JP4116979B2 - Photothermal conversion measuring apparatus and method - Google Patents

Description

  The present invention is a photothermal conversion measuring device that is used when analyzing a substance contained in a sample, and that measures a change in the characteristics of a sample based on a change in refractive index generated in the sample due to a photothermal effect when the sample is irradiated with excitation light, and its It is about the method.

In the analysis of substances contained in various samples, improvement of analysis sensitivity is important in order to reduce the amount of reagents, simplify the sample concentration process, increase the efficiency of analysis, and reduce costs.
By the way, when the sample is irradiated with excitation light, the irradiated portion generates heat by absorbing the excitation light. This is called the photothermal effect, and measuring this heat generation is called photothermal conversion measurement.
Conventionally, as a high-sensitivity analysis method of a sample by this photothermal conversion measurement, there is a method using the thermal lens effect formed on the sample by the photothermal effect (hereinafter referred to as the thermal lens method), and an analysis device (photothermal conversion) by the thermal lens method (A spectroscopic analyzer) is known (for example, refer to Patent Document 1).
FIG. 6 is a configuration diagram of a sample analyzer using the thermal lens method disclosed in Patent Document 1 (see FIG. 1 of Patent Document 1). As shown in FIG. 6, the excitation light A from the excitation light source 10 is converted into intermittent light (that is, intensity modulated periodically) by the chopper 11, and the beam expander 12, position control mirrors 30, 31, 32, The sample 40 is irradiated through the lens 34 and the microscope 35. As a result, the sample 40 absorbs the excitation light A and generates heat, and its refractive index changes.
The detection light B from the detection light source 20 becomes a coaxial path with the excitation light A via the beam expander 22 and is reflected by the position control mirrors 31 and 32, and further irradiated to the sample 40 via the lens 34 and the microscope 35. The Then, the detection light C that has passed through the sample 40 is condensed by the condenser lens 50, passes through the opening 51A (pinhole), is received by the detector 53, and its light intensity is detected. Here, since the condensing state of the detection light B in the sample 40 changes due to the change in the refractive index of the sample 40, the intensity of the detection light C obtained through the pinhole 51A is a change in the refractive index of the sample 40 ( That is, it varies according to the amount of light absorption according to the amount of substance contained in the sample. By measuring the intensity change of the detection light C, the change in the refractive index of the sample 40 can be measured, and the amount of the substance contained in the sample 40 can be evaluated based on the measurement result.
Japanese Patent Laid-Open No. 10-232210

In the analysis of the sample by the thermal lens method, the refractive index change due to the heat generation of the sample is detected by the change in the light intensity (detection signal intensity) due to the change in the focusing state of the measurement light (detection light). The change in intensity (detection signal intensity) depends not only on the change in the refractive index of the sample, but also on the light receiving position of the detector 53 (photoelectric conversion means), the intensity of measurement light, its intensity distribution, and the like. For this reason, there is a problem that it is difficult to analyze the sample (measure the refractive index change) with good reproducibility (stable).
If the measurement sensitivity can be increased and a strong detection signal can be received, the influence of factors other than the change in the refractive index of the sample such as the light receiving position of the detector 53 becomes relatively small, and this problem can be solved. However, in the invention described in Patent Document 1, in order to increase the measurement sensitivity, the intensity of the excitation light A is increased, or the diameter of the pinhole 51A through which the measurement light C after passing through the sample is reduced. Increasing the intensity of the excitation light A causes an increase in power consumption and cost, and reducing the diameter of the pinhole 51A reduces the S / N ratio due to a decrease in the amount of light received by the detector 53. As a result, there is a problem that the measurement time is prolonged due to the small diameter of the measurement area. Furthermore, in general, the sample is measured in a cell (container) such as glass, and at this time, the excitation light is irradiated to the sample through the cell. When the excitation light is absorbed in the cell, a temperature change occurs in the cell itself due to irradiation of the excitation light, so that the refractive index of the cell changes. Even with this change in the refractive index of the cell, the measurement light passing through the cell is deflected, which may affect the analysis result. In particular, when the excitation light absorption by the sample is very small, there is a problem that the measurement accuracy of the temperature change of the sample is deteriorated due to the strong influence of the temperature change of the cell.
The present invention has been made in view of the above circumstances, and the object of the present invention is to be able to stably and accurately measure changes in characteristics due to the photothermal effect of a sample, and to increase power consumption and cost. An object of the present invention is to provide a photothermal conversion measuring apparatus and method capable of easily measuring with high sensitivity while preventing a decrease in S / N ratio and a long measurement time.

