KR101215362B1 - Apparatus and method for detecting photothermal effect - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting a photothermal effect, and more particularly, comprising: a first light source for irradiating probe light toward a measurement object; A second light source to irradiate the excitation light at a predetermined period toward the measurement object; A camera measuring an image of an irradiated area of the measurement object; And an analysis device for analyzing the image signal measured by the camera, and the photothermal effect detection apparatus and method according to the present invention may be generated by the photothermal effect even when it is difficult to access the measurement object or the measurement range is wide. Signals can be detected to analyze internal defects, thermal properties, or changes in concentration of the subject.

Photothermal effect, probe light, excitation light, camera, video display

Description

Apparatus and method for detecting photothermal effect

The present invention relates to an apparatus and method for detecting a photothermal effect, and more particularly, to detect a signal due to the photothermal effect even when it is difficult to access a measurement object or a wide range of measurement to analyze an internal defect, thermal property or concentration change of the measurement object. The present invention relates to an apparatus and method for detecting photothermal effects.

The photothermal effect is based on thermal changes due to the absorption of light, and optoacoustic (optoacoustic or photoacoustic) spectroscopy, a method of representing such effects, is a process in which a pressure wave is generated by a substance absorbing light energy. Say.

Unlike conventional spectroscopy, photoacoustic spectroscopy is a method that has a good detection sensitivity even when applied to a material having low light absorption by directly measuring energy absorbed by the material by interaction between light and the material.

In this case, the detection signal is proportional to the absorption rate absorbed by the sample, and can be applied to the case where the sample is a gas, a solid, or a liquid, and has a great advantage as a non-destructive measurement method that does not require a pretreatment process.

On the other hand, the photoacoustic effect shows a tendency to depend not only on the optical and thermal properties of the sample but also on its geometric structure or elastic properties.

That is, when light is irradiated onto the sample, the photoacoustic signal changes because the absorption or reflection characteristics at that point change depending on the physical properties and geometry.

Therefore, if a defect exists on or inside the analyte, the local heat wave changes, which leads to a change in the photoacoustic signal, thereby detecting the defects, and confirming that any impurities exist at each microscopic point. have.

Photoacoustic methods also enable depth-profiling analysis. First, when the light transmission depth is determined by the change of the wavelength of the temporary light, an optoacoustic signal is generated, and when the irradiation period of the light is changed, the transmission depth of the heat wave is changed. That is, since the thermal diffusion length is dependent on the irradiation period of light, it is possible to analyze the depth image at various frequencies.

This photoacoustic effect has been applied to measuring various samples as a high sensitivity detection method, but there is a problem that the analyte and the detector should be close in the acoustic wave measuring method. This problem can be a disadvantage when the photoacoustic effect is applied throughout the industry.

In addition, conventionally, since the acoustic wave generated by the photoacoustic effect is directly detected by a microphone or an ultrasonic sensor, or the probe light that is reflected back is analyzed by a sensor, it is applied when the target sample is far away or its application range is wide. There was a problem that was difficult to do.

The present invention is to solve the above problems, an object of the present invention is to detect a signal due to the photothermal effect even if the measurement object is difficult to access or a wide range of measurement to change the internal defects, thermal properties or concentration of the measurement object It is to provide an apparatus and method for detecting a photothermal effect that can be analyzed.

In order to achieve the above object,

The present invention includes a first light source for irradiating probe light toward the measurement object; A second light source to irradiate the excitation light at a predetermined period toward the measurement object; A camera measuring an image of probe light formed or passed through the measurement object; And an analysis device for analyzing the image signal measured by the camera.

In addition, the present invention includes a first light source for irradiating probe light toward the measurement object that is a fluid; A second light source for irradiating excitation light at a predetermined period toward the measurement object which is a fluid; A screen to which each light passing through the measurement object which is a fluid is irradiated; A camera measuring an image of probe light formed on the screen; And an analysis device for analyzing the image signal measured by the camera.

In addition, the present invention comprises the steps of (a) irradiating the probe light toward the measurement object; (b) irradiating the excitation light at regular intervals toward the measurement object; And (c) analyzing an image signal by measuring an image of the probe light formed or passed through the measurement object.

