CN114236570B - Laser atmospheric data system and calculation method - Google Patents

Abstract

The invention discloses a laser atmospheric data system and a calculation method, which relate to the field of atmospheric parameter measurement. The invention accurately measures the intensity information of the laser spectrum on each characteristic frequency by utilizing the etalon with a plurality of channels, fits the original spectrum signal with high precision, and can independently and accurately invert the atmospheric data information on the premise of not being supported by other principle atmospheric data sensors. The laser atmospheric data system and the traditional atmospheric data system form a non-similar redundancy atmospheric data system, so that the reliability of the flight atmospheric parameters can be greatly improved, and the flight safety of the airplane is guaranteed.

Description

Laser atmospheric data system and calculation method

Technical Field

The invention relates to the field of atmospheric parameter measurement, in particular to a laser atmospheric data system and a calculation method.

Background

The air data system is taken as a flight safety key system, and receives high attention in design, development and commercial operation of civil aircraft models. In order to ensure flight safety and match the design requirements of a multi-channel flight control system, modern civil aircrafts are provided with a plurality of sets of redundant backup atmospheric data sensors and sensors. Currently, in mainstream civil aircraft, three independent air data systems and one standby air data system are generally required to be configured.

Although the airborne atmospheric data system adopts a redundant configuration of multi-channel monitoring and backup, the principle adopted by the channels is consistent, so that the condition that the whole-aircraft atmospheric data system fails due to common-mode faults such as airspeed head icing and attack angle sensor faults cannot be avoided. Many of the major impacts of air crashes are related to some information failures of the air data system. As in 2009, a french aviation AF447 flight (airbus a 330) entered the convective cloud at a cruising height of 37000 feet. The three airspeeds are frozen at the same time, so that all airspeeds are indicated abnormally, and the airplane stalls and crashes. An Indonesia lion voyage JT610 flight in 2018 and an Etsu airline ET302 flight in 2019 (both Boeing 737 MAX) have attack angle sensor faults after takeoff, wrong attack angle data activate an automatic anti-stall system (a maneuvering characteristic enhancement system MCAS), and the pilot contends for airplane control right and the airplane crashes out of control.

From the major impact of the occurrence of air crash and the reason and the occurrence thereof, the multi-channel redundant system scheme of the air data system causing the aircraft accident and the adopted airborne equipment can not well achieve the expected design and safety target, which is related to the specific realization of the multi-channel redundant air data system, the same working principle of the redundant equipment, similar environmental adaptability and the existence of common hidden danger. The potential safety impact of common hazards in multi-channel redundancy designs due to the same principle of individual channels is greater than the failure and malfunction of a single channel or a single component. Therefore, aiming at the design target of future novel civil aircraft, such as safety, high efficiency, comfort and economy, an air data system which is different from the current measurement principle of the airborne system and independent from an information source is very necessary to be further added on the basis of the current multi-channel redundancy design, the monitoring range and accuracy of the air data information are fundamentally improved, and a key system and a key information source foundation are laid for improving the safety of the aircraft.

Ground-based atmospheric detection lidar used for atmospheric physics research tends to use 532nm green light as a detection light source, since molecular iodine absorption spectrometers have excellent absorption spectral lines near 532 nm. However, due to the concerns of laser eye safety requirements, laser atmospheric data systems cannot use light sources that are more harmful to the human eye, such as green light.

The laser atmosphere has a plurality of technical problems at present, which causes the laser atmosphere to enter the application slowly, and the key core problem is the complexity of laser spectrum analysis. The laser atmospheric data system needs to simultaneously extract atmospheric data information such as speed, temperature, density, etc. from the scattered light, and these information are coupled with each other, resulting in difficulty in calculation. For example, a photoelectric detection system based on a CCD detects the emergent signal of the F-P etalon, the capacity of frequency spectrum information is increased, but the calculation program is complex and the calibration is difficult. The related optical air data system disclosed in U.S. patent publication No. US10444367B2 requires the use of a conventional air data system to provide temperature/pressure signals for resolution and does not meet the independent operating requirements of the critical sensor system for civil aviation.

Disclosure of Invention

Aiming at the defects in the prior art, the laser atmosphere data system and the calculation method provided by the invention solve the technical problems that the speed, the temperature and the density of atmosphere data in the laser spectrum analysis process of the conventional laser atmosphere data system are difficult to be considered, and the simultaneous and accurate measurement cannot be realized.

In order to achieve the purpose of the invention, the invention adopts the technical scheme that:

the laser atmospheric data system comprises an ultraviolet laser, an optical window, a transceiving antenna, a receiving and collimating component, a multi-channel etalon, a photoelectric detection component and a data acquisition and processing component; wherein:

an ultraviolet laser for generating probe light and reference light; wherein the reference light is directly delivered to the receiving collimating assembly; the detection light is emitted to the outside through the receiving and transmitting antenna and the optical window, and generates scattering light carrying atmosphere data information under the scattering action with the atmosphere environment outside the aircraft, and the scattering light is transmitted to the receiving collimation assembly after being collected by the receiving and transmitting antenna through the optical window;

the receiving collimation assembly is used for respectively transmitting the scattered light and the reference light to the multi-channel etalon after collimation and filtering;

the multi-channel etalon comprises a reference light channel and at least three signal light channels; wherein the reference optical channel is used for generating a reference optical frequency point optical signal by the collimated and filtered reference light; the signal light channel is used for generating a signal light frequency point light signal through the collimated and filtered scattered light;

the photoelectric detection component comprises photoelectric detectors with the number more than or equal to that of the channels of the multi-channel etalon and is used for converting the light signal intensity of the frequency points into light intensity electric signals to obtain a reference light intensity characteristic point and a group of signal light intensity characteristic values consisting of at least three signal light intensity points;

the data acquisition and processing assembly is used for fitting the signal light intensity characteristic value to obtain a scattered light spectrum signal; correcting the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal; and processing the scattered light spectrum calibration signal to obtain and output atmospheric data.

The beneficial effect of this scheme is: the system accurately measures the intensity information of the laser spectrum on each characteristic frequency by utilizing the etalon with a plurality of channels, fits the original spectrum signal with high precision, and can independently and accurately invert the atmospheric data information on the premise of not being supported by other principle atmospheric data sensors. The laser atmospheric data system and the traditional atmospheric data system form a non-similar redundancy atmospheric data system, so that the reliability of the flight atmospheric parameters can be greatly improved, and the flight safety of the airplane is guaranteed.

Furthermore, the transmitting and receiving antenna is a paraxial transmitting and receiving antenna and comprises a transmitting antenna and a receiving antenna which are arranged side by side, and the optical window is arranged in front of the transmitting antenna and the receiving antenna which are arranged side by side; the transmitting antenna is used for transmitting the detection light; the receiving antenna is used for receiving scattered light.

Furthermore, the transmitting and receiving antenna is a coaxial transmitting and receiving antenna, and the optical window is arranged in front of the coaxial transmitting and receiving antenna.

Furthermore, the receiving and transmitting antenna is a prism scanning type receiving and transmitting antenna and comprises a Cassegrain antenna, a reflector and a scanning prism which are arranged in sequence; the detection light is emitted from the ultraviolet laser, reflected to the scanning prism through the reflector and refracted to the optical window through the scanning prism;

the scattered light reflected back from the outside is refracted to the edge portion of the cassegrain antenna by the scanning prism, reflected to the reflecting mirror by the cassegrain antenna, reflected to the central portion of the cassegrain antenna by the reflecting mirror and passes through the cassegrain antenna.

The beneficial effects of the further scheme are as follows: the scanning prism has the function of rotating along the axial direction of the receiving and transmitting antenna 3, and in any state of the scanning prism, the detection light and the axial direction of the receiving and transmitting antenna form a specific included angle and form conical scanning around the axial direction of the receiving and transmitting antenna, so that the receiving and transmitting antenna has the scanning function and is convenient for measuring the three-dimensional vector speed.

