A detection device for the number of output pulses triggered by a pulsed laser

Abstract

The present application relates to a kind of detection device of the number of times of output pulse triggered by pulse laser, at least including pulse laser and pulse number detection circuit: the output end of pulse laser is to ranging target body after collimator, the lens of two different focal lengths in collimator is coincided in focal length, and pinhole diaphragm is placed in focal length coinciding point, the output light before collimation of pulse laser becomes relatively thin collimated output light after collimation and pinhole diaphragm filtering, the side of optical axis in front end of pinhole diaphragm is fixed with photodiode, and photodiode is used to receive filtered heat dissipation light, and the heat dissipation light received by photodiode becomes electrical signal, and is connected to the input end of pulse number detection circuit by interface.The present application can accurately and effectively detect single and double pulse of laser, eliminate the misjudgment to the performance index of laser, and improve production efficiency.

Description

Technical Field

[0001] This invention relates to a pulsed laser measurement technology, and more particularly to a device for detecting the number of pulses triggered by a pulsed laser. Background Technology

[0002] Pulsed lasers are crucial components for rangefinding in aiming scopes. Each activation of a pulsed laser produces one pulse, corresponding to one rangefinding operation. If the pulsed laser is not properly calibrated, it will emit consecutive double pulses, making it impossible for the timer to determine the closing time and thus hindering accurate rangefinding. Therefore, before assembling the laser component into the product, the single-pulse range of the laser must be calibrated, tested, and required to meet environmental performance standards. This ensures accurate rangefinding in aiming scopes. False alarms or mismeasurements will severely impact a tank's ability to achieve precise strikes.

[0003] Devices for detecting single-pulse and dual-pulse pulsed lasers consist of two parts: a laser acquisition probe and a circuit processing system. Due to the high energy and power of lasers, most current devices for detecting single-pulse and dual-pulse pulsed lasers use an indirect method to acquire the laser, i.e., receiving diffusely reflected laser light. This places strict requirements on the relative position of the laser and the detection device, as well as the laser's reflecting surface.

[0004] Currently, the production site uses an indirect method to acquire laser light. During production, it was found that adjusting the angle between the acquisition probe and the laser emission axis resulted in different display values. Due to the different reflective surfaces, the laser may undergo multiple reflections in multiple directions indoors (or in a high / low temperature chamber), causing a "false double pulse" phenomenon during testing. Slightly adjusting the probe direction eliminates the double pulse phenomenon. However, when the probe direction is adjusted too much, no light is emitted. Therefore, it is evident that the device using an indirect laser acquisition method can cause misjudgments of laser performance indicators during testing, significantly affecting the laser's pass rate. Summary of the Invention

[0005] The purpose of this invention is to provide a device for detecting the number of pulsed laser trigger output pulses that can accurately and effectively detect single and double pulses of a laser, eliminate misjudgments of laser performance indicators, and improve production efficiency.

[0006] The technical solution of this invention is as follows: a device for detecting the number of pulses triggered by a pulsed laser, comprising at least a pulsed laser and a pulse count detection circuit: the output end of the pulsed laser passes through a collimator to the ranging target, two lenses with different focal lengths within the collimator coincide at their focal lengths, and a pinhole aperture is placed at the focal length coincidence point. The output light of the pulsed laser before collimation is filtered by the collimator and the pinhole aperture to become a finer collimated output light. A photodiode is fixed on one side of the optical axis at the front end of the pinhole aperture. The photodiode is used to receive the filtered heat dissipation light and converts the received heat dissipation light into an electrical signal, which is then connected to the input end of the pulse count detection circuit via an interface.

[0007] The focal length ratio of the two lenses with different focal lengths in the collimator is 2-5 times.

[0008] The collimator cavity is an optically sealed cavity, and the photodiode exhibits a high-resistance state when there is no pulsed laser output light.

