JPH09281134A - Laser current meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser current meter enabling simple and accurate measurement of the velocity and the direction of a flow of a fluid to be measured and being small-sized, compact and excellent in mobility. SOLUTION: In the laser current meter 11, a scanning optical system 16 has two semiconductor lasers 12a and 12b, collimators 13a and 13b whereby laser lights 1a and 1b outputted from the semiconductor lasers 12a and 12b respectively are made parallel light fluxes, a beam splitter 14 splitting at least one of the output laser lights and a converging means 15 which converges laser lights 1a1, 1a2 and 1b as three focuses at least in a measuring area 3a of a fluid 3 to be measured. Besides, a reflecting optical system 21 has photoelectric conversion means 20a and 20b which receive scattered laser lights from the focuses and output electric signals. The direction of a flow of a particulate P and a time interval of the signals are measured by processing the signal outputs from the photoelectric conversion means 20a and 20b, the flow velocity of the particulate P is determined on the basis of the measured time interval and a distance between the focuses and the velocity and the direction of the flow of the fluid 3 to be measured are calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser anemometer for measuring a flow velocity and a flow direction of a fluid to be measured by using a laser beam, and in particular, it is possible to accurately measure the flow velocity of the fluid to be measured and is excellent in maneuverability. The present invention relates to a laser velocity meter such as a small and compact semiconductor laser velocity meter.

[0002]

2. Description of the Related Art A pitot tube or a hot wire anemometer has been conventionally used as an anemometer for measuring the velocity of a fluid to be measured such as air or water. Recently, a laser velocimeter using a laser beam of a gas laser or a semiconductor laser has been used in place of the Pitot tube or the like. A laser doppler velocimeter of a backscattering type is available as a commercially available laser velocimeter.

In the conventional laser light Doppler velocimeter, since a large output gas laser argon ion laser is used as a laser device, the laser device becomes large.
This anemometer has a length of 1 m or more and becomes large in size, and the weight thereof increases. For this reason, the conventional laser anemometer cannot be a handy type, and there is a problem that mobility of the fluid to be measured is not sufficient.

As a laser anemometer that solves the problem of an increase in the size of the entire apparatus, there is a semiconductor laser anemometer disclosed in Japanese Patent Laid-Open No. 5-249129. This laser anemometer is
A backscattering laser velocimeter configured as shown in FIG. 17 in which a measurement optical system 2 is configured by using a red semiconductor laser 1 as a laser device and a measurement region 3a is set in a fluid 3 to be measured.

In the conventional laser velocimeter, the collimator lens 4 is placed on the optical axis of the laser light 1 output from the semiconductor laser 1.
The collimator lens 4 reduces the divergence angle of the laser light 1 to form a parallel light beam. At the output side of the collimator lens 4, a laser beam 1
A Wollaston prism 5 is provided as a polarizing prism that divides the light into ₁ and l ₂ with equal intensity and changes the polarization direction. The Wollaston prism 5 functions as a beam splitter.

On the output side of the Wollaston prism 5, a condenser lens 6 which is a condenser means is provided.
Then, the two laser beams l ₁ and l ₂ divided into the measurement region 3a of the fluid 3 to be measured are focused as two focal points. The vicinity of two focal points due to the laser beams l ₁ and l ₂ focused on the measurement area 3a is represented as shown in FIG.

As shown in FIG. 18, the diameters of the two laser beams l ₁ and l ₂ are narrowed by a condenser lens 15. The diameter of the laser beam is narrowed down to the minimum diameter at the focal position of the measurement area 3a and then expanded again. Measurement area 3a
The interval between the two focal points formed in the above is set to a predetermined value.

By flowing the fluid to be measured 3 into the measurement area 3a, the fine particles P existing in the fluid to be measured 3 also pass through the measurement area 3a at the same speed. That is, it passes through two focal points. When the fine particles P pass through the two focal points, they scatter the laser light. The scattered laser light is focused by the condenser lens 6 to be a parallel laser light. For the parallel laser light, only one of the scattered lights is selected by the deflection filters 7a and 7b whose polarization angles are different by 90 degrees, and the lenses 8a and 8b are selected.
The semiconductor light receiving elements 9a and 9b as photoelectric conversion elements by
To receive light. The semiconductor light receiving elements 9a and 9b input the scattered light, output an electric signal, and input the signal output to a signal processor 10 as a signal processing means. Signal processor 10
Then, the input signal is converted into a square wave to measure the time interval, and the flow velocity of the fine particles P is calculated by dividing the two focal lengths of the measurement region 3a by the measured time interval. It is output as the flow velocity of the measurement fluid 3.

[0009]

In the conventional laser velocimeter using the gas laser as the laser device, the entire device becomes large in size, and the laser velocimeter cannot be made small and compact, which is excellent in maneuverability. It is difficult to provide a handheld laser anemometer.

Further, when a small red semiconductor laser is used as a laser device, a laser velocity meter can be made compact and compact, and a handy type having excellent maneuverability can be provided. There is a problem that only the flow velocity of the fluid to be measured can be measured, and information about the flow direction of the fluid to be measured cannot be obtained, which hinders accurate flow velocity measurement.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser velocimeter capable of confirming the flow direction and easily and accurately measuring the flow velocity of a fluid to be measured.

The present invention is another object of the present invention to provide a handy type laser velocimeter which can secure a sufficient amount of scattered laser light, can accurately and easily carry out the flow velocity of a fluid to be measured, and is excellent in mobility. There is.

[0013]

In order to solve the above-mentioned problems, a laser anemometer according to the present invention measures the particle velocity in a fluid to be measured by using laser light as described in claim 1. In a laser velocity meter that outputs this particle velocity as a fluid velocity to be measured, two semiconductor lasers that output laser beams having different wavelengths and a parallel light flux that reduces the divergence angle of the laser beams output from the semiconductor lasers. Collimator for forming a laser beam, a beam splitter for splitting one of the parallel-beam laser beams into two laser beams, and the two split laser beams and the other laser beam for the measurement area of the fluid to be measured. Light converging means for condensing at least three focal points in the above, and photoelectric conversion means for receiving scattered laser light from each focal point of the measurement region and outputting an electric signal,
A signal processing means for measuring the flow direction of the particles and the time interval of the signal based on the signal output from the photoelectric conversion means, and calculating the flow velocity of the particles from the measured time interval and each of the focal distances. Measurement with the above signal processing means
The flow direction and flow velocity of the particles to be processed are set as the flow direction and flow velocity of the fluid to be measured.