In order to achieve the above object, the present invention provides an excitation light irradiation means for irradiating excitation light for exciting a measurement region of a sample, and measurement light irradiation for irradiating measurement light to the measurement region of the sample irradiated with the excitation light. A photothermal conversion measuring apparatus for measuring a change in characteristics of the sample caused by a photothermal change of the sample irradiated with the excitation light based on a change in the measurement light irradiated on the measurement area of the sample. The excitation light irradiating means generates an interference fringe in the measurement area of the sample by the intersection of two or more coherent excitation laser beams. In the measurement area where the interference fringe is generated by the excitation light irradiating means, By making the measurement light emitted from the measurement light irradiation means incident , the optical relationship between the excitation light emitted from the excitation light irradiation means and the measurement light emitted from the measurement light irradiation means is applied to the sample. Light The reflected light or diffracted light satisfying the Bragg condition is generated from the measured light, and the reflected light or diffracted light satisfying the Bragg condition generated from the measured light irradiated on the sample is measured. It is configured as a photothermal conversion measuring device characterized by detecting from the light intensity of light.
Thus, the optical relationship between the excitation light and the measurement light for generating reflected light or diffracted light that satisfies the Bragg condition can be set. The Bragg intensity of satisfying the reflected or diffracted light is very strong, in order to detect a characteristic change in the sample from the intensity of the reflected light or diffracted light, to obtain a better detection result sensitive and reproducible Is possible.

Furthermore, if the excitation light is light whose intensity is periodically modulated and the intensity change of the reflected light or diffracted light of the measurement light is measured for the same period component as the intensity modulation period of the excitation light, Since the characteristics of the measurement part of the sample change at the same period as the intensity modulation period, it is possible to measure only the characteristic change of the sample due to the intensity change of the measurement light by removing the influence of noise that does not have the same periodic component. This improves the S / N ratio for detecting the characteristic change.

The present invention also includes excitation light irradiating means for irradiating excitation light for exciting the measurement area of the sample, and measurement light irradiating means for irradiating measurement light to the measurement area of the sample irradiated with the excitation light. In the photothermal conversion measuring apparatus for measuring the change in the characteristics of the sample caused by the photothermal change of the sample irradiated with the excitation light based on the change in the measurement light irradiated on the measurement area of the sample, the excitation light irradiation Reflecting light or diffracted light that satisfies the Bragg condition is generated from the measurement light irradiated to the sample with respect to the optical relationship between the excitation light emitted from the means and the measurement light emitted from the measurement light irradiation means. And detecting the characteristic change of the sample from the light intensity of reflected light or diffracted light that satisfies the Bragg condition generated from the measurement light irradiated on the sample. A modulated light configured as photothermal conversion measuring instrument, characterized in that the change in intensity of reflected light or diffracted light of the measurement light formed by the measurement for the intensity modulation period and the periodic component of the excitation light.
As a result, the characteristic of the measurement part of the sample changes in the same period as the intensity modulation period, so that the influence of noise that does not have the same periodic component is removed, and only the characteristic change of the sample due to the intensity change of the measurement light is removed. Can be measured, and the S / N ratio of the characteristic change detection is improved.

Further, the present invention may be understood as a photothermal conversion measurement method performed by the photothermal conversion measurement device.
That is, by irradiating the measurement area of the sample irradiated with the excitation light and irradiating the measurement area of the sample irradiated with the excitation light, it is caused by the photothermal change of the sample irradiated with the excitation light. In the photothermal conversion measurement method for measuring the characteristic change of the sample based on the change of the measurement light irradiated on the measurement area of the sample, the excitation light is two or more coherent excitation laser beams. to generate interference fringes in the measurement region of the sample by the intersection of more coherent excitation laser light, by entering the measurement light to the measurement zone which the interference fringes are generated, before Ki励 Okoshiko before Symbol the optical relationship between measured constant light Prefecture, with the Bragg condition is satisfied reflected light or diffracted light from the measuring light applied to the sample is set to occur, which is irradiated with the characteristic change of said sample to said sample said Measurement A photothermal conversion measuring method characterized by detecting the light intensity of the Bragg condition is satisfied reflected light or diffracted light generated from light.

