JPS61137047A - Apparatus for measuring scattering of light - Google Patents

Abstract

PURPOSE:To measure the scattering of light containing a light scattering component having a large scattering angle with high sensitivity and high accuracy, by irradiating intermittent light and absorbing the scattered light thereof to convert the same to heat energy before detecting the refractivity distribution of light due to the change in temp. of said energy. CONSTITUTION:Light incident as shown by the arrow is converted to intermittent irradiation beam 2 by a chopper 10 and said beam is converted by a lens 13 to irradiate matter 1 to be inspected. The scattered beam 3 thereof transmits through a transparent flat plate 7a to be absorbed by an absorbing substance 7 to be converted to intermittent heat. The detection beam 15 from a light source 16 and a mirror 17 is refracted in the vicinity of the absorbing substance 7 by said heat and converted to an electric signal by a position sensor 18 to be sent to a lock-in amplifier 12. This electric signal is subjected to frequency synchronous detection on the basis of the reference signal from the chopper 10 and the result thereof is recorded on a recorder 14.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an apparatus that uses light scattering to analyze physical properties on the surface of an object and inside an object, and in particular, to a device that uses light scattering to analyze the physical properties of an object surface and inside an object, and in particular, converts the scattered light into thermal energy for measurement. related to a device for

[Prior art] Conventionally, light scattering has been used to determine the physical properties of the surface and interior of an object.
As shown in Fig. 3, the analysis device is
2, the scattered light 3 is passed through a lens 4 with a large aperture angle, and in order to further reduce the influence of light distribution, it is passed through an integrating sphere 5 to a photodetector (e.g., photomultiply, binphoto, etc.). ) was guided to the photosensitive surface 6. However, in this case, if the scattering angle is larger than the aperture angle, the protruding scattered components may enter the lens. It was not possible to measure it. In order to detect the protruding scattered components, a method has been devised in which a transmission-type diffusion surface is placed near the test object and a photodetector is placed behind it, but the characteristics of the diffusion plate, the method of installing the photodetector, etc. This has made it difficult to measure with high accuracy and sensitivity.

[Problems to be Solved by the Invention] In view of the above, the present invention aims to achieve high accuracy and high sensitivity, including light scattering components with large scattering angles, which are difficult to measure with conventional light scattering measurements. Measurement is a problem to be solved.

[Means for Solving the Problems] In the present invention, the means taken to solve the problems include an intermittent light irradiation means that irradiates the test object with intermittent light, and a test object that uses the irradiation light to A light-to-heat conversion medium that absorbs scattered light intermittently emitted from the surface of the object according to the physical properties of the object and converts it into thermal energy, and a refractive index distribution based on the temperature change that occurs near the light-to-heat conversion medium. The present invention is characterized in that it includes a photothermal deflection detection means for detecting a photothermal deflection signal, and a thermal change measuring means for measuring the thermal energy from the detected photothermal deflection signal.

A well-known light source and a chip are used as the intermittent light irradiation means, and a light-absorbing material that has large absorption characteristics for the wavelength of the scattered light to be measured and has good thermal conductivity is used as the light-to-heat conversion medium. For example, if carbon and a mixture mainly composed of carbon are used, a wide wavelength range can be covered. By measuring the spectral absorption characteristics of the light-absorbing material in advance, it is possible to correct the output signal and correct sensitivity unevenness for each wavelength. By adding irregularities to the surface of the light-absorbing material that are slightly larger than the wavelength of the scattered light, it is possible to not only improve complete diffusivity and eliminate the effects of the scattering angle, but also increase absorption efficiency. .

The object to be tested is not limited to solids, but may also be liquids, and by applying irradiation light onto the liquid surface, a monomolecular so-called LB film (Langmuir-Prodgett film) can be formed on the liquid surface.
It can also be applied to the evaluation of microparticles in the liquid near the adsorbed molecule interface.

[Function] FIG. 4 is a basic configuration diagram of the light scattering measuring device according to the present invention. In FIG. 4, when a test object 1 is irradiated with intermittent light 2, scattered light 3 due to light within the test object is intermittently emitted from the surface of the test object at various exit angles. When these scattered lights 3 are irradiated onto a light-absorbing substance 7, they are absorbed and become intermittent energy signals 8, which are guided to an energy signal detection means 9. The light-absorbing material 7 can convert light energy into heat energy etc. for any incident angle, so if the size and position of the light-absorbing material 7 are appropriately set, it can be easily converted even when the scattering angle is large. can be detected. The intermittent energy signal obtained in this way can be detected with high sensitivity by using the photoacoustic effect, which is a phenomenon that indicates an acoustic response.