In order to solve the above-mentioned problems, in the laser velocity meter according to the present invention, as described in claim 2, the beam splitter uses the laser light of wavelengths λ1 and λ2 output from the semiconductor laser. One is split, and the split laser beam and the other laser beam are focused by the focusing means, and λ 1, λ 1, λ 2 or wavelength λ 2, in the measurement region of the fluid to be measured.
The light is condensed as three focal points of λ2 and λ1, and the scattered laser light from these three focal points is received by the photoelectric conversion means through the interference filter. Further, as described in claim 3, the beam splitter is One of the laser beams having the wavelengths λ1 and λ2 output from the semiconductor laser is split, and the split laser beam and the other laser beam are focused by the converging means, and λ1, λ2, λ1 or Wavelength λ2
, Λ1 and λ2 are focused as three focal points.
The scattered laser light from one focal point is received by the photoelectric conversion means through the interference filter.

In order to solve the above-mentioned problems, the laser anemometer according to the present invention measures the particle velocity in the fluid to be measured by using laser light, and this particle velocity is measured. In a laser velocimeter that outputs as a fluid velocity to be measured, two semiconductor lasers that output laser light having different wavelengths and a divergence angle of the laser light output from the semiconductor laser are reduced to form a laser light of parallel light flux. A collimator, a beam splitter that splits each laser beam of parallel light flux into two laser beams, and a focusing unit that focuses the four split laser beams into four focal points in the measurement region of the fluid to be measured. , Photoelectric conversion means for receiving scattered laser light from the four focal points of the measurement area and outputting an electric signal, and a flow of fine particles based on the signal output from the photoelectric conversion means. The time interval of the counter and the signal is measured,
A signal processing means for calculating the flow velocity of the fine particles from the measured time intervals and the distances between the focal points; and the flow direction and flow velocity of the fine particles measured / processed by the signal processing means, It is set as the flow velocity.

Further, in order to solve the above-mentioned problems,
In the laser velocity meter according to the present invention, as described in claim 5, the beam splitter includes a first beam splitter for splitting a laser beam having a wavelength λ1 output from one semiconductor laser and an output from the other semiconductor laser. A second beam splitter for splitting the laser light having the wavelength λ2, and the laser light split by the beam splitter is collected by the condensing means into the measurement region of the fluid to be measured, where the wavelengths λ1, λ1, λ2,
λ2 or light having four wavelengths λ1, λ2, λ1, and λ2 condensed at the four focal points, and scattered laser light from these four focal points is received by two photoelectric conversion means having wavelengths λ1 and λ2 through an interference filter. Is.

Further, in order to solve the above-mentioned problems, the laser anemometer according to the present invention measures the velocity of fine particles in the fluid to be measured by using laser light, In a laser anemometer that outputs this particle velocity as a fluid velocity to be measured, a laser device that outputs at least two laser beams having different wavelengths and at least one of the laser beams output from this laser device A beam splitter that splits the laser beam into two laser beams, and at least three of the laser beam split by this beam splitter and the other laser beam in the measurement region of the fluid to be measured.
Based on the signal output from the photoelectric conversion means for receiving the scattered laser light from the fine particles passing through each focus of the measurement area and outputting an electric signal, Measuring the flow direction and time interval of the fine particles, having a signal processing means for calculating the flow velocity of the fine particles from the measured time interval and the distance between each focus,
The flow direction and flow velocity of the fine particles measured and processed by the signal processing means are set as the flow direction and flow velocity of the fluid to be measured.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a laser velocity meter according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of a laser anemometer according to the present invention. The laser velocimeter 11 is a small and compact handy type using small semiconductor lasers 12a and 12b as a laser device, and is manufactured to have a size of, for example, about 50 mm and a length of 150 mm. This laser velocimeter is capable of measuring not only the flow velocity of a fluid to be measured such as air and water but also the flow direction.

This laser velocimeter 11 comprises, as a laser device, two semiconductor lasers, a first semiconductor laser 12a for outputting a laser beam la of wavelength λ1 and a second semiconductor laser 12b for outputting a laser beam lb of wavelength λ2. . Collimator lenses 13a and 13b as collimators are installed on the optical axes of the semiconductor lasers 12a and 12b, respectively, and the collimator lenses 13a and 13b reduce the divergence angle of the laser light to form a parallel light beam, and two parallel light beams are formed. Is shaped into a laser beam.

On the output side of one collimator lens 13a, a laser beam la is supplied as two equal intensity laser beams la1 and l.
A beam splitter 14 for splitting into a2 is provided. As the beam splitter 14, a half mirror, a Savart plate, a Fresnel zone plate or the like may be used instead of the prism. On the output side of the beam splitter 14, a condensing lens 15 is installed as a condensing means for converging the laser light. With this condensing lens 15, two split laser lights la1 and la2 having a wavelength λ1 and a laser light having a wavelength λ2 are provided. lb is focused on the measurement region 3a of the fluid to be measured 3 such as air or water as three focal points.

In this way, the semiconductor lasers 12a, 1
The optical system from 2b to the condenser lens 15 is integrally assembled to form a scanning optical system 16. The scanning optical system 1
Laser beams la and lb of wavelengths λ1 and λ2 from the two semiconductor lasers 12a and 12b are scanned through 6 so that the measurement area 3a of the fluid 3 to be measured has three focal points.

FIG. 2 shows the vicinity of the measurement area 3a of the fluid 3 to be measured having three focal points, and the measurement area 3a
The three focal points formed in the
And it is adjusted in advance so as to be a predetermined value. The three focal points are formed independently for each of the wavelengths λ 1, λ 1, λ 2 of the laser light. As shown in FIG. 2, the focal positions are wavelengths λ 1, λ 1,
The order is λ 2. The respective laser beams la1, la2, lb that are irradiated onto the measurement region 3a of the fluid to be measured 3 are focused by the condenser lens 15 so that the laser beam diameter is reduced to the minimum diameter so as to form three focal points in the measurement region 3a. After being given, it expands again.

By flowing the fluid to be measured 3 such as air into the measuring area 3a, the fine particles P existing in the fluid to be measured 3 also flow in the measuring area 3 at the same speed and pass through the three focal points in order. Various fluids can be considered as the fluid to be measured 3 in addition to air and water, and the fine particles P existing in the fluid to be measured 3
Is a minute foreign particle of about several μm to several tens of μm. When the fine particles P do not exist in the fluid to be measured 3, atomizer (not shown) may be used to atomize the fluid into fine particles, and the fine particles may be sprayed into the fluid to be measured 3.

When the fine particles P existing in the fluid to be measured 3 pass through the measurement region 3a and sequentially cross the three focal points, the laser beam irradiated on the measurement region 3a is reflected by the scattering action of the fine particles P. The scattered (reflected) laser light scattered at the three focal positions is collected by the condenser lens 15 and made into parallel light. The collimated laser light is emitted from the interference filters 18a and 18b.
Through the condenser lenses 19a and 19b, and the light is received by the semiconductor light receiving elements 20a and 20b as photoelectric conversion means. The interference filters 18a and 18b are adapted to select and transmit a specific wavelength of the scattered laser light,
One interference filter 18a transmits the scattered laser light of wavelength λ1, and the other interference filter 18b transmits the scattered laser light of wavelength λ2.