As described above, according to the present invention, extremely strong reflected light or diffracted light of measurement light can be obtained, and a minute change in the refractive index of the sample can be detected with high sensitivity from the intensity change of the reflected light or diffracted light. In addition, the influence on the measurement result due to factors other than the change in the characteristics of the sample becomes relatively small, and the sample can be analyzed with good reproducibility.
Further, since the reflected light or diffracted light is generated from the inside of the sample, it is possible to measure the characteristic change of the sample without being influenced by the characteristic change of the cell due to the excitation light, and it is possible to measure with higher accuracy.

Hereinafter, embodiments and examples of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. It should be noted that the following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention.
Here, FIG. 1 is a schematic configuration diagram of a photothermal conversion measuring apparatus according to the first embodiment of the present invention, FIG. 2 is a schematic diagram showing a structure of interference fringes, and FIG. 3 is a Bragg in the first embodiment. FIG. 4 is a schematic diagram illustrating a photothermal conversion measuring device according to the second embodiment of the present invention, and FIG. 5 is a Bragg in the second embodiment. It is the conceptual diagram which demonstrated the case where conditions were satisfied using the vector.

<Embodiment 1> First, the schematic structure of the photothermal conversion measuring apparatus which concerns on the 1st Embodiment of this invention is demonstrated using the schematic block diagram of FIG.
The beam diameter of the excitation light (for example, laser (YAG multiple wave) having a wavelength (λ ₀ ) of 523 nm and an output of 100 mW) output from a predetermined excitation light source 1 is adjusted by the lens system 3. Thereafter, the laser beam is reflected by the mirror 4 and then divided by the half mirror 5. The bisected excitation lights A and B are reflected by mirrors 6 and 7, respectively, pass through a container (cell) 8, and are irradiated onto a sample 9 in the cell. Here, when the installation angles of the mirrors 6 and 7 are adjusted and the excitation light A and B intersect within the sample 9, the excitation light A and B interfere with each other at the intersection, Interference fringes as shown in FIG. 1 are generated at the excitation light intersection in the sample 9.
The sample 9 irradiated with the excitation light A and B absorbs the excitation light A and B and generates heat, and the refractive index of the sample 9 changes (photothermal effect) due to the temperature change (rise). The size varies spatially according to the interference fringes.
On the other hand, the measurement light (for example, a He—Ne laser having a wavelength (λ) of 633 nm and an output of 1 mW) output from the laser light source 10 that outputs the measurement light passes through the beam splitter 11 and is excited with the interference fringes generated. The light is irradiated to the intersection (measurement unit) of light A and B. When the wave number vector of incident light with respect to the sample of the measurement light is ki and the wave number vector of reflected light or diffracted light from the sample is kr, ki is a vector having the same direction as the traveling direction of the measurement light and a magnitude of 2π / λ. , Kr are defined as vectors having the same direction as the traveling direction of the reflected light or diffracted light of the measuring light and the same magnitude of 2π / λ.
Next, the structure of the interference fringes will be described with reference to FIG.
As shown in FIGS. 2A to 2C, when the excitation light A and the excitation light B are crossed at an intersection angle θ, interference fringes are generated in a direction parallel to the bisector L of the intersection angle θ. Is done. Here, the crossing angle means the smaller one of the angles formed by two intersecting excitation lights. In the example shown in FIG. 2A, θ = θ _A + θ _B , FIGS. 2B and 2C. In the example shown in FIG. 5, θ = 180 ° − (θ _A + θ _B ) (where θ _A and θ _B are incident angles of the excitation light A and B with respect to the measurement surface of the sample 9). Further, when θ = 0 ° or θ = 90 °, no interference fringes are generated, and therefore 0 ° <θ <90 °.
As shown in FIG. 2A, when θ = θ _A + θ _B and θ _A = θ _B , the interference fringes are generated horizontally with respect to the measurement surface direction of the sample 9. This corresponds to the case of the first embodiment of the present invention shown in FIG.
As shown in FIG. 2B, θ = 180 ° − (θ _A + θ _B ), and when θ _A = θ _B , the interference fringes are generated perpendicularly to the measurement surface direction of the sample 9, This corresponds to the case of a second embodiment of the present invention described later shown in FIG.
Further, as shown in FIG. 2C, when θ _A ≠ θ _B , the interference fringes are generated obliquely with respect to the measurement surface direction of the sample 9.
The interval Λ of the interference fringes is expressed by the following equation.
Λ = λ ₀ / (2n · sin θ) (1)
Where λ ₀ is the wavelength of the excitation light, n is the refractive index of the sample, and θ is the crossing angle.
The interference fringe lattice vector K is a vector defined by a magnitude of 2π / Λ in the direction perpendicular to the interference fringe direction. When this grating vector K satisfies the relationship of the following equation (2) between the incident light wave number vector ki and the reflected light (diffracted light) wave vector kr, the m-order Bragg condition is satisfied, and measurement is performed as described later. Strong reflected light or diffracted light is generated.
mK = ki-kr (2)
The intensity I of the reflected or diffracted light that satisfies the mth order Bragg condition of the measurement light is expressed by the following equation.
I = P · J _m ² (2πΔn · T / λ) (3)
Where P is the incident light (measurement light) intensity, J _m is the mth order Bessel function, Δn is the refractive index change, T is the length of the periodic structure (= Λ × number of interference fringes), and λ is the incident light (measurement light) ).
From this equation (3), it is understood that the refractive index change Δn (an example of characteristic change) of the sample 9 can be measured by measuring the intensity I of the reflected light or diffracted light that satisfies the Bragg condition of the measurement light.

