector 3b at the center, and Be focused. This adjustment can be easily performed on the video image by the CCD detector. Next, the focusing position and the irradiation position of the laser beam with the detector 3 are lowered, and focusing is performed with the laser beam incident on the sample. Focusing is performed by adjusting the angle of the laser light source 2 or the position in the Z-axis (height) direction.
Then, based on the depth from the surface of the sample 4 to be measured, the required detection sensitivity, and the accuracy in the depth direction, that is, the resolution, the detection area and the zoom magnification are set to optimal values. This operation is also performed while confirming the position of the laser beam on the video image.

The resolution ΔD in the depth direction can be obtained by the following equation when the incident angle of the laser beam is set to θ, the zoom magnification is set to M, and the detection area on the CCD is set to L in the laser incident direction. ΔD = L / (M · tan θ)

Next, the emission or fluorescence wavelength to be measured is set to 2
It is set by the stage combination filter 5. The filter is selected so that any one of them can completely cut off the reflected laser beam.

Thereafter, the condenser / detector 3 is gradually lowered. By measuring the amount of light with a CCD detector, it is possible to detect and measure the emission or fluorescence in the depth direction of the sample.

Incidentally, the position may be shifted due to unevenness of the sample surface or a change in the refractive index. Also, the locus of the laser light in the sample may not be clear. In such a case, focusing can be performed by adjusting the irradiation angle of the laser beam so that the light amount of the two-dimensional detector is maximized.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples. As a sample, a size of 200 mm × 200 mm and a thickness of 10 mm synthesized under an oxygen excess atmosphere
Was used. This synthetic quartz glass emits red fluorescence having a wavelength of 650 nm based on the presence of excess oxygen or non-crosslinked oxygen holes when irradiated with ultraviolet light or the like. The surface of this synthetic quartz glass plate sample was heated in a stream of hydrogen gas to reduce excess oxygen and non-crosslinked oxygen near the sample surface and its depth direction, so that no fluorescence was observed near the surface. Therefore, by observing the fluorescence generation state in the depth direction of this sample, that is, by measuring the change in the fluorescence intensity in the depth direction, it is possible to determine at which depth of the sample hydrogen has penetrated to remove excess oxygen. It can be determined non-destructively.

The laser light source used for the measurement was an Ar ion laser, a wavelength band of 488 nm was selected, and the other oscillation lines were cut by a band-pass filter. An optical fiber was connected to a laser oscillator to introduce laser light, and its free end was fixed to a four-axis actuator attached to a condenser / detector. The irradiation position of the laser beam on the sample was observed with a CCD camera and adjusted so that it was at the center. Then, the condenser / detector was lowered, and the laser beam was allowed to enter the inside of the sample to perform focusing. . In addition, CCD
Has 256 × 256 elements and a light receiving area of 12 × 12 m
A high-sensitivity type m whose measurement area can be set by digital photometry was used. The incident angle of the laser beam is 3
0 °, the zoom magnification was 200 times, and the CCD detection area was 6 mm. The resolution in the depth direction at this time is: ΔD = L / (M · tan θ) = 6 / (100 × 0.58)
= 0.0258, which is about 25 μm.

In order to select the fluorescence wavelength by a filter, first, a 488 nm Ar laser line is removed by a notch filter, and then a color glass filter that cuts a wavelength shorter than 600 nm and a color glass filter that cuts a wavelength longer than 700 nm. Using a combination of 6 sheets,
Laser light in the wavelength range of 00 to 700 nm was transmitted.
The condenser / detector was gradually lowered, and the intensity of fluorescence having a center at 650 nm was measured from the surface toward the inside. The measurement was performed in a dark place. FIG. 5 shows the obtained fluorescence intensity measurement results in the sample depth direction.

FIG. 5 shows that the fluorescence intensity of the sample was lower than the surface to a depth of 2 mm, and that excess oxygen was removed to the same depth by heating in hydrogen.

[0032]

By using the fluorescence detection and measurement apparatus according to the present invention, it has become possible to measure and evaluate non-destructive light emission and fluorescence in the depth direction of glass products and the like, which were difficult in the past.
For this reason, the fluorescence detection / measurement device can be used as a means for evaluating the optical properties of a product, and can be used very effectively in the manufacture of optical products and the like. Further, since the fluorescence detection and measurement device according to the present invention can be standardized in handling and operation and can be automated, it can be easily operated without requiring a special measurement technique.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a fluorescence detection and measurement device according to the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a usage mode of the fluorescence detection and measurement device according to the present invention.

FIG. 3 is a schematic configuration diagram showing another example of a usage mode of the fluorescence detection and measurement device according to the present invention.

FIG. 4 is a schematic diagram showing a fluorescence detection / measurement device according to the present invention in a mode in which measurement instruments are housed in a housing.

FIG. 5 is a diagram showing fluorescence intensity measurement data in a depth direction of a quartz glass plate sample in an example.

FIG. 6 is a schematic configuration diagram showing an example of a conventional fluorescence detection and measurement device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Laser light source 3 Condenser / detector 3a Condenser 3b Detector 4 Sample 5 Filter 6 Control device 7 Sample stand 8 Stand 9a, 9b Gear 10 Table 11 Arm 12 Enclosure (housing) 20 Ar laser light DESCRIPTION OF SYMBOLS 21 Half mirror 22 Objective lens 23 Spectroscope 24a, 24b Pinhole or slit 25 Diffraction grating 26 Imaging lens 27 Light receiving element 28 Control / analysis apparatus

Claims (5)

[Claims] 1. A light source / irradiation system for generating a laser beam having a wavelength that can be transmitted through a sample and irradiating the surface of the sample with the laser beam, and collecting and detecting fluorescence emitted from the sample irradiated with the laser beam. A condensing / detection system, and a fluorescence detection / measurement device including at least a control system for adjusting and controlling the light source / irradiation system and the condensing / detection system. A fluorescence detection / measuring device characterized by evaluating the optical properties in the depth direction of a sample by condensing and detecting fluorescence emitted from the inside of the sample by incident laser light. 2. An irradiation light source in the light source / irradiation system,
The condensing / detecting system is housed in the same housing, and the housing is vertically moved with respect to the sample surface to change the depth of penetration of the laser light from the sample surface into the inside. The fluorescence detection and measurement device according to claim 1, wherein 3. The system according to claim 1, wherein the focusing / detecting system includes a zoom lens,
3. The fluorescence detection and measurement device according to claim 1, comprising a two-dimensional detector. 4. The control system according to claim 1, wherein the control system has a function of controlling a zoom operation in the light collection / detection system and a fluorescence detection area of the two-dimensional detector. The fluorescence detection and measurement device according to claim 1. 5. The light collection / detection system according to claim 1, wherein the light collection / detection system includes a two-stage color filter, and is configured to selectively detect fluorescence in a specific wavelength region.
The fluorescence detection measurement device according to any one of the above.