阅读说明：本技术 一种基于数字光频梳与微腔阵列的高灵敏超声探测方法 (High-sensitivity ultrasonic detection method based on digital optical frequency comb and microcavity array ) 是由 张斌 潘竞顺 李朝晖 赵佳鑫 于 2020-05-13 设计创作，主要内容包括：本发明属于光信号处理领域与传感领域,涉及一种基于数字光频梳与微腔阵列的高灵敏超声探测方法。利用了光通信领域先进信号处理技术,得到了具有一定带宽的数字光频梳信号,利用数字光频梳信号对微腔光子器件进行扫描,得到超快以及高精度的微腔谐振峰扫描谱线。同时,还制作了只需要一条光路系统耦合多个微腔结构,实现多个微腔的谐振峰的等间隔波长分布。通过设计多个微腔的谐振峰的波长位置,可实现数字光频梳对这大量微腔结构的各自谐振峰的频率、功率进行快速、高精度的探测,可显著提高超声波阵列探测的效率以及处理难度,可应用于超声波的阵列探测、光声成像等领域,同时也为实现集成化、小型化的超声相控阵探测器的研究提供了基础。(The invention belongs to the field of optical signal processing and sensing, and relates to a high-sensitivity ultrasonic detection method based on a digital optical frequency comb and a microcavity array. The method utilizes the advanced signal processing technology in the field of optical communication to obtain a digital optical frequency comb signal with a certain bandwidth, and utilizes the digital optical frequency comb signal to scan the microcavity photonic device to obtain an ultrafast and high-precision microcavity resonance peak scanning spectral line. Meanwhile, only one optical path system is required to couple a plurality of microcavity structures, so that the equidistant wavelength distribution of the resonance peaks of a plurality of microcavities is realized. Through designing the wavelength position of the resonance peak of a plurality of microcavities, the digital optical frequency comb can quickly and accurately detect the frequency and the power of the respective resonance peak of a large number of microcavity structures, the detection efficiency and the processing difficulty of an ultrasonic array can be obviously improved, the digital optical frequency comb can be applied to the fields of ultrasonic array detection, photoacoustic imaging and the like, and a foundation is provided for the research of an integrated and miniaturized ultrasonic phased array detector.)

1. A high-sensitivity ultrasonic detection method based on a digital optical frequency comb and a microcavity array is characterized by comprising a detection signal transmitting unit, a microcavity array (6) sensing unit, a detection device and a signal demodulation unit; the detection signal transmitting unit comprises a continuous laser (1), a frequency shifter (2) and an arbitrary signal generator (3); the sensing unit of the microcavity array (6) comprises an optical coupler (4), a coupling light path (5) and a microcavity array (6); the detection device and the signal demodulation unit comprise a photoelectric detector (7), an analog-to-digital converter and a signal processing unit (8); the method specifically comprises the following steps:

s1, firstly, a detection signal transmitting unit sends out a proper detection signal; emitting a frequency f from a continuous laser (1)₀The single-frequency continuous optical signal passes through the frequency shifter (2), the frequency shifter (2) is modulated by the arbitrary signal generator (3), and an equidistant frequency spectrum electric signal program is compiled for the arbitrary signal generator (3); the electric frequency spectrum interval delta f can be set at will and can be adjusted from 1Hz to 20MHz at will; the spectral bandwidth Bw of the electrical signal can be adjusted from 1MHz to 60GHz at will, so that any signal generator (3) generates a frequency comb of the electrical frequency domain, where the frequency comb generated in the electrical domain is used to drive the frequency shifter (2), and thus to the continuous single-frequency optical signal f₀Modulation is carried out to generate a signal with f₀An optical signal which is a central carrier, the bandwidth of a sideband signal is Bw, and the optical spectrum interval is delta f;

s2, then, the detection light enters a transmission link for transmission, and the modulated optical signal with the Bw bandwidth in the step S1 is coupled into an optical path system through an optical coupler (4);

