An angle measuring device for the optical system of a laser semi-active seeker

Abstract

The present invention discloses an angle measuring device for an optical system of a laser semi-active seeker, comprising: an optical system component, a four-quadrant detector, a preamplifier circuit, a main amplifier circuit, an analog-to-digital conversion circuit and a main control unit; wherein the optical system component is located at the front end, and is used to receive the laser beam diffusely reflected by the target, and screen out the target laser signal; the four-quadrant detector is located behind the optical system component, and is used to detect the target laser signal and convert it into a current signal; the preamplifier circuit includes a transimpedance amplifier, which is used to convert the current signal into a voltage signal; the main amplifier circuit includes a voltage-controlled amplifier, which is used to amplify the voltage signal. The present invention adopts a four-quadrant detector to obtain spot information, and by designing a signal processing circuit for the detection information, it realizes effective suppression of common-mode noise, and at the same time realizes accurate measurement of the target angle, and has good real-time performance.

Description

Technical Field

[0001] The invention relates to the technical field of laser guidance equipment, and in particular to an angle measuring device for an optical system of a laser semi-active seeker. Background Art

[0002] In the process of tracking the target, the laser semi-active seeker is often unable to obtain accurate tracking instructions due to the influence of environmental and background factors. The main reason is the interference signals from the environment and background. At the same time, under the same optical system and detector, the inaccurate tracking instructions are also caused by the inaccurate and untimely processing of angle information when the target is detected. Therefore, how to eliminate the interference signals from the environment and background and use laser to measure the angle information of the target in real time and accurately is crucial for the precise guidance of the missile. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to propose an angle measuring device for the optical system of a laser semi-active seeker, which adopts a four-quadrant detector to obtain light spot information, and realizes effective suppression of common mode noise by designing a signal processing circuit for the detection information, while realizing accurate measurement of the target angle with good real-time performance.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions to achieve it.

[0005] An angle measuring device for an optical system of a laser semi-active seeker comprises: an optical system component, a four-quadrant detector, a preamplifier circuit, a main amplifier circuit, an analog-to-digital conversion circuit and a main control unit; wherein the optical system component is located at the front end of the angle measuring device, and is used to receive a laser beam diffusely reflected by a target, filter out a target laser signal, and converge the target laser signal on a photosensitive surface of the four-quadrant detector;

[0006] The four-quadrant detector is located behind the optical system component and is used to detect the target laser signal, convert the target laser signal into a current signal, and transmit the current signal to the preamplifier circuit;

[0007] The preamplifier circuit includes a transimpedance amplifier and is a four-way parallel circuit, which is used to convert the current signal of each quadrant of the four-quadrant detector into a voltage signal and transmit the voltage signal to the main amplifier circuit;

[0008] The main amplifier circuit includes a voltage-controlled amplifier, and is a four-way parallel circuit, which is used to amplify each voltage signal so that it meets the requirements of analog-to-digital conversion processing and then is transmitted to the analog-to-digital conversion circuit;

[0009] The analog-to-digital conversion circuit converts the analog voltage signal into a digital signal and transmits the digital signal to the main control unit;

[0010] The main control unit calculates the deflection angle information according to the input digital signal; and generates a gate signal to control the sampling process of the analog-to-digital conversion circuit on the analog voltage signal.

[0011] The characteristics and further improvements of the technical solution of the present invention are:

[0012] Furthermore, the optical system component is a transmissive optical system, which is composed of a filter, a first convex lens, a second convex lens and a third convex lens which are coaxially arranged in sequence front and back.

[0013] Furthermore, the radii of the first convex lens, the second convex lens and the third convex lens decrease successively, and the thicknesses increase successively.

[0014] Furthermore, the preamplifier circuit includes a transimpedance amplifier module and a first peak holding module that are electrically connected in sequence. The transimpedance amplifier module converts the current signal of each quadrant into a voltage signal and then amplifies it. The amplified voltage signal passes through the first peak holding module to obtain a pulse signal proportional to the peak value of the electrical pulse.