Furthermore, the receiving and transmitting antenna is a receiving and transmitting antenna of an off-type optical switch, and comprises a first beam splitter, a beam combiner, at least three off-type optical switches, at least three transmitting antennas and at least three receiving antennas;

the input end of the first beam splitter is connected with the output end of the ultraviolet laser, the output end of the first beam splitter is respectively connected with the input ends of all the turn-off optical switches, and the output end of each turn-off optical switch is connected with one transmitting antenna;

the output end of the beam combiner is connected with the receiving collimation assembly, and the input end of the beam combiner is connected with each receiving antenna respectively.

Furthermore, the included angles between two adjacent transmitting antennas are allJ(ii) a The included angles between two adjacent receiving antennas are allJ。

Furthermore, the transmitting and receiving antenna is a switching optical switch, and comprises a first switching optical switch, a second switching optical switch, at least three transmitting antennas and at least three receiving antennas;

the input end of the first switching optical switch is connected with the output end of the ultraviolet laser, and the output end of the first switching optical switch is respectively connected with each transmitting antenna;

the output end of the second switching optical switch is connected with the receiving collimation assembly, and the input end of the second switching optical switch is connected with each receiving antenna respectively.

Furthermore, the included angles between two adjacent transmitting antennas are allJ(ii) a The included angles between two adjacent receiving antennas are allJ。

The beneficial effect of adopting the further scheme is that: the system can be adapted to various receiving and transmitting antennas, is convenient to arrange at different positions of different aircrafts and is suitable for various environments.

Furthermore, the receiving collimation assembly comprises two receiving collimation modules, and each receiving collimation module comprises a first collimation mirror and a narrow-band optical filter; the input end of the first collimating mirror is the input end of the receiving collimating module, the output end of the first collimating mirror is connected with the input end of the narrow-band filter, and the output end of the narrow-band filter is the output end of the receiving collimating module; the two receiving collimation modules are respectively used for receiving the scattered light and the reference light.

Further, the first collimating mirror includes a concave lens and a convex lens, and the concave lens is disposed at a front end of the convex lens.

The beneficial effect of adopting the further scheme is that: the collimating lens is composed of a plurality of lenses, the Galileo telescope configuration is adopted, and light beams do not have convergence points in the collimating lens. Generally, the divergence angles of the original incident beams are large, the divergence angles of the original incident beams are gradually compressed by a plurality of lenses through a collimating mirror, and the collimation degree of the beams is adjusted by controlling the material, the surface curvature and the lens interval of each lens glass in the combination. The collimated reference beams respectively pass through a plurality of narrow-band filters with the center wavelength of 355nm by the narrow-band filters to filter out interference light in other bands outside the band; the narrow-band filters pass the collimated signal beams through a plurality of narrow-band filters with the center wavelength of 355nm respectively, and out-of-band background noise (the signal light mainly comprises background stray light from the sky) is filtered. The narrow-band filters realize the band-pass function by plating the dielectric films meeting the bandwidth requirement on two sides, and the combination use of a plurality of narrow-band filters can greatly improve the signal-to-noise ratio of the central wavelength, so that the reference light 61 and the signal light 71 only comprising 355nm wavelength are transmitted to subsequent components.

Further, the reference light channel comprises a first etalon channel; the at least three signal light channels include a second beam splitter and at least three second etalon channels; the output end of the second beam splitter is respectively connected with each second etalon channel; the output of the first etalon channel and the output of all of the second etalon channels together serve as the output of the multi-channel etalon.

Furthermore, the first etalon channel and the second etalon channel have the same structure and respectively comprise a transmitting end, a second collimating mirror, a first parallel plate, a second parallel plate, a receiving mirror and a receiving end which are sequentially arranged; one surface of the first parallel plate facing the second parallel plate and one surface of the second parallel plate facing the first parallel plate are both provided with high-reflection films;

and the transmitting end is used for transmitting the received signal to the second collimating mirror.

The beneficial effect of adopting the further scheme is that: the light beam forms multiple reflections in two parallel planes of the parallel plate, and the reflected light and the transmitted light form multiple beam interference, so that the light intensity capable of transmitting through the parallel plate is mainly determined by the distance between the parallel plates and the wavelength, namely, only the light with a specific wavelength can be emitted to the receiving mirror to finally enter a receiving end. The etalon can accurately extract optical signals in a specific narrow-band wavelength range in the broadband light source, so that a basis is provided for identifying frequency spectrum information of the broadband light source.

Further, the photodetector includes a focusing objective lens and a photoelectric converter;

the focusing objective lens is used for focusing the received signals and sending the focused signals to the photoelectric converter;

and the photoelectric converter is used for converting the received optical signal into an optical intensity electric signal.

Further, the data acquisition and processing assembly comprises a fitting calculation unit, a calibration calculation unit and an atmospheric data resolving unit which are sequentially connected;

the fitting calculation unit is used for fitting the signal light intensity characteristic value sent by the photoelectric detection component into a scattered light spectrum signal;

the calibration calculation unit is used for correcting the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal;

and the atmospheric data resolving unit is used for processing the scattered light spectrum calibration signal to obtain atmospheric data and outputting the atmospheric data.

The laser atmospheric data calculation method comprises the following steps:

s1, generating detection light and reference light by an ultraviolet laser;

s2, emitting the detection light to the outside through the transceiving antenna and the optical window, and receiving the scattered light which carries the atmospheric data information and is generated by the scattering effect of the detection light and the atmospheric environment outside the aircraft;

s3, collimating and filtering the scattered light and the reference light by the receiving collimating component, and then respectively transmitting the collimated light and the reference light to the multi-channel etalon;

s4, generating a reference light frequency point light signal based on the collimated and filtered reference light through the multi-channel etalon; generating a signal light frequency point light signal based on the collimated and filtered scattered light by a multi-channel etalon;

s5, the photoelectric detection component converts the light signal intensity of the frequency point into a light intensity electric signal to obtain a reference light intensity characteristic point and a group of signal light intensity characteristic values consisting of at least three signal light intensity points;

s6, fitting the signal light intensity characteristic values to obtain scattered light spectrum signals;

s7, correcting the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal;

and S8, processing the scattered light spectrum calibration signal to obtain and output atmospheric data.

The method has the beneficial effects that: the etalon with a plurality of channels is used for accurately measuring the intensity information of the laser spectrum on each characteristic frequency, the original spectrum signal is fitted with high precision, and the atmospheric data information can be independently and accurately inverted on the premise of no support of other principle atmospheric data sensors. The laser atmospheric data system and the traditional atmospheric data system form a non-similar redundancy atmospheric data system, so that the reliability of the flight atmospheric parameters can be greatly improved, and the flight safety of the airplane is guaranteed.

Further, the fitting method of step S6 includes the following sub-steps:

s6-1, according to the formula:

constructing a fitted feature matrixF(ii) a Wherein

The signal frequency of the 1 st signal light;

the signal frequency of the 2 nd signal light;

is a firstnA signal frequency of the signal light;

s6-2, according to the formula:

constructing signal light feature vectorsI(ii) a Wherein

Is a firstnThe signal light intensity characteristic value;

is composed of

The adjustment coefficient of (a);

s6-3, according to the formula:

obtaining a vector of eigenvaluesv(ii) a Wherein

Represents a transpose of a matrix;

s6-4, according to the formula:

obtaining scattered light spectrum signals

(ii) a Wherein

Is a curve equation of the spectrum signal.

Further, the specific method of step S7 is:

according to the formula:

correcting the scattered light spectrum signal to obtain a scattered light spectrum calibration signal

(ii) a Wherein

In order to calibrate the equations for the scatter spectra,

in order to refer to the characteristic value of the light,

is composed of

The adjustment coefficient of (2).