s3, then, the optical signal is transmitted to the sensing unit of the microcavity array (6) through the transmission link; the optical signals rapidly and sequentially pass through a plurality of micro-cavities with high quality factors at the light speed to obtain the transmission spectrum of the micro-cavity array (6);

s4, finally, the optical signal responded by the micro-cavity array (6) is emitted to a detection device and a signal demodulation unit through an optical link; the transmission spectrum passes through the array with the plurality of micro-cavities, the obtained micro-cavity transmission spectrum is collected to a photoelectric converter through a coupling light path to convert an optical signal into an electric signal, then the electric signal is quantized through an analog-to-digital converter, and a transmission spectrum curve at each time T can be obtained through subsequent digital signal processing, so that the demodulation of the resonant frequency of the micro-cavity array (6) is realized; with the increase of the acquisition time, the change curves of all the resonant frequencies along with T can be obtained, when ultrasonic waves exist outside, the resonant frequencies of all the micro-cavities can generate frequency shift jitter with different time and amplitude and constant frequency in the ultrasonic waves, and the positioning of the ultrasonic waves can be realized by analyzing the time point when the ultrasonic waves reach each micro-cavity, the phase difference of the frequency shift and the intensity.

2. The method for high-sensitivity ultrasonic detection based on the digital optical-frequency comb and the microcavity array according to claim 1, wherein in the step S1, Bw is set to 40 GHz; since this is a modulated signal, a complete demodulation of a set of modulated signals requires a complete acquisition of a period of time, defined as T1/Δ f, where the optical signal interval Δ f is 1Hz to 20MHz, which is converted into a wavelength interval with a wavelength less than 0.01pm, and belongs to a wavelength interval range with high precision, and therefore the length of T is 50ns to 1 s.

3. The method for high-sensitivity ultrasonic detection based on the digital optical-frequency comb and the microcavity array as claimed in claim 1, wherein the optical path system in the step S2 is any one of spatial optical path coupling, optical fiber coupling and on-chip waveguide coupling.

4. The high-sensitivity ultrasonic detection method based on the digital optical frequency comb and the microcavity array as claimed in claim 1, wherein in the step S3, the Q value of the microcavity is more than 6, that is, the half-peak width of the resonant frequency of each microcavity is 1MHz to 50MHz, and the interval of the center frequency of the resonant peak of each microcavity is Δ f_qIn the range of 100MHz to 10 GHz.

5. The high-sensitivity ultrasonic detection method based on the digital optical frequency comb and the microcavity array according to any one of claims 1 to 4, wherein an orthogonal frequency division multiplexing algorithm and a pseudo-random sequence algorithm in a communication algorithm are used to obtain a frequency comb of an electrical frequency domain, and the electrical frequency comb is modulated to an optical domain by a modulator to obtain an optical frequency comb signal; the signal bandwidth of the digital optical frequency comb can be flexibly set and ranges from 1Hz to 1 THz.

6. The high-sensitivity ultrasonic detection method based on the digital optical-frequency comb and the microcavity array as claimed in claim 5, wherein the preparation method of the microcavity comprises: heating the hollow optical fiber structure to be softened by a carbon dioxide laser heating method, an electric arc heating method or a heating wire heating method, and adding certain pressure into the optical fiber to expand the optical fiber to form a micro-cavity structure; and continuously adjusting the air pressure and the heating temperature of the input optical fiber to ensure that the heating point of the optical fiber continuously expands to 1-5 times of the original heating point.

7. The high-sensitivity ultrasonic detection method based on the digital optical frequency comb and the microcavity array is characterized in that the microcavity array (6) is prepared by coupling a plurality of microcavity structures through one optical path, and the number of the coupled microcavity structures is 1-1000.

