JP3280131B2 - Liquid surface waveform measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the surface tension of a liquid by generating a periodic surface wave on the surface of the liquid.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional typical liquid surface tension measuring apparatus 100 includes an AC power supply 101, a laser irradiation unit 102, and a phase detection unit 103. AC power supply 10
1 generates a periodic surface wave 104 on the liquid surface. The laser irradiation unit 102 is provided above the liquid surface, and irradiates the liquid surface with one laser beam 105. Phase detector 10
3 receives the reflected light 106 of the laser beam 105 and detects the phase of the periodic surface wave 104. The phase detection unit 103 detects a phase difference between the AC power supply 101 and the periodic surface wave 104.
Then, based on the change in the phase difference, a relative change from the initial value of the surface tension of the liquid is obtained to measure the surface tension.

[0003]

However, the periodic surface wave 104 is disturbed by external noise, and
May detect the wrong phase. The reflected light 106 of the laser beam 105 may deviate from the phase detection unit 103 due to disturbance due to vibration or impact. For this reason, the conventional typical liquid surface tension measuring apparatus 100 has a problem that continuous measurement of phase data is interrupted, and it is necessary to measure the phase again. An object of the present invention is to simultaneously detect the respective phases of surface waves generated on a liquid surface during measurement at two positions arranged in the same traveling direction of the surface waves and measure the surface tension with high accuracy based on the phase difference. Liquid tension measuring device.

[0004]

According to the present invention, there is provided an oscillator for generating an oscillating electric field at a fixed position on the surface of a liquid to be measured to generate a periodic surface wave on the surface of the liquid, and provided above the surface of the liquid. A laser irradiation unit that irradiates a first laser beam and a second laser beam to a first irradiation position and a second irradiation position of a liquid surface arranged in the same traveling direction of the periodic surface wave, A phase detection unit provided above and detecting the phase of the periodic surface wave at each irradiation position by the first and second laser beams reflected from each irradiation position on the liquid surface, and the detected period at each irradiation position. Calculating means for calculating the surface tension of the liquid from the wavelength of the periodic surface wave calculated based on the phase difference between the surface waves.

[0005]

According to the present invention, a periodic surface wave is generated at a fixed position by generating an electric field that oscillates at a fixed position on the liquid surface.
A surface wave in which the periodic surface wave is combined with an intermittently disturbed waveform due to external noise travels on the entire liquid surface.
The laser irradiation unit irradiates the first laser beam and the second laser beam to the first irradiation position and the second irradiation position, respectively.

The phase detector receives the first laser beam reflected at the first irradiation position on the surface of the liquid when the first laser beam is not hindered by disturbance due to vibration or impact, and detects the phase of the first laser beam at the first irradiation position. To detect. At the time of this detection, the phase detection unit receives the second laser beam reflected at the second irradiation position on the liquid surface if it is not hindered by disturbance due to vibration or impact,
The phase of the second laser beam at the second irradiation position is detected. The calculating means calculates and measures the surface tension based on the wavelength of the periodic surface wave calculated from these phase differences.

[0007]

[0008]

Next, a method for measuring the liquid surface tension by the liquid surface tension measuring device of the present invention will be described with reference to an embodiment shown in the drawings. 1 and 2 show a liquid surface tension measuring device. FIG. 1 is a basic configuration diagram of the liquid surface tension measuring device.
FIG. 2 is a partial detailed view of a liquid surface tension measuring device.

[Configuration of Embodiment] The liquid surface tension measuring apparatus 1 of the present embodiment is installed near the surface of a water surface to measure the surface tension of the water surface provided with a monomolecular film, and acts on the water surface. The liquid surface tension measuring device 1 has an oscillating unit 2 that generates a periodic surface wave 10 on the water surface by a vibrating electric field. A laser irradiation unit 8 that irradiates the first irradiation position 4 and the second irradiation position 5 on the water surface arranged in the same traveling direction 3 of the periodic surface wave 10 with the first laser beam 6 and the second laser beam 7 from above. Is provided above the water surface. Further, the first laser beam 6 reflected at the first irradiation position 4 and the second laser beam 7 reflected at the second irradiation position 5
And a phase detector 9 for detecting the respective phases based on the fluctuation of the reflection direction on the water surface is provided above the water surface.