[0009] The pulse count detection circuit consists of a four-channel dual-input NAND gate circuit SN54LS00, a resettable monostable multivibrator SN54LS123, an SN54S112, a single-pulse output circuit, and a double-pulse output circuit. The photoelectric signal received by the photodiode is filtered and then inverted twice by the two dual-input NAND gate circuits in the SN54LS00 before being sent to the single-pulse detection circuit. It is then inverted once by one dual-input NAND gate circuit in the SN54LS00 before being sent to the double-pulse detection circuit.

[0010] The single-pulse detection circuit is composed of cascaded SN54LS123A and SN54S112A, and the double-pulse detection circuit is composed of cascaded SN54LS123B and SN54S112B.

[0011] The SN54LS123A, by configuring the time constants of capacitor C5 and resistor R5, outputs a pulse width T1 at the Q terminal when a single pulse is input; and outputs a pulse width 2T1 at the Q terminal when two single pulses are input.

[0012] The photodiode converts the optical signal into an electrical signal. After passing through a filter circuit and being inverted once, the signal is used as the input signal at terminal A of the SN54LS123B. By adjusting the resistor R11 in the external time constant of the SN54LS123B, the output pulse width can be adjusted so that the output pulse width at terminal Q of the SN54LS123B is T3 greater than T1 and T3 less than T2.

[0013] The JK flip-flop of the SN54S112A in the single-pulse output circuit flips the Q terminal to a high level. The Q terminal drives the transistor Q1 through resistor R7. When transistor Q1 is turned on, it drives the green LED to light up through the collector. At the same time, the NAND gate controls the reset terminal of SN54S112B to zero, and the output of SN54S112B is low, turning off the red LED.

[0014] The JK flip-flop of the SN54S112A is set to 0 in advance when the falling edge arrives, the Q output is low, the transistor Q2 is cut off, and the green light is off. At the same time, the reset terminal of the SN54S112B is set to high. When the clock pulse of the SN54S112B arrives, the output flips, the Q output of the SN54S112B is high, the transistor Q2 is turned on, and the red light is on. This realizes the function of the single and double peak detection circuit. When there is a single peak, the green light is on; when there is a double peak, the red light is on.

[0015] The advantages of this invention are as follows: In order to accurately acquire laser pulse signals, this invention adopts a direct laser coupling method to detect single-peak and double-peak laser signals. Since the laser energy is large and concentrated, to avoid excessive laser energy, the output of the pulsed laser is collimated before reaching the ranging target. Two lenses with different focal lengths within the collimator coincide at their focal lengths, and a pinhole aperture is placed at the focal length coincidence point. The pre-collimated output light of the pulsed laser is filtered by the collimator and the pinhole aperture, becoming a finer collimated output light. A photodiode is fixed to one side of the optical axis at the front end of the pinhole aperture. The photodiode receives the filtered heat dissipation light and converts the received heat dissipation light into an electrical signal, which is then connected to the input of the pulse count detection circuit via an interface. This scheme improves beam quality, eliminates external interference light, making the acquired signal more reliable, and has a reasonable structure.

[0016] The designed circuit acquisition system can convert laser pulse signals into electrical pulse signals. After processing the electrical pulse signals through the circuit processing system, the system can intuitively display whether the laser is a single pulse or a double pulse using LED indicator lights. If the laser is a single pulse, the green indicator light will be on; if the laser is a double pulse, the red indicator light will be on. Attached Figure Description

[0017] Figure 1 This is a diagram illustrating the principle of laser energy attenuation.

[0018] Figure 2 It is a pulse count detection circuit;

[0019] Figure 3 This is the timing diagram of the pulse count detection circuit.