[0015] Furthermore, the main amplifier circuit comprises an analog operation module, a second peak holding module, a normalization module and a power amplifier module which are electrically connected in sequence; the analog operation module processes the pulse signal after the peak holding by using the sum-difference analog operation to obtain a pulse signal U reflecting the target x direction. x , reflecting the pulse signal U in the y direction of the target y and the pulse signal U that reflects the total energy of the target spot ∑ The three pulse signals are respectively extended by the second peak holding module to form an extended pulse signal U xh , U yh and U ∑h ; Normalization module for the expanded pulse signal U xh and U yh Normalization processing is performed respectively, and a signal U is output to reflect the distance information of the target light spot from the center of the seeker. xH and U yH ; The power amplifier modules are respectively xH and U yH Perform power amplification and transmit the amplified signal to the main control unit for deflection angle calculation;

[0016] Among them, the x direction and y direction correspond to the x axis and y axis of the four-quadrant detector; U xh is the extended pulse signal reflecting the target x direction, U yh is the extended pulse signal reflecting the target y direction, U ∑h It is the expanded pulse signal reflecting the total energy of the target light spot.

[0017] Furthermore, the pulse signal U reflecting the target x direction x , reflecting the pulse signal U in the y direction of the target y and the pulse signal U that reflects the total energy of the target spot ∑ The acquisition process is:

[0018] U x =K[(A+D)-(B+C)]

[0019] U y =K[(A+B)-(C+D)]

[0020] U ∑ =K′(A+D+B+C),

[0021] Wherein, A, B, C, and D represent the pulse signals after peak holding corresponding to the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant of the four-quadrant detector, respectively, K is the distance proportional coefficient, and K′ is the energy proportional coefficient;

[0022] The normalization process is:

[0023] U xH =U xh / U ∑h

[0024] U yH =U xh / U ∑h ;

[0025] Among them, U xH To reflect the distance of the target light spot from the center of the seeker in the x direction, U xH Reflects the distance that the target light spot deviates from the center of the seeker in the y direction.

[0026] Furthermore, the four-quadrant detector is a four-quadrant silicon photodetector.

[0027] Furthermore, the transimpedance amplifier circuit uses NE5210 model as an integrated transimpedance amplifier, and its bandwidth at -3db is 200MHz.

[0028] Furthermore, the voltage-controlled amplifier circuit adopts a voltage-controlled amplifier model AD8330, and its input signal and output signal are differential signals respectively.

[0029] Furthermore, the analog-to-digital conversion circuit adopts a 200Mbps high-speed AD converter.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention adopts a four-quadrant detector as a laser detection receiving component, and through the design of four parallel amplifier circuits and each amplifier circuit, accurate measurement of angle information is achieved through a two-level peak holding module, thereby ensuring real-time performance; through the two-stage combined action of a transimpedance amplifier and a voltage-controlled amplifier, common-mode noise interference signals caused by the environment and background are effectively eliminated, thereby greatly improving the accuracy of the device's angle measurement, and the device cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 A schematic diagram of the structural connection of an angle measuring device for an optical system of a laser semi-active seeker according to an embodiment of the present invention;

[0034] Figure 2 is an internal structure diagram of an optical system component according to an embodiment of the present invention;

[0035] Figure 3 The figure is a schematic diagram of the structural connection of the preamplifier circuit and the main amplifier circuit according to an embodiment of the present invention.

[0036] In the above figure, 1 optical system component; 101 filter; 102 first convex lens; 103 second convex lens; 104 third convex lens; 2 four-quadrant detector; 3 preamplifier circuit; 301 transimpedance amplifier module; 302 first peak holding module; 4 main amplifier circuit; 401 analog operation module; 402 second peak holding module; 403 normalization module; 404 power amplifier module; 5 analog-to-digital conversion circuit; 6 main control unit. DETAILED DESCRIPTION

[0037] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0038] refer to Figure 1 The present invention provides an angle measuring device for an optical system of a laser semi-active seeker, comprising: an optical system component, a four-quadrant detector, a preamplifier circuit, a main amplifier circuit, an analog-to-digital conversion circuit and a main control unit; wherein the optical system component is located at the front end of the angle measuring device, and is used to receive a laser beam diffusely reflected by a target, and filter out a target laser signal, and converge the target laser signal on a photosensitive surface of the four-quadrant detector;

[0039] The four-quadrant detector is located behind the optical system component and is used to detect the target laser signal, convert the target laser signal into a current signal, and transmit the current signal to the preamplifier circuit;

[0040] The preamplifier circuit includes a transimpedance amplifier and is a four-way parallel circuit, which is used to convert the current signal of each quadrant of the four-quadrant detector into a voltage signal and transmit the voltage signal to the main amplifier circuit;

[0041] The main amplifier circuit includes a voltage-controlled amplifier, and is a four-way parallel circuit, which is used to amplify each voltage signal so that it meets the requirements of analog-to-digital conversion processing and then is transmitted to the analog-to-digital conversion circuit;

[0042] The analog-to-digital conversion circuit converts the analog voltage signal into a digital signal and transmits the digital signal to the main control unit;

[0043] The main control unit calculates the deflection angle information according to the input digital signal; and generates a gate signal to control the sampling process of the analog-to-digital conversion circuit on the analog voltage signal.