These condenser lens 15 and interference filter 1
A reflective optical system 21 is configured by integrally combining 8a, 18b, condenser lenses 19a, 19b, and semiconductor light receiving elements 20a, 20b. The laser velocimeter 11 is integrated by combining the reflection optical system 21 and the scanning optical system 16 to form a small and compact measuring optical system 22. The measurement optical system 22 does not require optical axis adjustment and is maintenance-free. The laser anemometer 11 is a so-called backscattering type semiconductor laser anemometer in which a measurement region 3a is formed in the fluid 3 to be measured.

The semiconductor light receiving elements 20a and 20b include, for example, pin photodiodes, avalanche photodiodes, etc., and are used as small photoelectric conversion elements. The scattered laser light input to the semiconductor light receiving elements 20a and 20b is converted into a pulsed electric signal and input to the signal processor 23 as signal processing means. The signal processor 23 measures the time interval of the fine particles P passing between each focus and the flow direction of the fluid 3 to be measured based on the pulsed signal output from each semiconductor light receiving element 20a, 20b, and the measured time is measured. The flow velocity of the fine particles P is calculated and calculated from the interval and the distance between the focal points, and the flow velocity of the fine particles P is output as the flow velocity of the measured fluid 3.

Specifically, the signal processor 23 measures the time interval for the fine particles P to pass from the first focus to the second focus and the time interval for the fine particles P to pass from the second focus to the third focus. When both time intervals are equal, the inter-focal distance is divided by the measured time interval to determine the particle flow velocity. In this case, the focal lengths are adjusted in advance to be equal, and the focal lengths are preset to required values.

On the other hand, the fine particles P existing in the fluid 3 to be measured.
If the time interval of passing through the first focus to the second focus is not equal to the time interval of passing through the second focus from the second focus to the third focus, the signal data is treated as noise and the flow velocity calculation is stopped. By canceling this flow velocity calculation,
The flow velocity of the fluid to be measured can be accurately measured.

Laser light from the semiconductor lasers 12a and 12b is scanned by the scanning optical system 16 so as to independently form three focal points of wavelengths λ1, λ1 and λ2 on the measurement region 3a of the fluid 3 to be measured, Wavelengths λ1, λ1 in the measurement area 3a
, Λ2 laser beams form three focal points.

Now, assuming that the fluid to be measured 3 flows in the measurement region 3a from the lower side to the upper side in FIG. 2, the fine particles P in the fluid to be measured 3 output one pulse of an electric signal from one semiconductor light receiving element 20b. , The other semiconductor light receiving element 2
A 2-pulse electric signal is output from 0a.

If the fluid 3 to be measured flows from the upper side to the lower side in FIG.
After the pulse electric signal is output, the semiconductor light receiving element 20
An electric signal of 1 pulse is output from b. Therefore,
By counting the electric signals output from the semiconductor light receiving elements 20a and 20b, the flow direction of the fluid 3 to be measured can be accurately determined.

In this laser velocimeter 11, output laser beams la and lb from two small semiconductor lasers 12a and 12b form a measurement region 3a of the fluid 3 to be measured.
By converging as one focus, a larger amount of reflected laser light can be obtained than that of the conventional laser Doppler velocimeter that forms interference fringes in the measurement area 3a. As a result, the semiconductor light receiving element 20 which is a small photoelectric conversion element as photoelectric conversion means.
Even if a and 20b are used, an electric signal having an S / N ratio sufficient for signal processing can be obtained.

Further, the measuring optical system 22 from the semiconductor lasers 12a and 12b to the semiconductor light receiving elements 20a and 20b can be optically assembled into one body, and the optical axis adjustment is not required when measuring the flow velocity of the measuring fluid 3 and the life is long. Makes maintenance easier. Moreover, the measuring optical system 22 can be made into a small and compact handy type having a diameter of 50 mm and a length of 150 mm, for example, by adopting the small semiconductor lasers 12a and 12b and the semiconductor light receiving elements 20a and 20b. Is improved.

Further, since the measurement optical system 22 constituting the laser velocity meter 11 is designed to be small and compact, it is easy to carry it to the measurement place, set it for measurement, and assemble it to another device, and Not only the flow velocity of the measurement fluid 3 but also its flow direction can be measured easily and accurately. Moreover, since the flow direction of the fluid to be measured 3 is known, the flow velocity can be measured more accurately.

FIG. 3 shows a second embodiment of the laser anemometer according to the present invention.

This laser velocimeter 11A basically has the same configuration as the laser velocimeter 11 shown in FIG. 1 except for the arrangement of the two semiconductor lasers 12a and 12b as a laser device, and therefore the same parts are the same. The reference numerals are given and the description is omitted.

The laser velocimeter 11A shown in FIG. 3 is different from the laser velocimeter 11 shown in FIG. 1 in that the arrangement of the semiconductor laser 12a for the wavelength λ1 and the semiconductor laser 12b for the wavelength λ2 constituting the laser device is exchanged. It was replaced. By replacing the semiconductor lasers 12a and 12b with the semiconductor laser shown in FIG.
The laser lights la and lb output from the
b is divided into two laser beams lb1 and lb2, and wavelengths λ2,
It is focused and focused so that it has three focal points of λ2 and λ1 at equal intervals.

By flowing the fluid to be measured 3 into the measurement area 3a, the fine particles P existing in the fluid to be measured 3 also flow in the measurement area 3a at the same speed and sequentially pass through the three focal points.

When the fine particles P pass through the three focal points, the irradiated laser beams lb1, lb2, la are scattered.
The scattered laser light is collimated by the condenser lens 15 of the reflection optical system 21. The collimated laser light is then transmitted by the interference filters 18a and 18b to the wavelengths λ1 and λ2 of the transmitted laser light.
Is selected, and is condensed by the condenser lenses 19a and 19b to be received on the semiconductor light receiving elements 20a and 20b as photoelectric conversion means. These semiconductor light receiving elements 20a, 20b
The electric signal from the signal processor 23 is a signal processing means.
And is processed by the signal processor 23.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity of the fine particles P passing through the measurement region 3a and the direction of the flow thereof are calculated and obtained. Specifically, the time interval at which the fine particles P pass the first focus and the second focus of the measurement area 3a and the time interval at which the fine particles P pass the second focus and the third focus are measured, and both time intervals are equal. In this case, the flow velocity is calculated by dividing the focal length by this time interval. When the time interval for the particle P to pass the first focus and the second focus and the time interval for the particle P to pass the second focus and the third focus are not equal, the flow velocity calculation is stopped because there is noise in the signal data. .

