KR20100071327A - Laser targeting system using multiple wavelength pulse modulation - Google Patents

Abstract

PURPOSE: A laser target designator system using the multi frequency pulse modulation is provided so that the password leakage possibility can be reduced in the decryption algorithm. CONSTITUTION: The code selector(110) selects the specific encryption code of a plurality of encryption codes. The code encoder(120) occurs the series of digital pulse from the selected encryption code. The series of digital pulse mixes the pulse spacing number of kinds with the pulse spacing conditioning side tub mode to plurality. The pulse controller(130) is created the laser trigger pulse train from the series of digital pulse.

Description

Laser targeting system using multiple wavelength pulse modulation

The present invention relates to a target indicator and a searcher used for laser guided weapons, and is used in the guidance device for irradiating a laser pulse encoded in the target indicator to the target and the bomber equipped to find and destroy the target. The target indicator is equipped with a device for converting the laser oscillation wavelength into a wavelength different from the fundamental wavelength, and by coding two wavelengths, the number of cases for the encryption of the pulse transmitted from the target indicator is increased, so that the enemy enemy except for the friendly searcher It is about a device that makes it difficult to decrypt.

In the target indicator and the searcher used in the laser guided weapon, the tracking principle is applied to transmit the pulse in which the target indicator is encoded to the target, and the searcher receives the pulse reflected from the target.

Conventional laser target indicators may include distance measurement functions. In this case, only the fundamental wavelength is used for the target indicator, and the laser pulses wavelength-converted into the eye-safe band are separated for the distance measurement. I use it. In the case of the laser range finder, the receiver is combined with the laser transmitter. Therefore, in order to protect the eyes of the device operator, after converting the wavelength into the eye-safe wavelength band, the laser is measured to measure the distance to the target.

On the other hand, in relation to the encryption method of the pulse, a pulse interval modulation (PIM) method that modulates the pulse interval of the Nd: YAG laser having a single wavelength (for example, wavelength = 1.06um) has been conventionally used.

For example, according to the apparatus described in US Pat. No. 5,023,888, as shown in FIG. 6, the apparatus includes a laser transmitter 20 that performs PIM encryption and a receiver 24 that performs PIM decryption. A method of irradiating a target object using a pulse interval modulation (PIM) method using a single wavelength of an Nd: YAG laser beam, and a decoding method using a shift register circuit is used for the receiver 24. have.

However, the device according to the patent uses a single wavelength as a transmission laser, and is a structure that is easy to be decrypted by an enemy because it is a modulation method that adjusts only a pulse interval for encryption. That is, in the case of the device according to the patent, the enemy can receive a laser beam with a photodetector, and then, by using a generally known shift register circuit, the target indicator can be easily reversed.

On the other hand, in order to make decryption more difficult, encryption is required to be more complicated. Even if the number of encryption cases is increased by only increasing the number of pulse interval modulations on the time axis, the decryption principle is the same. It only takes more time, and there are limits to what makes the decryption itself impossible or difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and the present invention has been made in view of the technical problem of improving a conventional target indicator and a receiving device using PIM modulation, which is an encryption method for adjusting pulse intervals with only a single wavelength.

That is, an object of the present invention is to attach a wavelength conversion module element such as OPO (Optical Parametric Oscillation), Raman shift to the transmitter to generate a plurality of wavelengths (for example, 2) in accordance with the encryption code and combine with the existing PIM modulation code The technical challenge is to achieve a very high level of encryption in proportion to the code length.

In order to achieve the above object, the present invention provides a laser target indicator system using a multi-wavelength pulse modulation, comprising: a code selector (110) for selecting a specific encryption code among a plurality of encryption codes conforming to encryption and decryption rules; A code encryptor (120) for generating a digital pulse train in which a plurality of pulse intervals are combined (N) by a pulse interval modulation (PIM) method from an encryption code selected by the code selector (110); A pulse controller (130) for generating a laser trigger pulse sequence from the digital pulse sequence generated by the code encryptor (120); Pulses configured such that the number of pulse intervals is plural (N) from the laser trigger pulse string generated by the pulse controller 130 and the number of (M) of the wavelengths that each pulse can have is plural (preferably two). It characterized in that it comprises a multi-wavelength pulse laser generator 140 for generating a laser; to perform the role of a laser target indicator.