[0044] In the above embodiments, the off-site guided laser irradiates the target, and the laser beam is diffusely reflected on the target surface. The diffusely reflected laser beam is received by the optical system component located at the front end of the angle measuring device, and the signals of other wavelengths other than the selected wavelength are filtered out to obtain the target laser signal, and the target laser signal is converged on the photosensitive surface of the four-quadrant detector; the four-quadrant photoelectric detector converts the detected target laser signal into a current signal, each quadrant corresponds to a current signal, and the size of the current signal is proportional to the spot area of ​​each quadrant, and the current signal is transmitted to the preamplifier circuit; the preamplifier circuit includes a transimpedance amplifier, which can suppress common-mode noise and realize IV conversion, and the main amplifier circuit includes a voltage-controlled amplifier, which amplifies the weak voltage signal to meet the requirements of the post-stage processing through voltage control and then sends it to the 200Mbps high-speed analog-to-digital conversion circuit (ADC), which can further suppress the common-mode noise of the system and improve the signal accuracy. The high-speed ADC circuit converts the analog signal output by the amplifier into a digital signal that can be processed by the processor. The main control unit of this implementation selects FPGA, generates a gating signal to realize the control of the high-speed ADC sampling process, and completes the processing and solution of data information to obtain the deflection angle information. Finally, it is uploaded to the host computer software via RS485. The present invention uses a four-quadrant detector to obtain the spot information, and through the four-way parallel signal amplification processing corresponding to the four quadrants, the target reflected laser information is effectively acquired and quickly processed. A transimpedance amplifier and a voltage-controlled amplifier are set in each signal amplification process to achieve two-stage cascade suppression of common-mode noise, effectively eliminating the common-mode noise interference signal brought by the environment and background, greatly improving the accuracy of the device's angle measurement, and the device cost is low.

[0045] refer to Figure 2According to one embodiment of the present invention, the optical system component is a transmission optical system, which is composed of a filter, a first convex lens, a second convex lens and a third convex lens coaxially arranged in sequence front and back. The radius of the first convex lens, the second convex lens and the third convex lens decreases in sequence, and the thickness increases in sequence. In the above embodiments, the laser beam diffusely reflected by the target first passes through the filter to filter out the light signals of the redundant spectral bands, so that the light signals of the specific bands can pass through; the light signal is then focused by the first convex lens, the second convex lens and the third convex lens, whose radius decreases in sequence and whose thickness increases in sequence, so that the focused light spot finally falls on the photosensitive surface of the four-quadrant detector. Through the design of the three convex lenses, the brightness of the final focused light spot is large and the light energy loss is small, which is beneficial to the subsequent signal processing process.

[0046] refer to Figure 3 , according to one embodiment of the present invention, Figure 3 Ar, Br, Cr, and Dr are the electrical pulse signals corresponding to each quadrant after the target light spot falls in each quadrant of the four-quadrant detector and is converted by the photoelectric detector. The preamplifier circuit comprises a transimpedance amplifier module and a first peak holding module which are electrically connected in sequence. The core component of the transimpedance amplifier module is a transimpedance amplifier, which converts the current signals Ar, Br, Cr, and Dr of each quadrant into voltage signals and then amplifies them. The amplified voltage signals are passed through the first peak holding module to obtain a pulse signal proportional to the peak value of the electrical pulse.

[0047] Further, refer to Figure 3 The main amplifier circuit comprises an analog operation module, a second peak holding module, a normalization module and a power amplifier module which are electrically connected in sequence; the analog operation module processes the pulse signal after the peak holding by using the sum-difference analog operation to obtain a pulse signal U reflecting the target x direction. x , reflecting the pulse signal U in the y direction of the target y and the pulse signal U that reflects the total energy of the target spot ∑ The three pulse signals are respectively extended by the second peak holding module to form an extended pulse signal U xh , U yh and U ∑h ; Normalization module for the expanded pulse signal U xh and U yh Normalization processing is performed respectively, and a signal U is output to reflect the distance information of the target light spot from the center of the seeker. xH and U yH ; The power amplifier modules are respectively xH and U yH Perform power amplification and transmit the amplified signal to the main control unit for deflection angle calculation;

[0048] Among them, the x direction and y direction correspond to the x axis and y axis of the four-quadrant detector; U xh is the extended pulse signal reflecting the target x direction, U yh is the extended pulse signal reflecting the target y direction, U ∑h It is the expanded pulse signal reflecting the total energy of the target light spot.

