JP2004286577A - Spectrum analyzer for hot lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized spectrum analyzer for a hot lens which analyzes a sample with high precision. <P>SOLUTION: The spectrum analyzer for the hot lens is constituted so as to allow probe light P to be incident on the hot lens produced in a sample solution S by the incidence of exciting light E to analyze the sample solution S on the basis of the change due to the hot lens of the probe light P, and equipped with: a condensing lens 5 for condensing the exciting light E incident on the sample solution S and the probe light P incident on the hot lens to a beam diameter of 0.2-50 &mu;m; a sample cell 6 for housing the sample solution S; and an optical fiber 8 for receiving the probe light P transmitted through the sample cell 6 to guide the same to a detection means for detecting the probe light P. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermal lens spectroscopic analyzer that is small and capable of analyzing a sample with high accuracy.
[0002]
[Prior art]
Analysis for bedside diagnosis (POC (point of care) analysis) that performs measurements necessary for medical diagnosis in the vicinity of patients and analysis of harmful substances in rivers and wastes are performed at sites such as rivers and waste disposal sites. Analysis and measurement at or near the site where analysis and measurement is required, such as contamination inspection at each site of cooking, harvesting, and importing food (hereinafter referred to as “POC analysis, etc.” The importance of) is drawing attention. In recent years, development of a detection method and a detection device applied to such POC analysis and the like has been gaining importance.
[0003]
Such detection methods and detection devices applied to POC analysis and the like require that analysis be performed at low cost and that the device be small. Further, in medical diagnosis and environmental analysis, it is generally required that high-sensitivity and high-precision analysis be performed in order to accurately compare with a standard value determined by a country. Furthermore, it is important that the sample cell for storing the sample is thrown away every time it is used, in order to prevent the analysis operator from being infected by the sample or causing contamination between the samples. Therefore, there is an example in which a resin sample cell is used as a low-cost sample cell (Japanese Patent Application Laid-Open No. 12-2675).
[0004]
In recent years, grooves of several tens to several hundreds of μm have been cut on the surface of glass or silicon flat chips of about 10 cm to several cm square or less, and all the necessary reactions, separations, and detections are performed in these grooves. Research on μ-TAS (micro total analysis system) performed in a short time has been actively conducted (for example, JP-A-2-245655). In this μ-TAS, a chip having the groove serves as a sample cell.
[0005]
The use of μ-TAS reduces the amount of a specimen, the amount of a reagent required for detection, the amount of waste such as consumables used for detection, and the amount of waste liquid, and the time required for detection is generally short. This μ-TAS is suitable for POC analysis and the like. For the purpose of developing a low-cost disposable chip, a method of forming a chip with a resin (RM McCormick et al., Anal. Chem. Vol. 69, 2626-2630, 1997, Japanese Patent Laid-Open No. 2-259557) And Japanese Patent No. 2639087) have also been proposed.
[0006]
However, in μ-TAS, the optical path length is several tens μm to several hundred μm, which is 1/10 to 1/100 as compared with normal conditions. There is a problem of shortage. In addition to the μ-TAS, when the sample amount or the sample amount is small, the optical path length is shortened accordingly, and the sensitivity becomes insufficient as described above.
[0007]
On the other hand, photothermal conversion spectroscopy, in which a substance such as a dye in a solution absorbs light and measures the amount of heat generated in the relaxation process, is known as a highly sensitive concentration measurement method. In particular, thermal lens spectroscopy using a refractive index distribution based on a temperature distribution generated by generated heat is known to be 100 times or more more sensitive than an absorptiometry that measures the amount of transmitted light. (For example, Manabu Tokeshi et al., J. Lumin. Vol. 83-84, 261-264, 1999).
[0008]
In thermal lens spectroscopy, the sensitivity decreases as the optical path length decreases, but the temperature gradient increases and the sensitivity improves by reducing the beam diameter to 0.2 to 50 μm, which is about one-fourth or less of the conventional value. (Takehiko Kitamori et al., Anal. Sci. Vol. 17, s454-s457, 2001, and International Publication WO 01/55706).
