JPS61137045A - Apparatus for measuring light scattering - Google Patents

Abstract

PURPOSE:To measure the scattering of light containing a light scattering component having a large scattering angle with high accuracy, by irradiating intermittent light and absorbing the scattered light thereof to convert the same to heat energy while converting said energy to an electric signal by a thermocouple to measure the quantity of heat energy. CONSTITUTION:Light incident as shown by the arrow is converted to intermittent irradiation beam 2 by a chopper 10 and said beam 2 is converged by a lens 13 to irradiate matter 1 to be inspected. Scattered light 3 is absorbed by an absorbing substance 7 to be converted to intermittent heat which is, in turn, detected as an electric signal by a heat detection means 11 consisting of two thermocouples 15a, 15b, heat conductors 16, 17 and a detection signal processing part 18. This electric signal is sent to a lock-in amplifier 12 and measured beam 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. [Prior art] Conventionally, as a device for analyzing the physical properties of an object surface and inside an object using light scattering, as shown in Fig. 3,
The scattered light 3 is passed through a lens 4 with a large aperture angle, and an integrating sphere 5 is used to further reduce the influence of light distribution.
The light was guided to the photosensitive surface 6 of a photodetector (eg, Photomaru, Pinphoto, etc.) through the photodetector. However, in this case, if the scattering angle was larger than the aperture angle, the protruding scattered components could not enter the lens, making measurement impossible. 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. Due to these problems, it was difficult to measure with high accuracy and sensitivity.

[Problems to be Solved by the Invention] In view of the above, the present invention measures with high precision and high sensitivity, including light scattering components with large scattering angles, which are difficult to measure with conventional light scattering measurements. This is the single point that needs to be resolved.

[Means for Solving the Problems] The means taken to solve one problem in the present invention include an intermittent light irradiation means for irradiating an object to be examined with intermittent light, and a means for irradiating an object to be examined with intermittent light. A light-to-heat conversion medium 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 thermocouple converts the temperature change caused in the light-to-heat conversion medium into electrical energy. It is characterized by comprising a heat detecting means for converting into a signal, and a thermal change measuring means for measuring the amount of the thermal energy from the electric signal.

A known light source and a chopper are used as the intermittent light irradiation means, and the light-to-heat conversion medium is preferably a light-absorbing material that has large absorption characteristics for the wavelength of the scattered light to be measured and has good thermal conductivity. 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 shining light onto the liquid surface, the state of development of a single molecule so-called LB film (Langmuir-Prodgett film) on the liquid surface, and the vicinity of the adsorbed molecule interface can be detected. It can also be applied to the evaluation of fine particles in liquids.

[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 photoacoustics, an effect, etc., which is a phenomenon that shows an acoustic response.

FIG. 5 is a diagram showing the basic principle of the photoacoustic effect. In FIG. 5, the photoacoustic effect consists of four processes, and shows a state in which energy propagates through a material when the material absorbs light. Shows the process of being absorbed by hitting an absorbing substance,
Process B shows the process in which this energy becomes intermittent heat through a non-radiative relaxation process and propagates through the material as heat waves. Process C shows the process in which the heat waves that reach the surface of the material intermittently spread the gas in contact with the material. Shows the case of heating and generating sound waves,
In process D, thermal waves traveling through a substance are converted into elastic waves,
For example, the present invention attempts to detect the temperature change on the surface of the light absorbing substance 7 at the stage of the above-mentioned process B, and the energy signal detection means is a thermal detection using a thermocouple. It uses means.