[0049] The pulse signal U reflecting the target x direction x , reflecting the pulse signal U in the y direction of the target y and the pulse signal U that reflects the total energy of the target spot ∑ The acquisition process is:

[0050] U x =K[(A+D)-(B+C)]

[0051] U y =K[(A+B)-(C+D)]

[0052] U ∑ =K′(A+D+B+C),

[0053] Wherein, A, B, C, and D represent the pulse signals after peak holding corresponding to the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant of the four-quadrant detector, respectively, K is the distance proportional coefficient, and K′ is the energy proportional coefficient;

[0054] The normalization process is:

[0055] U xH =U xh / U ∑h

[0056] U yH =U xh / U ∑h ;

[0057] Among them, U xH To reflect the distance of the target light spot from the center of the seeker in the x direction, U xH Reflects the distance that the target light spot deviates from the center of the seeker in the y direction.

[0058] The calculation process of the deflection angle is as follows: xH and U yH The signal U after power amplification xHm and U yHm Calculate U yHm / U xHm The tangent value of the angle is obtained, and then the angle value is obtained. The servo turntable is driven to rotate through the pulse width modulator to realize the rotation and tracking of the optical axis.

[0059] Further, refer to Figure 1 and Figure 2 The four-quadrant detector of the embodiment of the present invention is a four-quadrant silicon photodetector GT111, which has the advantages of fast response speed, small blind area, low noise, good uniformity and symmetry.

[0060] Furthermore, the transimpedance amplifier circuit adopts the NE5210 model as an integrated transimpedance amplifier, and its bandwidth at -3db is 200MHz. Specifically, the transimpedance amplifier is the NE5210 integrated transimpedance amplifier produced by Philips, which has the advantages of low noise, wide bandwidth and moderate transimpedance. Its output is in differential form, which is conducive to suppressing common-mode noise. The differential transimpedance value of NE5210 is 7kΩ, so the gain of the preamplifier circuit is 38db; the -3dB bandwidth of NE5210 is 200MHz, and there is no other form of low-pass circuit in the circuit, so the upper cutoff frequency can be considered to be 200MHz, which can amplify the signal pulse with a pulse width of 20ns without distortion, thereby improving the angle measurement accuracy.

[0061] Furthermore, the voltage-controlled amplifier circuit adopts a voltage-controlled amplifier model AD8330, whose input signal and output signal are differential signals, which is conducive to suppressing common-mode noise. Specifically, the function of the voltage-controlled amplifier circuit is to amplify the output voltage signal of the transimpedance amplifier module, and the circuit gain can be controlled by voltage. Ideally, the output voltage signal does not change with distance. The voltage-controlled amplifier of this embodiment is AD8330 produced by AD Company, which has the advantages of large gain adjustment range, low noise and high bandwidth. It also has another significant advantage that the bandwidth is fixed in the entire gain range, and has two gain control methods: linear gain control and exponential gain control.

[0062] Further, refer to Figure 1 The analog-to-digital conversion circuit adopts a 200Mbps high-speed AD converter. Specifically, a high-speed AD converter of National model ADC08200CIMI is adopted, which has the characteristics of small size, low power consumption and single-ended input.

[0063] The main control unit FPGA of this embodiment mainly realizes the control sampling process of the high-speed ADC, the processing and solution of the data, the RS485 transmission of the deflection information and the output of the gate signal. The Cyclone II series chip is used as the main control unit, which has the advantages of low cost, low power consumption, up to 68416 logic units (LE) and 1.1M bits of embedded memory, and is easy to read and portable.

[0064] The laser semi-active seeker angle measuring device of the present invention receives the laser light waves diffusely reflected by the target through a four-quadrant photoelectric detector, and completes the real-time measurement and processing of the target space angle information through a preamplifier circuit and a main amplifier circuit, a 200Mbps high-speed analog-to-digital conversion circuit and an FPGA main control unit, effectively suppresses the common mode noise in the system, and can obtain accurate angle information instructions, so that the missile steering gear system can timely drive and adjust the flight direction according to the angle information, thereby achieving accurate tracking and striking of the target.