Here, the multi-wavelength pulse laser generator 140 includes: a pulse laser generator 141 for oscillating a pulse laser having a fundamental wavelength from the laser trigger pulse train generated by the pulse controller 130; An electro-optic switch element 142 for bypassing the fundamental wavelength pulse laser oscillated by the pulse laser generator 141 into a plurality of optical paths; A wavelength converter (144) for converting pulse wavelengths for the fundamental wavelength pulsed lasers along one or more optical paths (M) of the plurality of optical paths; Of the plurality of optical paths, the pulse wavelength of the pulse wavelength converted by the wavelength converter 144 and the fundamental wavelength pulse by the wavelength converter 144 by adjusting the optical path of the fundamental wavelength pulse laser is not converted by the wavelength converter 144 It is preferable to include a; beam splitter 143 for synthesizing a laser.

In addition, the device according to the embodiment of the present invention may have a function of a distance measurer in addition to the role of the laser target indicator by mounting the target unit as well as the transmitter 100 and the receiver 200 together.

On the other hand, the receiver 200 includes a receiver 240 for receiving the reflected pulse laser is reflected by the pulse laser generated in the transmitter 100 from the target (T) to detect the wavelength and pulse interval of the received pulse laser; A code selector 210 for selecting a specific encryption code among a plurality of encryption codes that follow encryption and decryption rules; A code decoder (220) for combining the wavelength information and the pulse interval information obtained from the receiver (240) and decrypting the encryption code with reference to the encryption code of the code selector; And a controller 230 for distinguishing the other signal from the signal sent from the transmitter 100 by the signal decoded by the code decoder 220 to track the target T.

The receiver 240 includes: a wavelength division filter 241 for separating the reflected pulse laser into a plurality of optical paths according to wavelengths; A photodetector 242 separated by the wavelength division filter 241 for detecting each wavelength of a plurality of M reflected pulse lasers along each optical path and converting the wavelengths into electrical signals; And a signal processor 243 for detecting the interval between pulses of the reflected pulse laser by combining the electrical signals converted by the photodetecting elements 242 on the time axis.

According to the present invention, not only the number of pulse intervals is plural (N) but also the number of wavelengths of each pulse is plural (M, preferably two), so that encryption by multi- (preferably double) wavelength pulses is possible. Do. Therefore, the present invention has a sharp increase in the number of cases of encryption compared to the conventional case where only a single number N of pulse intervals in a single wavelength has a large possibility of encryption leakage during decryption.

That is, since the enemy must perform the decryption by the number of wavelengths (M) and the decryption by the number of pulse interval types (N) at the same time, the decryption becomes very difficult.

In addition, the present invention can be applied to various fields, first of all, the field of the defense industry to which the present invention can be applied is laser-guided guided weapons (missiles, shells, unmanned aerial vehicles, etc.), laser target indicators and laser trackers ( seekers), and can be applied to other information and communication security industries in addition to the defense industry.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 shows the overall configuration of a laser target indicator system according to the present invention, and FIGS. 2 and 3 show detailed configurations of the transmitter 100 and the receiver 200 constituting the system according to the present invention, respectively. .

The system according to the present invention can generate and receive a pulse laser configured such that there are a plurality (N) of pulse intervals and a plurality of (M) of wavelengths each pulse can have. Here, the number of wavelengths M may be set to two or more, that is, multiple wavelengths, but in the example shown below, a dual wavelength pulse modulation system having two wavelengths of M is described.

First, as shown in Figure 1, the laser target indicator system using the dual wavelength pulse modulation according to the present invention is composed of a transmitter 100 and a receiver 200, the laser from the transmitter 100 to the target (T) After the beam L is fired, the receiver 200 receives the reflected laser beam L 'reflected from the target T.

Although the transmitter 100 and the receiver 200 are separated from each other in the illustrated example, the transmitter 100 and the receiver 200 may be implemented in various forms. That is, in some cases, the transmitter 100 and the receiver 200 may be configured as one module, or may be mounted separately for the target indicator and the guided weapon, respectively.

When the transmitter 100 and the receiver 200 are configured as a single module as in the former case, when only the transmitter 100 is used, for the purpose of the target indication, when both the transmitter 100 and the receiver 200 are used, It can be used for range finder.

On the other hand, in the latter case, the receiving unit is mounted on the guided weapon to destroy the target, and the target indicator corresponding to the transmitting unit is used to indicate the target until the target is destroyed by a helicopter, an armored vehicle or a portable unit.

Referring back to FIG. 1, the transmitter 100 of the apparatus according to the present invention comprises a code selector 110, a code encryptor 120, a pulse controller 130, and a multi-wavelength pulse laser generator 140. have.

The code selector 110 selects a specific encryption code from among a plurality of encryption codes that follow encryption and decryption rules.

The code encryptor 120 generates a digital pulse train in which a plurality of pulse intervals are combined (N) by a pulse interval control modulation (PIM) method from the encryption code selected by the code selector 110.

