CN109323659B - Method and device for measuring baseline length of airborne synthetic aperture radar - Google Patents
Method and device for measuring baseline length of airborne synthetic aperture radar Download PDFInfo
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- CN109323659B CN109323659B CN201811146975.XA CN201811146975A CN109323659B CN 109323659 B CN109323659 B CN 109323659B CN 201811146975 A CN201811146975 A CN 201811146975A CN 109323659 B CN109323659 B CN 109323659B
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- 238000000034 method Methods 0.000 title claims abstract description 22
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- 238000005259 measurement Methods 0.000 claims abstract description 81
- 239000013307 optical fiber Substances 0.000 claims abstract description 66
- 239000000835 fiber Substances 0.000 claims description 57
- 230000003287 optical effect Effects 0.000 claims description 5
- 229910001285 shape-memory alloy Inorganic materials 0.000 claims description 5
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- 238000013461 design Methods 0.000 description 4
- 238000009434 installation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
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Abstract
The invention relates to the technical field of synthetic aperture radar measurement and discloses a method and a device for measuring the baseline length of an airborne synthetic aperture radar. The measuring method comprises the steps of installing a measuring optical fiber engraved with an optical fiber Bragg grating on a measuring substrate, wherein the measuring substrate is arranged on a wing and is connected with an airborne synthetic aperture radar subarray; the shape function of the measuring substrate is reconstructed by measuring the strain and curvature of the substrate, thereby calculating the baseline length between the radar subarrays. The invention can realize the modeling without depending on the wing movement, is not influenced by the modeling precision of the wing movement, successfully solves the problem of measuring the baseline length of the airborne synthetic aperture radar, has high measuring precision, and has the advantages of small influence on the wing structure, light weight and no influence from weather.
Description
Technical Field
The invention relates to the technical field of synthetic aperture radar measurement, in particular to a method and a device for measuring the baseline length of an airborne synthetic aperture radar.
Background
For a carrier with a subarray mounted on a wing, deformation of the wing during flight can cause a change in the baseline length of the airborne synthetic aperture radar. The baseline length is an important parameter in the image reconstruction process of the airborne synthetic aperture radar, and is directly related to the quality of the final reconstructed image of the synthetic aperture radar.
The existing radar baseline length measurement system mainly comprises a baseline measurement system which is developed by the German FGSN-FHR research institute and adopts a single POS system and a laser/CCD combined sensor. The measurement of the baseline length by the system relies on modeling the movement of the wing deformation and is susceptible to weather conditions.
In the prior art, as in application number CN200510069053.X, a combined measuring device of an airborne interference synthetic aperture radar baseline is disclosed, a rigid platform is installed under the belly of an aircraft, two digital cameras, two laser rangefinders and an inertial measuring unit are fixedly installed on the platform, and at least three obvious LED marks are respectively arranged on two antennas; the two digital cameras, the two laser rangefinders and the inertia measuring unit are electrically connected with the control processor and are in signal communication. The digital camera and the laser range finder measure the instantaneous position and the gesture of the interference synthetic aperture radar antenna, the inertia measurement unit measures the position and the gesture of a platform where the digital camera and the laser range finder are positioned, and the three are combined to finally realize the dynamic measurement of the interference synthetic aperture radar dual-antenna. The method requires an additional device on the aircraft, has great influence on the aircraft structure, and has great measuring precision influenced by weather environment.
The fiber Bragg grating sensor has the advantages of small volume, high measurement precision, electromagnetic interference resistance and the like.
Disclosure of Invention
The invention aims to overcome at least one defect in the prior art, and provides an airborne synthetic aperture radar baseline length measurement method which does not depend on wing motion modeling and is not affected by weather.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the method comprises the steps that a measuring optical fiber engraved with an optical fiber Bragg grating is arranged on a measuring substrate, and the measuring substrate is arranged on a wing and is connected with an airborne synthetic aperture radar subarray; the shape function of the measuring substrate is reconstructed by measuring the strain and curvature of the substrate, thereby calculating the baseline length between the radar subarrays.