[0020] The attached figures are labeled as follows:

[0021] 1. Pulsed laser; 2. Collimator; 3. Pinhole aperture; 4. Photodiode; 5. Interface; 6. Output light before collimation; 7. Output light after collimation; 8. Pulse count detection circuit; 9. Target object for ranging. Detailed Implementation

[0022] like Figure 1 As shown, a device for detecting the number of pulses triggered by a pulsed laser includes at least a pulsed laser and a pulse count detection circuit: the output of the pulsed laser 1 passes through a collimator 2 to the ranging target 9. Two lenses with different focal lengths overlap at the collimator 2, and a pinhole aperture 3 is placed at the focal length overlap point. The pre-collimated output light 6 of the pulsed laser 1 is collimated and filtered by the collimator and the pinhole aperture 3 to become a finer collimated output light 7. A photodiode 4 is fixed on one side of the optical axis at the front end of the pinhole aperture 3. The photodiode 4 is used to receive the filtered heat dissipation light and converts the received heat dissipation light into an electrical signal, which is connected to the input of the pulse count detection circuit 8 via an interface 5.

[0023] The focal length ratio of the two lenses with different focal lengths in the collimator is 2-5 times.

[0024] The collimator cavity is an optically sealed cavity, and when there is no pulsed laser output light, the photodiode 4 exhibits a high-resistance state.

[0025] like Figure 2 As shown, the pulse count detection circuit 8 includes: a four-channel dual-input NAND gate circuit SN54LS00, a resettable monostable multivibrator SN54LS123, an SN54S112, a single-pulse output circuit, and a double-pulse output circuit. The photoelectric signal received by the photodiode is filtered and then inverted twice by the two dual-input NAND gate circuits in SN54LS00 to the single-pulse detection circuit, and then inverted once by one dual-input NAND gate circuit in SN54LS00 to the double-pulse detection circuit.

[0026] The single-pulse detection circuit is composed of cascaded SN54LS123A and SN54S112A, and the double-pulse detection circuit is composed of cascaded SN54LS123B and SN54S112B.

[0027] like Figure 2 and Figure 3 As shown, the resettable monostable multivibrator SN54LS123A, by configuring the time constants of capacitor C5 and resistor R5, outputs a pulse width T1 at the Q terminal when a single pulse is input; and outputs a pulse width 2T1 at the Q terminal when two single pulses are input. The width of T1 is determined by capacitor C5 and resistor R5.

[0028] In this invention, SN54S112 comprises two identical ICs. SN54S112A is designated U3A, and SN54S112B is designated U3B. Similarly, SN54LS123 comprises two identical ICs. In this invention, SN54LS123A is represented by the symbol U2A, and SN54LS123B is represented by the symbol U2B. SN54 has a wider temperature range than SN74, but their circuit structures are identical.

[0029] In this invention, the four gates of the four-channel dual-input NAND gate circuit SN54LS00 are labeled 1UA, 1UB, 1UC, and 1UD. Two dual-input NAND gate circuits in SN54LS00 are cascaded from 1UA and 1UD. The output of 1UD in SN54LS00 is sent to the A trigger terminal of U2A. The output of one dual-input NAND gate circuit 1UA in SN54LS00 is inverted and sent to the A trigger terminal of U2B.

[0030] The laser pulse signal is converted into an electrical signal by a photodiode. After passing through a filter circuit and being inverted once, it becomes the input signal at terminal A of the SN54LS123B. By adjusting the resistor R11 in the external time constant of the SN54LS123B, the output pulse width can be adjusted so that the output pulse width at terminal Q of the SN54LS123B is T3 greater than T1 and T3 less than T2.

[0031] When a single pulse is input, the JK flip-flop of the SN54S112A in the single pulse output circuit flips the Q terminal to a high level. The Q terminal drives the transistor Q1 through resistor R7, and the transistor Q1 conducts. The collector drives the green LED to light up. At the same time, the NAND gate controls the reset terminal of SN54S112B to zero, and the output of SN54S112B is low, turning off the red LED.

[0032] When the input is a double pulse, the clock width of the double pulse is greater than the output pulse width of the SN54LS123B. The JK flip-flop of the SN54S112A is set to 0 in advance when the falling edge arrives, the output of the Q terminal is low, the transistor Q2 is cut off, and the green light is off.

[0033] Simultaneously, the reset pin of SN54S112B is set to a high level. When the clock pulse of SN54LS112B arrives, the output flips, the Q output of SN54S112B becomes high, the transistor Q2 turns on, and the red light illuminates. This achieves the function of the single / double peak detection circuit: green light illuminates when there is a single peak, and red light illuminates when there is a double peak.