[0009]
[Patent Document 1]
JP-A-12-2675
[Patent Document 2]
JP-A-2-245655
[Patent Document 3]
JP-A-2-259557
[Patent Document 4]
Japanese Patent No. 2639087
[Patent Document 5]
International Publication WO01 / 55706
[Non-patent document 1]
R. M. McCormick et al. , Anal. Chem. Vol. 69, 2626-2630, 1997
[Non-patent document 2]
Manabu Tokyoshi et al. , J. et al. Lumin. Vol. 83-84, 261-264, 1999
[Non-Patent Document 3]
Takehiko Kitamori et al. , Anal. Sci. Vol. 17, s454-s457, 2001
[0010]
[Problems to be solved by the invention]
Conventionally, when the beam diameter is small (0.2 to 50 μm) as in International Publication WO 01/55706, the focal length of the condenser lens is short, and the divergence angle of light is large. Therefore, it is necessary to bring the light transmitted through the sample cell into a state close to parallel light by a lens and guide the light to the stop. Therefore, a lens for parallel light conversion is required, and there is a problem that the system becomes complicated.
[0011]
Further, when the sample cell after the analysis is removed from the analyzer and a new sample cell is installed, the inclination of the sample cell with respect to the optical axis of the probe light usually occurs about ± 0.5 to 1.0 °. If the inclination of the sample cell with respect to the optical axis occurs, the thermal lens signal value changes by 5 to 20% even if the inclination is slight as described above, causing an error. Usually, such errors are unacceptable in medical diagnosis, POC analysis such as environmental analysis, etc., which require accuracy of 1% or less.
[0012]
In order to correct this tilt, it is effective to introduce a tilt sensor using light, but the system is complicated, for example, a new dedicated optical system is required, and a reflective film must be provided on the sample cell. Had the disadvantage of becoming
Therefore, an object of the present invention is to solve the problems of the conventional thermal lens spectrometer described above and to provide a thermal lens spectrometer which is small and capable of analyzing a sample with high accuracy.
[0013]
[Means for Solving the Problems]
In order to solve the above problem, the present invention has the following configuration. That is, the thermal lens spectroscopic analyzer according to claim 1 of the present invention is configured such that probe light is incident on a thermal lens generated in a sample by the incidence of excitation light, and based on a change of the probe light by the thermal lens at that time. A thermal lens spectrometer for analyzing the sample, wherein the condenser lens focuses the excitation light incident on the sample and the probe light incident on the thermal lens to a beam diameter of 0.2 to 50 μm. And a sample cell for storing the sample, and an optical fiber for receiving the probe light transmitted through the thermal lens and the sample cell and guiding the probe light to detection means for detecting the probe light.
[0014]
With such a configuration, even if the inclination of the sample cell with respect to the optical axis of the probe light occurs by about ± 1.0 °, the error of the thermal lens signal value resulting from the inclination is suppressed to 1% or less. In the case where the beam diameter of the probe light is in the range of 0.2 to 50 μm, it has conventionally been necessary to receive light with a lens and guide it to the detection means. The resulting thermal lens signal value error can be significantly improved.
[0015]
Note that the tilt of the sample cell is an angle between the sample cell and the optical axis of the probe light. More specifically, it is the angle between the surface of the sample cell surface where the probe light is incident and transmitted and the optical axis of the probe light.
In addition, since the optical fiber is used for the light receiving unit optical system that receives the probe light and guides the probe light to the detection unit, the light receiving unit optical system becomes small, and as a result, the thermal lens spectroscopic analyzer becomes small.
[0016]
A thermal lens spectrometer according to a second aspect of the present invention is the thermal lens spectrometer according to the first aspect, wherein a light source of the excitation light is constituted by a semiconductor laser light emitting unit, and a light source of the probe light is provided. It is characterized by comprising another semiconductor laser light emitting means.
With such a configuration, the condenser lens optical system from both light sources to the condenser lens is reduced in size. Since the condensing lens optical system is small and the light receiving unit optical system is small by using an optical fiber as described above, the thermal lens spectroscopic analyzer is required to be portable enough for POC analysis and the like. Can be reduced in size.
[0017]
Furthermore, a thermal lens spectrometer according to claim 3 of the present invention is characterized in that, in the thermal lens spectrometer according to claim 1 or 2, the core diameter of the optical fiber is 500 to 2000 μm. I do. With such a configuration, the sensitivity of the thermal lens spectral analysis is excellent.