In the scheme, the fiber bragg grating is used for measuring the curvature information of the measurement substrate, the position information of the grating is also known, and curve fitting can be performed by using the position and the curvature information to obtain the coordinates of the substrate on a two-dimensional plane so as to obtain the base line length. In the scheme, the fiber bragg grating is used for measuring the strain and the curvature of the substrate instead of directly detecting the strain and the curvature of the wing, so that the baseline length of the airborne synthetic aperture radar can be measured under the condition of not carrying out wing mechanical modeling, the detection difficulty is reduced, and the detection precision is ensured.
Further, the method comprises the following steps of
S1, determining the length of a measuring substrate and the distance between radar subarrays;
s2, mounting the measuring optical fiber on a measuring substrate; the measuring substrate is fixedly connected with the radar subarrays, and the measuring substrate is kept in a buckling state;
s3, curve fitting is carried out by utilizing curvature information and position information obtained by the fiber Bragg grating, so that the baseline length is obtained.
Further, in the step S1, the positions of the radar subarrays are measured to obtain the distances between the radar subarrays; if the number of the radar subarrays is n, dividing the measuring substrate into n-1 sections; wherein the length of each section of the measuring substrate is larger than the distance between two adjacent radar subarrays. In the scheme, the measuring substrate is divided into a plurality of sections, and the number of the sections is 1 less than that of the radar subarrays, so that the measuring substrate is arranged between every two radar subarrays; and the length of each section of the measuring substrate and the distance between the two radar subarrays are set, so that the measuring substrate can keep a buckling state, and the matching performance of deformation of the random wings of the measuring substrate is further improved.
Further, in the step S2, the end portion of the measurement substrate and the demarcation point of each segment are fixed on the radar subarray by adopting a welding manner. In this scheme, adopt tip and demarcation point as fixed position to the welding is fixed mode for measure the base plate and when stable the being connected of radar subarray, reduce unnecessary connection, further improve the measuring base plate and take place the matchability that deformation was taken place to the random wing, improve measurement accuracy.
Further, in the step S3, wavelength drift information of each grating is demodulated in real time by an optical fiber demodulator, the wavelength drift information of each grating is uploaded to an upper computer, a coordinate system is established at the center of the machine body, curvature information and position information obtained by measuring each optical fiber grating are utilized to fit a curve, and further, a base line length is calculated.
Further, in the step S3, a formula is used to calculate the correspondence between the wavelength drift amount and the curvature
Where k is the curvature of the fiber, Δλ B As the central wavelength drift amount lambda B For the central wavelength of the grating, P e And h is the distance from the center of the optical fiber to the center of the substrate.
Further, the measuring substrate adopts a memory alloy. In the scheme, the memory alloy material can be used as the measurement substrate, so that the deformation recovery performance of the measurement substrate is improved.
Further, the measuring substrate adopts a substrate with a continuous cross section of rectangular shape with grooves, and the measuring optical fiber is fixed in the grooves of the measuring substrate. In this scheme, the measurement optical fiber is arranged in the measurement substrate groove with the rectangular groove, so that the risk of precision measurement errors caused by the torsional deformation of the measurement substrate can be greatly reduced.
The invention further aims to provide an airborne synthetic aperture radar baseline length measuring device which comprises a measuring optical fiber, a measuring substrate, an optical fiber grating demodulator and an upper computer; the measuring optical fiber is arranged on the measuring substrate; the measuring substrate is arranged on the wing and is fixedly connected with the synthetic aperture radar subarrays; the head of the measuring optical fiber is connected with an optical fiber grating demodulator, and the grating demodulator is connected with an upper computer.
According to the scheme, the measuring base plate is subjected to multi-point strain measurement along with deformation of the wing through the measuring optical fiber, the measuring parameters of the measuring optical fiber are demodulated by the fiber bragg grating demodulator, and the measuring parameters are transmitted to the upper computer to carry out radar baseline length calculation. The fiber bragg grating demodulator and the upper computer in the scheme can be arranged in the machine body. Because the optical fiber measurement combination formed by the measurement optical fiber and the measurement substrate has very small volume, the influence on the wing structure is small, the weight is light, and the influence of weather is avoided.
Further, to prevent the end reflection of the fiber from affecting the light source and demodulation, the tail of the measuring fiber is connected with an optical isolator.