The laser velocimeter 11A is the scanning optical system 1
As shown in FIG. 4, three focal points of wavelengths λ2, λ2, λ1 are independently formed in order in the measurement area 3a of the fluid to be measured 3 by the focal point arrangement of the wavelengths λ2, λ2, λ1. Assuming that the fluid to be measured 3 flows from the lower side to the upper side in FIG. 4, the semiconductor light receiving element 20a outputs one pulse electric signal after the semiconductor light receiving element 20a outputs one pulse due to the fine particles P existing in the fluid to be measured 3. On the contrary, if a flow is generated from the upper side to the lower side in FIG. 4, the semiconductor light receiving element 20b
After outputting 2 pulses, the semiconductor light receiving element 20a outputs 1 pulse, and the flow direction can be accurately known.

FIG. 5 shows a third laser velocity meter according to the present invention.
1 shows an embodiment.

This laser velocimeter 11B is different from the laser velocimeter 11 shown in FIG. 1 in the arrangement structure of the scanning optical system 16A, and other constitutions are not different.

The laser velocimeter 11B shown in FIG. 5 includes two semiconductor lasers 12 as laser devices in the scanning optical system 16A.
The point provided with a and 12b is common to the laser velocity meter 11 of FIG. However, the laser velocity meter 11B in FIG.
The laser light output from the semiconductor laser 12a for use in the laser beam is shaped into a parallel light flux through the collimator lens 20a, and is split by the beam splitter 14 into laser light of two wavelengths .lambda.1 with equal intensity. And the two divided wavelengths λ1
The laser light lb output from the semiconductor laser 12b for wavelength λ2 is output between the laser lights la1 and lb2 via the collimator lens 20b. The three laser beams la1, la2, lb outputted from the respective semiconductor lasers 12a, 12b are focused by a condenser lens 15 as a condensing means, and have three independent focal points on the measurement region 3a of the fluid 3 to be measured. It is focused so that it will be held at equal intervals. The three focal points have a focal point arrangement of wavelengths λ1, λ2, and λ1, and the diameter of each laser beam is narrowed to the minimum diameter at the focal point and then scanned so as to expand again.

By flowing the fluid to be measured 3 into the measurement area 3a, the fine particles P existing in the fluid to be measured 3 also flow in the measurement area 3a at the same speed and sequentially pass through the three focal points.
When the fine particles P pass through the three focal points, the fine particles P scatter the irradiation laser light la1, la2, lb. The scattered laser light is condensed by the condenser lens 15 of the reflection optical system 21 to be parallel light.

This parallel laser light is transmitted to the interference filter 18a,
The wavelengths λ1 and λ2 of the transmitted laser beam are selected by 18b, and the transmitted laser beams of the wavelengths λ1 and λ2 are further condensed by the condenser lenses 19a and 19b, and the semiconductor light receiving elements 20a and 20b as photoelectric conversion means. Received on.
The electric signals from the semiconductor light receiving elements 20a and 20b are
It is input to a signal processor 23 as a signal processing means, and signal processing is performed by this signal processor 23.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity and direction of the flow of the fine particles P passing through the measurement region 3a are arithmetically processed from the input electric signal. I am asking for. Specifically, the time interval for the fine particles P to pass the first focus and the second focus and the time interval for the fine particles P to pass the second focus and the third focus are determined. The flow velocity of the particles is calculated by dividing the distance by this time interval. The time interval for the fine particles P to pass the first focus and the second focus and the fine particles P
If the time intervals for passing the focal point and the third focal point are not equal,
Stop the flow velocity calculation because there is noise in the signal data.

The laser velocimeter 11B is the scanning optical system 1
As shown in FIG. 6, three focal points of wavelengths .lambda.1, .lambda.2, .lambda.1 are sequentially and independently formed in the measurement region 3a of the fluid 3 to be measured by 6A. Assuming that the fluid to be measured 3 flows from the lower side to the upper side in FIG. 6 due to the focus arrangement of the wavelengths λ 1, λ 2, and λ 1, the semiconductor light receiving element 20 a outputs one pulse after the semiconductor light receiving element 20 a is output by the fine particles P existing in the fluid to be measured 3. The light receiving element 20b outputs one pulse, and further the semiconductor light receiving element 2
0a outputs one pulse larger than the previous one pulse output. Assuming that a flow is generated from the upper side to the lower side in FIG. 6, the semiconductor light receiving element 20a outputs one pulse and then the semiconductor light receiving element 2
0b outputs one pulse, and the semiconductor light receiving element 20a outputs one pulse smaller than the previous one pulse output. By comparing the pulse outputs, the flow direction can be known.

FIG. 7 shows a fourth example of the laser velocity meter according to the present invention.
1 shows an embodiment.

The laser anemometer 11 shown in this embodiment
C has the same structure as the laser velocity meter 11B shown in FIG. 5 except for the arrangement of the two semiconductor lasers that form the laser device, and therefore the same parts are designated by the same reference numerals and description thereof is omitted.

The laser velocimeter 11C shown in FIG. 7 is obtained by exchanging the laser velocimeter 11B shown in FIG. 5 with a semiconductor laser 12a for wavelength λ1 and a semiconductor laser 12b for wavelength λ2. is there. Semiconductor laser 12a,
By replacing 12b with the semiconductor laser shown in FIG. 5, one of the laser lights la and lb output from the semiconductor lasers 12a and 12b is divided into two laser lights lb1 and lb2. The three laser beams 1a, 1b1, and 1b2 are scanned by the scanning optical system 16B, and the condensing lens 15 as the condensing means causes the wavelength to be measured in the measurement region 3a of the fluid 3 to be measured as shown in FIG. λ 2, λ
It is focused and focused so that it has three focal points of 1 and λ2 at equal intervals.

By flowing the fluid to be measured 3 into the measurement area 3a, the fine particles P existing in the fluid 3 to be measured also flow in the measurement area 3a at the same speed in a floating state and pass through the three focal points in order.

When the fine particles P pass through the three focal points in order, the irradiated laser beams lb1, 1a, lb2 are scattered in order. The scattered (reflected) laser light is reflected by the reflection optical system 21.
It is made into parallel light by the condenser lens 15. The wavelengths λ1 and λ2 of the transmitted laser light of the parallel laser light are subsequently selected by the interference filters 18a and 18b, and the condenser lenses 19a and 1a are selected.
The light is focused on 9b and received on the semiconductor light receiving elements 20a and 20b as photoelectric conversion means. The electric signals from the semiconductor light receiving elements 20a and 20b are input to a signal processor 23 as signal processing means, and the signal processor 23 processes the signals.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity of the fine particles P passing through the measurement region 3a and the direction of the flow thereof are calculated and obtained. Specifically, the time interval at which the fine particles P pass the first focus and the second focus of the measurement area 3a and the time interval at which the fine particles P pass the second focus and the third focus are measured, and both time intervals are equal. In this case, the flow distance of the fine particles P is calculated by dividing the focal length by this time interval. When the time interval for the particle P to pass the first focus and the second focus and the time interval for the particle P to pass the second focus and the third focus are not equal, the flow velocity calculation is stopped because there is noise in the signal data. .