[0065] Although the present invention has been described in detail in general terms and in specific embodiments in this specification, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. An angle measuring device for an optical system of a laser semi-active seeker, characterized in that: include: An optical system component, a four-quadrant detector, a preamplifier circuit, a main amplifier circuit, an analog-to-digital conversion circuit and a main control unit; wherein the optical system component is located at the front end of the angle measuring device, and is used to receive the laser beam diffusely reflected by the target, and filter out the target laser signal, and converge the target laser signal on the photosensitive surface of the four-quadrant detector; The four-quadrant detector is located behind the optical system component and is used to detect the target laser signal, convert the target laser signal into a current signal, and transmit the current signal to the preamplifier circuit; The preamplifier circuit includes a transimpedance amplifier and is a four-way parallel circuit, which is used to convert the current signal of each quadrant of the four-quadrant detector into a voltage signal and transmit the voltage signal to the main amplifier circuit; The main amplifier circuit includes a voltage-controlled amplifier, and is a four-way parallel circuit, which is used to amplify each voltage signal so that it meets the requirements of analog-to-digital conversion processing and then is transmitted to the analog-to-digital conversion circuit; The analog-to-digital conversion circuit converts the analog voltage signal into a digital signal and transmits the digital signal to the main control unit; The main control unit calculates the deflection angle information according to the input digital signal; and generates a gate signal to control the sampling process of the analog-to-digital conversion circuit on the analog voltage signal; The preamplifier circuit comprises a transimpedance amplifier module and a first peak holding module which are electrically connected in sequence, the transimpedance amplifier module converts the current signal of each quadrant into a voltage signal and then amplifies it, and the amplified voltage signal passes through the first peak holding module to obtain a pulse signal proportional to the peak value of the electrical pulse of the voltage signal; The main amplifier circuit comprises an analog operation module, a second peak holding module, a normalization module and a power amplifier module which are electrically connected in sequence; the analog operation module processes the pulse signal after the peak holding by using the sum-difference analog operation to obtain a pulse signal U reflecting the target x direction. x , reflecting the pulse signal U in the y direction of the target y and the pulse signal U that reflects the total energy of the target spot ∑ The three pulse signals are respectively extended by the second peak holding module to form an extended pulse signal U xh , U yh and U ∑h ; Normalization module for the expanded pulse signal U xh and U yh Normalization processing is performed respectively, and a signal U is output to reflect the distance information of the target light spot from the center of the seeker. xH and U yH ; The power amplifier modules are respectively xH and U yH Perform power amplification and transmit the amplified signal to the main control unit for deflection angle calculation; Among them, the x direction and y direction correspond to the x axis and y axis of the four-quadrant detector; U xh is the extended pulse signal reflecting the target x direction, U yh is the extended pulse signal reflecting the target y direction, U ∑h is the expanded pulse signal reflecting the total energy of the target light spot; The pulse signal U reflecting the target x direction x , reflecting the pulse signal U in the y direction of the target y and the pulse signal U that reflects the total energy of the target spot ∑ The acquisition process is: U x =K[(A+D)-(B+C)] U y =K[(A+B)-(C+D)] U ∑ =K´(A+D+B+C), Wherein, A, B, C, and D represent the pulse signals after peak holding corresponding to the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant of the four-quadrant detector, respectively; K is the distance proportional coefficient, and K´ is the energy proportional coefficient; The normalization process is: IN xH =U xh / IN ∑h IN yH =U xh / IN ∑h ; Among them, U xH To reflect the distance of the target light spot from the center of the seeker in the x direction, U yH Reflects the distance that the target light spot deviates from the center of the seeker in the y direction.

2. The angle measuring device for the optical system of a laser semi-active guidance head according to claim 1, characterized in that: The optical system component is a transmission optical system, which is composed of a filter, a first convex lens, a second convex lens and a third convex lens which are coaxially arranged in sequence.

3. The angle measuring device for the optical system of a laser semi-active guidance head according to claim 2, characterized in that: The radii of the first convex lens, the second convex lens and the third convex lens decrease successively, and the thicknesses increase successively.

4. The angle measuring device for the optical system of a laser semi-active guidance head according to claim 1, characterized in that: The four-quadrant detector is a four-quadrant silicon photodetector.

5. The angle measuring device for the optical system of a laser semi-active guidance head according to claim 1, characterized in that: The transimpedance amplifier module adopts NE5210 model as an integrated transimpedance amplifier, and its bandwidth at -3db is 200MHz.

6. The angle measuring device for the optical system of a laser semi-active guidance head according to claim 1, characterized in that: The voltage-controlled amplifier model is AD8330, and its input signal and output signal are differential signals respectively.

7. The angle measuring device for the optical system of a laser semi-active guidance head according to claim 1, characterized in that: The analog-to-digital conversion circuit adopts a 200Mbps high-speed AD converter.

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