[0034] The capacitor C5 has a capacitance of 470pF, and the resistor R5 has a capacitance of 5.1kΩ.

Claims

1. A device for detecting the number of output pulses triggered by a pulsed laser, comprising at least a pulsed laser and a pulse count detection circuit: the output of the pulsed laser is collimated before reaching the ranging target, characterized in that: The collimator is provided with two lenses with different focal lengths, and a pinhole diaphragm is arranged at the focal length coincidence position; the collimated light output by the pulse laser is filtered by the pinhole diaphragm to become a thinner collimated light output; a photodiode is fixed on one side of the light axis of the front end of the pinhole diaphragm; the photodiode is located on the scattering light path of the pinhole diaphragm and is used for directly receiving the scattered light leaked after being filtered by the pinhole diaphragm and converting the received scattered light into an electrical signal; and the electrical signal is connected to the input end of the pulse number detection circuit through an interface; The pulse number detection circuit is composed of a four-way double-input NAND gate circuit SN54LS00, a resettable monostable trigger SN54LS123, a SN54S112, a single-pulse output circuit and a double-pulse output circuit; the photoelectric signal received by the photodiode is filtered by the filtering circuit, and then is inverted twice in the SN54LS00 and input into the single-pulse detection circuit and inverted once in the SN54LS00 and input into the double-pulse detection circuit. The detection device can convert the laser pulse signal into an electrical pulse signal, and then directly display the single pulse or double pulse of the laser through the light-emitting diode indicator light after processing the electrical pulse signal by the pulse number detection circuit, so that the single pulse and the double pulse are distinguished and displayed.

2. The detection device of the number of output pulses of the pulsed laser according to claim 1, characterized in that: The focal length ratio of the two lenses with different focal lengths in the collimator is 2-5 times.

3. The device for detecting the number of pulsed laser-triggered output pulses according to claim 1, characterized in that: The cavity in the collimator is a light-tight cavity, and the photodiode is in a high resistance state when there is no output light of the pulse laser.

4. The detection device of the number of output pulses of the pulsed laser according to claim 3, characterized in that: The single-pulse detection circuit is composed of a cascade connection of SN54LS123A and SN54S112A, and the double-pulse detection circuit is composed of a cascade connection of SN54LS123B and SN54S112B.

5. The detection device of the number of output pulses of the pulsed laser according to claim 3, characterized in that: The time constant of the resettable monostable trigger SN54LS123A is configured by the capacitor C5 and the resistor R5, so that when a single pulse is input, the Q end of the SN54LS123A outputs a pulse width T1, and when two single pulses are input, the Q end of the SN54LS123A outputs a pulse width 2T1.

6. The detection device of the number of output pulses of the pulsed laser according to claim 3, characterized in that: The JK trigger of the SN54S112A of the single-pulse output circuit realizes the high-level output of the Q end, the Q end drives the transistor Q1 through the resistor R7, the transistor Q1 is turned on, the green LED is lit through the collector, and the clear zero end of the SN54S112B is zero, the output of the SN54S112B is low, and the red light is off.

7. The detection device of the number of output pulses of the pulsed laser according to claim 4, characterized in that: The JK trigger of the SN54S112A is set to 0 in advance when the falling edge comes, the Q end output is low, the transistor Q2 is cut off, and the green light is off; at the same time, the clear zero end of the SN54S112B is high, the output of the SN54S112B realizes flip-flop when the clock pulse comes, the Q end output of the SN54S112B is high, the transistor Q2 is turned on, and the red light is on, so that the function of the single / double peak detection circuit is realized, the green light is on when the single peak is on, and the red light is on when the double peak is on.

8. The detection device of the number of output pulses of the pulsed laser according to claim 5, characterized in that: The capacitance of the capacitor C5 is 470PF, and the resistance of the resistor R5 is 5.1KΩ.

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