Compared with the prior art, the invention has the following beneficial effects:
the invention creatively designs a base line length resolving system which comprises a high-precision strain sensing network based on a fiber grating sensor and a measuring substrate, is based on a fiber grating demodulator and an upper computer and takes the curvature of the measuring substrate and the position of the fiber grating as input information. The measuring method can realize independent wing movement modeling, is not influenced by the wing movement modeling precision, successfully solves the problem of measuring the baseline length of the airborne synthetic aperture radar, and has high measuring precision.
Specifically, the invention further greatly reduces the measurement error through the design of the position relation between the radar subarrays and the measurement substrate, the design of the length relation between the radar subarrays and the measurement substrate between the radar subarrays and the design of the fixing mode of the radar subarrays and the measurement substrate.
Meanwhile, the invention improves the measurement accuracy by limiting the curvature of the optical fiber within a certain range. Specifically, the length of the optical fiber measurement combination is set to be larger than the distance between the two radar subarrays, so that the optical fiber measurement combination is always in a buckling state; the length of the optical fiber measuring combination is selected, the curvature of the optical fiber measuring combination after installation can be controlled, the optical fiber curvature is limited in a certain range by reasonably selecting the length of the optical fiber measuring combination, and the problem of measurement accuracy reduction caused by overlarge and undersize optical fiber curvature in the prior art is solved.
In addition, the invention optimizes the shape and the material of the measuring substrate and the mounting mode of the measuring substrate and the measuring optical fiber, thereby further improving the measuring precision.
Furthermore, the invention installs the important device in the aircraft, has little influence on the wing structure, and can effectively avoid the influence of factors such as weather, air flow and the like; the defects that in the prior art, an additional device is needed outside the machine body, the appearance of the aircraft can be damaged, and the aircraft is easily interfered by external environments such as weather and the like are overcome.
The measuring method and the measuring device can effectively overcome the defects of the prior art, provide baseline length information for the image reconstruction of the airborne synthetic aperture radar, improve the image reconstruction precision of the airborne synthetic aperture radar, and have important application value.
Drawings
Fig. 1 is a schematic installation diagram of an onboard synthetic aperture radar baseline length measuring device of embodiment 1.
FIG. 2 is a three-dimensional schematic view of the mounting of the example 1 fiber optic measurement assembly on a wing.
FIG. 3 is a rear view of the fiber optic measurement combination of example 1 after installation on a wing.
Fig. 4 is a schematic diagram showing deformation of the optical fiber measurement combination of example 1 in a wing bending state.
Fig. 5 is a partial view of the example 2 fiber optic measurement combination on a wing.
Fig. 6 is a schematic diagram of the cross-sectional shape of the measurement substrate of example 2.
Fig. 7 is a schematic diagram of an end face of the measurement optical fiber and measurement substrate combination of embodiment 2.
Fig. 8 is a schematic diagram of a baseline reconstruction method in example 3.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the present patent;
for the purpose of better illustrating the embodiments, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the actual product dimensions; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. It will be understood by those of ordinary skill in the art that the terms described above are in the specific sense of the present invention. The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.
Example 1
As shown in fig. 1, the embodiment provides an airborne synthetic aperture radar baseline length measurement device, which comprises a measurement optical fiber, a measurement substrate, a fiber bragg grating demodulator and an upper computer; the measuring optical fiber is arranged on the measuring substrate; the measuring substrate is arranged on the wing and is fixedly connected with the synthetic aperture radar subarrays; the head of the measuring optical fiber is connected with the fiber grating demodulator, and the tail end of the measuring optical fiber is respectively connected with an optical isolator. The grating demodulator is connected with the upper computer.
Specifically, a series of fiber gratings are inscribed inside the measurement fiber. Each grating has a different center wavelength with a certain spacing between the center wavelengths to ensure that no frequency aliasing occurs during the measurement. In this embodiment, the measurement fiber is internally inscribed with a fiber bragg grating. Inside the fiber, fiber Bragg gratings were written every 10mm and the center wavelengths of these fiber Bragg gratings were arranged appropriately. In particular, a fiber bragg grating sensor may be employed.
As a specific implementation manner of this embodiment, the measurement substrate is connected to the radar subarrays by a welding manner; specifically, the rest of the measurement substrate is not soldered except for the connection portions with the respective radar subarrays.
As a specific implementation manner of this embodiment, as shown in fig. 2 and 3, the measurement optical fiber and the measurement substrate form an optical fiber measurement combination, and are disposed along the wing. An airborne synthetic aperture radar sub-antenna is disposed on the wing. It will be appreciated that since the optical fiber measuring combination is very thin, the dimensional proportion of the optical fiber measuring combination in fig. 2 is not actually proportional to the optical fiber measuring combination, and the enlarged display processing is performed for the sake of clarity of the positional relationship.
In this embodiment, the fiber bragg grating demodulator is connected to the upper computer through a network cable. The fiber bragg grating demodulator and the upper computer can be arranged in the machine body, and adverse effects of factors such as weather, air flow and the like can be effectively avoided.
As shown in fig. 4, the deformation of the substrate along with the deformation of the wing during the flight of the aircraft is measured. It will be appreciated that for clarity of illustration, the deformation of the wing and the measurement substrate is not true to scale in the figures for ease of understanding.
The working principle of this embodiment is as follows: the fiber Bragg grating sensor can be connected with a plurality of fiber Bragg grating strain sensors in series on one fiber in a wavelength division multiplexing mode, so that strain measurement for a plurality of points is realized; in the embodiment, the measuring substrate is arranged, the multi-point strain measurement is carried out on the measuring substrate, and the curvature of the measuring substrate can be measured through the strain according to the theory of material mechanics. Further, by combining the position information of the fiber Bragg grating, curve fitting is performed to obtain a shape function of the measurement substrate, so that the baseline length between the two radar subarrays can be obtained without directly measuring the wing deformation of the aircraft. And by arranging the optical isolator, the influence of the reflection of the tail end of the optical fiber on the light source and demodulation can be further prevented.
The principle of measuring the curvature of the substrate by the optical fiber is as follows: when the measuring substrate is bent along with the wings, the surface of the measuring substrate is strained, the fiber bragg grating is stuck with the measuring substrate, and the surface strain of the measuring substrate also causes the fiber to stretch or compress, so that the central wavelength of the echo is changed. The following formula can be deduced:
where k is the curvature of the fiber, Δλ B As the central wavelength drift amount lambda B For the central wavelength of the grating, P e And h is the distance from the center of the optical fiber to the center of the substrate. Thus, the correspondence relationship between the wavelength shift amount and the curvature can be obtained.
And demodulating the wavelength drift information of each grating in real time through a fiber bragg grating demodulator, and uploading the wavelength drift information of each grating to an upper computer. And the upper computer fits the curvature information and the position information to obtain a fitting curve, so that the length of the base line is calculated.
According to the embodiment, the high-precision strain sensing network is established by adopting the fiber Bragg grating, the measuring substrate deformed along with the wing and the measuring optical fiber are ingeniously utilized, a baseline length resolving system which takes a fiber grating demodulator capable of demodulating grating wavelength drift information and an upper computer as cores is formed, and high-precision measurement of the radar baseline length is realized. The device for measuring the length of the baseline of the airborne synthetic aperture radar overcomes the defects that in the prior art, an additional device is needed outside a machine body, the appearance of an aircraft is damaged, and the device is easily interfered by external environments such as weather, and the like, and can effectively avoid the influence of factors such as weather, air flow and the like.
Example 2
The present embodiment is different from embodiment 1 in that, as shown in fig. 5 to 7, as a specific implementation of the present embodiment, the measurement substrate is a substrate having a continuous cross section of a rectangular shape with grooves, and specifically, may be a substrate having a concave cross section. The material of the measurement substrate may be a memory alloy. It will be appreciated that the length of the measurement substrate may be adjusted according to the particular airborne synthetic aperture radar subarray length. The state in which the fiber bragg grating is mounted on the bottom of the measurement substrate groove is as shown in fig. 7, and the measurement substrate processed with the memory alloy is below, and the measurement fiber is precisely mounted in a right angle in the groove of the measurement substrate.
The measuring substrate of this embodiment has the difficult torsional deformation's of being difficult for characteristics, and this embodiment has overcome the result error that produces because of measuring substrate's self factor deformation, and measuring device measures radar baseline length's measurement accuracy is higher.
