A laser warning device based on piezoelectric drive and FP interference

Abstract

The present invention belongs to the technical field of laser warning devices, and specifically relates to a laser warning device based on piezoelectric drive and FP interference, including a laser wavelength measurement part, an azimuth and elevation angle measurement part, and a control and data processing system. The laser wavelength measurement part and the azimuth and elevation angle measurement part are both arranged in the optical path direction of the laser beam, and the laser wavelength measurement part and the azimuth and elevation angle measurement part are both electrically connected to the control and data processing system through wires. The laser warning device based on piezoelectric drive and FP interference adopted by the present invention can not only effectively shield the DC background signal, thereby eliminating the interference of the background light, but also has the advantages of large field of view, low false alarm rate, high angular resolution, etc. At the same time, with the addition of a grating, the azimuth and elevation angle of the measured laser can be more accurately measured, and an accurate early warning effect can be played.

Description

Technical Field

[0001] The invention belongs to the technical field of laser warning devices, and in particular relates to a laser warning device based on piezoelectric drive and FP interference. Background Art

[0002] With the continuous development of laser technology, laser threats are becoming increasingly serious, and the development of laser warning technology has become an important aspect of optoelectronic confrontation. Laser warning devices are passive detection devices that are used to reliably detect lasers of various different bands within a large field of view, determine the type of laser, attack direction, power and other information, and make rapid responses. Laser warning devices often work under sunlight or in harsh environments with lightning and fire. The intensity of sunlight flicker is often greater than the intensity of the detected laser. In order to identify non-laser phenomena, when the target laser is relative to the non-laser laser warning receiver, the target laser has high coherence relative to the non-laser. Traditional laser warning devices are easily interfered, resulting in an increase in the false alarm rate and false alarm rate of laser warning. Summary of the invention

[0003] In order to solve the technical problems of high false alarm rate and false alarm rate in the above-mentioned traditional laser warning devices, the present invention provides a laser warning device based on piezoelectric drive and FP interference, which has a large field of view, low false alarm rate, high angular resolution and accurate warning.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A laser warning device based on piezoelectric drive and FP interference includes a laser wavelength measurement part, an azimuth and elevation angle measurement part, and a control and data processing system. The laser wavelength measurement part and the azimuth and elevation angle measurement part are both arranged in the optical path direction of the laser beam, and the laser wavelength measurement part and the azimuth and elevation angle measurement part are both electrically connected to the control and data processing system through wires.

[0006] The laser wavelength measurement part includes a field of view compression alignment system, an FP interferometer, a lens, a filter, and a high-speed photoelectric detector. The field of view compression alignment system is arranged in the optical path direction of the laser beam, the FP interferometer is arranged in the optical path direction of the field of view compression alignment system, the lens is arranged in the optical path direction of the FP interferometer, the filter is arranged in the optical path direction of the lens, and the high-speed photoelectric detector is arranged in the optical path direction of the filter. The signal output end of the high-speed photoelectric detector is electrically connected to a control and data processing system through a wire, and the FP interferometer is electrically connected to a control and data processing system through a wire.

[0007] The azimuth and elevation angle measuring part includes a two-dimensional grating, a lens group, and an array detector. The two-dimensional grating is arranged in the optical path direction of the laser beam, the lens group is arranged in the optical path direction of the two-dimensional grating, and the array detector is arranged in the optical path direction of the lens group. The array detector is electrically connected to a control and data processing system through wires.

[0008] Piezoelectric ceramics are arranged inside the FP interferometer, and semi-transparent and semi-reflective films are attached to both sides of the FP interferometer.

[0009] The area array detector is arranged at the focal plane of the lens group.

[0010] A method for measuring a laser warning device based on piezoelectric drive and FP interference comprises the following steps:

[0011] S1, the laser beam enters the FP interferometer through the field compression collimation system;

[0012] S2, calculating the cavity spacing of the FP interferometer by the frequency of the piezoelectric ceramic;

[0013] S3, calculating the incident wavelength of the laser beam;

[0014] S4, the laser beam is diffracted by a two-dimensional grating to produce diffracted light, and the diffracted light is divided into an x ​​direction and a y direction;

[0015] S5. The diffracted light is converged on the area array detector through the lens group to form a light spot. The control and data processing system processes the position of the light spot on the area array detector by an algorithm, thereby realizing the measurement of the azimuth and elevation angle of the laser beam.