The laser velocity meter 11C is the scanning optical system 1
As shown in FIG. 8, three focal points of wavelengths .lambda.2, .lambda.1 and .lambda.2 are sequentially formed independently in the measurement region 3a of the fluid 3 to be measured by 6B. Assuming that the fluid 3 to be measured flows upward from the lower part of FIG. 8 due to the focus arrangement of the wavelengths λ 2, λ 1, and λ 2, the semiconductor light receiving element 20 b outputs one pulse of electric signal by the fine particles P existing in the fluid 3 to be measured. Then, the semiconductor light receiving element 20a outputs one pulse, and the semiconductor light receiving element 20b outputs one pulse smaller than the previous one pulse output. Assuming that a flow occurs from the upper side to the lower side in FIG. 8,
The semiconductor light receiving element 20b outputs one pulse, and then the semiconductor light receiving element 20a outputs one pulse.
b outputs one pulse larger than the previous one pulse output, and the direction of the flow can be known by comparing the output pulse signals.

FIG. 9 shows a fifth example of the laser anemometer according to the present invention.
1 shows an embodiment.

Laser velocity meter 11 shown in this embodiment
D is a scanning optical system 1 from the laser velocity meter 11 shown in FIG.
The arrangement structure of 6C is basically different, and other configurations are not substantially different, and therefore, the same reference numerals are given and the description thereof is omitted.

A laser velocimeter 11D shown in FIG. 9 is a semiconductor laser device including two semiconductor lasers 12a, 12 having different wavelengths.
The configuration in which b is prepared and two collimator lenses 13a and 13b as collimators are provided on the optical axes of the laser beams output from the respective semiconductor lasers 12a and 12b is not different from the laser velocity meter 11 shown in FIG. Laser velocity meter 1 in FIG. 9
1D is provided with beam splitters 14a and 14b for splitting a laser beam into two laser beams with equal intensity on the output side of each collimator lens 13a and 13b. On the output side of each beam splitter 14a, 14b, the split wavelength λ1
Laser light la1, 1a2 and laser light lb1 of wavelength λ2
, 1b2 each of which is focused on the measurement region 3a of the fluid to be measured 3 is provided with a condenser lens 15 as a condensing optical system 16C.

A total of four laser beams la1, la2, lb1, and 1b2 each having two wavelengths λ1 and λ2 are used in the scanning optical system 1.
It is focused by the condenser lens 15 of 6C and is condensed so as to have four focal points at equal intervals in the measurement region 3a of the fluid 3 to be measured. Each focus has a wavelength λ1 as shown in FIG.
, Λ1, λ2, λ2 are formed in this order. The diameters of the four laser beams la1, la2, lb1, and 1b2 are narrowed down by the condenser lens 15 to the minimum diameter at the lens focus position, and the four wavelengths λ1, λ1, λ2, and λ2 are obtained.
After forming one focal point, it is gradually expanding again.

By flowing the fluid to be measured 3 into the measurement area 3a, the fine particles P existing in the fluid to be measured 3 and floating also flow at the same speed and sequentially pass through the four focal points. 4 particles P
Irradiation laser light la1, la2 when passing through one focal point
, Lb1 and 1b2 are scattered. The scattered laser light is then collected by the condenser lens 15 of the reflection optical system 21 and made into parallel light. This collimated laser light is emitted from the interference filters 18a, 1
The wavelengths λ1 and λ2 of the transmitted light are selected by using 8b,
One interference filter 18a selects the laser light of wavelength λ1 and the other interference filter 18b selects and transmits the laser light of wavelength λ2.

The transmitted laser beams of wavelengths λ1 and λ2 are subsequently condensed by condenser lenses 19a and 19b and received by small semiconductor light receiving elements 20a and 20b as photoelectric conversion means. It is converted into an electric signal. The electric signals from the semiconductor light receiving elements 20a and 20b are input to the signal processor 23 as a signal processing means and subjected to signal processing.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity of the fine particles P passing through the measurement region 3a and the flow direction thereof are arithmetically processed from the input electric signal. I am asking for. Specifically, the time interval at which the fine particles P existing in the fluid to be measured 3 pass through the first focus and the second focus and the time interval at which the fine particles P pass through the third focus and the fourth focus are measured, When both time intervals are the same, the flow distance of the fine particles P is calculated by dividing the focal length by this time interval. If the time interval for the particle P to pass through the first focus and the second focus and the time interval for the particle P to pass through the third focus and the fourth focus are not equal, the flow velocity calculation is stopped because there is noise in the signal data. .

The laser velocity meter 11D is the scanning optical system 1
As shown in FIG. 10, four focal points of wavelengths .lambda.1, .lambda.1, .lambda.2, .lambda.2 are formed independently at equal intervals in the measurement region 3a of the fluid 3 to be measured by 6C. This wavelength λ1, λ1
, Λ2, and λ2 are arranged so that the fluid 3 to be measured is shown in FIG.
If it is assumed that the fluid flows from the lower side to the upper side at 0, the semiconductor light receiving element 20b outputs 2 pulses after the semiconductor light receiving element 20b outputs 2 pulses by the fine particles P existing in the fluid to be measured 3. If a flow occurs below the upper side of FIG. 10,
After the semiconductor light receiving element 20a outputs 2 pulses, the semiconductor light receiving element 20b outputs 2 pulses.
You can see the flow direction of.

In this laser velocimeter 11D, the output laser beams la and lb from the two small semiconductor lasers 12a and 12b are respectively divided and focused as four focal points forming the measurement region 3a of the fluid 3 to be measured. By doing so, a larger amount of reflected laser light can be obtained as compared with the conventional laser Doppler velocimeter that forms interference fringes in the measurement region. As a result, a small semiconductor light receiving element 20a serving as a photoelectric conversion unit,
Even if 20b is used, an electric signal having a sufficient S / N ratio for signal processing can be obtained.

Further, the measuring optical system 22 from the semiconductor lasers 12a and 12b to the semiconductor light receiving elements 20a and 20b can be optically assembled integrally, and the optical axis adjustment is not required when measuring the flow velocity of the measuring fluid 3, so that the life is long. Makes maintenance easier. Moreover, the measuring optical system 22 can be made into a small and compact handy type having a diameter of 50 mm and a length of 150 mm, for example, by adopting the small semiconductor lasers 12a and 12b and the semiconductor light receiving elements 20a and 20b. Is improved.

