JPH0346054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an optical device for precision measurement that uses an optical system to precisely measure physical quantities in general.
In particular, the present invention is designed to automatically carry out precise measurements of changes in physical quantities using a portable device.

(Prior Art) Precision measuring devices for physical quantities in general, particularly atmospheric pressure, which is a preferred object of the present invention, have conventionally been fixed types, and representative examples include mercury barometers and aneroid barometers. The former has good measurement accuracy and high reliability, but cannot be said to be easy to measure and handle.The latter is fairly easy to measure and handle, but does not provide as good a measurement accuracy as the former. Not yet.

However, atmospheric pressure requires much more accurate measurement values than other meteorological parameters, such as snowfall and humidity. There is no problem with the above, but the measurement error of atmospheric pressure must be kept below 0.2 to 0.3mb, and this error value is, assuming the measured value is 1000mb.
This corresponds to an error of about 0.03%, which requires measurement accuracy that is two orders of magnitude higher than the measurement error of snowfall.

(Problems to be Solved by the Invention) Although there has been a strong demand for a barometric pressure measuring device that can obtain such high measurement accuracy, is portable, and can perform automatic measurements with easy handling, , has not yet been developed. In particular, there is a demand for the development of a high-precision barometric pressure measurement device that is configured to be compatible with information transmission mechanisms and information display mechanisms related to atmospheric pressure measurement results, but such requests have not been met in the past. Not satisfied.

The above-mentioned problems regarding precision measuring devices with high measurement accuracy are not limited to the example of the above-mentioned barometric pressure measuring device, but are common to precision measuring devices for general physical quantities such as temperature as well as other fluid pressures.
There is a need for the development of precision measuring devices that have both high measurement accuracy and ease of use such as easy handling, portability, immediacy, automation, and information transferability for physical quantities in general.

(Means for solving the problems) An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an optical device for precision measurement that skillfully utilizes an optical system and is capable of immediately and automatically measuring physical quantities such as atmospheric pressure with high precision.

That is, the optical device for precision measurement of the present invention converts a mechanical output quantity such as a stroke of a physical quantity sensor such as a bellows that is sensitive to atmospheric pressure into a rotation angle of a diffraction grating, and calculates the spectral distribution of laser light separated by the diffraction grating. It is designed to calculate the physical quantity to be measured from the change, and consists of a laser light source and a diffraction grating that allows the laser light guided from the laser light source to rotate around an axis perpendicular to the plane containing the optical path of the laser light. a functional element that changes the incident angle of the laser beam by rotating the diffraction grating according to changes in the physical quantity to be measured; The present invention is characterized by comprising a spectrum calculation processing section that calculates the physical quantity to be measured based on an electrical signal that corresponds to a value width.

(Function) Therefore, if the present invention is applied to atmospheric pressure measurement, it is possible to provide a portable automatic pressure precision measurement device, and furthermore, it is possible to provide an automatic automatic pressure measurement device that can instantly and precisely measure changes in atmospheric pressure due to differences in ground altitude. It is possible to realize a barometric pressure measurement system, and in addition to the altitude differential pressure measuring device, it can be skillfully combined with various physical quantity sensors such as a depth differential water pressure measuring device, a gas pressure measuring device, a pressure switch, a flow rate measuring device, etc. Automatic precision measuring devices for various physical quantities can be developed.

(Example) The present invention will be described in detail below with reference to the drawings.

First, an example of the schematic configuration of the optical device for precision measurement of the present invention is shown in FIG. In the illustrated schematic configuration,
The output laser beam of a laser light source 1 such as a long wavelength semiconductor laser or a He-Ne laser is split into two, and a part of the output laser beam is directly guided to a spectrum calculation processing unit 6 that is a combination of an optical spectrum analyzer and a personal computer. , another output laser beam is transmitted through an optical fiber 2 such as a single mode optical fiber or a polarization constant optical fiber, for example, as shown in FIG. 4a.
As will be described later in ~c, the light was guided to a simple spectrometer 3 constructed by combining a pressure sensor such as a bellows sensitive to atmospheric pressure with a diffraction grating, and the mechanical output of the pressure sensor responsive to atmospheric pressure was detected. The spectroscopic laser beam is guided to an optical power meter 5 via an optical fiber 4, its output is checked, and then input to the aforementioned spectrum calculation processing section 6, where the spectral output laser beam is calculated. The spectral distribution is compared and analyzed with the spectral distribution of the input laser light from the laser light source 1 described above, and the atmospheric pressure to be measured corresponding to the spectral distribution is calculated and output and displayed.