In addition, the present invention comprises the steps of (a) irradiating probe light toward the measurement object that is fluid; (b) irradiating excitation light at regular intervals toward a measurement object that is fluid; And (c) analyzing an image signal by measuring an image of a screen irradiated with probe light that has passed through the measurement object, which is a fluid.

As described above, the apparatus and method for detecting photothermal effects according to the present invention detects a signal due to the photothermal effect even when it is difficult to access the measurement object or the measurement range is wide, thereby detecting a change in internal defects, thermal properties, or concentration of the measurement object. Can be analyzed.

Hereinafter, an apparatus and a method for detecting a photothermal effect according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. The accompanying drawings show exemplary forms of the present invention, which are provided to explain the present invention in more detail, and the technical scope of the present invention is not limited thereto.

1 is a block diagram of a photothermal effect detection apparatus according to an embodiment of the present invention, Figure 2 is a block diagram of a photothermal effect detection apparatus according to an embodiment of the present invention when the measurement object is a solid, When the measurement object is a fluid (liquid or gas) is a block diagram of a photothermal effect detection apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the photothermal effect detection apparatus 1 according to an exemplary embodiment of the present invention may include a first light source 3 and a measurement object 6 that irradiate the probe light 8 toward the measurement object 6. And a second light source 2 for irradiating the excitation light 7a, 7b.

At this time, if the probe light 8 irradiated from the first light source 3 is light having straightness, various kinds of light may be used, and it is preferable to select an appropriate light source according to the type of measurement object.

On the other hand, the excitation light (7a, 7b) irradiated from the second light source 2, if the light of the wavelength that can be absorbed by the measurement object, can be used in a variety of types of light, may include a laser.

The photothermal effect detection device 1 also includes a chopper disposed between the second light source 2 and the measurement object 6 to modulate the frequency of the excitation light 7a irradiated from the second light source. do.

In addition, the photothermal effect detection apparatus 1 includes a camera 4 measuring the irradiated area of the measurement object 6 and an analysis device 9 analyzing the image signal measured by the camera.

In this case, the analysis device 9 includes a calculation unit for Fourier transforming the image signal measured from the camera 4 and an image display unit for displaying the result calculated by the calculation unit on the monitor.

Meanwhile, as shown in FIGS. 1 and 2 when the measurement object 6 is a solid, the liquid or gas 6 when the measurement object 6 is a fluid (liquid or gas) as shown in FIG. 3. Each of the light passing through the screen 11 is further included, wherein the camera 4 measures the image of the area irradiated on the screen.

Hereinafter, a process of analyzing information of a measurement object through the photothermal effect detection apparatus 1 configured as described above will be described in detail with reference to FIGS. 1 and 2.

The photothermal effect detection apparatus 1 according to the embodiment of the present invention is based on the photothermal effect, which is a kind of photoacoustic spectroscopy effect.

When the excitation light having a constant brightness modulation frequency f is irradiated to the measurement object at a certain distance by the photothermal effect, a thermal pressure wave corresponding to the f frequency is generated around the sample.

When strong excitation light 7a, 7b that can be absorbed by the measurement object 6 to be analyzed is irradiated from the second light source 2 to the measurement object 6, heat is emitted from the irradiated area of the measurement object 6. This heat is generated to heat around the irradiated area of the measurement object.

At this time, if the irradiation and blocking of the light is repeated with a constant period of the excitation light (7a, 7b) heating and cooling is repeated with a constant period around the irradiated point, the temperature change occurs.

On the other hand, the irradiation and blocking of the excitation light (7a, 7b) to the measurement object 6 is performed by the chopper 5 described above, the irradiation and blocking of the excitation light (7a, 7b) by adjusting the chopper (5) Can be adjusted.

Such a temperature change causes a pressure change and a density change in the peripheral area of the measurement object 6, and a change in refractive index occurs near the irradiation area.

At this time, when the probe light 8 is irradiated from the first light source 3 to the measurement object 6, the size, shape, or location of the probe light 8 is changed by the refractive index changed near the irradiation area of the measurement object 6. Will change.

Since the pressure wave or the refractive index change is periodically generated at the irradiation point of the excitation light 7b or around the measurement object 6, the shape or position change of the probe light 8 also has a periodicity.