'Figure 5 is a diagram of the basic principle of the photoacoustic effect. 5th □
'b□''-, the photoacoustic effect consists of four processes) jr, , (□,, Process A, which shows the state in which energy propagates through a substance when the substance absorbs light.
Process B shows the process in which an intermittently modulated incident light beam 3 hits an absorbing material and is absorbed. Process B shows that this energy becomes intermittent heat through a non-radiative relaxation process and propagates through the material as a heat wave. Process C is a process in which heat waves that reach the surface of a material intermittently heat the gas that is in contact with the material.
Process D shows a case in which a sound wave is generated, and Process D shows a case in which a thermal wave that propagates through a substance is converted into an elastic wave and propagates in, for example, a sample M. The purpose is to detect the refractive index distribution occurring inside the sensor, and a photothermal deflection means equipped with a position sensor is used as the energy signal detection means.

Scattering to be analyzed by the present invention includes so-called elastic scattering in which the scattered light is not accompanied by a wavelength shift, and inelastic scattering in which the scattered light is accompanied by a wavelength shift such as Raman scattering and Prillouin scattering. For example, an analysis that uses both the
One method is to use all of the scattered light as an information source. The scattered light in this case includes light of all wavelength components, and is a simple method for determining refractive index fluctuations and the presence of fine particles on the surface and inside of the object to be measured.

Regarding analysis using inelastic scattering, for example, by analyzing Raman scattering (or laser Raman spectroscopy) generated using monochromatic light such as laser light, it is possible to analyze molecular structure theory in minute parts inside the test object. For example, phase transition analysis can be obtained by changing the frequency of scattered light caused by changes in lattice vibrations. In particular, by using the analysis method of the present invention while changing the temperature of the test object, it is possible to obtain phase transition information. Various information can be obtained regarding local changes.

Furthermore, in Prillouin scattering, the information source is scattered light with a wavelength shift caused by the interaction between phonons within the test object and the irradiated light, so if this is analyzed spectrally, it is possible to determine, for example, the phase of a crystal sample. It is effective for analyzing transition and glass transition of polymeric materials.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples and drawings.

FIG. 1 is a configuration diagram showing a preferred example of a light scattering measuring device embodying the present invention. In the process C, a change in refractive index near the surface due to a temperature change on the surface of a light-absorbing substance is detected as a deflection of a light beam. This is an example. In Figure 1,
As the intermittent light irradiation means constituting the light scattering measuring device, a known light source and CHI:1-/PA10 are used, and the light-to-heat conversion medium is formed of the light absorbing material 7, and the light-to-heat deflection due to thermal energy is detected. Photothermal deflection detection means l! and a lock-in amplifier 12 as a thermal change measuring means for measuring the amount of thermal energy from the detected amount of photothermal deflection. The irradiation light beam 2 interrupted by the chopper 1O is guided to the object 1 by the lens I3, and the scattered light 3 is absorbed by the light absorbing material 7 and becomes intermittent heat, which is refracted near the surface of the absorbing material. A photothermal deflection detection means that changes the rate and deflects the direction of light passage in that area! l
is converted into an electrical signal. This photothermal deflection detection means l! The signal is sent to the lock-in amplifier 12, where it is subjected to frequency synchronous detection based on the reference signal from the chopper 10 that cuts off the measurement light beam, and the result is output to the recorder I4. The intensity of the photothermal deflection signal detected in this way is
It increases as the intensity of scattered light irradiated to the absorbing substance increases, and this relationship has also been confirmed theoretically. Therefore, it becomes possible to quantitatively measure the scattered light intensity.

Note that measurement becomes more stable if the incident light intensity is monitored and fluctuations in the irradiated light intensity are removed. Moreover, the light scattering distribution can also be measured by moving the light irradiation position of the test object. The light may be irradiated onto the object to be inspected not only from the direction shown in FIG. 1 but also from any arbitrary direction.

FIG. 2 is a structural diagram showing an example of the photothermal deflection detection means in this embodiment. In FIG. 2, the scattered light passes through a transparent flat plate 7a and is absorbed by the absorbing substance 7 present on the surface of the flat plate 7a, generating intermittent heat. This heat changes the refractive index near the surface of the absorbing material, and the direction of the probe light beam 15 passing through that region changes intermittently. The probe light beam 15 is preferably a laser beam or the like with good directivity and a small beam diameter. In the figure, the probe light beam 15 is emitted from a light source 1B, is refracted by a mirror 17, and is arranged so as to pass near an absorbing substance. has been done. A position sensor 18 detects the positional deviation due to the deflection of the probe light beam 15, converts it into an electrical signal, and sends it to the lock-in amplifier 12, thereby measuring the intensity of the scattered light.