Further, the specific method of step S8 includes the following sub-steps:

s8-1, obtaining Doppler frequency shift by resolving the difference between the central frequency and the central frequency of laser emitted by the ultraviolet laser, wherein the expression is as follows:

wherein

Is a Doppler shift;

for resolving the central frequency, i.e. by calibrating the signal by the spectrum of the scattered light

A calculated center frequency;

lasing for ultraviolet lasersA center frequency;

s8-2, calculating the velocity of the line of sight according to the Doppler frequency shiftVThe calculation expression is:

wherein

Emitting a laser center wavelength for an ultraviolet laser;

s8-3, calibrating signal by resolving scattered light spectrum

Obtaining atmospheric static temperature by spectral broadening

The calculation expression is:

wherein

Is a temperature adjustment coefficient;

calculating a model for the spectral broadening;

s8-4, calibrating signal by resolving scattered light spectrum

Envelope area of

Obtaining the atmospheric density

The calculation expression is:

wherein

Calculating a model for the envelope area;

is a density adjustment factor;

s8-5, calculating the three-axis vector airspeed according to the sight velocities in different detection directions, wherein the calculation expression is as follows:

wherein

Is composed ofxAn axial vector airspeed;

is composed ofyAn axial vector airspeed;

is composed ofzAn axial vector airspeed;

is an angle correction matrix;

projecting an angle correction matrix for the line of sight velocity;

is as followsnLine-of-sight speed for each detection direction;

s8-6, acquiring the vacuum velocity TAS and the angle of attack based on the three-axis vector airspeed

And sideslip angle

The calculation expression is:

wherein

Is an arctangent function;

s8-7, obtaining sound velocity corresponding to the temperature based on atmospheric static temperatureaThe calculation formula is as follows:

；

s8-8, calculating Mach number based on vacuum speed and sound speedMThe calculation formula is as follows:

；

s8-9, calculating the total temperature of the atmosphere based on the Mach number and the static temperature of the atmosphere

The calculation formula is as follows:

；

s8-10, calculating the atmospheric static pressure based on the atmospheric static temperature and the atmospheric density

The calculation formula is as follows:

；

s8-11, calculating the barometric altitude based on the atmospheric static pressure

And the lifting speed

The calculation formula is as follows:

wherein

The air pressure height at the current moment;

the air pressure height at the previous moment;

the time difference between the current time and the last time is obtained;

s8-12, calculating the total atmospheric pressure based on the Mach number and the atmospheric static pressure

The calculation formula is as follows:

；

s8-13, calculating atmospheric pressure based on atmospheric static pressure and atmospheric total pressure

The calculation formula is as follows:

；

s8-13, according to the formula:

the calibrated space velocity CAS is calculated based on the atmospheric dynamic pressure.

The beneficial effects of the above further scheme are: the atmosphere data resolving algorithm occupies less avionic computing resources, and the calibration data/table occupies less avionic storage resources. The independent working requirements of the civil aviation key sensor system can be met without using a traditional atmospheric data system to provide temperature/pressure signals for calculation.

Drawings

FIG. 1 is a block diagram of the present system;

FIG. 2 is a schematic diagram of a paraxial transceiving antenna;

fig. 3 is a schematic diagram of a coaxial transceiver antenna;

FIG. 4 is a schematic diagram of a transmitting/receiving antenna using a prism scanning method;

FIG. 5 is a schematic diagram of a transmit/receive antenna based on an off-type optical switch;

FIG. 6 is a schematic diagram of a switch-based optical switch for transmitting and receiving antenna;

FIG. 7 is a schematic view of three probing directions;

FIG. 8 is a schematic diagram of four probing directions;

FIG. 9 is a schematic view of the system in an overhead projection;

FIG. 10 is a schematic diagram of the operation of the receive collimating assembly;

FIG. 11 is a schematic diagram of the etalon operating principle;

FIG. 12 is a schematic diagram of the operating principle of a multi-channel etalon;

FIG. 13 is a schematic diagram of a multi-channel etalon transmittance curve;

FIG. 14 is a graph of a histogram transmittance curve;

FIG. 15 is a schematic diagram showing the relationship between scattering signal and air pressure height;

FIG. 16 is a graph showing the transmission peaks at various characteristic frequencies for a 0 meter stationary standard atmospheric scattering signal spectrum;

FIG. 17 is a graph showing the transmission peaks at various characteristic frequencies of a stationary standard atmospheric scattering signal spectrum of 3000 meters;

FIG. 18 is a graph showing the transmission peaks at various characteristic frequencies for a 6000-meter stationary standard atmospheric scattering signal spectrum;

FIG. 19 is a graph showing the transmittance peaks at various characteristic frequencies for a 9000 meter stationary standard atmospheric scattering signal spectrum;

FIG. 20 is a graph showing the transmission peaks at various characteristic frequencies for a 12000 m static standard atmospheric scattering signal spectrum;

FIG. 21 is a graph showing the transmission peaks at various characteristic frequencies of the stationary standard atmospheric scattering signal spectrum at 15000 meters;

FIG. 22 is a graph showing the transmission peaks at various characteristic frequencies for a 18000m stationary standard atmospheric scattering signal spectrum;

FIG. 23 is an enlarged view of FIG. 22;

FIG. 24 is a graph showing the transmission peaks at various characteristic frequencies of the atmospheric scattering signal spectrum flying at 0.6Ma speed;

FIG. 25 is a graph showing the transmission peaks at various characteristic frequencies of an atmospheric scattering signal spectrum flying at 0.7 Ma;

FIG. 26 is a graph showing the transmission peaks at various characteristic frequencies of an atmospheric scattering signal spectrum flying at 0.8 Ma;

FIG. 27 is a graph showing the transmission peaks at various characteristic frequencies of an atmospheric scattering signal spectrum flying at 0.9 Ma;

FIG. 28 is a schematic view of the photoelectric detection assembly and the data acquisition and processing assembly;

FIG. 29 is a schematic flow chart of the method.

Wherein: 1. scattering light; 2. an optical window; 3. a transmit-receive antenna; 4. detecting light; 5. an ultraviolet laser; 6. a reference light; 7. a signal light; 8. receiving a collimating assembly; 9. a multi-channel etalon; 10. a photodetection component; 11. a data acquisition processing component; 31. a paraxial transmit-receive antenna; 32. a coaxial transceiver antenna; 311. a transmitting antenna; 312. a receiving antenna; 33. a scanning prism; 34. a Cassegrain antenna; 35. a mirror; 36. a first beam splitter; 37. a switch-off optical switch; 38. a beam combiner; 39. a first switching optical switch; 40. a second switching optical switch; 81. a first collimating mirror; 82. a narrow band filter; 12. a transmitting end; 13. a second collimating mirror; 14. a first parallel plate; 15. a highly reflective film; 16. a second parallel plate; 17. a receiving mirror; 18. a receiving end; 91. a first etalon channel; 92. a second etalon channel; 93. a second beam splitter; 101. a focusing objective lens; 102. a photoelectric converter; 111. a fitting calculation unit; 112. a calibration calculation unit; 113. and an atmospheric data resolving unit.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.

Example 1:

referring to fig. 1, in the embodiment described below, the laser atmospheric data system is composed of an ultraviolet laser 5, an optical window 2, a transceiver antenna 3, a receiving collimation assembly 8, a multi-channel etalon 9, a photoelectric detection assembly 10, and a data acquisition processing assembly 11. The ultraviolet laser 5 generates detection light 4 and reference light 6, the detection light 4 is emitted to the outside through the transceiving antenna 3 and the optical window 2, and the reference light 6 (all light signals obtained from the light in subsequent components are referred to as reference light) is directly transmitted to the receiving collimation component 8. The detection light 4 and the atmospheric environment outside the aircraft generate scattering action to generate scattered light 1 carrying atmospheric data information, and the scattered light 1 is collected by the transceiving antenna 3 through the optical window 2 to generate signal light 7 (all optical signals obtained from the light in subsequent components are called signal light) and is transmitted to the receiving collimation component 8. The receiving collimating component 8 collimates and filters the signal light 7 and the reference light 6, and then respectively transmits the collimated and filtered signals to the multi-channel etalon 9. The multi-channel etalon 9 contains a reference light channel and at least three signal light channels, each channel has a specific frequency transmission range, and the signal light and the reference light pass through the multi-channel etalon 9 to generate a reference light frequency point light signal and at least three signal light frequency point light signals and enter the photoelectric detection assembly 10. The photoelectric detection component 10 contains a photoelectric detector with the number equal to the number of the channels of the multi-channel etalon 9, and the photoelectric detector converts the light signal intensity of each frequency point into light intensity described by an electric signal to obtain a reference light intensity characteristic point and a group of signal light intensity characteristic values consisting of not less than three signal light intensity points. The data acquisition processing assembly 11 receives the reference light intensity point and the signal light intensity characteristic value, fits the signal light intensity characteristic value to obtain a scattering signal spectrum of the signal light, calibrates the scattering signal spectrum of the signal light based on the reference light intensity characteristic value to obtain a standard scattering spectrum, processes the standard scattering spectrum to obtain atmospheric data and outputs the atmospheric data.