[0016] The method for calculating the cavity spacing of the FP interferometer in S2 is:

[0017] The cavity spacing L of the FP interferometer is calculated by the frequency of the piezoelectric ceramic,

[0018] L=L 0 cos(2πft) (a)

[0019] The L 0 is the piezoelectric coefficient of the piezoelectric ceramic, and f is the frequency applied by the piezoelectric ceramic driving power supply.

[0020] The method for calculating the incident wavelength of the laser beam in S3 is:

[0021] When the phase change of the reflected light at the interface of the parallel mirror is not considered in the FP interferometer, the phase difference between each wave and its previous wave is

[0022]

[0023] The n is the refractive index of the medium, the θ is the refraction angle of the laser beam relative to the mirror, the L is the cavity spacing of the FP interferometer, and the λ is the incident wavelength of the laser beam;

[0024] When n=1, the refraction angle θ of the laser beam relative to the mirror is zero, and the incident wavelength λ of the laser beam is proportional to the cavity spacing L of the FP interferometer. The wavelength is measured by adjusting the cavity spacing L of the FP interferometer.

[0025] The laser beam is reflected and transmitted multiple times in the FP interferometer, and the reflected light and the transmitted light undergo multi-beam interference. The output light intensity I 1 and the incident light intensity I 0 The ratio is

[0026]

[0027] R is the reflectivity. Since a semi-transmissive and semi-reflective film is provided on both sides of the FP interferometer, the reflectivity R=0.5;

[0028] According to the calculation formula of light intensity:

[0029]

[0030] Substituting formula (a) into formula (d) yields:

[0031]

[0032] From equations (c), (d), (e) and Bessel function, we can get

[0033]

[0034] The J 2 is the Bessel second-order function, the J 4 is the Bessel second-order function, and I is the intensity of the laser beam;

[0035] According to the ratio of double frequency to quadruple frequency:

[0036]

[0037] The incident wavelength λ of the laser beam is calculated according to equation (g).

[0038] The method for measuring the azimuth and elevation angles of the laser beam in S5 is as follows: in the x direction, the zero-order spectrum position is x 0 , the +1 level spectrum is x +1 , the -1 level spectrum is x -1 , the position of the laser beam after diffraction in the y direction on the area array detector is y, the grating constant of the two-dimensional grating is d, and the focal length of the lens group is F;

[0039]

[0040] The β +1 is the +1 order diffraction angle, the β -1 is the -1 order diffraction angle;

[0041] The array detector is located at the focal plane of the lens group with a focal length of F, and converts the diffracted light signal into an electrical signal, where the positions of level 0, level +1, and level -1 are

[0042]

[0043] The pitch angle α and azimuth angle γ are determined by equations (h) and (i)

[0044]

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The laser warning device based on piezoelectric drive and FP interferometer of the present invention changes the vibration frequency of piezoelectric ceramics, and the cavity length of the FP interferometer can be calculated through a formula, and then the wavelength of the measured laser can be calculated according to the relationship between the cavity length of the FP interferometer and the wavelength of the measured laser. At the same time, the azimuth and elevation angles of the measured laser can be obtained by imaging with a planar array detector and performing data processing on the position of the light spot. The laser warning device based on piezoelectric drive and FP interference of the present invention can not only effectively shield the DC background signal, thereby eliminating the interference of the background light, but also has the advantages of large field of view, low false alarm rate, high angular resolution, etc. At the same time, with the addition of a grating, the azimuth and elevation angles of the measured laser can be more accurately measured, and an accurate early warning effect can be played. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0048] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0049] Figure 1It is a structural schematic diagram of the present invention;

[0050] Figure 2 It is a structural schematic diagram of the FP interferometer of the present invention;

[0051] Figure 3 is a schematic diagram of the grating in the x direction after diffraction in the present invention;

[0052] Figure 4 It is a schematic diagram of the grating in the y direction after diffraction in the present invention.

[0053] Among them: 1 is the laser wavelength measurement part, 2 is the azimuth and elevation angle measurement part, 3 is the control and data processing system, 101 is the field of view compression calibration system, 102 is the FP interferometer, 103 is the lens, 104 is the filter, 105 is the high-speed photoelectric detector, 106 is the piezoelectric ceramic, 107 is the semi-transparent and semi-reflective film, 201 is the two-dimensional grating, 202 is the lens group, and 203 is the area array detector. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0055] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0056] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0057] In this embodiment, if Figure 1As shown, the laser warning device is mainly composed of two parts. The laser wavelength measurement part 1 is composed of a field of view compression calibration system 101, an FP interferometer 102, a lens 103, a filter 104, and a high-speed photoelectric detector 105; the azimuth and elevation angle measurement part 2 is composed of a two-dimensional grating 201, a lens group 202, and a planar array detector 203. The overall device is composed of the above two parts and a control and data processing system 3.