8. The high-sensitivity ultrasonic detection method based on the digital optical frequency comb and the microcavity array is characterized in that the material of the optical fiber structure is any one of silicon dioxide, rare earth-doped optical fiber and fluoride optical fiber.

Technical Field

The invention belongs to the field of optical signal processing and the field of sensing technology, and particularly relates to a high-sensitivity ultrasonic detection method based on a digital optical frequency comb and a microcavity array.

Background

The array ultrasonic detection has been widely researched and applied in the fields of industrial engineering such as national defense security, biomedicine, aerospace, photoacoustic tomography, ultrasonic imaging and interface detection. Contactless ultrasound detection is particularly important in extreme environments (e.g., imaging of sensitive wounds or hazardous samples, binder inspection, functional ophthalmic imaging) or in complex confined environments (e.g., stray electromagnetic fields, confined spaces, forced dry environments, etc.). In the application of the ultrasonic sensing, a single ultrasonic sensing point cannot meet the application requirements of most occasions, and the array type ultrasonic sensing technology is beneficial to improving the detection efficiency in large-scale engineering. The traditional array ultrasonic transducer probe is characterized in that a plurality of different ultrasonic transducers work simultaneously and independently, ultrasonic signals are converted into electric signals which are respectively collected to a processing unit for demodulation and analysis, and each ultrasonic transducer needs power supply and a signal return circuit, so that a more complex wiring system is needed while the ultrasonic transducers with large number have high power consumption, and the volume is also large, so that how to realize ultrasonic detection of a highly integrated ultrasonic array with large number and lower power consumption becomes a current difficulty.

Disclosure of Invention

The invention provides a high-sensitivity ultrasonic detection method based on a digital optical frequency comb and a microcavity array, aiming at overcoming the defects in the prior art, one coupled optical path can finish signal return of a large number of sensing points, the cost is low, and the detection precision is high.

In order to solve the technical problems, the invention adopts the technical scheme that: a high-sensitivity ultrasonic detection method based on a digital optical frequency comb and a microcavity array comprises a detection signal transmitting unit, a microcavity array sensing unit, a detection device and a signal demodulation unit; the three components can be connected in a wired mode through optical fibers, and can also be connected in a wireless mode through a space optical path. The detection signal transmitting unit comprises a continuous laser, a frequency shifter and an arbitrary signal generator; the microcavity array sensing unit comprises an optical coupler, a coupling light path and a microcavity array; the detection device and signal demodulation unit comprises a photoelectric detector, an analog-to-digital converter and a signal processing unit; the method specifically comprises the following steps:

s1, firstly, a detection signal transmitting unit sends out a proper detection signal; emitted by a continuous laser at a frequency f₀The single-frequency continuous optical signal passes through the frequency shifter, the frequency shifter is modulated by any signal generator, and an equidistant frequency spectrum electric signal program is compiled for any signal generator; the electric frequency spectrum interval delta f can be set at will and can be adjusted from 1Hz to 20MHz at will; the frequency spectrum bandwidth Bw of the electric signal can be adjusted from 1MHz to 60GHz randomly, so that any signal generator generates a frequency comb of an electric frequency domain, the frequency comb generated on the electric domain is used for driving a frequency shifter, and then a continuous single-frequency optical signal f is subjected to frequency shift₀Modulation is carried out to generate a signal with f₀An optical signal which is a central carrier, the bandwidth of a sideband signal is Bw, and the optical spectrum interval is delta f;

s2, then, the detection light enters a transmission link for transmission, and the modulated optical signal with the Bw bandwidth in the step S1 passes through a shopping coupler and is coupled into an optical path system;

s3, then, the optical signal is transmitted to the microcavity array sensing unit through the transmission link; the optical signals rapidly and sequentially pass through a plurality of micro-cavities with high quality factors at the speed of light to obtain the transmission spectrum of the micro-cavity array;