The oscillating section 2 includes an electrode 21 installed at a position of about 1 mm above the water surface, and an AC power supply 22 connected to the electrode 21 and applying an AC voltage. The laser irradiation unit 8 includes a first laser irradiation source 81 that emits the first laser beam 6, a second laser irradiation source 82 that emits the second laser beam 7, And a first dichroic mirror 83 that reflects the laser beam 6. The first laser irradiation source 81 is a semiconductor laser irradiation source having a wavelength of 650 mm (red). The second laser irradiation source 82
This is a semiconductor laser irradiation source having a wavelength of 750 mm (near infrared).

The phase detector 9 reflects a reflected light 91 from the first irradiation position 4 and transmits a reflected light 92 from the second irradiation position 5, and a second dichroic mirror 93.
A first phase detector 95 that receives the reflected light 94 from the first irradiation position 4 is provided. Further, the phase detector 9 includes a second phase detector 96 that receives the reflected light 92 from the second irradiation position 5.

[Operation of Embodiment] A voltage of about 500 V is applied to an AC power
Periodic surface wave 1 with a frequency of about 250 Hz from the nearby water surface position
Generates 0. Then, a water surface wave obtained by synthesizing the periodic surface wave 10 with an intermittently disturbed waveform due to external noise is caused to travel on the entire water surface. The first laser beam 6 emitted from the first laser irradiation source 81 is reflected by the first dichroic mirror 83, reaches the water surface, and is reflected at the first irradiation position 4. The first laser beam 6 reflected at the first irradiation position 4 is
When not disturbed by disturbance due to vibration or shock, the light is reflected by the second dichroic mirror 93 and reaches the first phase detector 95.

The second laser beam 7 emitted from the second laser irradiation source 82 passes through the first dichroic mirror 83,
The light is reflected by the first dichroic mirror 83, reaches the water surface in parallel and close to the first laser beam 6 toward the first irradiation position 4, and is reflected at the second irradiation position 5. Then, when not disturbed by disturbance due to vibration or shock, the second laser beam 7 parallel and close to the first laser beam 6 toward the first phase detector 95 passes through the second dichroic mirror 93 and passes through the first dichroic mirror 93. From the laser beam 6 to the second phase detector 96.

The first phase detector 95 receives the first laser beam 6 when not disturbed by disturbances due to vibrations or shocks, and outputs an output signal 11 (corresponding to the phase of the water wave at the first irradiation position 4). (See FIG. 3). The second phase detector 96 also receives the second laser beam 7 when not disturbed by disturbance due to vibration or shock, and thereby outputs the output signal 1 corresponding to the phase of the water wave at the second irradiation position 5.
2 (see FIG. 3) are output simultaneously.

Accordingly, the first phase detector 95 travels in the first irradiation position 4 and the second irradiation position 5 in which the water surface wave having only the periodic surface wave component without the waveform component disturbed by the external noise approaches. Sometimes, the first phase of the periodic surface wave 10 at the first irradiation position 4 is output. The second phase detector 96 includes:
The second phase of the periodic surface wave 10 at the second irradiation position 5 is output simultaneously with the first phase detector 95. The wavelength 13 of the periodic surface wave 10 is known from the distance between the first irradiation position 4 and the second irradiation position 5 and the phase difference between the first phase and the second phase. On the other hand, the equation of the surface tension wave is as follows: ρ is the density, ω is the angular frequency (2
π × frequency), γ is surface tension, κ is wave number (2π × wavelength 1)
If 3), it is expressed by ρω ² ≒ γκ ³ . The surface tension is calculated from the expression of the surface tension wave and the wavelength 13.

[Example of Numerical Calculation] Frequency f = 250 Hz, ρ ≒
When the pressure is 1 kg / m ³ , the surface pressure is 0 Pa (the surface tension is about 72 Pa).
mN / m), the wavelength 13 is about 1.2 mm and the surface pressure is 50 Pa
(The surface tension is about 22 mN / m), the wavelength 13 is about 0.
8 mm. Therefore, practically, about 0.8 mm to about 1.2
The diameter of the first laser beam 6 and the second laser beam 7 should be 0.4 mm or less because it is sufficient if the wavelength 13 between the first laser beam 6 and the second laser beam 7 can be measured. The interval needs to be 0.8 mm or less.