[0058] like Figure 2 As shown, in this embodiment, semi-transparent and semi-reflective films 107 are attached to both sides of the FP interferometer 102, the piezoelectric ceramic 106 is placed inside the FP interferometer 102 and connected to the control and data processing system 3, and the signal output end of the high-speed photodetector 105 is also connected to the control and data processing system 3.

[0059] By calculating the size of the spacing L of the FP interferometer 102, the wavelength of the corresponding laser beam is calculated. The specific calculation method is as follows: The cavity spacing L of the FP interferometer 102 is related to the frequency applied by the piezoelectric ceramic, and its size is:

[0060] L=L 0 cos(2πft) (a)

[0061] In formula (a), L 0 is the piezoelectric coefficient of the piezoelectric ceramic, and f is the frequency of the piezoelectric ceramic driving power supply.

[0062] When the phase change of the reflected light at the interface of the parallel mirror is not considered in the FP interferometer 102, the phase difference between each wave and its previous wave is

[0063]

[0064] Where n is the refractive index of the medium, θ is the refraction angle of the laser beam relative to the mirror, L is the cavity spacing of the FP interferometer 102, and λ is the incident wavelength of the laser beam. When n=1, the refraction angle θ of the laser beam relative to the mirror is zero, and the FP incident wavelength is proportional to the cavity length L, so the wavelength can be measured by adjusting the cavity length L.

[0065] The incident light is reflected and transmitted multiple times in the FP interferometer 102, and the reflected light and the transmitted light undergo multi-beam interference. The output light intensity I of the FP cavity is 1 and the incident light intensity I 0 The ratio is

[0066]

[0067] In formula (c), R is the reflectivity. Since the FP interferometer 102 uses a semi-transmissive and semi-reflective film 107, R = 0.5

[0068] According to the calculation formula of light intensity:

[0069]

[0070] Substituting formula (a) into formula (d) yields:

[0071]

[0072] From equations (c), (d), (e) and Bessel function, we can get

[0073]

[0074] Where J2 is the Bessel second-order function and J4 is the Bessel second-order function.

[0075] According to the ratio of the double frequency to the quadruple frequency, as shown in formula (g):

[0076]

[0077] The wavelength of the measured laser can be deduced according to the above formula.

[0078] The azimuth and elevation angle measuring part 2 of the device is composed of a two-dimensional grating 201, a lens group 202, and a planar array detector 203. The planar array detector 203 is placed at the focal plane. The direction information of the laser to be measured includes not only the azimuth angle α, but also the elevation angle γ. After the laser beam is diffracted by the two-dimensional grating 201, it is converged and interfered by the lens group 202 and imaged on the planar array detector 203. Figure 3 , Figure 4 As shown, in the x direction, the zero-order spectrum position is x 0 , +1 level spectrum is x +1 , the -1 level spectrum is x -1 , the position of the laser beam after diffraction in the y direction on the area array detector 203 is y, the grating constant of the two-dimensional grating 201 is d, and the focal length of the lens group 202 is F.

[0079]

[0080] Where: β +1 is the +1 order diffraction angle, β -1 is the -1 order diffraction angle;

[0081] The area array detector 203 is located at the focal plane of the lens group 202 with a focal length of F, and converts the diffracted light signal into an electrical signal. The positions of the 0th level, +1st level, and -1st level are shown in (i).