The pulse controller 130 generates a laser trigger pulse train from the digital pulse train generated by the code encryptor 120.

The multi-wavelength pulse laser generator 140 has a plurality of pulse intervals (N) from the laser trigger pulse sequence generated by the pulse controller 130 and a plurality of wavelengths (M) of wavelengths that each pulse may have (for example, To generate two) pulse lasers.

A detailed configuration of the multi-wavelength pulse laser generator 140 will be described with reference to FIG. 2.

As shown in FIG. 2, the multi-wavelength pulse laser generator 140 is composed of a pulse laser generator 141, an electro-optic switch element 142, a beam splitter 143, and a wavelength converter 144. .

The pulse laser generator 141 oscillates a pulse laser that emits a fundamental wavelength from the laser trigger pulse train generated by the pulse controller 130.

The electro-optic switch element 142 bypasses the fundamental wavelength pulse laser oscillated by the pulse laser generator 141 to a plurality of (preferably two) optical paths.

Wavelength converter 144 converts the pulse wavelength for the fundamental wavelength pulsed laser. When the fundamental wavelength digital pulse passes through the wavelength converter 144, the wavelength of the pulse laser is changed by a nonlinear optical phenomenon caused by nonlinear crystals such as KTP and KDP set to the phase matching angle (L2).

The beam splitter 143 adjusts the optical path of the basic wavelength pulse laser L1 whose pulse wavelength is not converted by the wavelength converter 144 among the plurality of optical paths, thereby converting the wavelength by the wavelength converter 144. (L2) and the fundamental wavelength pulse laser (L1) are synthesized.

Next, referring again to FIG. 1, the receiver 200 includes a receiver 240, a code selector 210, a code decoder 220, and a controller 230.

The code selector 210 selects a specific encryption code from among a plurality of encryption codes that follow encryption and decryption rules.

The code decoder 220 combines the wavelength information and the pulse interval information obtained from the receiver 240 and decrypts the encryption code by referring to the encryption code of the code selector.

The controller 230 tracks the target T by distinguishing the other signal from the signal sent from the transmitter 100 by the signal decoded by the code decoder 220.

The receiver 240 receives the reflected pulse laser L 'from which the pulse laser generated by the transmitter 100 is reflected from the target T to detect the wavelength and pulse interval of the received pulse laser L'. The pulse train of the reflected laser beam L 'has different wavelengths between pulses and different pulse intervals according to a preset rule.

Detailed configuration of the receiver 240 will be described with reference to FIG. 3.

As shown in FIG. 3, the receiver 240 includes a wavelength division filter 241, a photodetector 242, and a signal processor 243.

The wavelength division filter 241 separates the reflected pulse laser beam L 'into a plurality of optical paths M according to the wavelength. The wavelength division element constituting the wavelength division filter 241 may be configured as a WDM (Wavelength Division Multiplex) element in the form of a thin film or a bulk.

The photodetector 242 is separated by the wavelength division filter 241 to detect each wavelength of the plurality of M reflected pulse lasers along each optical path and convert the wavelengths into electrical signals. As the photodetecting device 242, a photodiode can be adopted as a representative.

The signal processor 243 combines the electrical signals converted by the photodetecting elements 242 on the time axis to detect the interval between pulses of the reflected pulse laser.

The operation of the laser target indicator system according to the present invention according to the above configuration will be described with reference to FIGS.

First, referring to FIG. 1, the code selector 110 aligns an encryption code according to a decryption rule and an encryption set in advance with a receiver and a transmitter.

Then, when a specific encryption code is selected by the code selector 110, the code encryptor 120 generates digital pulses having a combination N of various pulse intervals. This digital pulse train is generated by a pulse spacing modulation scheme (PIM).

Subsequently, when the pulse controller 130 generates the laser trigger pulse train P (see FIG. 2) according to PIM modulation, the number of pulse intervals in the dual wavelength laser pulse generator 140 is plural (N), The pulse laser L configured to have two false-numbered wavelengths M of pulses may be generated and sent toward the target T. FIG.

Meanwhile, the driving of the dual wavelength laser pulse generator 140 in the transmitter 100 will be described with reference to FIG. 2.

Referring to FIG. 2, the dual wavelength laser generator 141 oscillates a pulse laser Lo that emits a fundamental wavelength from the digital pulse P generated by the code encryptor 120.

The oscillated fundamental wavelength pulse laser Lo is separated into a plurality of optical paths according to the wavelength by the electro-optic switch element 142. The electro-optic switch element 142 is synchronized with the pulse controller 130 to return the polarization of the laser pulse by a predetermined program to vary the optical path according to the wavelength. For example, by applying an encrypted digital pulse to the electro-optic switch element 142, the optical path can be diverted in the direction of the wavelength converter 144 or the beam splitter 142.