s4, finally, the optical signal responded by the microcavity array is emitted to a detection device and a signal demodulation unit through an optical link; the transmission spectrum passes through the array with the plurality of micro-cavities, the obtained micro-cavity transmission spectrum is collected to a photoelectric converter through a coupling light path to convert an optical signal into an electric signal, then the electric signal is quantized through an analog-to-digital converter, and a transmission spectrum curve at each time T can be obtained through subsequent digital signal processing, so that the demodulation of the resonant frequency of the micro-cavity array is realized; with the increase of the acquisition time, the change curves of all the resonant frequencies along with T can be obtained, when ultrasonic waves exist outside, the resonant frequencies of all the micro-cavities can generate frequency shift jitter with different time and amplitude and constant frequency in the ultrasonic waves, and the positioning of the ultrasonic waves can be realized by analyzing the time point when the ultrasonic waves reach each micro-cavity, the phase difference of the frequency shift and the intensity.

According to the invention, by utilizing the characteristics of wide bandwidth and high frequency sweeping speed of the digital optical frequency comb and combining the advantages of large ultrasonic sensitivity and high Q-value resonance frequency of the microcavity structure, a plurality of microcavity structures are coupled at the same time through one coupling optical path, so that the simultaneous high-speed and high-precision spectrum scanning of the resonance frequency of the plurality of microcavities is realized. Under the action of ultrasound, the resonance frequencies of a plurality of microcavities can generate frequency shifts to different degrees, the obtained frequency shift data are respectively analyzed in a time domain and a frequency domain, so that the response characteristic of the ultrasound frequency and the positioning of the ultrasound can be obtained, and the sensing detection of a large number of ultrasound arrays can be simultaneously realized by using only one coupling light path, so that a solution is provided for the ultrasound application such as the ultrasound positioning, the ultrasound imaging, the photoacoustic tomography and the like with higher density and higher precision.

In one embodiment, in the step S1, Bw is set to 40 GHz; since this is a modulated signal, a complete demodulation of a set of modulated signals requires a complete acquisition of a period of time, defined as T1/Δ f, where the optical signal interval Δ f is 1Hz to 20MHz, which is converted into a wavelength interval with a wavelength less than 0.01pm, and belongs to a wavelength interval range with high precision, and therefore the length of T is 50ns to 1 s.

In one embodiment, the optical path system in S2 is any one of spatial optical path coupling, optical fiber coupling, and on-chip waveguide coupling.

In one embodiment, in the step S3, the Q value of the microcavity is more than 6, that is, the half-peak width of the resonant frequency of each microcavity is 1MHz to 50MHz, and meanwhile, the interval of the central frequencies of the resonant peaks of each microcavity is Δ fq, which ranges from 100MHz to 10 GHz.

In one embodiment, an orthogonal frequency division multiplexing algorithm and a pseudo-random sequence algorithm in a communication algorithm are utilized to obtain a frequency comb of an electrical frequency domain, and the electrical frequency comb is modulated to an optical domain through a modulator to obtain an optical frequency comb signal; the signal bandwidth of the digital optical frequency comb can be flexibly set and ranges from 1Hz to 1 THz.

In one embodiment, the method for preparing the microcavity comprises the following steps: heating the hollow optical fiber structure to be softened by a carbon dioxide laser heating method, an electric arc heating method or a heating wire heating method, and adding certain pressure into the optical fiber to expand the optical fiber to form a micro-cavity structure; and continuously adjusting the air pressure and the heating temperature of the input optical fiber to ensure that the heating point of the optical fiber continuously expands to 1-5 times of the original heating point. The preparation process comprises the following steps:

1. cutting a section of hollow structure optical fiber, blocking one end, and connecting an air valve at the other end;

2. connecting the air valve in the step 1 with an air pressure output device to adjust the initial state of air pressure;

3. heating a certain section of position in the optical fiber by using an arc method, and observing the expansion state of the optical fiber;

4. and 3, continuously adjusting the air pressure and the heating temperature of the input optical fiber to enable the heating point of the optical fiber to be continuously expanded to 1-5 times of the original heating point.