Next, the detailed structure and operating principle of each block in the overall structure shown in the first drawing will be explained in sequence with reference to each drawing.

First, an example of the power spectrum distribution characteristics of the output laser light from the laser light source 1 using a long wavelength semiconductor laser or a He-He laser is shown in FIG. 2a or FIG. 2b, respectively. Generally, the quality of a laser light source is evaluated based on the power spectral distribution, and it is usually said that the narrower the half-width 7 or 8 of the spectral distribution characteristic curve and the closer it is to a single spectrum, the better the laser light source is. . However, the laser light source 1 used in the optical device of the present invention
As described later, the atmospheric pressure to be measured is calculated from the amount of change in the half-value width of the spectral distribution characteristic curve of the laser beam separated by the diffraction grating, so it is easy to obtain a clear linear correspondence between the two. In addition, it is preferable to use a laser element whose spectral distribution characteristic curve has a wide half-width and exhibits good linearity in the region to be measured.

In the optical device of the present invention, the laser beam from the light source 1 having such spectral distribution characteristics is
As shown in Figure a, the light is injected into the optical fiber 12 through a combination of microlenses 9 and 10, and is taken out from the output end as a parallel light beam 16 by the microlens 14, or as shown in Figure 3b. , a parallel light beam from another optical fiber is passed through the optical fiber 1 by the microlens 11.
At the same time, the parallel light beams 17 are extracted from the output end by a microlens 15 and made incident on a simple spectrometer 3, respectively.

The main body of the simple spectrometer 3 is constructed, for example, as shown in FIG. 4a. That is, as described above, the parallel light beam 16 extracted from the optical fiber 12 made of, for example, a single-mode optical fiber via the microlens 14 is sequentially reflected by the total reflection mirrors 18 and 19 and is appropriately applied to the diffraction grating 20. The parallel light beam is incident at a certain angle, diffracted and separated by the diffraction grating 20, and is sequentially reflected by the total reflection mirrors 21 and 22, and is transmitted through the microlens 23 to an optical fiber 24 made of, for example, a single mode optical fiber. Inject and remove from the vessel. This spectral output light beam is split by the diffraction action of the diffraction grating 20, and exhibits a spectral output light spectral distribution with a half-width wider than the light source output spectral distribution shown in FIGS. 2a and 2b, for example, and that spectral distribution The degree of spread varies depending on the angle of incidence of the parallel light beam 16 on the diffraction grating 20. Therefore, if the diffraction grating 20 is rotated around an axis perpendicular to the plane that includes the optical path of the parallel light beam 16, and the rotation angle is changed according to changes in the physical quantity to be measured, such as atmospheric pressure, the A spectral output spectrum distribution with a half-value width corresponding to the measured physical quantity is obtained, and a physical quantity to be measured, such as atmospheric pressure, can be calculated based on the spectral output spectral distribution.

In order to be able to set the rotation angle Δθ of the above-mentioned diffraction grating 20 in response to changes in the physical quantity to be measured, such as atmospheric pressure, the sensor box 25 is equipped with a simple spectrometer, as shown in FIG. 4b, for example. Attach to the main body of device 3. In the sensor box 25,
For example, when atmospheric pressure is the measured quantity, a bellows 26 for atmospheric pressure measurement is installed, and the change Δl in the mechanical output of the bellows 26 is transmitted via the transmission fitting 27.
The diffraction grating 20 is transmitted to a rotatable support that is rotatably supported as described above. The illustrated metal fittings 27
The sensor output transmission mechanism shown in Fig. 1 shows a very basic configuration, and in reality, it is a transmission of an appropriate configuration that precisely and precisely transmits minute changes in the mechanical output of the sensor to the rotating support of the diffraction grating. It is necessary to use a mechanism, and specifically, various configurations are possible.

Here, with reference to FIG. 4c, the mutual relationship between the half-width Δλ of the spectral output spectral distribution characteristic curve, the rotation angle Δθ of the diffraction grating 20, and the mechanical output expansion/contraction length Δl of the air pressure measurement bellows 26 will be explained. Then, when the expansion/contraction length Δl of the bellows 26 as a functional element sensitive to the physical quantity to be measured is made to correspond to the rotation angle Δθ of the diffraction grating 20 according to the above-mentioned principle configuration, the spectral output light spectral distribution characteristic curve by the diffraction grating 20 is obtained. Since the half-width Δλ of can be made approximately proportional to the rotation angle Δθ of the diffraction grating 20, a proportional relationship of Δλ∝Δθ∝Δl can be obtained between the mechanical output change Δl of the functional element 26.

Although it is difficult to faithfully establish the proportional relationship described above, by rotating the diffraction grating 20 by an extremely small angle, the spectral distribution of the light source light as shown in FIGS. 2a and 2b can be changed. The half-width of the spectral output spectral distribution, which has been greatly expanded by the spectral action of the diffraction grating 20, changes substantially proportionally. This means that it can respond sensitively to subtle changes in atmospheric pressure. Therefore, even if it is difficult to establish a faithful proportional relationship between the three factors mentioned above, the bellows 26 corresponds to the amount of change Δλ in the half-value width of the spectral output spectral distribution and the rotation angle Δθ of the diffraction grating. By accurately measuring in advance the correspondence between the expansion and contraction length Δl, atmospheric pressure fluctuations of arbitrary magnitude can be measured extremely faithfully and smoothly.

As mentioned above, the simple spectrometer 3 can faithfully and sensitively respond to changes in atmospheric pressure as a physical quantity to be measured.
The spectral output is guided to an optical power meter 5 via an optical fiber 4 and detected. That is, as shown in FIG. 5, the rotation angle Δθ of the diffraction grating 20 is
The parallel light beam 16 that has been split into spectra corresponds to the microlens 28 , enters the optical fiber 29 and propagates, is focused by the microlens 30 , and is detected by the optical power meter 31 . Note that, for this optical power meter 31, it is necessary to appropriately select and use, for example, a silicon solar cell or a germanium solar cell, depending on the wavelength of the light source light to be used.

As mentioned above, the spectral output light that conveys information on the physical quantity to be measured is further guided to the spectrum calculation processing section 6, which serves as an optical spectrum analyzer and a microcomputer, where the optical spectrum distribution is analyzed, as shown in FIG. Then, the optical spectrum spectral characteristic curve of the analysis result is displayed on the spectrum analyzer 32 along with the analysis result of the light source light, and the physical quantity to be measured corresponding to the half width, such as atmospheric pressure, is digitally displayed on the output of the microcomputer 33. . That is, the output laser light of the light source 1 consisting of a semiconductor laser or He-Ne laser and the spectral output light from the photodetector 5 are analyzed by the spectrum analyzer 32 and the microcomputer 33, and the physical quantity to be measured, e.g. , atmospheric pressure can be determined.

Next, examples of the specific configuration of the sensor output transmission mechanism for the diffraction grating whose principle configuration is shown in FIG. 4b are shown in FIGS. 7a to 7c, respectively. The configuration example shown in FIG. 7a is of an indirect constant magnification type, in which the stroke of the mechanical output of the bellows 26 is converted into hydraulic pressure by a hydraulic piston 34 and transmitted to the hydraulic piston 36 via a tube 35. The diffraction grating 20 rotatably supported by the support stand 37 is rotated. Note that by making the hydraulic pistons 34 and 36 different in diameter, the stroke of the bellows 26 can be amplified several times.

The configuration example shown in FIG. 7b is a direct constant magnification type having almost the same configuration as the configuration example described above with reference to FIG. The stroke of the bellows 26 is transmitted to the vane 39 and directly converted into a rotation angle of the diffraction grating 20.

Furthermore, FIG. 7c shows that the stroke of the bellows 26 is amplified by the combination of the connecting rods 40, 41, 42, and the lever 44 of the rotary table 43 supporting the diffraction grating 20 is rotated. , 42 in an appropriate ratio, the stroke of the bellows 26 is optionally amplified and converted into a stroke of the connecting rod 42 that pushes the lever 44.