Example 2:

this embodiment is a further extension of embodiment 1, and referring to fig. 2, the transceiver antenna 3 in the laser atmosphere data system may be implemented as a paraxial transceiver antenna 31. For a single detection point in the atmospheric environment, the paraxial transmitting and receiving antenna 31 is composed of a transmitting antenna 311 and a receiving antenna 312, the transmitting antenna 311 has a laser transmitting function, and the receiving antenna 312 has a scattered light collecting function. The transmitting antenna 311 transmits the detection light 4 to the atmosphere, the detection light 4 generates scattering action with the atmosphere environment after passing through the optical window 2 to generate scattered light 1 carrying atmosphere data information, and the returned scattered light 1 is collected by the receiving antenna 312 after passing through the optical window 2.

Example 3:

this embodiment is a further extension of embodiment 1, and referring to fig. 3, the transmitting/receiving antenna 3 in the laser atmosphere data system may be implemented by a coaxial transmitting/receiving antenna 32. The coaxial transmitting/receiving antenna 32 has both laser emission and scattered light reception functions. For a single detection point in the atmospheric environment, the coaxial transceiver antenna 32 emits the detection light 4 to the atmosphere, the detection light 4 generates a scattering effect with the atmospheric environment after passing through the optical window 2 to generate the scattered light 1 carrying atmospheric data information, and the returned scattered light 1 is collected by the coaxial transceiver antenna 32 after passing through the optical window 2.

In the flight atmosphere parameters output by the laser atmosphere data system, the speed is a three-dimensional speed vector defined by airspeed, attack angle and sideslip angle. In order to measure the three-dimensional vector velocity, the transmitting and receiving antenna 3 needs to have a scanning function. The transmitting and receiving antenna 3 in the laser atmosphere data system can adopt a prism scanning embodiment, a turn-off optical switch 37 embodiment or a switching optical switch embodiment.

Example 4:

this embodiment is a further extension of embodiment 1, and with reference to fig. 4, is an embodiment of a transmitting/receiving antenna 3 with scanning function implemented in a prism scanning manner. The transmitting and receiving antenna 3 is composed of a cassegrain antenna 34, a reflecting mirror 35 and a scanning prism 33. The detection light entering from the side surface of the receiving and transmitting antenna 3 enters the scanning prism 33 along the axial direction of the receiving and transmitting antenna 3 after being reflected by the reflecting mirror 35, is refracted in the scanning prism 33, enters the optical window 2 along the direction forming a specific included angle with the axial direction of the receiving and transmitting antenna 3, and is emitted to the outside of the aircraft. The scattered light 1 returns to the optical window 2 along the original path, enters the scanning prism 33, is refracted in the scanning prism 33, enters the cassegrain antenna 34 along the axial direction of the transmitting and receiving antenna 3, and is converged by the cassegrain antenna 34 to be output as signal light. The scanning prism 33 has a function of rotating along the axial direction of the transmitting/receiving antenna 3, and in any state of the scanning prism 33, the detecting light 4 forms a specific included angle with the axial direction of the transmitting/receiving antenna 3, and forms a conical scanning around the axial direction of the transmitting/receiving antenna 3. Since the movement paths of the scattered light 1 and the probe light 4 are the same, the present embodiment is a coaxial transmitting/receiving antenna.

Example 5:

this embodiment is a further extension of embodiment 1, and referring to fig. 5, it is an embodiment of a transmitting/receiving antenna 3 with a scanning function implemented based on an off-type optical switch 37. The transceiving antenna 3 is composed of a first beam splitter 36, a beam combiner 38, 3 off-type optical switches 37, 3 transmitting antennas 311, and 3 receiving antennas 312. The No. 1 transmitting antenna and the No. 1 receiving antenna form a group of paraxial transceiving antennas, the No. 2 transmitting antenna and the No. 2 receiving antenna form a group of paraxial transceiving antennas, and the No. 3 transmitting antenna and the No. 3 receiving antenna form a group of paraxial transceiving antennas. The No. 1 transmitting antenna, the No. 2 transmitting antenna and the No. 3 transmitting antenna point to different directions in an orthogonal mode, and therefore the scanning function is achieved. The detection light 4 is equally divided into 3 parts after entering the first beam splitter 36, and is sent to the No. 1 off optical switch, the No. 2 off optical switch, and the No. 3 off optical switch, respectively. At each moment, two of the three off-state optical switches are in an off-state and one is in an on-state. When the No. 1 turn-off type optical switch is turned on, the detection light 4 enters the No. 1 transmitting antenna through the No. 1 turn-off type optical switch, then enters the optical window 2 and is transmitted to the outside of the aircraft. The scattered light 1 is received and converged by the receiving antenna No. 1 and enters the combiner 38, and meanwhile, the receiving antenna No. 2 and the receiving antenna No. 3 receive background stray light from the sky and enter the combiner 38. The scattered light 1 is combined with the stray light and output as signal light 7. When the No. 2 switch-off type optical switch is switched on, the detection light 4 enters the No. 2 transmitting antenna through the No. 2 switch-off type optical switch, then enters the optical window 2 and is transmitted to the outside of the aircraft. The scattered light 1 is received and converged by the No. 2 receiving antenna and then enters the combiner 38, and meanwhile, the No. 1 receiving antenna and the No. 3 receiving antenna receive background stray light from the sky and enter the combiner 38. The scattered light 1 is combined with the stray light and output as signal light 7. When the No. 3 switch-off type optical switch is switched on, the detection light 4 enters the No. 3 transmitting antenna through the No. 3 switch-off type optical switch, then enters the optical window 2 and is transmitted to the outside of the aircraft. The scattered light 1 is received and converged by the receiving antenna No. 3 and enters the combiner 38, and meanwhile, the receiving antenna No. 1 and the receiving antenna No. 2 receive background stray light from the sky and enter the combiner 38. The scattered light 1 is combined with the stray light and output as signal light 7.

Example 6:

this embodiment is a further extension of embodiment 1, and is an embodiment of a transmitting/receiving antenna 3 with a scanning function implemented based on a switching optical switch, with reference to fig. 6. The transceiving antenna 3 is composed of a first switching optical switch 39, a second switching optical switch 40, a number 1 transmitting antenna, a number 2 transmitting antenna, a number 3 transmitting antenna, a number 1 receiving antenna, a number 2 receiving antenna, and a number 3 receiving antenna. The No. 1 transmitting antenna and the No. 1 receiving antenna form a group of paraxial transceiving antennas, the No. 2 transmitting antenna and the No. 2 receiving antenna form a group of paraxial transceiving antennas, and the No. 3 transmitting antenna and the No. 3 receiving antenna form a group of paraxial transceiving antennas. The No. 1 transmitting antenna, the No. 2 transmitting antenna and the No. 3 transmitting antenna point to different directions in an orthogonal mode, and therefore the scanning function is achieved. The first switching optical switch 39 and the second switching optical switch 40 have three operating states, and the operating states of the No. 1 switching optical switch and the No. 2 switching optical switch are completely the same at each time. In a first working state, the first switching optical switch 39 switches on the light propagation path between the probe light 4 and the transmitting antenna No. 1, the second switching optical switch 40 switches on the light propagation path between the receiving antenna No. 1 and the subsequent components, and the probe light 4 enters the transmitting antenna No. 1 through the first switching optical switch 39 and then enters the optical window 2 to be transmitted to the outside of the aircraft. The scattered light 1 is received by the No. 1 receiving antenna, enters the second switching optical switch 40, and is output as the signal light 7. Background stray light from the sky received by the receiving antennas # 2 and # 3 is shielded by the second switch-type optical switch 40. In the second working state, the first switching optical switch 39 switches on the light propagation path between the probe light 4 and the No. 2 transmitting antenna, the second switching optical switch 40 switches on the light propagation path between the No. 2 receiving antenna and the subsequent components, and the probe light 4 enters the No. 2 transmitting antenna through the first switching optical switch 39 and then enters the optical window 2 to be transmitted to the outside of the aircraft. The scattered light 1 is received by the receiving antenna No. 2, enters the second switching optical switch 40, and is output as the signal light 7. Background stray light from the sky received by the receiving antennas # 1 and # 3 is shielded by the second switch-type optical switch 40. In the third working state, the first switching optical switch 39 switches on the light propagation path between the probe light 4 and the No. 3 transmitting antenna, the second switching optical switch 40 switches on the light propagation path between the No. 3 receiving antenna and the subsequent components, and the probe light 4 enters the No. 3 transmitting antenna through the first switching optical switch 39 and then enters the optical window 2 to be transmitted to the outside of the aircraft. The scattered light 1 is received by the receiving antenna No. 3, enters the second switching optical switch 40, and is output as the signal light 7. Background stray light from the sky received by the receiving antenna 1 and the receiving antenna 2 is shielded by the second switch-type optical switch 40.