On the other hand, when the basic wavelength digital pulses bypassed by the electro-optic switch element 142 toward the wavelength converter 144 pass through the wavelength converter 144, nonlinear optics by nonlinear crystals such as KTP, KDP, etc., set at the phase matching angle are provided. The wavelength of the pulse laser is changed by the phenomenon (L2).

The pulse laser L2 having the wavelength converted by the wavelength converter 144 is combined with the fundamental wavelength pulse laser L1 passed through the optical splitter 143. As a result, a dual wavelength pulse laser L having a plurality of N number of pulse intervals and two number M of wavelengths each pulse can have is generated.

When the pulse laser L is irradiated to the target object T by the operation of the transmitter 100, the reflected laser light pulse L 'is spread in all directions by the diffuse reflection. The laser pulse reaching the position of the receiver 200 among the diffusely reflected light pulses L 'is photodetected by the receiver 240 and restored to the digital pulse.

The operation of the receiver 200 will be described in detail with reference to FIG. 3. The pulse train L ′ reflected from the target T has two optical paths L1 and L2 according to the wavelength by the wavelength division filter 241. To be separated.

The two pulse trains L1 and L2 separated along the respective optical paths according to the wavelength of the wavelength division filter 241 are converted into electrical signals by the photodetector 242 and the wavelength of each pulse train is detected.

On the other hand, the signal processor 243 combines two signals on the time axis to detect the pulse interval of the reflected laser light pulse L '.

Next, the code decoder 220 combines the wavelength information obtained from the photodetector 242 with the pulse interval information obtained from the signal processor 243 and then decodes the signal by referring to the encryption code of the code selector 210. By decoding the signal, it is possible to distinguish a signal sent from the transmitter 100 from other signals.

Meanwhile, the signal decoded by the code decoder 220 is sent to the controller 230 so as to track the target.

4 shows an example of an encryption code having a plurality of types N of pulse intervals and a number M of pulse wavelengths according to an embodiment of the present invention.

As shown, if the type (N) of the pulse interval is three types of A, B, C, two kinds of the number (M) of the wavelength (M) of the wavelength that can be generated using the wavelength converter 144, Assume

First, code 1 is a case where the interval between pulse trains is A, B, and C sequentially, and only the first pulse has a wavelength of 1 and the remaining pulses have a wavelength of 2. In the case of Code 1 of this type, a series of cipher codes must be repeated, such as {(1A) (2B) (2C) (2A)} {(1A) (2B) (2C) (2A)} ... Becomes

Code 2 is a case where the wavelength of the third pulse train is converted from 1 to 2 under the same pulse train condition as code 1. As shown, the encryption code form of code 2 is {(1A) (2B) (1C) (2A)} {(1A) (2B) (1C) (2A)} ....

Code 3 is a case where the order of pulse widths in code 1 is changed from A, B, C to C, A, B, and the wavelength of the fourth pulse string is converted from 2 to 1. As shown, the code form of the code 3 is {(1C) (2A) (2B) (1A)} {(1C) (2A) (2B) (1A)} ....

As can be seen by comparing Code 1 and Code 2, when using only PIM modulation that modulates only pulse intervals, Code 1 and Code 2 are the same. For example, two), code 1 and code 2 may be recognized differently. In other words, by setting a plurality of types of wavelengths as well as pulse intervals, it is possible to generate encryption codes in more cases.

For example, when there are N types of pulse intervals, the number of pulse sequences that can be obtained by using only the PIM method that can modulate only the pulse interval is N! According to the present invention, although the number of pulse intervals is set to N and the number of wavelength branches that each pulse can have for each pulse is enabled by the WDM (Wavelength Division Multiplex) device, the total number of cases is 2 ^N! It becomes a dog. When the type (N) of the pulse interval is increased to 2, 3, 4, the number of ciphers proposed by the conventional PIM method and the present invention is as follows.

N PIM method WDM-PIM mixed method 2 2 4 3 6 64 4 24 16,777,216

That is, in the conventional PIM method, when N = 4, the number of 24 (= 4!) Types of encryption cases can be used, whereas the case proposed by the present invention is 16,777,216 (= 2 ^4! ) Types, and is suitable for the enemy group. Decryption is almost impossible.

5 illustrates a modification of the receiver 240 of FIG. 3.

The receiver 240 of FIG. 5 is applied when the wavelength converted by the wavelength converter 144 of the transmitter 100 is not fixed to a specific value but determined by an arbitrary nonlinear crystal.