FIG. 6 is a structural diagram showing another example of the photothermal deflection detection means. In FIG. 6, the photothermal deflection detection means includes a probe light beam 15! and 15y are passed in a matrix on the surface of the absorbing material 7, and the amount of deflection at each position is detected by the corresponding position sensor 18x and toy. Light distribution can be obtained. The probe light beam 15 may be scanned using a rotating mirror or the like, or
2.Alternatively, separate light sources may be set at each corresponding position and measured at once. 〉, By filling the region where the light beam is deflected with a material whose refractive index changes significantly with changes in temperature, a heated region with a large refractive index change due to a small temperature change can be created.
The path of the light beam can be changed significantly, allowing for highly sensitive measurements.

FIG. 7 is a graph showing that the light absorption rate differs for each substance. If the wavelength characteristics of the light absorbing material 7 shown in the basic configuration diagram of FIG. 4 are different from those shown in FIG. 7 with different wavelength inputs, it is possible to measure the scattered light intensity of each corresponding wavelength. This makes it possible to measure inelastic scattering.

Furthermore, as shown in FIG. 8, similar measurements can be made by placing a filter 18 before the scattered light is absorbed by the light absorbing substance 7 and controlling the measurement wavelength range of the scattered light.

No. 911 is an example in which highly sensitive and highly accurate light scattering measurement is made possible by arranging a reflecting plate 20 behind the light absorbing material 7 to drastically reduce the effective thickness of the absorbing layer.

FIG. 10 shows an example in which the present invention is applied to light scattering by a monomolecular film on a liquid surface. In FIG. 10, the irradiation light 2 is incident from below the surface of the liquid 21, and is incident at an angle such that it is totally reflected at the liquid interface. On the total reflection interface, the light energy is transmitted as an evanescent wave to the monomolecular film 22 on the liquid surface, and light scattering 3 occurs.

The light scattering characteristics of the monomolecular film 22 and the absorbing material 7 can be detected by detecting the light absorbing material 7 placed on the liquid surface and the energy signal detecting means 9 based on each of the methods described above. .

FIG. 11 is an example of evaluating the light scattering characteristics below the liquid surface in the LB film forming apparatus. Liquid 2! scattering factor 23 in
By measuring the scattered light, the state of the single molecule developing solution can be detected, and film formation can be controlled based on this information.

In addition, by narrowing down the irradiation light beam diameter as necessary, removing the influence of the scattered light beams within the object to be inspected, and scanning the irradiation light beam along a predetermined surface within the object to be inspected,
It is also possible to pattern information on each part. Then, by computer processing the electrical signals and scanning signals obtained in this way and displaying them on a display, microscopic information can be captured in a patterned manner.

[Effects of the Invention] As explained above, according to the present invention, light scattering including elastic scattering and inelastic scattering, including light scattering components with large scattering angles that were conventionally difficult to measure.

Can measure with high sensitivity and precision. Therefore, it is not only possible to detect refractive index fluctuations and the presence of fine particles within the test object, but also to obtain information on molecular structure. This makes it possible to make an extremely large contribution to the analysis of physical properties.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of the photothermal deflection detection means of the embodiment, and FIG. 3 is a configuration diagram of a conventional example.
Fig. 4 is a block diagram of the present invention, Fig. 5 is a diagram of the principle of the photoacoustic effect, Fig. 6 is a separate block diagram of the photothermal deflection detection means, Fig. 7 is a diagram of the absorption characteristics of the light-to-heat conversion medium, and Fig. 8 to 11 are longitudinal sectional views of each medium and the detection means. 1... Test object, 2... Irradiation light beam, 3... Scattered light, 7... Light-thermal conversion medium, lO... Intermittent light irradiation means, 11... Photothermal deflection detection means , 12...1 Heat change measuring means. 15... Light beam for probe, 18... Position sensor.

Claims (1)

[Claims] 1) Intermittent light irradiation means that irradiates intermittent light onto a test object, and the irradiation light absorbs scattered light that is intermittently emitted from the surface of the test object according to the physical properties of the test object, and converts it into thermal energy. a light-to-heat conversion medium, a photothermal deflection detection means for detecting a refractive index distribution based on a temperature change occurring near the light-to-heat conversion medium, and a thermal change measurement device for measuring the thermal energy from the detected photothermal deflection signal. A light scattering measurement device comprising: means.