In one embodiment, the microcavity array is prepared by coupling a plurality of microcavity structures through one optical path, and the number of the coupled microcavity structures ranges from 1 to 1000.

In one embodiment, the optical fiber structure is made of any one of silica, rare earth doped fiber and fluoride fiber.

Compared with the prior art, the beneficial effects are: the high-sensitivity ultrasonic detection method based on the digital optical frequency comb and the microcavity array has the advantages of high integration degree, no need of power supply for a sensing circuit, capability of completing signal return of a large number of sensing points by using a coupling light path, low cost, high detection precision and the like, can be used for simultaneously detecting more than 400 sensing array points, has an ultrasonic detection range of 20 kHz-1 MHz, and can be widely applied to the fields of ultrasonic imaging and the like.

Drawings

FIG. 1 is a schematic diagram of the connection relationship of each unit according to the present invention.

Fig. 2 is a schematic diagram of the connection relationship between the structures of the present invention.

FIG. 3 is a schematic diagram of the present invention for demodulating ultrasonic waves during detection of ultrasonic waves by the microcavity array.

Wherein 1 is a continuous laser; 2 is a frequency shifter; 3 is an arbitrary signal generator; 4 is an optical coupler; 5 is a coupling optical path; 6 is a microcavity array; 7 is a photoelectric detector; and 8, an analog-to-digital converter and a signal processing unit.

Detailed Description

The drawings are for illustration purposes only and are not to be construed as limiting the invention; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the invention.

As shown in fig. 1 and fig. 2, a high-sensitivity ultrasonic detection method based on a digital optical frequency comb and a microcavity array 6 includes a detection signal transmitting unit, a microcavity array 6 sensing unit, a detection device and a signal demodulating unit; the three components can be connected in a wired mode through optical fibers, and can also be connected in a wireless mode through a space optical path. The detection signal transmitting unit comprises a continuous laser 1, a frequency shifter 2 and an arbitrary signal generator 3; the microcavity array 6 sensing unit comprises an optical coupler 4, a coupling light path 5 and a microcavity array 6; the detection device and signal demodulation unit comprises a photoelectric detector 7, an analog-to-digital converter and a signal processing unit 8; the method specifically comprises the following steps:

s1, firstly, a detection signal transmitting unit sends out a proper detection signal; emitted by a continuous laser 1 at a frequency f₀The single-frequency continuous optical signal passes through the frequency shifter 2, the frequency shifter 2 is modulated by the arbitrary signal generator 3, and an equidistant frequency spectrum electric signal program is compiled for the arbitrary signal generator 3; the electric frequency spectrum interval delta f can be set at will and can be adjusted from 1Hz to 20MHz at will; the frequency spectrum bandwidth Bw of the electrical signal can be arbitrarily adjusted from 1MHz to 60GHz, so that an arbitrary signal generator 3 generates a frequency comb of the electrical frequency domain, where the frequency comb generated in the electrical domain is used to drive the frequency shifter 2, and further, for a continuous single-frequency optical signal f₀Is modulated to generatef₀An optical signal which is a central carrier, the bandwidth of a sideband signal is Bw, and the optical spectrum interval is delta f; typically, Bw is set to 40GHz here. Since this is a modulated signal, a complete demodulation of a set of modulated signals requires a complete acquisition of a period of time, defined as T1/Δ f, where the optical signal interval Δ f is 1Hz to 20MHz, which is converted into a wavelength interval with a wavelength less than 0.01pm, and belongs to a wavelength interval range with high precision, and therefore the length of T is 50ns to 1 s. Typically, Δ f is set to 1MHz, and T is set to 1 μ s.

S2, then, the detection light enters a transmission link for transmission, and the modulated optical signal with the Bw bandwidth in the step S1 passes through a shopping coupler and is coupled into an optical path system; the optical path system can be optical fiber connection or space optical coupling.