Scattering to be analyzed by the present invention includes so-called elastic scattering in which the scattered light does not involve a wavelength shift, and inelastic scattering in which the scattered light involves a wavelength shift such as Raman scattering and Prillouin scattering. An example of an analysis that can be used together is, for example, a method in which a transparent crystal is irradiated with light focused to a predetermined diameter and all of the scattered light is used 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, 1. For example, by analyzing Raman scattering (or laser Raman spectroscopy) generated using monochromatic light such as laser light, it is possible to analyze the molecular structure of minute parts inside the object being examined. For example, phase transition analysis can be obtained by changing the frequency of scattered light caused by changes in lattice vibrations. In particular, by changing the temperature of the test object and using the analysis method of the present invention, 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 measurement device embodying the present invention, and is an example in which temperature changes on the surface of an absorbing substance are directly detected using a thermocouple in the process B. In FIG. 1, a known light source and a chigopper 10 are used as the intermittent light irradiation means constituting the light scattering measurement device, and the light-to-heat conversion medium is formed of the absorbing material 7, and the temperature change of the absorbing material is detected by a thermocouple. The heat detecting means 11 converts the electric signal into an electric signal and detects it, and the lock-in amplifier 12 serves as a thermal change measuring means that calculates the amount of thermal energy from the electric signal. The irradiation light beam 2 interrupted by the chopper 10 is directed to the object l by the lens 13.
The scattered light 3 is absorbed by the absorbing substance 7 and becomes intermittent heat, which is detected by the heat detection means 11 as an electric signal. This electrical signal is sent to a lock-in amplifier 12, where it is subjected to frequency synchronous detection based on a reference signal from a chopper 10 that cuts off the measurement light beam, and the result is output to a recorder 14. It has been theoretically confirmed that the intensity of the thermoelectric signal detected in this way is proportional to the intensity of the scattered light irradiated onto the absorbing substance.

Therefore, it becomes possible to quantitatively measure the scattered light intensity.

FIG. 2 is a structural diagram showing an example of the heat detection means in this embodiment. In FIG. 2, the heat detection means comprises two thermocouples 15a and 15b, the heat generated by the absorbing material 7 is detected by the first thermocouple 15a via the thermal conductor 1B, while the reference thermocouple The temperature in the conductor 17 is detected by the second thermocouple 15b, and a difference signal between the two is obtained by the detection signal processing section 18 and sent to the lock-in amplifier 12.

FIG. 6 is a structural diagram showing another example of the heat detection means in this embodiment. In FIG. 6, thermocouples placed at each position of the absorbing material 7 are arranged so that the heat distribution can be measured simultaneously, and it is possible to determine the intensity distribution according to each light distribution angle of the scattering direction.

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, a similar measurement can be made by arranging a filter 19 before the scattered light is absorbed by the absorbing substance 7 and controlling the measurement wavelength range of the scattered light. If a polarizing filter is used as a filter, it is also possible to obtain polarization characteristics of scattered light.

FIG. 9 shows an example in which highly sensitive and highly accurate light scattering measurement is made possible by arranging a reflecting plate 2o behind the absorbing material 7, thereby reducing the effective thickness of the absorbing layer to an order of magnitude.

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 the absorbing substance 7, which causes light scattering 3. The light scattering characteristics due to the monomolecular film 22 and the absorbing substance 7 can be detected by performing detection using the energy signal detection means 9 placed above the liquid surface 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. Scattering factor 23 in liquid 21
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 scattered light between each other 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, elastic and inelastic light scattering, including light scattering components with large scattering angles that were conventionally difficult to measure, can be measured with high sensitivity and high sensitivity. Can be measured accurately. 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 molecular structural information, and it can also be applied to LB film deposition equipment. This makes 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 vertical sectional view of a heat detection means of the embodiment, FIG. 3 is a configuration diagram of a conventional example, FIG. 4 is a configuration diagram of the present invention, and FIG. The figure is a diagram of the principle of photoacoustic effect, part 6.
The figures are separate structural diagrams of the heat detection means, FIG. 7 is an absorption characteristic diagram of the light-to-heat conversion medium, and FIGS. 8 to 11 are longitudinal sectional views of each medium and the detection means. l... Test object, 2... Irradiation light beam, 3... Scattered light, 7... Light-heat conversion medium, 10... Intermittent light irradiation means, 11... Heat detection means, 12...Thermal change measuring means, 14...Recorder, 15...Thermal conductor! 8・
··thermocouple.

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 heat detection means for converting a temperature change occurring in the light-to-heat conversion medium into an electric signal using a thermocouple, and a heat change measurement means for measuring the amount of thermal energy from the electric signal. A light scattering measuring device comprising: