KR20140135303A

KR20140135303A - External Environment Measurement System

Info

Publication number: KR20140135303A
Application number: KR1020130054923A
Authority: KR
Inventors: 송홍주; 이준호
Original assignee: 전자부품연구원
Priority date: 2013-05-15
Filing date: 2013-05-15
Publication date: 2014-11-26

Abstract

An FBG sensing system is provided. A sensing system according to an embodiment of the present invention filters light emitted from a light source to one of a plurality of filters and transmits the filtered light to the optical sensors. As a result, it becomes possible to realize multi-sensing with high performance and price competitiveness, and it is possible to simplify the configuration and to make it easy to manufacture, as well as to reduce the size and miniaturization, and to secure the price competitiveness by lowering the manufacturing cost.

Description

{External Environment Measurement System}

The present invention relates to a measurement system, and more particularly to a system for measuring an external environment such as temperature, pressure, and the like.

1 is a view showing a structure and a principle of a general optical fiber sensing system. 1, the optical fiber sensing system includes a light source 10, an optical coupler 20, FBG sensors 30, an optical signal processing module 40, an electrical signal processing module 50, and a monitor 60 ).

The light emitted from the light source 110 is incident on the FBG sensors 30 through the optical coupler 20 and reflected. The FBG sensors 30 are sensing units that cause a change in the optical signal in accordance with changes in physical quantities around them.

The FBG sensors 30 serve as mirrors for reflecting a specific wavelength, and the reflected waves are changed according to the state of surrounding physical quantities (temperature, pressure, strain, vibration, flow rate, etc.). Therefore, when the change of the reflected wave is detected, the change of the physical quantity causing the change can be known.

The light reflected by the FBG sensors 30 is amplified by the light source 10 and then incident on the optical signal processing module 40 to be photoelectrically converted and subjected to signal processing by the electric signal processing module 50 to generate sensing information, (60).

The FBG sensing system is classified into various types according to the optical signal processing method, and some of them have been commercialized. However, all the FBG sensing systems including the commercial type are expensive and bulky.

Specifically, a tunable fiber laser source, a wavelength tunable filter based on a mirror, or an optical signal processing module composed of a grating, a CCD array or an interferometer is used. As a result, a light source, which is a core element of the FBG sensing system, There is a problem that the processing module is complicated in configuration, is bulky, and has a high manufacturing cost.

Accordingly, there is a need to search for a solution to the problem of configuration, volume, and cost. Furthermore, there is a need for a scheme for performing effective multi-sensing in one system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an FBG sensing system and method capable of performing multi-sensing with high performance and price competitiveness.

Another object of the present invention is to provide an FBG sensing system having a simple structure, a small volume, a low manufacturing cost, and an optical signal processing module applied thereto.

According to an aspect of the present invention, there is provided an optical sensing system including: a light source for emitting light; And a multi-filter having a plurality of filters, wherein the multi-filter filters the light emitted from the light source to one of the filters and transmits the filtered light to the plurality of optical sensors.

The filters may be one-to-one correspondence to the optical sensors.

Further, the transmission wavelength of the filter may include the reflection wavelength of the corresponding optical sensor.

The multi-filter may then be driven by a mechanical device such that one of the filters is located on the optical path from the light source to the optical sensors.

The plurality of optical sensors may selectively reflect the light received through the multi-filter according to an external environment, and the optical sensing system may include an optical signal processing unit for outputting light reflected from the optical sensor as an electric signal module; And an electric signal processing module for outputting sensing information on the external environment based on a signal output from the optical signal processing module.

The optical signal processing module outputs the intensity and wavelength of the light reflected by the optical sensor as an electrical signal, and the electrical signal processing module controls the intensity and wavelength ratio of the light output from the optical signal processing module to the outside It can be outputted as sensing information about the environment.

The optical signal processing module may further include: a beam splitter for dividing the light reflected by the optical sensor and outputting to a first optical detector and a following optical filter; A first photodetector for converting the intensity of light split by the beam splitter into an electrical signal and outputting reference information; An optical filter for outputting wavelength information of light split by the beam splitter as light proportional to the wavelength information; And a second photodetector converting an intensity of light emitted from the optical filter into an electric signal to output wavelength information, wherein the electric signal processing module is configured to convert the ratio of the reference information and the wavelength information to the external environment Can be output as the sensing information for the sensor.

In the optical filter, the intensity of the outgoing light may be linear or nonlinear with respect to the wavelength of the incident light.

Further, the optical sensing system according to an embodiment of the present invention may further include an optical repeater provided between the multi-filter, the optical sensors, and the optical signal processing module, (R-SOA) that transmits light to the optical sensors through the optical repeater, amplifies the light received from the optical sensors through the optical repeater, and transmits the amplified light to the optical signal processing module through the optical repeater. Optical Amplifier).

According to another aspect of the present invention, there is provided an optical sensing method including: irradiating light; And filtering the irradiated light to one of the plurality of filters and delivering the filtered light to the plurality of optical sensors.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, multi-sensing is possible with high performance and price competitiveness. In addition, the FBG sensing system and the optical signal processing module applicable to the FBG sensing system can be manufactured easily by simplifying the configuration, can be miniaturized by reducing the volume, and can be manufactured at a lower cost to secure price competitiveness.

FIG. 1 illustrates the structure and principle of a conventional optical fiber sensing system,
FIGS. 2 and 3 illustrate an FBG sensing system according to a preferred embodiment of the present invention.
Fig. Detailed drawings of the optical signal processing module shown in FIG. 2 and FIG. 3,
5 is a graph showing the transmission characteristics of the linear transmission filter shown in Fig.

Hereinafter, the present invention will be described in detail with reference to the drawings.

2 is a block diagram of an FBG sensing system according to a preferred embodiment of the present invention. The FBG sensing system according to the present embodiment is a system for sensing an external environment (temperature, strain, pressure, vibration, chemical component, physical quantity measurable by the FBG sensor) such as temperature and pressure.

2, the FBG sensing system according to the present exemplary embodiment includes a light source 110, a multi-filter 120, an optical coupler 130, an FBG sensor (Fiber Bragg Grating Sensor) An optical signal processing module 140, an electrical signal processing module 150 and a monitor 160. [

In the FBG sensing system according to the present embodiment, the number of the light source 110, the optical signal processing module 140, the electric signal processing module 150, and the monitor 160 is one.

As a means for irradiating and amplifying light from the light source 110, it can be implemented as an R-SOA (Reflective Semiconductor Optical Amplifier).

The multi-filter 120 is a structure in which a plurality of filters are assembled in an assembly form. The number of filters constituting the multi-filter 120 is determined to be equal to the number of the FBG sensors 31, 32, ....

The filters constituting the multi-filter 120 are narrow band pass filters, and the transmission wavelength thereof is determined according to the reflection wavelength of the FBG sensors 31, 32, .... Specifically, the transmission wavelength of the first filter of the multi-filter 120 is the reflection wavelength? 1 of the FBG sensor-1 31, the transmission wavelength of the second filter is the reflection wavelength? 2 of the FBG sensor- ).

More specifically, when the temperature measurement range of the FBG sensors 31, 32, ... is 400 占 폚 and the FBG reflection wavelength range for this is 4 nm, the transmission wavelengths of the filters constituting the multi- The range includes the FBG reflection wavelength, but the range is slightly wider than 6 nm (plus 1 nm left / right).

The optical coupler 130 is an optical relay element provided between the multi-filter 120, the FBG sensors 31, 32, ..., and the optical signal processing module 140.

The FBG sensors 31, 32, ... are a kind of optical sensors that selectively reflect the light applied from the light source 110, and the selection wavelengths depend on the external environment such as temperature and pressure.

The optical signal processing module 140 generates sensing information from an electrical signal output from the optical signal processing module 140, and outputs the sensed information to the monitor 140. The optical signal processing module 140 is a module for generating an electrical signal from incident light, The controller 160 displays the sensing information generated by the electric signal processing module 150.

Hereinafter, the external environment sensing process in the FBG sensing system shown in FIG. 2 will be described in detail with reference to FIG. 3 to FIG.

The multi-filter 120 is driven by a drive motor (not shown) so that one of the filters constituting it is located on the optical path. First, the filter-1 (? 1) corresponding to the FBG sensor-1 (31) among the filters constituting the multi-filter 120 is located in the optical path by the drive motor.

Next, the light source 110 is driven to emit light of a broadband wavelength. The filter-1 transmits only its transmission wavelength? 1 to the optical coupler 130 (1).

Then, the light selectively reflected by the FBG sensor-1 31 according to the external environment is incident on the light source 110 through the optical coupler 130, amplified and then re-emitted to the multi- And is transmitted to the optical signal processing module 140 via the coupler 130 ((2) to (8)).

The optical signal processing module 140 generates and outputs an electrical signal I _R containing reference information and an electrical signal I _F containing wavelength information from the incident light.

The reference information is information indicating the intensity of light incident on the optical signal processing module 140 and ultimately information indicating the intensity of the light reflected and amplified by the FBG sensor-1.

The wavelength information is information indicating the wavelength of the light incident on the optical signal processing module 140 and ultimately information indicating the wavelength of the light reflected and amplified by the FBG sensor-1 31.

The optical signal processing process in the optical signal processing module 140 will be described in detail below with reference to FIG. 4 is a detailed view of the optical signal processing module 140 shown in FIG.

4, the optical signal processing module 140 includes a beam splitter 141, a PD (Photo Detector) -1 142, a linear transmittance optical filter 143, And PD-2 144. [

The beam splitter 141 divides the incident light (the light reflected by the FBG sensor-1 31 and amplified by the light source 110) into the PD-1 142 and the linear transmission filter 143. The distribution ratio may be "1: 1" or may be set at a different ratio. This is a problem of selection according to the specification of the optical signal processing module 140. [

The PD-1 142 converts the intensity of the light split by the beam splitter 141 into an electric signal and outputs the electric signal. The electric signal I _R emitted from the PD-1 142 is reference information applied to the electric signal processing module 150.

On the other hand, the linear transmission filter 143 is an optical filter that divides the wavelength information of the light split by the beam splitter 141 and outputs it as light intensity. The intensity of the outgoing light in the linear transmission filter 143 is proportional to the wavelength of the incident light (in direct proportion or in inverse proportion), and the proportional relationship is linear.

FIG. 5 is a graph showing transmission characteristics of the linear transmission filter 143. FIG. 5, it is confirmed that the intensity of the outgoing light in the linear transmission filter 143 is linearly inversely proportional to the wavelength of the incident light.

The transmission characteristics shown in Fig. 5 are merely illustrative and can be implemented differently. For example, the intensity of the outgoing light in the linear transmission filter 143 may be directly proportional to the wavelength of the incident light.

In this case, however, it is preferable that the intensity of the emitted light linearly increases with the wavelength of the incident light. It should be noted that the linearity referred to herein means substantially linear and does not require a theoretically perfect linearity.

The PD-2 144 converts the intensity of the light emitted from the linear transmission filter 143 into an electric signal and outputs the electric signal. The electric signal I _F emitted from the PD-2 144 is wavelength information applied to the electric signal processing module 150.

Referring again to FIG.

The electrical signal processing module 150 amplifies and A / D-converts the reference signal I _R and the wavelength signal I _F output from the optical signal processing module 140, and outputs a nominalized S _F / S _R as a digital signal.

S _F / S _R output from the electric signal processing module 150 is information indicating the ratio of the intensity and the wavelength of the light reflected and amplified by the FBG sensor-1 31, Information, which is displayed on the monitor 160.

The series of processes described so far is the sensing result (S _F / S _R ) of the FBG sensor-1 31 at time "t1".

Then, at time "t2 ", the filter-2 (lambda 2) corresponding to the FBG sensor-2 32 among the filters constituting the multi-filter 120 is located in the optical path by the drive motor, (32) is obtained / displayed.

Similarly, the above procedure is performed for FBG sensor 3 at time "t3", for FBG sensor -4 at time "t4", and for FBG sensor-8 at time "t8". Next, after the time "t8", it is repeated from the sensing by the FBG sensor-1 again.

Up to now, a preferred embodiment of the FBG sensing system has been described in detail.

In the above embodiment, it is assumed that the filters constituting the multi-filter 120 are arranged in a linear manner, but these are merely illustrative. The technical idea of the present invention can be applied even when the filters are arranged in a circle as well as in other forms.

The FBG sensing system proposed in the above embodiment is supposed to be a system for measuring the external environment such as temperature and pressure, but this is merely an example. The technical idea of the present invention is also applicable to a system for sensing an external environment (e.g., vibration, humidity, etc.) other than temperature and pressure.

Also, the implementation of the light source 110 in the R-SOA is also an example, and the technical idea of the present invention can also be applied to the case where the light source 110 is implemented by an element other than the R-SOA.

In addition, it is also possible to implement only the optical signal processing module 140 among the configurations of the FBG sensing system, and this case is also included in the scope of the present invention.

Meanwhile, the linear transmission filter 143 mentioned in the above embodiment can be replaced with another kind of filter in which the intensity of emitted light changes to the wavelength of the incident light. In the present invention, even though the diurnal transmittance is non-linear, the final output signal is linearized by electrical signal processing.

Further, the driving of the multi-filter 120 can be realized by a mechanical device other than the motor (for example, an actuator or the like). In addition, it is also possible to arbitrarily select one of the filters constituting the multi-filter 120 at a specific time point and to grasp the sensing result of the corresponding FBG sensor. In this case, the mechanical device operates so that the selected filter is located on the optical path.

At this time, the filter selection can be determined based on the sensing result. For example, it is possible to implement the filter selection so that the measurement period of the FBG sensor having an abnormal or dangerous value as the sensing result becomes smaller than that of the other FBG sensors. This can be implemented in such a way that the filter corresponding to the FBG sensor with abnormal / critical values is selected more frequently than the other filters.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

110: light source 120: multi-filter
130: Optocoupler 140: Optical signal processing module
141: Beam splitter 142, 144: PD (Photo Detector)
143: linear transmission filter 150: electric signal processing module
160: Monitor

Claims

A light source for emitting light; And
And a multi-filter having a plurality of filters, wherein the multi-filter filters the light emitted from the light source to one of the filters and transmits the filtered light to the plurality of optical sensors.

The method according to claim 1,
The filters,
Wherein the optical sensors are arranged in a one-to-one correspondence with the optical sensors.

3. The method of claim 2,
The transmission wavelength of the filter is,
And a reflected wavelength of the corresponding photosensor.

The method according to claim 1,
Wherein the multi-filter is driven by a mechanical device such that one of the filters is located on an optical path from the light source to the optical sensors.

The method according to claim 1,
The plurality of photosensors,
The light transmitted through the multi-filter is selectively reflected by the external environment according to the external environment,
The optical sensing system comprises:
An optical signal processing module for outputting the light reflected by the optical sensor as an electrical signal; And
And an electric signal processing module for outputting sensing information on the external environment based on a signal output from the optical signal processing module.

6. The method of claim 5,
The optical signal processing module includes:
And outputs the intensity and wavelength of the light reflected by the optical sensor as an electrical signal,
The electric signal processing module includes:
And outputs the ratio of the intensity and the wavelength of the light output from the optical signal processing module as sensing information for the external environment.

The method according to claim 6,
The optical signal processing module includes:
A beam splitter for dividing the light reflected from the optical sensor and outputting to a first optical detector and a following optical filter;
A first photodetector for converting the intensity of light split by the beam splitter into an electrical signal and outputting reference information;
An optical filter for outputting wavelength information of light split by the beam splitter as light proportional to the wavelength information; And
And a second photodetector for converting the intensity of light emitted from the optical filter into an electrical signal and outputting wavelength information,
The electric signal processing module includes:
And outputs the ratio of the reference information and the wavelength information as sensing information for the external environment.

8. The method of claim 7,
In the optical filter,
Wherein the intensity of the emitted light is linear or nonlinear at the wavelength of the incident light.

6. The method of claim 5,
And an optical repeater provided between the multi-filter, the optical sensors, and the optical signal processing module,
The light source includes:
And an optical repeater for transmitting light to the optical sensors through the multi-filter and the optical repeater, amplifying the light received from the optical sensors through the optical repeater, and transmitting the amplified light to the optical signal processing module through the optical repeater Gt; (SOA) < / RTI > (Reflective Semiconductor Optical Amplifier).

Irradiating light; And
And filtering the irradiated light to one of the plurality of filters and delivering the filtered light to the plurality of optical sensors.