It should be noted that the transmitting/receiving antenna with scanning function based on the prism scanning method (embodiments 4 to 6) can form any number of detection directions by setting the rotation angle of the prism. In practice, not less than three detection directions are generally set. Typical detection directions are three detection directions or four detection directions, but may be any number greater than 4.

It should be noted that the above-mentioned embodiments of the transceiver antenna with scanning function based on the off-type optical switch and the switching type optical switch are implemented in the form of three sets of transmitting antenna and receiving antenna forming three detection directions, since the motion speed in the three-dimensional space needs to be resolved by at least three orthogonal speed projections. In particular engineering practice, there are multiple directional embodiments in addition to the three detection directional embodiments. The increased direction can be realized by increasing the number of channels of the beam splitter, the beam combiner and the switching type optical switch. In the four-direction embodiment, any three probing directions form a set of orthogonal directions, and the fourth probing direction forms a redundancy direction, which has many advantages in improving system reliability and enhancing data stability. The angles between adjacent probing directions may be equal.

Referring to fig. 7, an embodiment of a laser atmosphere data system having three detection directions is installed on an airplane, the laser atmosphere data system is installed on the side surface of the airplane, and the emission light 4 is emitted to the side surface of the airplane to form the three detection directions. The three detection directions are uniformly distributed at 120 degrees with the projection of the plane vertical to the longitudinal axis of the airplane.

Referring to fig. 8, an embodiment of the laser atmosphere data system having four detection directions is installed on an airplane, the laser atmosphere data system is installed on the side surface of the airplane, and the emitted light 4 is emitted to the side surface of the airplane, thereby forming four detection directions. The four detection directions are uniformly distributed at 90 degrees with the projection of the plane vertical to the longitudinal axis of the airplane.

Referring to fig. 9, which is an overhead projection of an embodiment of the laser atmosphere data system installed on an airplane, the laser atmosphere data system is in an optical focusing mode or a time-of-flight gating mode, and the control system only receives scattered light generated by interaction between the emitted light 4 and the atmospheric environment at a specific position away from the airplane. In the present embodiment, the distance of the specific location from the airplane is designed to be 80 meters by the optical focusing manner or the time-of-flight gating manner. Because the depth of field (rayleigh length) or the time-of-flight gating range (range gate) of the optical focusing system is affected by the performance limits of the optical and electronic systems and cannot be made very small, the actual detection area of the laser atmospheric data system is not a point at a specific position, but a laser beam ten meters to tens of meters before and after the specific position. The sphere covering all the beam detection areas is a detection sphere. A smaller probe sphere radius can reduce the atmospheric turbulence uncertainty effect so that all lasers measure the same atmospheric environment as much as possible. The height of the detection ball is consistent with the height of the center of gravity of the airplane so as to reduce the influence of uneven distribution of the atmospheric density, and the atmospheric pressure height measured by the laser atmospheric data system is consistent with the airplane.

Example 7:

this embodiment is a further extension of any of embodiments 1 to 6, and referring to fig. 10, the receiving and collimating assembly 8 includes two receiving and collimating modules, each of which includes a first collimating mirror 81 and a narrowband filter 82. A first collimating lens 81 expands and collimates the incident reference light 6 and outputs a quasi-parallel thin light beam; and the other first collimating lens 81 expands and collimates the incident signal light 7 and outputs a quasi-parallel thin light beam. The first collimating lens 81 may be composed of a plurality of lenses, and the beams have no convergence point in the collimating lens combination by adopting a Galilean telescope configuration. Generally, the divergence angles of the original incident beams are all large, the divergence angles of the original incident beams are gradually compressed by a plurality of lenses through the first collimating mirror 81, and the collimation degrees of the beams are adjusted by controlling the material, the surface curvature and the lens interval of each lens glass in the first collimating mirror 81. Respectively passing the collimated reference light 6 through a plurality of narrow-band filters with the central wavelength of 355nm to filter out interference light in other out-of-band wave bands; the collimated signal light 7 passes through a plurality of narrow-band filters with the center wavelength of 355nm, and out-of-band background noise (the signal light mainly contains background stray light from the sky) is filtered. The narrow band filters 82 realize the band-pass function by plating the dielectric films meeting the bandwidth requirement on two sides, and the combination use of the narrow band filters 82 can greatly improve the signal-to-noise ratio of the central wavelength, so that the reference light and the signal light only comprising 355nm wavelength are transmitted to subsequent components.

Example 8:

this embodiment is a further extension of any of embodiments 1-7, and the operation principle of the etalon of the present invention will be briefly described with reference to fig. 11. An etalon is an optical filter that uses the principle of multi-beam interference to achieve specific wavelength gating. One etalon channel comprises a transmitting end 12, a second collimating mirror 13, a first parallel plate 14, a second parallel plate 16, a receiving mirror 17 and a receiving end 18; a high reflection film 15 is provided on both the side of the first parallel plate 14 facing the second parallel plate 16 and the side of the second parallel plate 16 facing the first parallel plate 14; the second collimator lens 13 conditions the signal light 7 emitted from the emission end into parallel light and is incident on the first parallel plate 14. The light beam forms multiple reflections in two parallel planes of the parallel plates, and the reflected light and the transmitted light form multiple beam interference, so that the light intensity capable of transmitting through the parallel plates is mainly determined by the spacing between the parallel plates and the wavelength, that is, only light of a specific wavelength can exit to the receiving mirror 17 and finally enter the receiving end 18. The etalon can accurately extract optical signals in a specific narrow-band wavelength range in the broadband light source, so that a basis is provided for identifying frequency spectrum information of the broadband light source.

Referring to fig. 12, the multi-channel etalon 9 comprises one reference light channel and at least three signal light channels; the reference light channel comprises a first etalon channel 91; the at least three signal optical channels include a second beam splitter 93 and at least three second etalon channels 92; the output of the second beam splitter 93 is connected to each of the second etalon channels 92. The reference light 6 enters the first etalon channel 91 directly; the signal light 7 is equally divided into at least 3 parts by the second beam splitter 93, and then enters at least three second etalon channels 92, respectively. Each second etalon channel 92 is formed by designing the spacing between the parallel plates such that it transmits optical signals of a specified wavelength. In the embodiment, the central wavelength of the laser emitted by the ultraviolet laser 5 is 355.000000nm, and the corresponding laser frequency is 844485.797 GHz; the transmission wavelength of the first etalon channel 91 is 354.999580nm, and the corresponding laser frequency is 844486.797 GHz; the transmission wavelength of the No. 1 second etalon channel is 354.998949nm, and the corresponding laser frequency is 844488.297 GHz; the transmission wavelength of the No. 2 second etalon channel is 354.998529nm, and the corresponding laser frequency is 844489.297 GHz; the transmission wavelength of the No. 3 second etalon channel is 355.001051nm, and the corresponding laser frequency is 844483.297 GHz. According to the relationship between the laser frequency corresponding to the four etalon channels and the laser frequency emitted by the ultraviolet laser 5, the difference between the central wavelength of the optical signal 61 emitted from the first etalon channel 91 and the central wavelength of the emitted laser is 1G, and the optical signal is recorded as reference light (1G); the difference between the central wavelength of the optical signal emitted from the No. 1 second etalon channel and the central wavelength of the emitted laser is 2.5G, and the optical signal is recorded as signal light (2.5G); the difference between the central wavelength of the optical signal emitted from the No. 2 second etalon channel and the central wavelength of the emitted laser is 3.5G, and the optical signal is recorded as signal light (3.5G); the difference between the central wavelength of the optical signal emitted from the second etalon channel No. 3 and the central wavelength of the emitted laser light is-2.5G, and the optical signal is recorded as signal light (-2.5G).

Referring to fig. 13, the multi-channel etalon 9 outputs a transmittance curve with the center frequency of the laser emitted by the ultraviolet laser 5 as the origin, that is, the reference light (1G) extracts a light intensity signal of the reference light with the center frequency of the laser emitted by the ultraviolet laser 5 being +1G, the signal light (2.5G) extracts a light intensity signal of the signal light with the center frequency of the laser emitted by the ultraviolet laser 5 being +2.5G, the signal light (3.5G) extracts a light intensity signal of the signal light with the center frequency of the laser emitted by the ultraviolet laser 5 being +3.5G, and the signal light (-2.5G) extracts a light intensity signal of the signal light with the center frequency of the laser emitted by the ultraviolet laser 5 being-2.5G. Each transmittance curve is a sharp Gaussian curve signal, and the full width at half maximum of the transmittance curve is about 1G.

Referring to fig. 14, for the convenience of understanding the present invention, the gaussian curve is simplified into a histogram to obtain a transmittance peak of the output of the multi-channel etalon 9 with the center frequency of the laser light emitted from the uv laser 5 as the origin. This simplification changes the performance of the transmittance curve but does not affect the implementation of this patent.

Referring to fig. 15, the scattered light generated by scattering of the emitted light atmosphere received by the laser atmosphere data system mainly includes the scattered signal generated by the interaction of the laser and the aerosol and the scattered signal generated by the interaction of the laser and the molecular nitrogen oxide. The laser and the aerosol generate scattering signals with high intensity and narrow spectrum width. The scattered signal generated by the action of the laser and the nitrogen-oxygen molecules has low intensity but wide spectral width. The laser atmospheric data system of this embodiment is designed to detect the scattered signal generated by the interaction of the laser and the molecular nitrogen, and the spectrum of the scattered signal is a gaussian curve following normal distribution. The difference between the center frequency of the scattered signal spectrum and the center frequency of the laser light emitted by the uv laser 5 indicates the doppler shift due to the relative velocity of the aircraft and the atmospheric environment in the direction of the laser beam, from which the line-of-sight velocity can be resolved. The full width at half maximum of the scattered signal spectrum indicates the doppler shift due to the vibration (thermal motion) of the atmospheric molecules, from which the atmospheric temperature can be resolved. The total intensity of the scattering signal, i.e. the height (area) of the scattering signal spectrum, indicates how many molecules in the detection region have an effect on the laser, and the atmospheric density and further the barometric height can be calculated according to the parameters.

Consider first the case of a stationary standard atmosphere, where the normalized scattered signal spectrum is shown at typical altitudes. The atmospheric temperature and the atmospheric density of the static standard atmosphere are reduced along with the increase of the atmospheric pressure height, so that the height of a scattered signal spectrum is reduced and the broadening and narrowing are realized along with the increase of the atmospheric pressure height.

Referring to fig. 16, 17, 18, 19, 20, 21, 22, and 23, the transmittance peaks of the signal light (2.5G), the signal light (3.5G), and the signal light (-2.5G) for the stationary standard atmospheric scattering signal spectra of different heights are shown for 3 channels of the signal light. As can be seen from the figure, the transmittance peak of each channel has a large change from the sea level to the atmospheric pressure height 18000m, and according to the characteristics of the gaussian curve, an original curve can be fitted with high accuracy based on not less than 3 characteristic values on the curve, so that the high-accuracy inversion of the scattering signal spectrum can be realized by using the embodiment.

Further consider the atmospheric environment in flight. The laser air data system is designed to be launched to the side of the aircraft so that the line-of-sight velocity measured in each laser beam direction of the laser air data system is a function of the aircraft true airspeed. For example, when the laser beam forms an angle of 70 degrees with the central axis of the airplane, i.e., the flying direction, the airplane flies at mach 0 to 0.9 (Ma), which is equivalent to the sight line speed measured in the laser beam direction is about 0 to 0.3Ma, i.e., about 0 to 100 m/s. For 355nm laser, the Doppler shift is about 0-560 MHz.

Referring to fig. 24, 25, 26 and 27, the transmittance peaks of the atmospheric scattering signal spectrum of 3 channels of signal light, i.e., signal light (2.5G), signal light (3.5G), signal light (-2.5G) flying at different speeds for the typical cruising altitude (9000 meters) of the airplane, are shown at various characteristic frequencies. As can be seen from the figure, as the flying speed increases, the center frequency of the scattering signal spectrum gradually shifts to the right, which is represented by the fact that the transmittance peak of the positive frequency channel, i.e., the signal light (2.5G) and the signal light (3.5G), gradually increases, and the transmittance peak of the negative frequency channel, i.e., the signal light (-2.5G), gradually decreases. According to the characteristics of the Gaussian curve, the original curve can be fitted with high precision based on not less than 3 characteristic values on the curve, so that the high-precision inversion of the scattering signal spectrum can be realized by using the embodiment.

Referring to fig. 28, the photodetection assembly 10 includes a set of focusing objective lens 101 and photoelectric converter 102, for each optical signal, the focusing objective lens 101 focuses the etalon output beam on the photosensitive surface of the photoelectric converter 102, and the photoelectric converter 102 converts the optical signal into an electrical signal. The photoelectric converter 102 is a high-gain weak light detecting device, and a photomultiplier tube (PMT) may be used, but is not limited thereto. Through the photoelectric detection component 10, the light intensity signal of the reference light (1G) channel, the light intensity signal of the signal light (2.5G) channel, the light intensity signal of the signal light (3.5G) channel, and the light intensity signal of the signal light (-2.5G) channel output by the multi-channel etalon are converted into electric signals, so as to form a characteristic value of the reference photosynthetic signal light, and the characteristic value of the reference light and the characteristic value of the signal light are sent to the data acquisition and processing component 11. The data acquisition and processing assembly 11 comprises a fitting calculation unit 111, a calibration calculation unit 112 and an atmospheric data calculation unit 113 which are connected in sequence;

a fitting calculation unit 111, configured to fit the signal light intensity characteristic value sent by the photodetection assembly 10 to a scattered light spectrum signal;

the calibration calculation unit 112 is configured to correct the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal;

and the atmospheric data resolving unit 113 is used for processing the scattered light spectrum calibration signal to obtain atmospheric data and outputting the atmospheric data.

In a specific implementation process, as shown in fig. 29, the calculation method of the laser atmosphere data system includes the following steps:

s1, generating detection light and reference light by an ultraviolet laser;

s2, emitting the detection light to the outside through the transceiving antenna and the optical window, and receiving the scattered light which carries the atmospheric data information and is generated by the scattering effect of the detection light and the atmospheric environment outside the aircraft;

s3, collimating and filtering the scattered light and the reference light by the receiving collimating component, and then respectively transmitting the collimated light and the reference light to the multi-channel etalon;

s4, generating a reference light frequency point light signal based on the collimated and filtered reference light through the multi-channel etalon; generating a signal light frequency point light signal based on the collimated and filtered scattered light by a multi-channel etalon;

s5, the photoelectric detection component converts the light signal intensity of the frequency point into a light intensity electric signal to obtain a reference light intensity characteristic point and a group of signal light intensity characteristic values consisting of at least three signal light intensity points;

s6, fitting the signal light intensity characteristic values to obtain scattered light spectrum signals;

s7, correcting the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal;

and S8, processing the scattered light spectrum calibration signal to obtain and output atmospheric data.

The fitting method of step S6 includes the following sub-steps:

s6-1, according to the formula:

constructing a fitted feature matrixF(ii) a Wherein

The signal frequency of the 1 st signal light;

the signal frequency of the 2 nd signal light;

is as followsnA signal frequency of the signal light;

s6-2, according to the formula:

constructing signal light feature vectorsI(ii) a Wherein

Is as followsnThe signal light intensity characteristic value;

is composed of

The adjustment coefficient of (a);

s6-3, according to the formula:

obtaining a vector of eigenvaluesv(ii) a Wherein

Represents a transpose of a matrix;

s6-4, according to the formula:

obtaining scattered light spectral signals

(ii) a Wherein

A curve equation of the frequency spectrum signal; depending on the particular fitting method, the equation may be a quadratic equation of unity, a gaussian equation, or other formal equation.

The specific method of step S7 is: according to the formula:

correcting the scattered light spectrum signal to obtain a scattered light spectrum calibration signal

(ii) a Wherein

In order to calibrate the equations for the scatter spectra,

as a reference light characteristic value, a value of,

is composed of

The adjustment coefficient of (2).

The specific method of step S8 includes the following substeps:

s8-1, obtaining Doppler frequency shift by resolving the difference between the central frequency and the central frequency of laser emitted by the ultraviolet laser, wherein the expression is as follows:

wherein

Is a Doppler shift;

for resolving the central frequency, i.e. by calibrating the signal by the spectrum of the scattered light

A calculated center frequency;

emitting laser center frequency for the ultraviolet laser;

s8-2, calculating the velocity of the line of sight according to the Doppler frequency shiftVThe calculation expression is:

wherein

Emitting a laser center wavelength for an ultraviolet laser;

s8-3, calibrating signal by resolving scattered light spectrum

Obtaining atmospheric static temperature by spectral broadening

The calculation expression is:

wherein

Is a temperature adjustment coefficient;

calculating a model for the spectral broadening; the calculation of the spectral broadening can use a full width at half maximum method, an integral method or other methods;

s8-4, calibrating signal by resolving scattered light spectrum

Envelope area of

Obtaining the atmospheric density

The computational expression is:

wherein

Calculating a model for the envelope area; the calculation of the envelope area can be obtained by integrating a curve equation or in other ways;

as a density adjusting systemCounting;

s8-5, calculating the three-axis vector airspeed according to the sight velocity in different detection directions, wherein the calculation expression is as follows:

wherein

Is composed ofxAn axial vector airspeed;

is composed ofyAn axial vector airspeed;

is composed ofzAn axial vector airspeed;

is an angle correction matrix;

projecting an angle correction matrix for the gaze velocity;

is as followsnLine-of-sight speed for each detection direction;

s8-6, acquiring the vacuum velocity TAS and the angle of attack based on the three-axis vector airspeed

And angle of sideslip

The calculation expression is:

wherein

Is an arctangent function;

s8-7, obtaining sound velocity corresponding to the temperature based on atmospheric static temperatureaThe calculation formula is as follows:

；

s8-8, calculating Mach number based on vacuum speed and sound speedMThe calculation formula is as follows:

；

s8-9, calculating the total temperature of the atmosphere based on the Mach number and the static temperature of the atmosphere

The calculation formula is as follows:

；

s8-10, calculating the atmospheric static pressure based on the atmospheric static temperature and the atmospheric density

The calculation formula is as follows:

；

s8-11, calculating the barometric altitude based on the atmospheric static pressure

And the lifting speed

The calculation formula is as follows:

wherein

The air pressure height at the current moment;

the air pressure height at the previous moment;

the time difference between the current time and the last time is obtained;

s8-12, calculating the total atmospheric pressure based on the Mach number and the atmospheric static pressure

The calculation formula is as follows:

；

s8-13, calculating atmospheric dynamic pressure based on atmospheric static pressure and atmospheric total pressure

The calculation formula is as follows:

；

s8-13, according to the formula:

calculate and calibrate the space velocity, CAS, based on atmospheric dynamic pressure

More than 50 km/h.

In summary, the etalon with multiple channels is used for accurately measuring the intensity information of the laser spectrum on each characteristic frequency, the original spectrum signal is fitted with high precision, and the atmospheric data information can be independently and accurately inverted on the premise of no support of other principle atmospheric data sensors. The laser atmospheric data system and the traditional atmospheric data system form a non-similar redundancy atmospheric data system, so that the reliability of the flight atmospheric parameters can be greatly improved, and the flight safety of the airplane is guaranteed.

Claims (16)

1. A laser atmospheric data system is characterized by comprising an ultraviolet laser, an optical window, a transmitting-receiving antenna, a receiving collimation assembly, a multi-channel etalon, a photoelectric detection assembly and a data acquisition processing assembly; wherein:

an ultraviolet laser for generating probe light and reference light; wherein the reference light is directly delivered to the receiving collimating assembly; the detection light is emitted to the outside through the receiving and transmitting antenna and the optical window, and generates scattering light carrying atmosphere data information under the scattering action with the atmosphere environment outside the aircraft, and the scattering light is transmitted to the receiving collimation assembly after being collected by the receiving and transmitting antenna through the optical window;

the receiving collimation assembly is used for respectively transmitting the scattered light and the reference light to the multi-channel etalon after collimation and filtering;

the multi-channel etalon comprises a reference light channel and at least three signal light channels; wherein the reference optical channel is used for generating a reference optical frequency point optical signal by the collimated and filtered reference light; the signal light channel is used for generating a signal light frequency point light signal through the collimated and filtered scattered light;

the photoelectric detection component comprises photoelectric detectors with the number more than or equal to that of the channels of the multi-channel etalon and is used for converting the light signal intensity of the frequency points into light intensity electric signals to obtain a reference light intensity characteristic point and a group of signal light intensity characteristic values consisting of at least three signal light intensity points;

the data acquisition and processing assembly is used for fitting the signal light intensity characteristic value to obtain a scattered light spectrum signal; correcting the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal; processing the scattered light spectrum calibration signal to obtain and output atmospheric data;

the method for fitting the signal light intensity characteristic value by the data acquisition and processing assembly comprises the following substeps:

s6-1, according to the formula:

constructing a fitted feature matrixF(ii) a Wherein

The signal frequency of the 1 st signal light;

the signal frequency of the 2 nd signal light;

is as followsnA signal frequency of the signal light;

s6-2, according to the formula:

constructing signal light feature vectorsI(ii) a Wherein

Is as followsnThe signal light intensity characteristic value;

is composed of

The adjustment coefficient of (a);

s6-3, according to the formula:

obtaining a vector of eigenvaluesv(ii) a Wherein

Represents a transpose of a matrix;

s6-4, according to the formula:

obtaining scattered light spectral signals

(ii) a Wherein

A curve equation of the frequency spectrum signal;

the formula for correcting the scattered light spectrum signal based on the reference light intensity characteristic point is as follows:

；

the signal is calibrated for the spectrum of the scattered light,

in order to calibrate the equations for the scatter spectra,

as a reference light characteristic value, a value of,

is composed of

The adjustment coefficient of (2).

2. The laser atmospheric data system of claim 1, wherein the transceiver antenna is a paraxial transceiver antenna comprising a transmitting antenna and a receiving antenna arranged side by side, and the optical window is arranged in front of the transmitting antenna and the receiving antenna arranged side by side; the transmitting antenna is used for transmitting the detection light; the receiving antenna is used for receiving scattered light.

3. The laser atmospheric data system of claim 1, wherein the transceiver antenna is a coaxial transceiver antenna, and the optical window is disposed in front of the coaxial transceiver antenna.

4. The laser atmospheric data system of claim 1, wherein the transceiver antenna is a prism-scanning transceiver antenna, and comprises a cassegrain antenna, a reflector and a scanning prism which are arranged in sequence; the detection light is emitted from the ultraviolet laser, reflected to the scanning prism through the reflector and refracted to the optical window through the scanning prism;

the scattered light reflected back from the outside is refracted to the fringe part of the cassegrain antenna by the scanning prism, reflected to the reflecting mirror by the cassegrain antenna, reflected to the central part of the cassegrain antenna by the reflecting mirror and passes through the cassegrain antenna.

5. The laser atmospheric data system of claim 1, wherein the transceiver antenna is a transceiver antenna of an off-type optical switch, and comprises a first beam splitter, a beam combiner, at least three off-type optical switches, at least three transmitting antennas, and at least three receiving antennas;

the input end of the first beam splitter is connected with the output end of the ultraviolet laser, the output end of the first beam splitter is respectively connected with the input ends of all the turn-off optical switches, and the output end of each turn-off optical switch is connected with one transmitting antenna;

the output end of the beam combiner is connected with the receiving collimation assembly, and the input end of the beam combiner is connected with each receiving antenna respectively.