Assuming that the distance between the first laser beam 6 and the second laser beam 7 when approaching is 0.4 mm, the surface pressure is 0 Pa
Is 120 °, the phase difference at a surface pressure of 50 Pa is 180 °, and the surface pressure is 0 Pa and the surface pressure is 5 Pa.
The difference in phase difference at 0 Pa is 60 °. The distance when the first laser beam 6 and the second laser beam 7 are close to each other is 0.8 mm
Then, when the surface pressure is 0 Pa, the phase difference is 240 °, and when the surface pressure is 50 Pa, the phase difference is 360 °. If a clock of about 1 MHz is used to detect the phase difference, a resolution of about 0.2 °, that is, a surface pressure measurement resolution of about 0.2 mN / m is obtained.

[Effects of the Embodiment] The liquid surface tension measuring method of the present embodiment selects the first irradiation position 4 and the second irradiation position 5 when there is no influence of external noise, vibration and shock. A phase difference can be detected. Therefore, the wavelength 13 of the periodic surface wave 10 can be reliably measured. Then, the absolute value of the surface tension can be measured from the wavelength 13. Further, according to the liquid surface tension measuring method of the present embodiment, the first phase detector 95 and the second phase detector 96
It is also possible to determine the damping constant from each phase output of one periodic surface and to know the surface viscosity. Further, in the liquid surface tension measuring method of the present embodiment, since the liquid surface is not in contact with the water surface, a defect is not given to the monomolecular film on the water surface, and the measurement is not interrupted.

[Modification] The wavelength 13 of the periodic surface wave 10 may be measured as follows. The first dichroic mirror 83 is configured to be rotatable, and the rotation angle is accurately detected by an encoder. First dichroic mirror 83 such that the output phase difference between first phase detector 95 and second phase detector 96 is always 360 °.
Is rotated to track the surface wave, and the wavelength 13 of the periodic surface wave 10 is calculated from the output of the encoder.

[Application Example] When the order of μm is required for processing a nonlinear optical material or the like, multilayer accumulation is performed. INDUSTRIAL APPLICABILITY The liquid surface tension measuring apparatus of the present invention can be applied to surface tension measurement when performing multilayer accumulation by a moving wall method because measurement is not interrupted by external noise even when the liquid is not in contact with the measurement surface. As a result, the liquid surface tension measuring device of the present invention has a number of layers of 500 to 2000, which was impossible with the conventional surface tension measuring method.
It is possible to achieve a degree of continuous multilayer film formation.

[Brief description of the drawings]

FIG. 1 is a diagram of a liquid surface tension measuring device.

FIG. 2 is a diagram of a liquid surface tension measuring device.

FIG. 3 is a diagram of an output waveform of a phase detection unit.

FIG. 4 is a diagram of a conventional liquid surface tension measuring device.

[Explanation of symbols]

2 oscillation section, 3 traveling direction, 4 first irradiation position, 5 second irradiation position, 6 first laser beam, 7 second laser beam, 8 laser irradiation section, 9 phase detection section, 10 period surface wave

Continuation of the front page (56) References JP-A-53-120488 (JP, A) JP-A-58-106419 (JP, A) JP-A-63-103918 (JP, A) JP-A-63-277972 (JP) JP-A-3-262915 (JP, A) JP-A-3-262916 (JP, A) JP-A-4-47286 (JP, A) JP-A-6-207821 (JP, A) 1-59844 (JP, U) JP 3-7885 (JP, B2) JP 58-502022 (JP, A) JP 4-505512 (JP, A) Rev. Sci. Instrument, C ENTRO-SYMMETRIC TECH. FOR MEASURING S HEAR MODUULUS, VISCO SITY, SURFACE TENSI ON OF SPREAD MONOL AYERS, B. M. ABRAHAM and K. MIYANO, S.M. Q. Xu, J. et al. B. KETTERSON, USA, American Institute of Physics, Vol. 2, pp. 213-219 (58) Fields investigated (Int.Cl. ⁷ , DB name) G01C 13/00 G01B 11/00 G01S 17/00 G01N 11/00 G01N 13/00

Claims (1)

(57) [Claims] An oscillator for generating an oscillating electric field at a fixed position on the surface of a liquid to be measured to generate a periodic surface wave on the surface of the liquid; a first laser beam and a second laser beam provided above the surface of the liquid; A laser irradiation unit that irradiates two laser beams to a first irradiation position and a second irradiation position of a liquid surface arranged in the same traveling direction of the periodic surface wave; and a laser irradiation unit provided above the liquid surface, A phase detector that detects the phase of the periodic surface wave at each irradiation position by the first and second laser beams reflected from each irradiation position, based on the phase difference between the detected periodic surface waves at each irradiation position. A calculating means for calculating the surface tension of the liquid from the calculated wavelength of the periodic surface wave.