Further, since the measurement optical system 22 constituting the laser anemometer 11D is designed to be small and compact, it is easy to carry it to the measurement place, make settings for the measurement, and assemble it to other equipment. Not only the flow velocity of the measurement fluid 3 but also its flow direction can be measured easily and accurately. Moreover, the flow velocity can be measured more accurately by measuring the flow direction of the fluid to be measured 3.

FIG. 11 shows a sixth embodiment of the laser anemometer according to the present invention.

This laser anemometer 11E has a reflection optical system 21.
Since the arrangement configuration of A is different from that of the laser velocity meter 11D shown in FIG. 9 and other configurations are substantially the same, the same reference numerals are given and description thereof will be omitted. The laser velocimeter 11E shown in FIG. 11 is obtained by exchanging and exchanging the two interference filters 18a and 18b forming the reflection optical system 21A.
That is, one interference filter 18a that passes laser light of wavelength .lambda.1 is combined with the other semiconductor light receiving element 20b, which is a photoelectric conversion means, via the condenser lens 19b, and the other interference filter 18b for wavelength .lambda.2 is combined with the condenser lens 19a. It is combined with one of the semiconductor light receiving elements 20a via the.

In this laser velocimeter 11E, the fluid to be measured 3 is made to flow by flowing the fluid to be measured 3 into the measurement area 3a.
The fine particles P present therein also flow through the measurement region 3a at the same speed, and successively pass through the four focal points of wavelengths λ1, λ1, λ2, and λ2.

When the fine particles P pass through the four focal points, the emitted laser beams la1, la2, lb1 and lb2 are scattered in order. The scattered laser light is collimated by the condenser lens 15 of the reflection optical system 21A. The wavelength of the transmitted laser light of the parallel laser light is subsequently selected by the two interference filters 18a and 18b. One interference filter 18
a and 18b select the laser light of wavelength .lambda.1 and the other interference filter 18b selects and transmits the laser light of wavelength .lambda.2. The laser beams whose wavelengths have been selected and transmitted by the interference filters 18a and 18b are collected by the condenser lenses 19a and 19b.
The light is collected by and is received on the semiconductor light receiving elements 20a and 20b. The electric signals from the semiconductor light receiving elements 20a and 20b are input to the signal processor 23 as a signal processing means and processed.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity of the fine particles P passing through the measurement region 3a and the direction of the flow thereof are calculated and obtained. Specifically, the fine particles P passing through the measurement area 3a
Measuring the time interval during which the particles pass through the first focus and the second focus and the time interval during which the particles P pass through the third focus and the fourth focus,
When both time intervals are the same, the flow distance of the fine particles P is calculated by dividing the focal length by this time interval. If the time interval for the particle P to pass through the first focus and the second focus and the time interval for the particle P to pass through the third focus and the fourth focus are not equal, the flow velocity calculation is stopped because there is noise in the signal data. .

Further, the laser velocity meter 11E is the scanning optical system 2
As shown in FIG. 12, four focal points of wavelengths λ1, λ1, λ2, and λ2 are sequentially formed independently in the measurement region 3a of the fluid 3 to be measured by 1A. Wavelengths λ1, λ1, λ2, λ2
Assuming that the fluid to be measured 3 flows upward from below in FIG. 12 due to the focal point arrangement, the semiconductor light receiving element 20a outputs 2 pulses after the semiconductor light receiving element 20a outputs 2 pulses due to the fine particles P in the fluid to be measured 3. If a flow occurs from the upper side to the lower side in FIG. 12, the semiconductor light receiving element 20b outputs two pulses, and then the semiconductor light receiving element 20a outputs two pulses, and the flow direction of the fine particles P, and thus the flow direction of the fluid 3 to be measured. I understand.

FIG. 13 shows a seventh embodiment of the laser anemometer according to the present invention.

Laser velocity meter 11 shown in this embodiment
F is the two collimator lenses 13 of the scanning optical system 16D.
two beam splitters 24a on the output side of a and 13b,
24b respectively, and each beam splitter 24a,
Two laser lights la1 divided into equal intensity by 24b,
One of la2, lb1 and lb2 is crossed with each other, and the four focal points condensed by the condensing lens 15 as the condensing means have the focal points of wavelengths λ1, λ2, λ1 and λ2. The other configurations are not different from those of the laser velocity meter 11D shown in FIG. 9, and thus the same reference numerals are given and the description thereof will be omitted.

This laser anemometer 11F has a scanning optical system 16
By combining the beam splitters 24a and 24b constituting D and the condenser lens 15, four focal points are formed in the measurement region 3a of the fluid 3 to be measured in the order of wavelengths λ1, λ2, λ1 and λ2. The four focal points formed in the measurement area 3a are shown in FIG.
As shown in, the focal lengths are equal and the wavelengths λ1, λ2, λ1
, Λ2, and the diameter of the irradiation laser beam is narrowed down to the minimum diameter by the converging lens 15 at four focal points, and then expanded again.

By flowing the fluid to be measured 3 into the measurement area 3a, the fine particles P existing in the measurement fluid 3 also flow in the measurement area 3a at the same speed and pass through the four focal points in order. When the fine particles P pass through the four focal points, the fine particles P scatter the irradiation laser light la1, la2, lb1, and lb2. The scattered laser light is condensed by the condenser lens 15 of the reflection optical system 21 to be parallel light.

This collimated laser beam is emitted by the interference filter 18a,
The wavelengths λ1 and λ2 of the transmitted laser light are selected by 18b, and the transmitted laser light of the wavelengths λ1 and λ2 is further condensed by the condenser lenses 19a and 19b, and a small semiconductor light receiving element 20a as photoelectric conversion means. , 20b is received. The electric signals from the semiconductor light receiving elements 20a and 20b are input to a signal processor 23 as a signal processing means and processed by the signal processor 23.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity and direction of flow of the fine particles P passing through the measurement region 3a are arithmetically processed from the input electric signal. I am asking for. Specifically, the time interval for the fine particles P to pass the first focus and the second focus and the time interval for the fine particles P to pass the third focus and the fourth focus are determined. The flow velocity of the particles is calculated by dividing the distance by this time interval. The time interval during which the fine particles P pass the first focus and the second focus and the fine particles P are
If the time intervals for passing the focal point and the fourth focal point are not equal,
Stop the flow velocity calculation because there is noise in the signal data.