Furthermore, a thermal lens spectrometer according to claim 4 of the present invention is characterized in that, in the thermal lens spectrometer according to any one of claims 1 to 3, the sample cell is made of resin.
With such a configuration, it is possible to significantly suppress the error of the thermal lens signal even if the sample cell made of resin is tilted due to warpage or the like as compared with the case made of glass.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a thermal lens spectroscopic analyzer according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram illustrating a configuration of a thermal lens spectrometer according to an embodiment of the present invention. Note that the present embodiment is an example of the present invention, and the present invention is not limited to the present embodiment.
[0019]
The thermal lens spectrometer of FIG. 1 includes a laser light emitting means 1 as a light source of the excitation light E, a laser light emitting means 2 as a light source of the probe light P, and a beam diameter of 0.2 to 0.2 mm. It comprises one condensing lens 5 for condensing light to 50 μm, a sample cell 6 for storing a sample solution S, an optical fiber 8 for receiving the probe light P, and a detecting means 9 for detecting the probe light P. . Note that two condensing lenses may be provided so that the excitation light E and the probe light P are condensed by different condensing lenses.
[0020]
In such a thermal lens spectroscopic analyzer, the excitation light E is output from the laser light emitting means 1, the probe light P is output from the laser light emitting means 2, and the probe light P is reflected by the reflector 3 to form a beam splitter. 4 is incident. Then, the excitation light E and the probe light P are made coaxial in the beam splitter 4 and guided to the condenser lens 5.
[0021]
The excitation light E having a beam diameter of 0.2 to 50 μm by the condenser lens 5 is condensed on the sample solution S, thereby forming a thermal lens (not shown). The probe light P having a beam diameter of 0.2 to 50 μm by the condensing lens 5 is condensed on the thermal lens and diverged or condensed by the thermal lens effect.
Only the excitation light E is removed from the excitation light E and the probe light P transmitted through the sample cell 6 by the excitation light cut filter 7, and only the probe light P transmitted through the thermal lens is received by the optical fiber 8. Then, the probe light P is guided to the detecting means 9 by the optical fiber 8, and its divergence or light concentration is measured.
[0022]
When the sample solution S is stored in the sample cell 6 and when the sample solution S is not stored, the measurement is performed, and the difference between the detection values of the detection means 9 may be used as the thermal lens signal. Usually, this thermal lens signal is proportional to the degree of thermal lens, that is, the concentration of the sample solution S.
Here, the respective components of such a thermal lens spectroscopic analyzer will be described.
[0023]
The type of laser used as the laser light emitting means 1 as a light source of the excitation light E is not particularly limited, and a gas laser, a solid-state laser, or the like can be used without any problem, but a semiconductor laser is preferable because it is inexpensive. . However, when a semiconductor laser is used, if the reflected light from each optical component again enters the light source of the excitation light E, it becomes noise due to a change in output, so that high-frequency superposition is applied to the semiconductor laser or a polarization dependent beam splitter and It is desirable to incorporate an optical isolator in combination with a quarter-wave plate. It should be noted that a light emitting diode can be used as a light source of the excitation light E, although it is not a laser, if sufficient sensitivity can be realized in the thermal lens measurement.
[0024]
Further, the type of laser used as the laser light emitting means 2 as a light source of the probe light P is not particularly limited, and a laser similar to the laser light emitting means 1 is used as long as the excitation light E has a different wavelength. be able to. Further, a light emitting diode can be used as a light source of the probe light P.
Further, the reflecting plate 3 guides the probe light P to the beam splitter 4, and can be used without any problem as long as it has a sufficient reflectance at the wavelength of the probe light P. However, it is desirable that the reflectance is close to 100%.
[0025]
Further, the beam splitter 4 is for making the excitation light E and the probe light P coaxial, and has a sufficiently high reflectance for the probe light P and a sufficiently high transmittance for the excitation light E. I just need. However, it is preferable to have a reflectance close to 100% for the probe light P and a transmittance close to 100% for the excitation light E. For example, there are those utilizing the fact that the wavelengths of the excitation light and the probe light are different, and those utilizing the fact that the polarization planes of the excitation light and the probe light are different.
