JPS6269129A - Water temperature measuring method - Google Patents

Abstract

PURPOSE:To accurately measure water temperature by measuring the water temperature under water by intensity of Raman scattered light depending on the water temperature of laser light. CONSTITUTION:An oscillation pulse from a reference oscillator 11 is inputted to a laser generating circuit 14 via a frequency divider 12 and a trigger signal generating circuit 13 and the laser light generated from the circuit 14 is pulsed 15 with high voltage and emitted in the water from a laser light emitting lens 18 as the pulse P via an optical fiber 16 and an optical connector 17. Then, the emitted laser light generates the Raman scattered light in the water and this light comes back to an image-forming lens 21 and is detected as the pulse P and transmitted through the photoelectric surface 22A to which semiconductor material 22B is applied and generates an afterimage on the fluorescent surface 22C and this afterimage is caught by a low afterimage type image pickup tube 23. The shutter timing of a high-speed shutter tube 22 at this time is controlled by a delay variable circuit 26 and a shutter pulse generating circuit 27 and the measurement depth is set by shutter actuation time. Further, detection information at the shutter tube 22 is processed at an information processing circuit 23 and a result is displayed 24 and recorded 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a water temperature measuring method, and more particularly to an indirect water temperature measuring method using laser light.

(Prior Art) In ocean Icl! measurements, fishery resource exploration, etc., the determination of underwater water temperature has important significance.

Conventionally, as a method for measuring underwater water temperature in the above case, for example, a bellows equipped with a temperature sensor is dropped into the water, and the water pressure, which increases with depth, is detected by the amount of deformation of the bellows, and this is used as depth information, and at that time. A means of capturing the detected temperature on a ship as temperature information, or dropping a weight with a temperature sensor attached into the water and calculating depth information by integrating the relationship between the sinking speed of the weight and time. There is a known method for capturing the detected temperature on board the ship as temperature information.

[Problems with conventional technology]

However, the former method has disadvantages in that the device is large and difficult to handle due to the need for a water-resistant and water-pressure resistant structure, and the device itself is expensive.

Further, although the latter method does not have the above-mentioned drawbacks, it has the disadvantage that it is difficult to accurately grasp the sinking speed of the weight, resulting in poor accuracy.

Furthermore, in any of the above methods, since depth information and temperature information are measured by separate means, there is no specification for detection even if there is a time or distance error between them. Measurement depends on the sensor, so response time is required for measurement. Therefore, even if depth information is obtained accurately, the temperature information does not necessarily correspond to depth information, and coupled with the difficulty of error detection mentioned above, it is difficult to accurately measure the temperature. The drawback is that accurate temperature information cannot be obtained.

[Problems solved by this invention]

SUMMARY OF THE INVENTION This invention has been made for the purpose of solving the above-mentioned problems and providing a water temperature measuring method that can quickly and accurately measure temperature or temperature distribution in water.

[Technology to solve problems]

The water temperature measuring method of the present invention irradiates water with a laser beam having a constant beam width, and the reflected light due to Raman scattering of the laser beam in the water has an optical absorption edge wavelength λ, and this λ9 is The light is received by a high-speed shutter tube whose photocathode is coated with a semiconductor material that falls within the spectrum of the laser scattered light, and by measuring the intensity of the received light, the amount of frequency shift of the Raman scattered light depending on the water temperature is detected. 8) l'
It is characterized by calculating the water temperature based on the detected information (■).

[Effect]

When a laser beam is irradiated into water, diffuse reflection occurs due to ice blocks, plankton, and other microscopic floating objects that have different salinity concentrations and temperatures in the water.

Raman scattering is a light scattering phenomenon known as the Raman effect of laser light. It is also known that displacement occurs.

Therefore, by irradiating a laser beam with a certain frequency into the water and measuring the frequency of the Raman scattered light returning from the water,
If the amount of displacement can be determined by comparing the obtained displacement frequency with the above-mentioned constant frequency, it becomes possible to calculate the water temperature at the depth where Raman scattering occurs from this amount of displacement.

However, measuring the frequency of Raman scattered light and comparing it with a reference frequency requires a complicated detection circuit and arithmetic circuit, and the measurement is also not easy.

Therefore, in order to quantitatively capture and directly measure this amount of frequency displacement, the optical absorption edge wavelength λ,
A semiconductor material having λ9 within the spectrum of the laser scattered light is coated as a filter so that the frequency shift can be detected by the size of the light-receiving layer.

That is, as shown in Fig. 1, if the emission spectrum of the Raman scattered light at the depth of the water where the laser beam is formed is 2g(T+), then this emission spectrum λ-(T+) will change as the water temperature in the measurement target area increases. Then, λ, (T) shifts to the longer wavelength side.

In this transition region, a semiconductor light-absorbing material having an optical absorption edge wavelength λ and a linear variation range ■ such that λ9 is in the emission spectrum λw(T, ) to λ9(Tz) is used as a filter to create a high-speed shutter. When the tube receives the Raman scattered light, the light incident on the photocathode, that is, the intensity of the transmitted light of the photocathode increases as the water temperature rises and the Raman scattered light shifts to the longer wavelength side.

Therefore, if we can measure the intensity of this incident light, we can quantitatively detect the amount of change in the Raman scattered light without specifically measuring its frequency, and based on this, we can measure the water temperature at the location where Raman scattering occurs in the water. It is.