Example 3
The embodiment provides a method for measuring the baseline length of an airborne synthetic aperture radar. Mounting a measurement optical fiber on a measurement substrate, wherein the measurement optical fiber is an optical fiber engraved with an optical fiber Bragg grating; the measuring substrate is arranged on the wing and is connected with the airborne synthetic aperture radar subarrays; the shape function of the measuring substrate is reconstructed by measuring the strain and curvature of the measuring substrate, thereby calculating the baseline length between the radar subarrays.
The present measurement method can be performed using the apparatus of example 1 or example 2.
Specifically, the measurement method includes the steps of:
s1, determining the length of a measuring substrate and the distance between radar subarrays.
And under the ground condition, measuring the positions of all the radar subarrays to obtain the distance between all the radar subarrays. Let the number of radar subarrays be n, divide the measuring substrate into n-1 segments. The length of each section of the measuring substrate is slightly larger than the distance between two adjacent radar subarrays. The demarcation points between each segment of the measurement substrate can be marked with a dye. The boundary line and the end of the measuring substrate are marks of the fixed points of the measuring substrate and the radar subarrays.
S2, mounting the measuring optical fiber on a measuring substrate; the measuring substrate is fixedly connected with the radar subarray, and the measuring substrate is kept in a buckling state.
In this embodiment, the measurement substrate may adopt a groove structure as shown in fig. 5, and the measurement optical fiber may be mounted on the measurement substrate by means of adhesion. When the cross section of the measurement substrate is concave, the measurement fiber may be installed in a groove of the concave shape. The measuring optical fiber and the measuring substrate together form an optical fiber measuring combination. The optical fiber measuring combination is arranged on the wing.
The position of the fiber bragg grating relative to the measuring substrate can be measured through a graduated scale, and one-dimensional coordinates of each grating relative to the first section of the measuring substrate are obtained: x1, x2 … xn. In this example, the fiber optic measurement assembly is divided into 4 segments, and the segments are marked with a dye.
The boundary between the end of the measurement substrate and each segment is fixed to the radar subarray. In this embodiment, the boundary between the end of the measurement substrate and each segment may be connected to the radar subarray by welding; the measurement substrate is not soldered except for the connection portion with each of the radar subarrays.
In this embodiment, the length of the measurement substrate between each radar subarray is slightly longer than the distance between the radar subarrays, so that the measurement substrate keeps a buckling state, and the deformation of the measurement substrate is ensured to correspond to the deformation of the wing, thereby further improving the measurement accuracy of the baseline.
The two tail parts of the measuring optical fiber are connected with an optical isolator with the central wavelength of 1550nm so as to prevent the reflection of the tail end of the optical fiber from influencing the light source and demodulation. The two fiber heads are connected to a fiber grating demodulator, respectively. The fiber bragg grating demodulator is connected with the upper computer through a network cable. Thus, the construction of the measurement network is completed.
S3, curve fitting is carried out by utilizing curvature information and position information obtained by the fiber Bragg grating, so that the baseline length is obtained.
The measurement fiber was connected to a fiber grating demodulator for demodulation. And obtaining real-time center wavelength information of each grating, and uploading the information to an upper computer through a network cable.
And (3) on the upper computer, calculating the curvature corresponding to each grating according to a formula (1) through the corresponding relation between the central wavelength drift amount and the curvature. The position information of each grating on the substrate is obtained, the position information of each grating corresponds to the curvature information of each grating one by one, and the coordinates of the two ends of the substrate on the two-dimensional plane can be obtained through curve fitting, so that the length of the base line can be obtained.
Specifically, after the carrier of the airborne synthetic aperture radar reaches the region to be observed, the fiber bragg grating demodulator starts to work. And demodulating wavelength drift information of each grating in real time, and uploading the wavelength drift information of each grating to an upper computer. In the upper computer, curve fitting is performed by using curvature information and position information obtained by the fiber bragg grating sensor, as shown in fig. 8, a coordinate system is established in the center of the machine body, a curve is fitted by using curvature information and position information obtained by measuring each fiber bragg grating, and further, the base line length is calculated.
The upper computer can store the baseline information and send the baseline information to the radar computer, can reconstruct radar images after the observation is finished, and can reconstruct radar images in real time.