[0026]
Further, the condenser lens 5 focuses the excitation light E on the sample solution S stored in the sample cell 6 and focuses the probe light P on a thermal lens generated in the sample solution S by the excitation light E. Things. The excitation light E is focused on the sample solution S to form a thermal lens, and the probe light P transmitted coaxially there is diverged or focused by the thermal lens effect. It is generally known that the sensitivity of the thermal lens signal increases as the beam diameter at the focusing position decreases, and therefore it is desirable that the numerical aperture of the focusing lens 5 be high. In the present embodiment, the beam diameters of the excitation light E and the probe light P are 0.2 to 50 μm at the focusing position.
[0027]
Further, the sample cell 6 is for storing a sample solution S to be measured. The material of the sample cell 6 is not particularly limited as long as it is transparent to the excitation light E and the probe light P, but it is desirable that the transmittance of the excitation light E and the probe light P be as high as possible. For example, resin materials such as polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), and cycloolefin-based resin, and glass are exemplified. Although the shape of the sample cell 6 is not particularly limited, it is preferable that a flat surface exists at a position where the excitation light E and the probe light P enter and transmit.
[0028]
Further, as the excitation light cut filter 7, any filter that can sufficiently remove the excitation light E can be used without any problem, but a filter having an optical density of 5 or more is preferable. For example, a color glass filter, an interference filter and the like can be mentioned. In the present embodiment, the excitation light cut filter 7 is integrated with the optical fiber 8, but may be separate.
[0029]
Further, the type of the optical fiber 8 is not particularly limited, and an SI (Step Index) type, a GI (Graded Index) type, or the like can be used. The waveguide mode may be either a single mode or a multimode. However, when the bending tolerance is required, the multi-mode is preferable because the tolerance is high. The material of the optical fiber 8 is not particularly limited, and any of resin, glass, and the like can be used without any problem. Considering that the cost can be reduced, a multi-mode waveguide type plastic optical fiber is most preferable.
[0030]
The type of the detection means 9 is not particularly limited as long as it has sufficient sensitivity to the probe light P, and examples thereof include a photodiode. In the present embodiment, the detection means 9 is integrated with the optical fiber 8, but may be separate.
(Example)
The measurement using the thermal lens spectrometer according to the present invention will be described in more detail with reference to examples. FIG. 2 is a configuration diagram illustrating the configuration of the thermal lens spectrometer used in the present embodiment. In this embodiment, several kinds of self-made optical components are used, but it is a matter of course that a commercially available optical component having similar characteristics may be used.
[0031]
As the excitation light source 21, a semiconductor laser light emitting device (LT051PS, manufactured by Sharp Corporation) having a wavelength of 635 nm and a rated output of 30 mW was used. As the light source 22 for the probe light, a semiconductor laser light emitting device (ML60114R, manufactured by Mitsubishi Electric Corporation) having a wavelength of 780 nm and a rated output of 50 mW was used. These semiconductor lasers can be controlled in output and current by using a commercially available LD driver (ALP-6323CA, manufactured by Asahi Data Systems) not shown.
[0032]
The LD driver is connected to a personal computer via a PCI card (NIPCI 6025E, manufactured by National Instruments), also not shown, and the output, current, and modulation frequency of the semiconductor laser light emitting device can be adjusted by the personal computer. ing. Further, the modulation frequency of the excitation light can be from 0 to 100 kHz. Furthermore, a high frequency of 350 MHz was superimposed on both the excitation light and the probe light to reduce the influence of noise generated by the return light.
[0033]
As the collimator lens 23 for the excitation light, a self-made lens having a numerical aperture of 0.34 and a focal length of 8 mm was used. As the probe light collimator lens 24, a self-made lens having a numerical aperture of 0.39 and a focal length of 7 mm was used. The probe light collimator lens 24 was attached to a not-shown micrometer head (MHT3-5, manufactured by Mitutoyo Corporation) so that it could be displaced in the optical axis direction at a resolution of the order of micrometers. Note that the method of displacement is not limited to this example.
[0034]
Further, as the excitation light prism 25 and the probe light prism 26, two self-made prisms whose inclined surfaces are opposed to each other were used. Note that the angle between the two prisms for the excitation light prism 25 was adjusted so that the enlargement ratio became three times. The angle between the two prisms for the probe light prism 26 was adjusted so that the magnification was 2.6 times.
[0035]
Furthermore, a self-made polarization dependent beam splitter having a transmittance of 100% for p-polarized light and a reflectance of 100% for s-polarized light was used as the beam splitter 27 for coaxializing the excitation light and the probe light. . In this case, since the excitation light is s-polarized and the probe light is p-polarized, the power loss in the beam splitter 27 is almost zero.
[0036]
Furthermore, a self-made lens having a numerical aperture of 0.2 and a focal length of 8 mm was used as the condenser lens 29 for condensing the excitation light and the probe light to a beam diameter of 0.2 to 50 μm. The beam diameters of the excitation light and the probe light were analyzed using a beam analyzer (not shown) (beam aligner 13SKP001SA, manufactured by Meles Griot Co., Ltd.). In order to guide the excitation light and the probe light having passed through the beam splitter 27 to the condenser lens 29, a self-made reflector prism 28 for refracting the two lights by 90 ° was used.
[0037]
Further, as the sample cell 30, a glass cell (AB20, manufactured by GL Sciences Inc.) having an optical path length of 50 μm was used.
Next, the optical system of the light receiving section will be described.
The optical fiber 41 is a self-made optical fiber assembly using a plastic optical fiber (SH2001, manufactured by Mitsubishi Rayon Co., Ltd.) having a core diameter of 500 μm. At both ends of the optical fiber 41, the end facing the sample cell 30 is provided with an excitation light cut filter (not shown) for sufficiently removing the excitation light, and the other end is provided with an SMA connector (not shown). Z) is attached.
[0038]
This SMA connector is connected to a not-shown photosensor amplifier (C6386, manufactured by Hamamatsu Photonics KK), which is a detecting means, and the probe light received by the optical fiber 41 is photoelectrically converted by the photosensor amplifier to generate an electric signal ( Voltage signal). The converted voltage signal is guided to a low noise preamplifier (LI-75A, manufactured by NF Circuit Block) with a gain of 100 times (not shown), and further a two-phase lock-in amplifier (5610B, NF Circuit Block Company) not shown. ) To extract only the signal synchronized with the modulation frequency of the excitation light, which is taken as the thermal lens signal value (output of the lock-in amplifier).
[0039]
This lock-in amplifier is connected to a connector (CB-50LP, manufactured by National Instruments Co., Ltd.) via a BNC cable, and the output from the connector is connected to a notebook computer by a data acquisition card (DAQCARD-700, manufactured by National Instruments Co., Ltd.). It is taken in. The thermal lens signal value taken into the notebook personal computer is displayed on the display screen of the notebook personal computer by software (LABVIEW 5.0, manufactured by National Instruments), and the thermal lens signal value and the temporal change of the thermal lens signal value are recorded. (Neither is shown).
[0040]
Further, as a stage (not shown) on which the sample cell 30 is mounted, an automatic positioning stage (MINI-60X MINI-5P, manufactured by Sigma Koki Co., Ltd.) capable of alignment in the optical axis direction with a resolution of 1 μm was used. . The inclination of the sample cell 30 with respect to the optical axis can be adjusted with a resolution of 0.1 ° by a micrometer (not shown).
[0041]
(Comparative example)
A comparative example of the thermal lens spectrometer according to the present invention will be described with reference to FIG. In this thermal lens spectroscopic analyzer, the optical system of the light receiving section is constituted by a lens.
As the excitation light source 121, a semiconductor laser light-emitting device (LT051PS, manufactured by Sharp Corporation) having a wavelength of 635 nm and a rated output of 30 mW was used. A semiconductor laser light emitting device (ML60114R, manufactured by Mitsubishi Electric Corporation) having a wavelength of 780 nm and a rated output of 50 mW was used as the light source 122 of the probe light. These semiconductor lasers can be controlled in output and current by using a commercially available LD driver (ALP-6323CA, manufactured by Asahi Data Systems) not shown.
[0042]
The LD driver is connected to a personal computer via a PCI card (NIPCI 6025E, manufactured by National Instruments), also not shown, and the output, current, and modulation frequency of the semiconductor laser light emitting device can be adjusted by the personal computer. ing. Further, the modulation frequency of the excitation light can be from 0 to 100 kHz. Furthermore, a high frequency of 350 MHz was superimposed on both the excitation light and the probe light to reduce the influence of noise generated by the return light.