6. The laser atmospheric data system of claim 5, wherein the included angles between two adjacent transmitting antennas are all anglesJ(ii) a The included angles between two adjacent receiving antennas are allJ。

7. The laser atmospheric data system of claim 1, wherein the transceiver antenna is a transceiver antenna of a switched optical switch, and comprises a first switched optical switch, a second switched optical switch, at least three transmitting antennas, and at least three receiving antennas;

the input end of the first switching optical switch is connected with the output end of the ultraviolet laser, and the output end of the first switching optical switch is respectively connected with each transmitting antenna;

the output end of the second switching optical switch is connected with the receiving collimation assembly, and the input end of the second switching optical switch is connected with each receiving antenna respectively.

8. The laser atmospheric data system of claim 7, wherein the angles between two adjacent transmitting antennas are all anglesJ(ii) a Adjacent to each otherThe included angles between the two receiving antennas are allJ。

9. The laser atmospheric data system of claim 1, wherein the receive collimating assembly comprises two receive collimating modules, each receive collimating module comprising a first collimating mirror and a narrow band filter; the input end of the first collimating mirror is the input end of the receiving collimating module, the output end of the first collimating mirror is connected with the input end of the narrow-band filter, and the output end of the narrow-band filter is the output end of the receiving collimating module; the two receiving collimation modules are respectively used for receiving the scattered light and the reference light.

10. The laser atmospheric data system of claim 9, wherein the first collimating mirror comprises a concave lens and a convex lens, the concave lens disposed at a front end of the convex lens.

11. The laser atmospheric data system of claim 1, wherein the reference light channel comprises a first etalon channel; the at least three signal light channels include a second beam splitter and at least three second etalon channels; the output end of the second beam splitter is respectively connected with each second etalon channel; the output of the first etalon channel and the output of all of the second etalon channels together serve as the output of the multi-channel etalon.

12. The laser atmospheric data system of claim 11, wherein the first etalon channel and the second etalon channel have the same structure, and each of the first etalon channel and the second etalon channel comprises a transmitting end, a second collimating mirror, a first parallel plate, a second parallel plate, a receiving mirror and a receiving end which are arranged in sequence; one surface of the first parallel plate facing the second parallel plate and one surface of the second parallel plate facing the first parallel plate are both provided with high-reflection films;

and the transmitting end is used for transmitting the received signal to the second collimating mirror.

13. The laser atmospheric data system of claim 1, wherein the photodetector comprises a focusing objective and a photoelectric converter;

the focusing objective lens is used for focusing the received signals and sending the focused signals to the photoelectric converter;

and the photoelectric converter is used for converting the received optical signal into an optical intensity electric signal.

14. The laser atmospheric data system of claim 1, wherein the data acquisition and processing assembly comprises a fitting calculation unit, a calibration calculation unit and an atmospheric data calculation unit which are connected in sequence;

the fitting calculation unit is used for fitting the signal light intensity characteristic value sent by the photoelectric detection component into a scattered light spectrum signal;

the calibration calculation unit is used for correcting the scattered light spectrum signal based on the reference light intensity characteristic point to obtain a scattered light spectrum calibration signal;

and the atmospheric data resolving unit is used for processing the scattered light spectrum calibration signal to obtain atmospheric data and outputting the atmospheric data.

15. A laser atmosphere data calculation method based on the laser atmosphere data system according to any one of claims 1 to 14, comprising the steps of:

s1, generating detection light and reference light by an ultraviolet laser;

s2, emitting the detection light to the outside through the transceiving antenna and the optical window, and receiving the scattered light which carries the atmospheric data information and is generated by the scattering effect of the detection light and the atmospheric environment outside the aircraft;

s3, collimating and filtering the scattered light and the reference light by the receiving collimating component, and then respectively transmitting the collimated light and the reference light to the multi-channel etalon;

s4, generating a reference light frequency point light signal based on the collimated and filtered reference light through the multi-channel etalon; generating a signal light frequency point light signal based on the collimated and filtered scattered light by a multi-channel etalon;

s5, the photoelectric detection component converts the light signal intensity of the frequency point into a light intensity electric signal to obtain a reference light intensity characteristic point and a group of signal light intensity characteristic values consisting of at least three signal light intensity points;

s6, fitting the signal light intensity characteristic values to obtain scattered light spectrum signals;

s7, based on the reference light intensity characteristic point, according to the formula:

correcting the scattered light spectrum signal to obtain a scattered light spectrum calibration signal

(ii) a Wherein

In order to calibrate the equations for the scatter spectra,

as a reference light characteristic value, a value of,

is composed of

The adjustment coefficient of (a);

s8, processing the scattered light spectrum calibration signal to obtain atmospheric data and output the atmospheric data;

the fitting method of step S6 includes the following sub-steps:

s6-1, according to the formula:

constructing a fitted feature matrixF(ii) a Wherein

The signal frequency of the 1 st signal light;

the signal frequency of the 2 nd signal light;

is as followsnA signal frequency of the signal light;

s6-2, according to the formula:

constructing signal light feature vectorsI(ii) a Wherein

Is as followsnThe signal light intensity characteristic value;

is composed of

The adjustment coefficient of (a);

s6-3, according to the formula:

obtaining a vector of eigenvaluesv(ii) a Wherein

Represents a transpose of a matrix;

s6-4, according to the formula:

obtaining scattered light spectral signals

(ii) a Wherein

Is a curve equation of the spectrum signal.

16. The laser atmospheric data calculation method according to claim 15, wherein the specific method of step S8 includes the following sub-steps:

s8-1, obtaining Doppler frequency shift by resolving the difference between the central frequency and the central frequency of laser emitted by the ultraviolet laser, wherein the expression is as follows:

wherein

Is the Doppler shift;

for resolving the central frequency, i.e. by calibrating the signal by the spectrum of the scattered light

A calculated center frequency;

emitting laser center frequency for the ultraviolet laser;

s8-2, calculating the velocity of the line of sight according to the Doppler frequency shiftVThe calculation expression is:

wherein

Emitting a laser center wavelength for an ultraviolet laser;

s8-3, calibrating signal by resolving scattered light spectrum

Obtaining atmospheric static temperature by spectral broadening

The calculation expression is:

wherein

Is a temperature adjustment coefficient;

calculating a model for the spectral broadening;

s8-4, calibrating signal by resolving scattered light spectrum

Envelope area of

Obtaining the atmospheric density

The calculation expression is:

wherein

Calculating a model for the envelope area;

is a density adjustment factor;

s8-5, calculating the three-axis vector airspeed according to the sight velocity in different detection directions, wherein the calculation expression is as follows:

wherein

Is composed ofxAn axial vector airspeed;

is composed ofyAn axial vector airspeed;

is composed ofzAn axial vector airspeed;

is an angle correction matrix;

projecting an angle correction matrix for the line of sight velocity;

is as followsnLine-of-sight speed for each detection direction;

s8-6, acquiring the vacuum velocity TAS and the angle of attack based on the three-axis vector airspeed

And angle of sideslip

The calculation expression is:

wherein

Is an arctangent function;

s8-7, obtaining sound velocity corresponding to the temperature based on atmospheric static temperatureaThe calculation formula is as follows:

；

s8-8, calculating Mach number based on vacuum speed and sound speedMThe calculation formula is as follows:

；

s8-9, calculating the total temperature of the atmosphere based on the Mach number and the static temperature of the atmosphere

The calculation formula is as follows:

；

s8-10, calculating the atmospheric static pressure based on the atmospheric static temperature and the atmospheric density

The calculation formula is as follows:

；

s8-11, calculating the barometric altitude based on the atmospheric static pressure

And the lifting speed

The calculation formula is as follows:

wherein

The air pressure height at the current moment;

the air pressure height at the previous moment;

the time difference between the current time and the last time is obtained;

s8-12 horse-basedCalculating total atmospheric pressure by using Hertz number and atmospheric static pressure

The calculation formula is as follows:

；

s8-13, calculating atmospheric dynamic pressure based on atmospheric static pressure and atmospheric total pressure

The calculation formula is as follows:

；

s8-14, according to the formula:

the calibrated space velocity CAS is calculated based on the atmospheric dynamic pressure.

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