S3, then, the optical signal is transmitted to the microcavity array 6 sensing unit through the transmission link; the optical signals rapidly and sequentially pass through a plurality of micro-cavities with high quality factors at the light speed to obtain the transmission spectrum of the micro-cavity array 6; here, the size of the microcavity array 6 is specially designed, so that the Q value of the microcavity is generally more than the power of 6, that is, the half-peak width of the resonant frequency of each microcavity is 1MHz to 50MHz, and meanwhile, the interval of the central frequency of the resonant peak of each microcavity is Δ f_qIn the range of 100MHz to 10 GHz. Typically, the half-peak width of each microcavity resonance frequency is designed to be 10MHz, Δ f_qFor 100MHz, the number of microcavities that can be accommodated is N ═ Bw/Δ f, corresponding to Bw ═ 40GHz and an interval of the resonance frequency of each microcavity of 100MHz_qI.e., where N is 400. The signal light traverses the 400 microcavity devices sequentially at the speed of light, capturing the spectral responses of the 400 microcavity devices. Since these microcavity array 6 devices are used for ultrasound detection, the vibrations of the ultrasound will cause slight changes in the structure and effective refractive index of these microcavity devices, and thus in the spectrum passing through them, and the information of the ultrasound can be obtained by demodulating this spectrum.

S4, finally, the optical signal responded by the microcavity array 6 is emitted to a detection device and a signal demodulation unit through an optical link; the transmission spectrum passes through the array with a plurality of micro-cavities, the obtained micro-cavity transmission spectrum is collected to a photoelectric converter through a coupling light path 5 to convert an optical signal into an electric signal, then the electric signal is quantized through an analog-to-digital converter, and a transmission spectrum curve at each time T can be obtained through subsequent digital signal processing, so that the demodulation of the resonant frequency of the micro-cavity array 6 is realized; with the increase of the acquisition time, the change curves of all the resonant frequencies along with T can be obtained, when ultrasonic waves exist outside, the resonant frequencies of all the micro-cavities can generate frequency shift jitter with different time and amplitude and constant frequency in the ultrasonic waves, and the positioning of the ultrasonic waves can be realized by analyzing the time point when the ultrasonic waves reach each micro-cavity, the phase difference of the frequency shift and the intensity. The specific analysis process is as follows: because the ultrasonic source is positioned at any point in the space, the microcavity array 6 placed on any plane has the difference of space positions, and the propagation speeds of the ultrasonic wave in the air are consistent, so that the ultrasonic wave reaches each microcavity on the microcavity array 6 from the transmitting end with a certain time difference, namely, phase difference exists for spectrum detection, the space position of the ultrasonic source can be restored by comparing the phase difference information, and meanwhile, the accuracy and the sensitivity of ultrasonic detection can be greatly enhanced by judging the phase difference of the ultrasonic source through hundreds of ultrasonic sensing units.

The invention utilizes the advanced signal processing technology in the field of optical communication to obtain a digital optical frequency comb signal with a certain bandwidth, and the digital optical frequency comb signal is utilized to scan the microcavity photonic device to obtain the ultrafast and high-precision microcavity resonance peak scanning spectral line. Meanwhile, a plurality of microcavity structures are coupled by only one optical path system (optical fiber or waveguide) to realize the equidistant wavelength distribution of the resonance peaks of the microcavities. Through designing the wavelength position of the resonance peak of a plurality of microcavities, the digital optical frequency comb can quickly and accurately detect the frequency and the power of the respective resonance peak of a large number of microcavity structures, the detection efficiency and the processing difficulty of an ultrasonic array can be obviously improved, the digital optical frequency comb can be applied to the fields of ultrasonic array detection, photoacoustic imaging and the like, and a foundation is provided for the research of an integrated and miniaturized ultrasonic phased array detector.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.