The measuring method overcomes the defect that the existing airborne synthetic aperture radar baseline measuring technology needs to model the wing, can measure the airborne synthetic aperture radar baseline length, and has high measuring precision.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. The method is characterized in that a measuring optical fiber engraved with an optical fiber Bragg grating is arranged on a measuring substrate, each grating has different center wavelengths, and certain intervals are arranged between the center wavelengths; the measuring substrate is arranged on the wing and is connected with the airborne synthetic aperture radar subarrays; and (3) measuring the strain and curvature of the substrate, performing curve fitting by combining the position information of the fiber Bragg grating, and reconstructing the shape function of the measured substrate, so as to calculate the baseline length between the radar subarrays.
2. The method for measuring the baseline length of the airborne synthetic aperture radar according to claim 1, comprising the steps of
S1, determining the length of a measuring substrate and the distance between radar subarrays;
s2, fixing the measuring optical fiber on a measuring substrate; the measuring substrate is fixedly connected with the radar subarrays, and the measuring substrate is kept in a buckling state;
s3, curve fitting is carried out by utilizing curvature information and position information obtained by the fiber Bragg grating, so that the baseline length is obtained.
3. The method for measuring the baseline length of the airborne synthetic aperture radar according to claim 2, wherein in the step S1, the positions of the radar subarrays are measured to obtain the distance between the radar subarrays; if the number of the radar subarrays is n, dividing the measuring substrate into n-1 sections; wherein the length of each section of the measuring substrate is larger than the distance between two adjacent radar subarrays.
4. The method for measuring the baseline length of the airborne synthetic aperture radar according to claim 3, wherein in the step S2, the end of the measuring substrate and the demarcation point of each segment are fixed on the radar subarray by welding.
5. The method for measuring the baseline length of the airborne synthetic aperture radar according to claim 2, wherein in the step S3, wavelength drift information of each grating is demodulated in real time by an optical fiber demodulator, the wavelength drift information of each grating is uploaded to an upper computer, a coordinate system is established in the center of the machine body, curvature information and position information measured by each optical fiber grating are used for fitting a curve, and the baseline length is calculated.
6. The method for measuring the baseline length of the airborne synthetic aperture radar according to any one of claims 2 to 5, wherein in the step S3, a formula is used to calculate the correspondence between the wavelength drift amount and the curvature
Where k is the curvature of the fiber, Δλ B As the central wavelength drift amount lambda B For the central wavelength of the grating, P e And h is the distance from the center of the optical fiber to the center of the measuring substrate.
7. The method for measuring the baseline length of the airborne synthetic aperture radar according to any one of claims 1 to 5, wherein the measuring substrate is made of a memory alloy.
8. The method for measuring the baseline length of the airborne synthetic aperture radar according to claim 7, wherein the measuring substrate is a substrate with a continuous cross section of a rectangular shape with grooves, and the measuring optical fiber is fixed in the grooves of the measuring substrate.
9. The device for measuring the baseline length of the airborne synthetic aperture radar is characterized by comprising a measuring optical fiber, a measuring substrate, an optical fiber grating demodulator and an upper computer; the measuring optical fiber is arranged on the measuring substrate; a series of fiber gratings are inscribed in the measuring fiber, each grating has different center wavelengths, and certain intervals are arranged between the center wavelengths; the measuring substrate is arranged on the wing and is fixedly connected with the synthetic aperture radar subarrays; the head of the measuring optical fiber is connected with an optical fiber grating demodulator, and the grating demodulator is connected with an upper computer.
10. The airborne synthetic aperture radar baseline length measurement apparatus of claim 9 wherein the tail of the measurement fiber is connected to an optical isolator.
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| CN109948245B (en) * | 2019-03-18 | 2023-06-06 | 东南大学 | Wing baseline dynamic position measurement method based on iFEM method and RZT theory |
| CN110068817B (en) * | 2019-05-07 | 2021-07-06 | 中国科学院电子学研究所 | Terrain mapping method, instrument and system based on laser ranging and InSAR |
| CN111288912B (en) * | 2020-03-24 | 2021-07-30 | 北京航空航天大学 | Fiber bragg grating deformation measurement method for airborne distributed POS |
| CN111854621B (en) * | 2020-06-05 | 2021-10-15 | 北京航空航天大学 | Fiber bragg grating sensor data fitting method and device for airborne distributed POS |
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