The laser velocity meter 11F is the scanning optical system 1
As shown in FIG. 14, four focal points of wavelengths λ1, λ2, λ1, and λ2 are sequentially formed independently in the measurement region 3a of the fluid 3 to be measured by 6D. This wavelength λ 1, λ 2, λ 1,
Assuming that the fluid to be measured 3 flows from the lower side to the upper side in FIG. 14 due to the focal point arrangement of λ2, the semiconductor light receiving element 20b outputs 1 pulse after the semiconductor light receiving element 20b outputs 1 pulse by the fine particles P existing in the fluid to be measured 3. After the semiconductor light receiving element 20b outputs one pulse smaller than the one pulse output of the previous semiconductor light receiving element 20b, the semiconductor light receiving element 20a outputs one pulse larger than the previous one pulse output. Assuming that a flow occurs below the upper side of FIG. 14,
The semiconductor light receiving element 20a outputs one pulse, and then the semiconductor light receiving element 20b outputs one pulse.
a is smaller than the previous 1-pulse output, the semiconductor light-receiving element 20b is larger than the previous 1-pulse output by 1
Since pulse output is performed, the flow direction can be known by comparing the pulse outputs.

FIG. 15 shows an eighth laser velocimeter according to the present invention.
1 shows an embodiment.

Laser velocity meter 11 shown in this embodiment
G shows the arrangement configuration of the reflective optical system 21A different from that shown in FIG. Since other configurations are the same as those of the laser velocity meter 11F shown in FIG. 13, the same reference numerals are given and description thereof is omitted. The laser velocimeter 11G shown in FIG. 15 has two interference filters 18a and 18b constituting the reflection optical system 21A arranged reversely to the laser velocimeter 11F shown in FIG.
It is the one in which b is replaced.

That is, one interference filter 18a for transmitting the laser beam of wavelength λ1 is combined with the other semiconductor light receiving element 20b via the condenser lens 19b, and the other interference filter 18b for wavelength λ2 is transmitted through the condenser lens 19a. One of them is combined with one of the semiconductor light receiving elements 20a.

This laser anemometer 11G has a measuring area 3a.
By flowing the fluid 3 to be measured, the fine particles P existing in the fluid 3 to be measured also flow at the same speed in the measurement region 3a and sequentially pass through the four focal points of wavelengths λ1, λ2, λ1 and λ2.

When the fine particles P pass through the four focal points, the irradiated laser beams la1, lb1, la2, lb2 are sequentially scattered. The scattered laser light is collimated by the condenser lens 15 of the reflection optical system 21A. The wavelength of the transmitted laser light of the parallel laser light is subsequently selected by the two interference filters 18a and 18b. One interference filter 18
a and 18b select the laser light of wavelength .lambda.1 and the other interference filter 18b selects and transmits the laser light of wavelength .lambda.2. The laser beams whose wavelengths have been selected and transmitted by the interference filters 18a and 18b are collected by the condenser lenses 19a and 19b.
The light is collected by and is received on the semiconductor light receiving elements 20a and 20b. The electric signals from the semiconductor light receiving elements 20a and 20b are input to the signal processor 23 as a signal processing means and processed.

A pulsed electric signal corresponding to the scattered laser light is input to the signal processor 23, and the velocity of the fine particles P passing through the measurement region 3a and the direction of the flow thereof are calculated and obtained. Specifically, the fine particles P passing through the measurement area 3a
Measuring the time interval during which the particles pass through the first focus and the second focus and the time interval during which the particles P pass through the third focus and the fourth focus,
When both time intervals are the same, the flow distance of the fine particles P is calculated by dividing the focal length by this time interval. If the time interval for the particle P to pass through the first focus and the second focus and the time interval for the particle P to pass through the third focus and the fourth focus are not equal, the flow velocity calculation is stopped because there is noise in the signal data. .

Further, the laser velocity meter 11G is the scanning optical system 1
As shown in FIG. 16, four focal points of wavelengths λ1, λ2, λ1, and λ2 are sequentially formed independently in the measurement region 3a of the fluid 3 to be measured by 6D. Wavelengths λ1, λ2, λ1, λ2
16, the semiconductor light receiving element 20a outputs one pulse after the semiconductor light receiving element 20a outputs one pulse due to the fine particles P in the fluid to be measured 3 and the semiconductor light receiving element 20b outputs one pulse. , Semiconductor light receiving element 20
a is larger than the previous 1-pulse output, the semiconductor light-receiving element 20b is smaller than the previous 1-pulse output 1
Output pulse. Assuming that a flow is generated from above in FIG. 16 to below, after the semiconductor light receiving element 20b outputs one pulse,
The semiconductor light receiving element 20a outputs one pulse, and after the semiconductor light receiving element 20b outputs one pulse larger than the previous one pulse output, the semiconductor light receiving element 20a outputs one pulse smaller than the previous one pulse output. Fine particle P
The flow direction of, and consequently the flow direction of the fluid 3 to be measured is known.

In each of the embodiments of the laser anemometer according to the present invention, the transmissive collimator is used as the collimator of the scanning optical system, but a reflective collimator may be adopted. When the reflection type collimator is adopted, the layout of the scanning optical system is changed according to the adoption.

In the laser anemometer according to the present invention, an example using a small semiconductor laser as the laser light source and a small semiconductor light receiving element as the photoelectric conversion means is shown.
A laser device such as a gas laser other than a semiconductor laser may be used as the laser light source, and a photoelectric conversion element such as a photomultiplier tube having a large amplification factor may be used as the photoelectric conversion means.
When a laser device other than a semiconductor laser or a photoelectric conversion element is used, the measurement optical system becomes large, but the laser device is caused to output two laser beams having different wavelengths, and the output laser beam is used as shown in FIGS. By scanning laser light with an optical system similar to the measurement optical system shown in 16 and performing signal processing, not only the flow velocity of the fluid to be measured but also the flow direction can be measured, and the flow velocity can be measured further. Can be done accurately.

[0090]

As described above, the laser anemometer according to the present invention adopts the backscattering method, uses two semiconductor lasers having different wavelengths as the laser light source, and outputs the laser light output from the semiconductor laser. At least one of them is divided by a beam splitter, and condensed by a condensing means into at least three focal points in the measurement region of the fluid to be measured, and at least
The scattered laser light from one focal point is received by the photoelectric conversion means and an electric signal is output, and the electric signal is processed by the signal processing means, so that a sufficiently large amount of reflected (scattered) light can be obtained and the measured signal can be measured. The flow velocity of the fluid can be measured, and at the same time, the flow direction of the fluid to be measured can be measured, and the accuracy of the flow velocity measurement can be improved.

Further, this laser velocimeter uses a small semiconductor laser, and the measuring optical system from the semiconductor laser to the photoelectric conversion means can be integrated into the backscattering method, and the optical axis adjustment is not necessary at the time of measurement, and maintenance is possible. While it is free and has a long life, it is compact and compact, improves mobility, makes it easy to carry it to the measurement location, make settings for measurement, and incorporate it into other devices. It is possible to accurately and easily measure the flow velocity and the flow direction.