[0082]

[0083] The pitch angle α and azimuth angle γ can be determined by formulas (h) and (i)

[0084]

[0085] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. A laser warning device based on piezoelectric drive and FP interference, Features: The invention comprises a laser wavelength measuring part (1), an azimuth and elevation angle measuring part (2), and a control and data processing system (3); the laser wavelength measuring part (1) and the azimuth and elevation angle measuring part (2) are both arranged in the optical path direction of the laser beam, and the laser wavelength measuring part (1) and the azimuth and elevation angle measuring part (2) are both electrically connected to the control and data processing system (3) through wires; the laser wavelength measuring part (1) comprises a field of view compression calibration system (101), an FP interferometer (102), a lens (103), a filter (104), and a high-speed photoelectric detector (105); the field of view compression calibration system (101) is arranged in the optical path direction of the laser beam, the FP interferometer (102) is arranged in the optical path direction of the field of view compression calibration system (101), the lens (103) is arranged in the optical path direction of the FP interferometer (102), and the The filter (104) is arranged in the optical path direction of the lens (103), the high-speed photodetector (105) is arranged in the optical path direction of the filter (104), the signal output end of the high-speed photodetector (105) is electrically connected to a control and data processing system (3) through a wire, and the FP interferometer (102) is electrically connected to the control and data processing system (3) through a wire; the azimuth and elevation angle measuring part (2) comprises a two-dimensional grating (201), a lens group (202), and a planar array detector (203); the two-dimensional grating (201) is arranged in the optical path direction of the laser beam, the lens group (202) is arranged in the optical path direction of the two-dimensional grating (201), the planar array detector (203) is arranged in the optical path direction of the lens group (202), and the planar array detector (203) is electrically connected to the control and data processing system (3) through a wire; The measuring method of the laser warning device based on piezoelectric drive and FP interference comprises the following steps: S1, the laser beam enters the FP interferometer through the field compression collimation system; S2, calculate the cavity spacing L of the FP interferometer by the frequency of the piezoelectric ceramic; calculate the cavity spacing L of the FP interferometer by the frequency of the piezoelectric ceramic, L = L 0 cos(2πft) (a) The L 0 is the piezoelectric coefficient of the piezoelectric ceramic, and f is the frequency applied by the piezoelectric ceramic driving power supply; S3. Calculate the incident wavelength of the laser beam. When the phase change of the reflected light at the interface of the parallel mirror is not considered in the FP interferometer, the phase difference between each wave and the previous wave is The n is the refractive index of the medium, the θ is the refraction angle of the laser beam relative to the mirror, the L is the cavity spacing of the FP interferometer, and the λ is the incident wavelength of the laser beam; When n=1, the refraction angle θ of the laser beam relative to the mirror is zero, and the incident wavelength λ of the laser beam is proportional to the cavity spacing L of the FP interferometer. The wavelength is measured by adjusting the cavity spacing L of the FP interferometer. The laser beam is reflected and transmitted multiple times in the FP interferometer, and the reflected light and the transmitted light undergo multi-beam interference. The output light intensity I 1 and the incident light intensity I 0 The ratio is R is the reflectivity. Since a semi-transmissive and semi-reflective film is provided on both sides of the FP interferometer, the reflectivity R=0.5; According to the calculation formula of light intensity: Substituting formula (a) into formula (d) yields: From equations (c), (d), (e) and Bessel function, we can get The J 2 is the Bessel second-order function, the J 4 is the Bessel fourth-order function, and I is the intensity of the laser beam; According to the ratio of double frequency to quadruple frequency: Calculate the incident wavelength λ of the laser beam according to formula (g); S4, the laser beam is diffracted by a two-dimensional grating to produce diffracted light, wherein the diffracted light is divided into an x ​​direction and a y direction; S5, the diffracted light is converged on the array detector through the lens group to form a light spot, and the control and data processing system processes the light spot position on the array detector by an algorithm, thereby realizing the measurement of the azimuth and elevation angle of the laser beam; in the x direction, the zero-order spectrum position is x 0 , the +1 level spectrum is x +1 , the -1 level spectrum is x -1 , the position of the laser beam after diffraction in the y direction on the area array detector is y, the grating constant of the two-dimensional grating is d, and the focal length of the lens group is F; The β +1 is the +1 order diffraction angle, the β -1 is the -1 order diffraction angle; The array detector is located at the focal plane of the lens group with a focal length of F, and converts the diffracted light signal into an electrical signal, where the positions of level 0, level +1, and level -1 are The pitch angle α and azimuth angle γ are determined by equations (h) and (i) 2. A laser warning device based on piezoelectric drive and FP interference according to claim 1, Features: The FP interferometer (102) is provided with a piezoelectric ceramic (106) inside, and semi-transparent and semi-reflective films (107) are attached to both sides of the FP interferometer (102).

3. A laser warning device based on piezoelectric drive and FP interference according to claim 1, Features: The area array detector (203) is arranged at the focal plane of the lens group (202).

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