[0043]
As the collimator lens 123 for the excitation light, a self-made lens having a numerical aperture of 0.34 and a focal length of 8 mm was used. A self-made lens having a numerical aperture of 0.39 and a focal length of 7 mm was used as the collimator lens 124 for probe light. The probe light collimator lens 124 was attached to a micrometer head (MHT3-5, manufactured by Mitutoyo Corporation), not shown, so that it could be displaced in the optical axis direction with a resolution on the order of micrometer.
[0044]
Further, as the excitation light prism 125 and the probe light prism 126, two self-made prisms whose inclined surfaces are opposed to each other were used. The angle between the two prisms for the excitation light prism 125 was adjusted so that the magnification was three times. Further, the angle between the two prisms for the probe light prism 126 was adjusted such that the magnification ratio became 2.6 times.
[0045]
Further, a self-made polarization dependent beam splitter having a transmittance of 100% for p-polarized light and a reflectance of 100% for s-polarized light was used as the beam splitter 127 for coaxializing the excitation light and the probe light. . In this case, since the excitation light is s-polarized light and the probe light is p-polarized, the power loss in the beam splitter 127 is almost zero.
[0046]
Further, a self-made lens having a numerical aperture of 0.2 and a focal length of 8 mm was used as the condenser lens 129 for condensing the excitation light and the probe light to a beam diameter of 0.2 to 50 μm. The beam diameters of the excitation light and the probe light were analyzed using a beam analyzer (not shown) (beam aligner 13SKP001SA, manufactured by Meles Griot Co., Ltd.). In order to guide the excitation light and the probe light having passed through the beam splitter 127 to the condenser lens 129, a self-made reflector prism 128 for refracting both lights by 90 ° was used.
[0047]
Further, as the sample cell 130, a glass cell (AB20, manufactured by GL Sciences Inc.) having an optical path length of 50 μm was used.
Next, the optical system of the light receiving section will be described.
The same lens as the condenser lens 129 was used as the light receiving lens 131 in order to convert the excitation light and the probe light transmitted through the sample cell 130 into parallel light. It should be noted that there is no problem if the numerical aperture of the light receiving lens 131 is larger than the numerical aperture of the condenser lens 129. Further, a laser line interference filter (03FIL056, manufactured by Meles Griot Co., Ltd.) having a center wavelength of 780 nm and a half width of 20 nm was used as the filter 132 for cutting the excitation light.
[0048]
The probe light transmitted through the filter 132 is transmitted through the pinhole 133 only at the central portion, is collected by the lens 134 (01LPX005, manufactured by Meles Griot Co., Ltd.) having a focal length of 10 mm, and is condensed on the detecting means 135 and converted into an electric signal. . As the detecting means 135, a four-division photodiode (S6344, manufactured by Hamamatsu Photonics KK) was used. In this comparative example, the sum of the electric signals of the four-division photodiode was calculated, and the signal was used as the output from the detection means 135. It is not always necessary to use a four-division photodiode for the detection means 135, and a non-division photodiode does not matter.
[0049]
The output from the four-division photodiode was converted from current to voltage by a home-built circuit. The conversion ratio from current to voltage was 1000 times. The current-to-voltage conversion circuit may be a commercially available product provided that the conversion magnification is 1000 times.
Further, the converted voltage signal is guided to a low-noise preamplifier (LI-75A, manufactured by NF Circuit Block Co., Ltd.) with a gain of 100 times (not shown), and further a two-phase lock-in amplifier (5610B, NF circuit) not shown. (Made by Brock Co., Ltd.), and only an electric signal synchronized with the modulation frequency of the excitation light is extracted.
[0050]
This lock-in amplifier is connected to a connector (CB-50LP, manufactured by National Instruments Co., Ltd.) via a BNC cable, and the output from the connector is connected to a notebook computer by a data acquisition card (DAQCARD 700, manufactured by National Instruments Co., Ltd.). It is captured. The thermal lens signal value taken into the notebook personal computer is displayed on the display screen of the notebook personal computer by software (LABVIEW 5.0, manufactured by National Instruments), and the thermal lens signal value and the temporal change of the thermal lens signal value are recorded. (Neither is shown).