Here, the point that the intensity I of the reflected light or diffracted light satisfying the Bragg condition of the measurement light is higher than the intensity of the reflected light not satisfying the Bragg condition will be described using the equation (3).
For example, the incident light (measurement light) intensity P = 1, refractive index change Δn = 1E−6, the length of the periodic structure T = 100 μm, the incident light (measurement light) wavelength λ = 523 nm, and the primary Bragg condition (m In the case of = 1), if this is substituted into the equation (3), I = 3.6E-7.
On the other hand, the reflectance Rs with respect to the refractive index change of the reflected light that does not satisfy the Bragg condition follows Snell's law.
Rs = {Δn / (2n + Δn)} ² (4)
It is represented by
Now, assuming that the refractive index change Δn = 1E-6 and the refractive index n is 1.3 under the same conditions as above, Rs = 2.5E-13 is obtained from the equation (4).
Since the incident light (measurement light) intensity P = 1, the intensity I ′ of the reflected light that does not satisfy the Bragg condition is I ′ = 2.5E-13.
As described above, it can be seen that the intensity I ′ of the reflected light that does not satisfy the Bragg condition is as low as about 1E-6 times the intensity I of the reflected or diffracted light that satisfies the Bragg condition. That is, it can be seen that the relationship of I ′ << I holds, and the intensity of reflected light or diffracted light that satisfies the Bragg condition is extremely higher than the intensity of reflected light that does not satisfy the Bragg condition.

In the case of the embodiment shown in FIG. 1, since the incident angles θ _A and θ _B of the excitation lights A and B with respect to the sample 9 are equal, the interference fringes are generated in the horizontal direction with respect to the measurement surface of the sample 9. Accordingly, the direction of the lattice vector K is perpendicular to the measurement surface of the sample as shown in FIG. 3A, and the crossing angle θ is expressed by θ = θ _A + θ _B, which is expressed as (1 By substituting into the equation (1), Λ is determined, and the magnitude 2π / Λ of the vector K is also determined, and the lattice vector K is determined.
The measurement light applied to the measurement part of the sample 9 having such interference fringes is generated so that reflected light or diffracted light that satisfies the Bragg condition is generated from the measurement light applied to the sample 9, that is, The optical relationship with the excitation light is set so as to satisfy the expression (2).
As shown in FIG. 3A, in the case of the first embodiment, kr = −ki, and the measurement light is regularly reflected. Therefore, | K | = 2 | ki |, for example, when the refractive index n = 1.33 and m = 1, the interference fringe interval Λ is about 240 nm if the crossing angle is set to about 55 °. By setting the excitation light wavelength λ ₀ = 523 nm and the measurement light wavelength λ = 633 nm, the expression (2) (primary Bragg condition) is satisfied.
As shown in FIG. 1, the reflected light satisfying this Bragg condition is reflected by the beam splitter 11, and the intensity of the reflected light is converted into an electric signal by the photodetector 12, and the electric signal is input to the signal processing 13. Is done. In the signal processing 13, the refractive index change Δn is measured from this intensity signal.
Here, the reflected light that satisfies the Bragg condition that is received by the photodetector 12 is light having an extremely strong intensity I as described above. Even if the refractive index change Δn is very small in the equation (3), this is reflected. It can measure with high sensitivity. Further, since the light intensity is high, the influence on the measurement result due to factors other than the photothermal effect of the sample 9 (for example, when the installation position of the photodetector 12 is shifted) becomes relatively small, and the reproducibility is good. Measurement can be performed.
Further, since this reflected light is generated mainly from the intersection of the excitation light in which the periodic refractive index change occurs, it is affected by the characteristic change of the cell 8 due to the sample container (cell) 8 absorbing the excitation light. Therefore, it is possible to measure the characteristic change of the sample 9, and the measurement accuracy is improved.