The change of the image of the probe light 8 may be obtained by the camera 4, and the analysis of the image change may be performed in real time by an analysis device 9 such as a computer to which the camera 4 is connected to obtain information about the measurement object 6. Get

On the other hand, the periodic image signal of the probe light 8 depends on the pressure wave 10 formed by the irradiation of the excitation light 7b, and the pressure wave 10 changes depending on the concentration or state of the measurement object 6. do.

Therefore, the information about the measurement object 6 may be obtained by changing the image of the probe light 8.

On the other hand, as described above, in the photoacoustic spectroscopy, the gas in this region acts as a kind of acoustic diaphragm by periodically heating the gas layer to which the generated heat is in contact, thereby generating an acoustic signal.

Therefore, acoustic waves determined by the inherent conductivity, heat capacity, and thermal transfer properties (thermal conductivity, thermal diffusivity), etc. of the measurement object are generated. The photoacoustic signal is a very powerful analysis method that can detect not only the concentration of the measurement object but also internal defects of the analysis object. .

Photothermal effect detection device 1 according to an embodiment of the present invention has the advantage of having a very good sensitivity and very simple detection device by the image analysis of the probe light according to this principle, according to the present invention In the case of analyzing the measurement object with the photothermal effect detection device 1, even if the analysis range is very broad or difficult to access, the analysis can be performed simply.

Example 1

An aluminum foil was used as a measurement object, and an argon ion (Ar ion, wavelength 459.9 to 514.5 nm) laser was used as an excitation light for generating a pressure wave to the measurement object, and a helium-neon (He-Ne) laser as a probe light. Was used.

In this case, a CMOS sensor camera with a zoom lens in front was used to observe the probe light formed on the measurement object, and the image obtained from the camera was analyzed using a computer.

The change signal of the image is changed to 3 Hz, which is the irradiation period by the chopper of the argon ion laser, and the frequency is analyzed by Fourier transform of the image signal. Through this, information on the concentration and the internal state of the target sample can be obtained.

4 is a graph showing the degree of image change of the probe light according to the absorption degree of the excitation light in the first embodiment.

The clean aluminum surface reflects most of the excitation light, resulting in less pressure waves, and the red-colored portion is absorbed, causing a change in the image size of the stronger probe light. In addition, blackened areas are analyzed for stronger signals due to higher absorption.

FIG. 5 is a graph illustrating an image change period through Fourier transform in the analysis apparatus of the first embodiment. FIG.

The Fourier transform was used to analyze the image change period of 3 Hz, which is the irradiation period of the excitation light, and the height of the peak provides information about the analysis target.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having various ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention. And additions should be considered to be within the scope of the following claims.

1 is a block diagram of a photothermal effect detection apparatus according to an embodiment of the present invention.

2 is a block diagram of a photothermal effect detection apparatus according to an embodiment of the present invention when the measurement object is a solid.

3 is a block diagram of a photothermal effect detection apparatus according to an embodiment of the present invention when the measurement object is a liquid or a gas.

4 is a graph showing the degree of image change of the probe light according to the degree of absorption of the excitation light in the photothermal effect detection apparatus according to an embodiment of the present invention.

FIG. 5 is a graph showing an image change period through Fourier transform in an analysis device configuring a photothermal effect detection device according to an embodiment of the present invention.

Claims (20)

A first light source irradiating probe light toward the measurement object and emitting straight light; A second light source irradiating excitation light toward a measurement object at regular intervals and emitting a wavelength that the measurement object can absorb; A camera measuring an image of probe light formed or passed through the measurement object; An analysis device for analyzing the image signal measured by the camera; And A chopper disposed between the second light source and the measurement object to modulate a frequency of the excitation light emitted from the second light source, The analysis device, A calculator for Fourier transforming the image signal measured by the camera; And And an image display unit for displaying the result calculated by the calculation unit on a monitor. delete delete delete delete A first light source that emits probe light toward a measurement object that is a fluid and emits straight light; A second light source irradiating excitation light toward a measurement object that is a fluid at regular intervals and emitting a wavelength that the measurement object can absorb; A screen to which each light passing through the measurement object which is a fluid is irradiated; A camera measuring an image of probe light formed on the screen; An analysis device for analyzing the image signal measured by the camera; And A chopper disposed between the second light source and the measurement object to modulate a frequency of the excitation light emitted from the second light source, The analysis device, A calculator for Fourier transforming the image signal measured by the camera; And And an image display unit for displaying the result calculated by the calculation unit on a monitor. delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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