The simple spectrometer 3 having such a configuration can be constructed as small as about 5 cm3, and if the diffraction grating 20 is integrated and manufactured, it can be further miniaturized to about 2 cm3.

Also, the reading accuracy of conventional mercury barometers
0.1mHg, aneroid barometer reading accuracy 1mHg
On the other hand, the measurement accuracy of a barometer using the optical device of the present invention varies depending on the manufacturing accuracy of the diffraction grating, but it is possible to obtain a resolution of 0.05 nm in the optical spectrum by setting the manufacturing accuracy of the diffraction grating to 1200 lines/mm. When you are faced with
We were able to significantly improve it to about 0.001mHg.

(Effects of the Invention) As is clear from the above description, according to the present invention, a change in the mechanical output of a functional element in a sensor box corresponding to a physical quantity to be measured is converted into rotation of a diffraction grating, and an optical By faithfully enlarging it, subtle changes in the physical quantity to be measured can be faithfully measured with high precision.By appropriately selecting the functional elements inside the sensor box, it is possible to measure not only atmospheric pressure but also
It is possible to measure minute changes in various pressures such as water pressure, gas pressure, oil pressure, wind pressure, or steam pressure, as well as changes in all other physical quantities such as temperature. A special effect can be obtained in that the output can be similarly optically magnified and measured with high precision.

In particular, in the optical device for precision measurement of the present invention,
As a light source, a laser light source with a large half-value width of the optical power spectrum distribution, which is not very good quality, is actively used, and by appropriately selecting the functional elements to be attached and combined with the spectrometer, it is possible to obtain any desired physical quantity. can be similarly measured, and furthermore,
By combining an optical spectrum analyzer and a microcomputer, physical quantity information can be analyzed and measured with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the schematic configuration of the optical measuring device of the present invention, FIGS. 2 a and b are characteristic curve diagrams showing examples of the spectral distribution characteristics of laser light, and FIGS. 3 a and b are FIGS. 4a, b, and c are diagrams each showing a configuration example of a part of the optical device of the present invention, and FIG. Similarly, FIG. 6 is a line diagram showing another example of the configuration of the optical device, and FIG. FIG. 3 is a diagram showing specific configuration examples of a sensor output transmission mechanism in the optical device. 1... Laser light source, 2, 4, 12, 13, 24,
29... Optical fiber, 3... Simple spectrometer, 5, 31
...Optical power meter, 6...Spectrum calculation processing unit,
7, 8... Half width, 9, 10, 11, 14, 15,
23, 28, 30...Micro lens, 16, 17
...Parallel light beam, 18, 19, 21, 22...Mirror, 20...Diffraction grating, 25...Sensor box, 2
6... Bellows, 27... Transmission fitting, 32... Spectrum analyzer, 33... Microcomputer, 3
4, 36...Hydraulic piston, 35...Tube, 37
...Support stand, 38...Casing, 39...Vane, 4
0, 41, 42...Connecting rod, 43...Rotary table, 44...
lever.

Claims (1)

[Scope of Claims] 1. A laser light source, a spectrometer that separates the laser light guided from the laser light source using a diffraction grating that is rotatably provided around an axis perpendicular to a plane containing the optical path of the laser light, and a A functional element that rotates the diffraction grating to change the incident angle of the laser beam according to a change in the measured physical quantity, and an electric signal that corresponds to the half-value width of a spectral distribution characteristic curve resulting from the spectroscopy of the laser beam guided from the spectrometer. 1. An optical device for precision measurement, comprising: a spectrum calculation processing section that calculates the physical quantity to be measured based on the measured physical quantity. 2. In the optical device according to claim 1, the functional element is constituted by a pressure sensor, and is capable of measuring at least one of atmospheric pressure, wind pressure, gas pressure, steam pressure, water pressure, and oil pressure. An optical device for precision measurement characterized by: 3. An optical device for precision measurement according to claim 2, wherein the pressure sensor is constructed of a bellows. 4. The optical device according to claim 1, wherein the functional element is made of a shape memory alloy,
An optical device for precision measurement characterized by being adapted to measure temperature.