<Embodiment 2> Next, a schematic configuration of a photothermal conversion measuring apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG.
The beam diameter of the excitation light output from the predetermined excitation light reduction 21 is adjusted by the lens system 3 and is divided into two by the half mirror 24. Of the bisected excitation light, the excitation light A is reflected by the half mirror 24, and the excitation light B is reflected by the mirror 25, passes through a container (cell) 26, and is irradiated onto a sample 27 in the cell. Here, when the installation angles of the half mirror 24 and the mirror 25 are adjusted and the excitation lights A and B are crossed inside the sample 27, as in the case of Embodiment 1 described above, The interference fringes as shown in FIG. 4 are generated by the interference between the excitation lights A and B.
In the case of the second embodiment, as described above, the intersection angle θ between the pumping lights A and B is 180 ° − (θ _A + θ _B ), and the incident angles θ _A and θ _B are equal. The interference fringes are generated in parallel to the bisector L of the incident angle θ, that is, in the direction perpendicular to the measurement surface of the sample 27 as shown in FIG.
In this case, the interference fringe interval Λ can be obtained by the equation (1).
Further, the optical power of the excitation light and the measurement light is such that the grating vector K, the incident light wave number vector ki of the measurement light, and the diffracted light wave vector kr satisfy the relationship of the expression (2), that is, the relationship shown in FIG. By setting the relationship, strong diffracted light that satisfies the Bragg condition can be obtained.
The diffracted light intensity I at this time is similarly determined by the equation (3), and the refractive index change Δn can be measured by detecting this.
Strong diffracted light that satisfies this Bragg condition is reflected by a mirror 27 set at a predetermined position and guided to a photodetector 28. The intensity of the diffracted light is converted into an electric signal by the photodetector 28, and the electric signal is input to the signal processing 29. In the signal processing 29, the refractive index change Δn is measured from this intensity signal.
Diffracted light that satisfies the Bragg condition that is received by the photodetector 28 is light having an extremely high intensity I, as in the first embodiment, and therefore measurement with good sensitivity and reproducibility is possible. . The same is true in that a highly accurate inspection can be performed without being affected by the characteristic change of the cell 26.

As shown in FIG. 1 or FIG. 4, the excitation light output from the excitation light source 1 or 21 is periodically intensity-modulated by the chopper 2 or 22 (period f). In the signal processing 13 or 29, the excitation light The signal component having the same period as the modulation period f may be detected.
As a result, it is possible to measure the characteristic change of the sample due to the excitation light irradiation while removing the influence of noise having no frequency f component, and the S / N ratio of the measurement is improved.

In the first and second embodiments, the incident angles θ _A and θ _B of the two excitation lights are equal, and thereby interference fringes are generated in the horizontal or vertical direction with respect to the measurement surface of the sample. However, it may be other than this. It is clear from the above formulas (1) and (2) that the incident angles θ _A and θ _B are equal (θ _A = θ _B ) are not an essential requirement for establishing the Bragg condition.
In short, if the optical relationship is set so as to satisfy the expression (2), a strong reflected light or diffracted light satisfying the Bragg condition can be obtained, and the same result can be obtained.
As long as the period length is finite (the number of the interference fringes is finite), the size of the lattice vector K has a finite width. Therefore, the optical relationship described in the above embodiment is not necessarily the only absolute condition, and the optimum irradiation is performed in consideration of the conditions of the equipment components such as the applicable laser conditions and the miniaturization of the optical system. , Light receiving conditions can be set.

Although only the case where interference fringes are generated by causing two excitation lights A and B to interfere with each other is described, interference fringes may be generated by interfering with three or more excitation lights. Even in such a case, it is within the scope of the present invention.
Furthermore, in the above-described embodiment and examples, only the configuration satisfying the primary Bragg condition (m = 1 in the equation (2)) has been described. However, in the high-order Bragg condition (in the equation (2), m > 1) may be satisfied, and such a case is within the scope of the present invention.

  Moreover, it is good also as a structure which converges excitation light and / or measurement light with a lens. Since the intensity density of the excitation light and / or measurement light converged by the lens is improved, the spatial resolution of measurement is increased and the S / N ratio is improved.