[0051]
Further, as a stage (not shown) on which the sample cell 130 is mounted, an automatic positioning stage (MINI-60X MINI-5P, manufactured by Sigma Koki Co., Ltd.) capable of performing alignment in the optical axis direction with a resolution of 1 μm was used. . The inclination of the sample cell 130 with respect to the optical axis can be adjusted with a resolution of 0.1 ° by a micrometer (not shown).
[0052]
(Example of analysis)
The xylene cyanol aqueous solution having a concentration of 5 μM was analyzed using the thermal lens spectrometers of the above-described example (optical fiber light receiving system) and comparative example (lens light receiving system). At that time, the thermal lens signal was measured by variously changing the angle (tilt of the sample cell) between the sample cell and the optical axis of the probe light in the range of -1 ° to + 1 °. The beam diameter at the position where the excitation light is focused is 3.7 μm, and the beam diameter at the position where the probe light is focused is 4.5 μm.
[0053]
The measurement result of the thermal lens signal is shown in the graph of FIG. The numerical value on the vertical axis of this graph is the ratio between the thermal lens signal value when the tilt of the sample cell is at a predetermined angle and the thermal lens signal value when the tilt of the sample cell is 0 °. When the thermal lens spectrometer of the comparative example was used, the thermal lens signal value changed as the inclination of the sample cell increased, and an error of about 20% occurred when the inclination of the sample cell was + 1 °. On the other hand, when the thermal lens spectrometer of the example was used, the error was within 1%.
[0054]
Therefore, according to the thermal lens spectrometer of the embodiment, even if a tilt of the sample cell occurs when the sample cell is replaced, high-precision analysis is possible, and high accuracy of usually 1% or less is required. It can be applied to medical diagnosis, POC analysis such as environmental analysis, and the like.
The reason for such a difference is presumed as follows. When light is received by a lens, the optical axis of the probe light shifts on the lens surface when the sample cell is tilted. Then, when the probe light is guided to the stop by the light receiving lens, the shift is amplified by the light receiving lens itself, so that the shift in the stop becomes large, and the thermal lens signal value greatly changes. On the other hand, when light is received by the optical fiber, the shift is not amplified as described above, and there is only the influence of the shift in the core (corresponding to the diaphragm) of the optical fiber. Seem.
[0055]
【The invention's effect】
As described above, the thermal lens spectroscopic analyzer of the present invention is small and can analyze a sample with high accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one embodiment of a thermal lens spectroscopic analyzer of the present invention.
FIG. 2 is a configuration diagram illustrating a configuration of a thermal lens spectrometer according to an embodiment.
FIG. 3 is a graph showing a correlation between a tilt of a sample cell and an error of a thermal lens signal value.
FIG. 4 is a configuration diagram illustrating a configuration of a thermal lens spectrometer according to a comparative example.
[Explanation of symbols]
1 Laser emitting means
2 Laser emission means
5 Condensing lens
6. Sample cell
8 Optical fiber
9 Detection means
E Excitation light
P probe light
S sample solution
21 Excitation light source
22 Probe light source
29 Condensing lens
30 sample cell
41 Optical fiber

Claims (4)

A thermal lens spectroscopic analyzer that analyzes the sample based on a change in the probe light caused by the thermal lens, wherein the probe light is incident on the thermal lens generated in the sample by the incidence of the excitation light,
A condenser lens for condensing the excitation light incident on the sample and the probe light incident on the thermal lens to a beam diameter of 0.2 to 50 μm, a sample cell containing the sample, the thermal lens, An optical fiber for receiving the probe light transmitted through the sample cell and guiding the probe light to detection means for detecting the probe light. 2. The thermal lens spectroscopic analyzer according to claim 1, wherein the light source of the excitation light is constituted by a semiconductor laser light emitting means, and the light source of the probe light is constituted by another semiconductor laser light emitting means. The thermal lens spectrometer according to claim 1, wherein the core diameter of the optical fiber is 500 to 2000 μm. The thermal lens spectrometer according to any one of claims 1 to 3, wherein the sample cell is made of a resin.

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