In this case, the receiver 240 uses a multi-channel WDM element 241-1 instead of the two-wavelength WDM element 241 shown in FIG. 3 as a wavelength division filter, and the photodetector is an array type photodetector 242-1. Can be used to determine the wavelength information determined arbitrarily.

Although specific embodiments of the present invention have been described above, the spirit and scope of the present invention are not limited to the specific embodiments, and various modifications and changes can be made without departing from the spirit of the present invention. Those skilled in the art will understand.

Therefore, since the embodiments described above are provided to completely inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

1 is an overall configuration diagram of a laser target indicator system according to the present invention.

2 is a detailed view of a transmitter in a laser target indicator system of the present invention.

3 is a detailed view of a receiver in a laser target indicator system of the present invention.

4 is a view for explaining a two-wavelength pulse interval modulation code scheme according to the present invention.

5 is a detailed view of a receiver according to a modification of the present invention.

6 is a schematic configuration diagram of the prior art.

DESCRIPTION OF THE REFERENCE NUMERALS OF THE DRAWINGS

100: transmitter 110: code selector

120: code encryptor 130: pulse controller

140: multi-wavelength pulse laser generator 141: pulse laser generator

142: electro-optic switch element 143: beam splitter

144: wavelength converter 200: receiver

210: code selector 220: code decoder

230: controller 240: receiver

241: wavelength division filter 242: photodetector element

243: signal processor

Claims (6)

A laser target indicator system using multi-wavelength pulse modulation, A code selector 110 for selecting a specific encryption code among a plurality of encryption codes that follow encryption and decryption rules; A code encryptor (120) for generating a digital pulse train in which a plurality of pulse intervals are combined (N) by a pulse interval modulation (PIM) method from an encryption code selected by the code selector (110); A pulse controller (130) for generating a laser trigger pulse sequence from the digital pulse sequence generated by the code encryptor (120); A multi-wavelength pulse laser generator 140 generating a pulse laser from the laser trigger pulse train generated by the pulse controller 130; Laser target indicator system using a multi-wavelength pulse modulation comprising a transmitter (100) consisting of. The method of claim 1, wherein the multi-wavelength pulse laser generator 140, A pulse laser generator (141) for oscillating a pulse laser having a fundamental wavelength from the laser trigger pulse train generated by the pulse controller (130); An electro-optic switch element 142 for bypassing the fundamental wavelength pulse laser oscillated by the pulse laser generator 141 into a plurality of optical paths; A wavelength converter (144) for converting pulse wavelengths for the fundamental wavelength pulsed lasers along one or more optical paths (M) of the plurality of optical paths; Of the plurality of optical paths, the pulse wavelength of the pulse wavelength converted by the wavelength converter 144 and the fundamental wavelength pulse by the wavelength converter 144 by adjusting the optical path of the fundamental wavelength pulse laser is not converted by the wavelength converter 144 A beam splitter 143 for synthesizing a laser; Laser target indicator system comprising a. The method of claim 1, A receiver (240) for receiving the reflected pulse laser reflected from the target (T) by the pulse laser generated by the transmitter (100) and detecting the wavelength and pulse interval of the received pulse laser; A code selector 210 for selecting a specific encryption code among a plurality of encryption codes that follow encryption and decryption rules; A code decoder (220) for combining the wavelength information and the pulse interval information obtained from the receiver (240) and decrypting the encryption code with reference to the encryption code of the code selector; A controller 230 for distinguishing the signal transmitted from the transmitter 100 by the signal decoded by the code decoder 220 to distinguish the other signal, and tracking the target T; Laser target indicator system using a multi-wavelength pulse modulation further comprising a receiving unit configured to. The method of claim 3, wherein the receiver 240, A wavelength division filter (241) for separating the reflected pulse laser into a plurality of optical paths according to wavelengths; A photodetector 242 separated by the wavelength division filter 241 for detecting each wavelength of a plurality of M reflected pulse lasers along each optical path and converting the wavelengths into electrical signals; A signal processor (243) for detecting the interval between pulses of the reflected pulse laser by combining the electrical signals converted by the photodetectors (242) on the time axis; Laser target indicator system using a multi-wavelength pulse modulation comprising a. 5. The laser target indicator system of claim 1, wherein the number M of wavelengths of each pulse included in the pulse laser is 2. 5. The method of claim 1, The multi-wavelength pulse laser generator 140 has a plurality of pulse intervals (N) from the laser trigger pulse string generated by the pulse controller 130 and a plurality of wavelengths (M) of wavelengths each pulse may have. A laser target indicator system using multi-wavelength pulse modulation, characterized in that it generates a pulse laser configured to be.

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