The schematic block diagram of the photothermal conversion measuring apparatus which concerns on the 1st Embodiment of this invention. It is the schematic which shows the structure of the interference fringe formed in the cross | intersection part of excitation light, Comprising: (a) is a case where an interference fringe is produced | generated horizontally with respect to the measurement surface of a sample (equivalent to 1st Embodiment). , (B) shows the case where the interference fringes are generated perpendicular to the measurement surface of the sample (corresponding to the second embodiment), and (c) shows that the interference fringes are generated obliquely with respect to the measurement surface of the sample. Show the case. The conceptual diagram which showed the case where the Bragg condition was materialized in the 1st Embodiment of this invention using the vector. The schematic block diagram of the photothermal conversion measuring apparatus which concerns on the 2nd Embodiment of this invention. The conceptual diagram which showed the case where the Bragg condition was materialized in the 2nd Embodiment of this invention using the vector. The schematic block diagram of the conventional photothermal conversion measuring apparatus (photothermal conversion spectroscopy analyzer).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,21 ... Excitation light source 2,22 ... Chopper 3,23 ... Lens 4,6,7,25,27 ... Mirror 5,24 ... Half mirror 8,26 ... Cell 9,27 ... Sample 10 ... Measurement light source 11 ... Beam Splitter 12, 28 ... Photodetector 13, 29 ... Signal processor

Claims (4)

Excitation light irradiation means for irradiating excitation light for exciting the measurement area of the sample, and measurement light irradiation means for irradiating measurement light to the measurement area of the sample irradiated with the excitation light. In a photothermal conversion measuring apparatus for measuring a change in the characteristics of the sample caused by a photothermal change of the measured sample based on a change in the measurement light irradiated to the measurement area of the sample,
The excitation light irradiation means generates interference fringes in the measurement region of the sample by the intersection of two or more coherent excitation laser beams;
By making the measurement light emitted from the measurement light irradiation means enter the measurement area where the interference fringes are generated by the excitation light irradiation means , the excitation light emitted from the excitation light irradiation means and the measurement light irradiation means The optical relationship with the measurement light emitted from the sample is set so that reflected light or diffracted light that satisfies the Bragg condition is generated from the measurement light emitted to the sample,
A photothermal conversion measurement apparatus, wherein a characteristic change of the sample is detected from a light intensity of reflected light or diffracted light that satisfies a Bragg condition generated from the measurement light irradiated on the sample. The excitation light is periodically intensity-modulated light, according to claim 1, changes in the intensity of the reflected light or diffracted light of the measurement light formed by the measurement for the intensity modulation period and the periodic component of the excitation light Photothermal conversion measuring device. Excitation light irradiation means for irradiating excitation light for exciting the measurement area of the sample, and measurement light irradiation means for irradiating measurement light to the measurement area of the sample irradiated with the excitation light. In a photothermal conversion measuring apparatus for measuring a change in the characteristics of the sample caused by a photothermal change of the measured sample based on a change in the measurement light irradiated to the measurement area of the sample,
The optical relationship between the excitation light emitted from the excitation light irradiating means and the measurement light emitted from the measurement light irradiating means indicates that the reflected light or diffracted light satisfying the Bragg condition satisfies the Bragg condition from the measurement light irradiated on the sample. Set it to occur,
A change in characteristics of the sample is detected from the light intensity of reflected or diffracted light that satisfies the Bragg condition generated from the measurement light irradiated on the sample;
The excitation light is light whose intensity is periodically modulated, and is obtained by measuring a change in intensity of reflected light or diffracted light of the measurement light with respect to a component having the same period as the intensity modulation period of the excitation light. Conversion measuring device. The sample generated by photothermal change of the sample irradiated with the excitation light by irradiating the measurement light of the sample irradiated with the excitation light while irradiating the excitation light for exciting the measurement region of the sample In the photothermal conversion measurement method for measuring the change in characteristics of the sample based on the change in the measurement light applied to the measurement area of the sample,
The excitation light is two or more coherent excitation laser beams, and an interference fringe is generated in the measurement region of the sample by the intersection of the two or more coherent excitation laser beams, and the interference fringe is generated. by entering the measurement light pass, before Ki励 optical relationship Okoshiko before Kihaka constant light Prefecture, so that the Bragg condition is satisfied reflected light or diffracted light generated from the measuring light applied to the sample And set
A photothermal conversion measurement method, wherein a change in characteristics of the sample is detected from light intensity of reflected light or diffracted light that satisfies a Bragg condition generated from the measurement light irradiated on the sample.

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