Further, when a laser device other than a semiconductor laser is used as the laser light source for this laser light, the laser output is increased to obtain a larger amount of reflected light,
Not only the flow velocity of the fluid to be measured but also the flow direction can be reliably and accurately measured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a measurement optical system showing a first embodiment of a laser anemometer according to the present invention.

FIG. 2 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 3 is a schematic configuration diagram of a measurement optical system showing a second embodiment of the laser anemometer according to the present invention.

FIG. 4 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 5 is a schematic configuration diagram of a measurement optical system showing a third embodiment of the laser anemometer according to the present invention.

6 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 7 is a schematic configuration diagram of a measurement optical system showing a fourth embodiment of the laser anemometer according to the present invention.

8 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 9 is a schematic configuration diagram of a measurement optical system showing a fifth embodiment of the laser anemometer according to the present invention.

10 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 11 is a schematic configuration diagram of a measurement optical system showing a sixth embodiment of the laser anemometer according to the present invention.

12 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 13 is a schematic configuration diagram of a measurement optical system showing a seventh embodiment of the laser anemometer according to the present invention.

14 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 15 is a schematic configuration diagram of a measurement optical system showing an eighth embodiment of the laser anemometer according to the present invention.

16 is an enlarged view showing a measurement region of the fluid to be measured shown in FIG.

FIG. 17 is a schematic configuration diagram showing a conventional laser anemometer.

FIG. 18 is an enlarged view showing a measurement region of a fluid to be measured in a conventional laser anemometer.

[Explanation of symbols]

3 fluid to be measured 3a measurement area 11, 11A, 11B, 11C, 11D, 11E, 11
F, 11G Laser velocity meter 12a, 12b Semiconductor laser 13a, 13b Collimator lens (collimator) 14, 14a, 14b, 24a, 24b Beam splitter 15 Focusing lens (focusing means) 16, 16A, 16B, 16C, 16D Scanning optics System 18a, 18b Interference filter 19a, 19b Condensing lens 20a, 20b Semiconductor light receiving element 21, 21A Reflective optical system 22 Measuring optical system 23 Signal processor (signal processing means) P Fine particles

Claims (6)

[Claims] 1. A laser anemometer for measuring a particle velocity in a fluid to be measured using a laser beam and outputting the particle velocity as a fluid velocity to be measured, comprising two semiconductor lasers which output laser beams having different wavelengths. A collimator that reduces the divergence angle of the laser light output from the semiconductor laser to form a laser beam of parallel light flux; and a beam splitter that splits one of the laser light of parallel light flux into two laser lights. Condensing means for condensing the two laser beams and the other laser beam into at least three focal points in the measurement region of the fluid to be measured, and the scattered laser beams from the respective focal points in the measurement region are received to generate an electric signal. Photoelectric conversion means for outputting
A signal processing means for measuring the flow direction of the particles and the time interval of the signal based on the signal output from the photoelectric conversion means, and calculating the flow velocity of the particles from the measured time interval and each of the focal distances. Measurement with the above signal processing means
A laser anemometer characterized in that a flow direction and a flow velocity of fine particles to be processed are set as a flow direction and a flow velocity of a fluid to be measured. 2. The beam splitter splits one of the laser beams of wavelengths λ1 and λ2 output from the semiconductor laser,
The split laser beam and the other laser beam are focused by the focusing means, and are focused on the measurement area of the fluid to be measured as three focal points of λ1, λ1, λ2 or wavelengths λ2, λ2, λ1, and these three focal points. The laser anemometer according to claim 1, wherein the scattered laser light from is received by the photoelectric conversion means via an interference filter. 3. The beam splitter splits one of the laser beams of wavelengths λ1 and λ2 output from the semiconductor laser,
The split laser beam and the other laser beam are focused by the focusing means, and are focused on the measurement area of the fluid to be measured as three focal points of λ1, λ2, λ1 or wavelengths λ2, λ1, λ2, and these three focal points are focused. The laser anemometer according to claim 1, wherein the scattered laser light from is received by the photoelectric conversion means via an interference filter. 4. A laser anemometer for measuring a particle velocity in a fluid to be measured using a laser beam and outputting the particle velocity as a fluid velocity to be measured, comprising two semiconductor lasers which output laser beams having different wavelengths. A collimator that reduces the divergence angle of the laser light output from the semiconductor laser to form a laser beam of parallel light flux; and a beam splitter that splits each laser light of the parallel light flux into two laser lights. Condensing means for condensing four laser beams into the measurement area of the fluid to be measured as four focal points, and photoelectric conversion means for receiving scattered laser light from the four focal points in the measurement area and outputting an electric signal. And the flow direction of the particles and the time interval of the signal are measured based on the signal output from this photoelectric conversion means, and the flow velocity of the particles is measured from the measured time interval and each focal distance. And a signal processing means for performing an arithmetic processing, and the flow direction and flow velocity of the fine particles measured and processed by the signal processing means are set as the flow direction and flow velocity of the fluid to be measured. 5. The beam splitter comprises a first beam splitter for splitting a laser beam of wavelength λ1 output from one semiconductor laser and a second beam splitter for splitting a laser beam of wavelength λ2 output from the other semiconductor laser. A splitter, and the laser light split by both of the above-mentioned beam splitters is focused on the measurement region of the fluid to be measured by the wavelength λ 1,
λ1, λ2, λ2 or wavelengths λ1, λ2, λ1, λ2 are condensed as four focal points, and the scattered laser light from these four focal points is wavelength λ1, wavelength λ2 through an interference filter.
5. The laser anemometer according to claim 4, wherein the two photoelectric conversion means are used to receive light. 6. A laser anemometer for measuring the velocity of fine particles in a fluid to be measured using laser light and outputting the velocity of the fine particles as the fluid velocity to be measured outputs at least two laser lights having different wavelengths. A laser device, a beam splitter that splits at least one of the laser beams output from this laser device into two laser beams, and a laser beam split by this beam splitter and the other laser beam. Condensing means for condensing at least three focal points in the measurement area of the measurement fluid, photoelectric conversion means for receiving scattered laser light from fine particles passing through each focal point of the measurement area and outputting an electric signal, and this photoelectric conversion The direction of the particle flow and the time interval are measured based on the signal output from the means, and the particle flow velocity is calculated from the measured time interval and the distance between the focal points. A laser velocimeter having a signal processing means for performing arithmetic processing, wherein a flow direction and a flow velocity of fine particles measured and processed by the signal processing means are set as a flow direction and a flow velocity of a fluid to be measured.