In Fig. 1, λ, (TO) is a comparison pulse for accurately measuring the transmitted light intensity, and is a comparison pulse from a long wavelength laser whose transmitted light intensity is almost constant with the emitted light pulse of the laser used. This is an emitted light pulse.

By emitting the comparison pulses alternately with the pulses of the laser used, uncertain errors due to loss of optical connector IA, water quality, fluctuations in transmission loss of the optical fiber, etc. can be removed, and measurement accuracy can be improved.

〔Example〕

Next, embodiments of the invention will be described.

FIG. 2 is a block diagram of a W 71 for carrying out the method of the present invention.

The device shown in FIG. 2 consists of a laser beam emitting section l and a laser beam receiving section 2. The device shown in FIG.

The laser beam emitting unit 1 includes a 4NJ, a laser trigger signal generation circuit 13 to which an oscillation pulse from an oscillator II is manually input via a frequency divider 12, and a laser beam generator that generates a laser beam of a constant oscillation wavelength by the trigger signal. It is comprised of a circuit 14, a high-voltage pulser 15 that converts laser light into high-pressure pulses, and a laser beam emitting lens 18 that emits the pulsed laser beam into the water via an optical fiber 16 and an optical connector 17.

Further, the laser light receiving section 2 receives incident light (Raman scattered light) from the imaging lens 21 with a photocathode 22A coated with a semiconductor material 22B, and a fluorescent surface 22C of the high speed shutter tube 22. A low afterimage type image pickup tube 23 that detects the afterimage of the Raman scattered light, an information processing circuit 23 that detects the return afterimage intensity of the Raman scattered light and calculates the water temperature based on this, display recorders 24 and 25 that display the processing results, and the high temperature It is comprised of a variable delay circuit 26 that can arbitrarily delay the reference pulse from the frequency divider 12 for controlling the operating timing of the speed shutter tube 22, and a shutter pulse generation circuit 27 that generates a shutter pulse using this pulse. ing.

In the above, the laser beam emitting section 1 and the laser beam receiving section 2
Examples of the specifications are shown in the table below.

Laser light emitting unit specification table fil Laser light generation circuit 14 Type Rb laser light generator tube oscillation wavelength 6943 people Repetition period 4P/l1in Excitation Xe lamp (2) High pressure pulser 15 (Q switch) Type Krybtochanin dye cell peak output
3 MW or more Pulse width 20n3 Pulse type Giant pulse repetition period 4P/lll1n (3) Laser beam emitting lens 18 Beam spread angle Close distance M 40 degrees Long distance N 1 degree Laser beam receiver specification table + 11 High speed shutter tube 22 Shutter Time 2Qns Delay time 350.044~350.888μ5
(2) Photocathode coated semiconductor material type 5i-APD (3) Imaging lens 21 Focal length F = 2.5 f = 15-150 1 (
(4) Dovetail image tube 23 Type Image dissector response sensitivity Several ns FIG. 3 is a time chart showing the operation timing of the above embodiment.

The laser beam generated by the laser beam generation circuit 14 is converted into high-voltage pulses by the high-voltage pulser 15, and then connected to the optical fiber 16.
, and is emitted as a pulse P into the water from the laser beam emitting lens 18 via the optical connector 17.

The emitted laser beam causes Raman scattering in water, returns to the imaging lens 21, is detected as a pulse p, and is transmitted through the photocathode 22A coated with a semiconductor material 22B, and then passes through the fluorescent surface 2.
2C, which is captured by the low-afterimage type image pickup tube 23. The shutter timing of the high-speed shack tube 22 at this time is controlled by a variable delay circuit 26 and a shutter pulse generation circuit 27, and the eco time, that is, the measurement depth is set by the shutter operation time. Note that the information detected by the high-speed shutter tube 22 is sent to the information processing circuit 23.
The results are displayed on the display 24 and recorded on the recorder 25.

Therefore, by continuously variable control of the variable delay circuit 26 and the shutter pulse generation circuit 27, it is possible to continuously measure the water temperature as the water depth increases.

〔effect〕

As explained above, this invention measures the water temperature in water by measuring the intensity of Raman scattered light that depends on the water temperature of the laser beam, so the response time is almost 0 and the water temperature at each water depth can be determined instantly. It is possible to measure water temperature, and the error can be kept within ±0.5°C, making it possible to measure water temperature extremely accurately.

Furthermore, since the frequency displacement of the Raman scattered light that depends on the water temperature is detected as the intensity of the returning light, there is no need for a complicated frequency measurement circuit, and there are various effects such as easy measurement.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation of the present invention, FIG. 2 is a block diagram of an apparatus for carrying out the method of the invention, and FIG. 3 is an explanatory diagram of the operation of an embodiment of the invention. T2 Enzzc (Firefly #: Bacteria)

Claims (1)

[Claims] (1) Irradiate the water with a laser beam with a constant beam width,
A high-speed shutter tube whose photocathode is coated with a semiconductor material that allows reflected light due to Raman scattering of the laser light in water to have an optical absorption edge wavelength λ_9, and where λ_9 is within the spectrum of the laser scattered light. A method for measuring water temperature, characterized in that the amount of frequency displacement of Raman scattered light that depends on the water temperature is detected by measuring the received light intensity, and the water temperature is calculated based on the detected information.