CN1333499C - Semiconductor laser driving current control method and multi-mode working driving power supply - Google Patents

Abstract

The present invention relates to a control method for drive current of a semiconductor laser and a multi-mode operating drive power supply, which belongs to the technical field of the semiconductor laser. In order to overcome the defects of the prior art, the present invention discloses the control method for the drive current of the semiconductor laser. Drive current values required by the semiconductor laser reaching certain output power under different temperatures are obtained with the experiment test standardization, so that a coincidence relation between the temperature and the drive current value can be obtained; the coincidence relation is input in a tabular form to a microcontroller via a keyboard input unit; by detecting the operating temperature of an LD and changing the drive current, power output variation caused by temperature variation is compensated in order to realize stable LD output power. The present invention also discloses the drive power supply operating based on multiple modes and realizing the control method of the drive current. The present invention can be used for various fields in which the semiconductor laser is used as a light source or a pumping source.

Description

Driving power supply for semiconductor laser working in two modes

technical field

The invention belongs to the technical field of semiconductor lasers, and in particular relates to a control method of a driving current of a semiconductor laser and a structural design of a driving power supply for a semiconductor laser or a semiconductor laser array.

Background technique

Semiconductor lasers (LD for short) or semiconductor laser arrays (LD array for short) are small in size, light in weight, high in efficiency and good in reliability, and have been used more and more widely. The principle is to rely on the radiative recombination of injected non-equilibrium carriers (electrons, holes), and release the energy generated by the recombination in the form of photons to emit laser light. The non-equilibrium carriers of the semiconductor laser are injected by its driving power supply.

The function of the semiconductor laser drive power supply (LD drive power supply for short) is to provide the required drive current for the semiconductor laser (array), as well as reliable protection and proper control, so that it can output the required laser radiation.

The traditional semiconductor laser driving power supply is composed of control circuit, switching element, monitoring circuit, protection circuit and energy storage capacitor, etc., as shown in Figure 1. The working principle of the LD driving power supply is: the external DC power supply stores energy in the energy storage capacitor, which can avoid the surge of the current output from the DC power supply to the semiconductor laser during the working process. The energy storage capacitor, semiconductor laser, switching element, and monitoring circuit constitute a discharge circuit, and the control circuit controls the conduction state of the switching element so that the working current of the semiconductor laser meets the requirements. Because semiconductor lasers are very fragile, they are prone to destructive failures. Therefore, the monitoring circuit is used to monitor the working status of the system in real time, and if there is any abnormality, the protection circuit will be activated to protect the semiconductor laser from various faults.

The traditional control method of the driving current of the semiconductor laser driving power supply only adopts the feedforward mode, and the user inputs the current parameters through the corresponding input unit, and the driving power supplies a predetermined current. This control method cannot meet the requirements of stabilizing the output power of the LD when the working environment of the LD (such as the working temperature) changes.

At present, most semiconductor laser drive power supplies work based on the above-mentioned control method, and output a preset specific drive current. Since the threshold current, output power and other characteristics of semiconductor lasers will change with the change of operating temperature, simply applying a fixed driving current cannot guarantee the stability of laser output characteristics. In order to stabilize the laser output characteristics, using the existing semiconductor laser with a fixed output drive power supply, it is generally necessary to configure cooling elements such as a semiconductor cooler (TEC) and a temperature control system to control the temperature of the semiconductor laser (array), so that the semiconductor laser ( array) at a constant operating temperature. The temperature control system not only increases the complexity of the whole system, but also causes energy consumption and reduces the efficiency of the system.

In addition, through retrieval, it is found that in the U.S. Patent (document number US6441364B1, the publication date is August 27, 2002), Regev et al. have proposed a kind of optical power source controller, and its main feature is by detecting the working parameter of semiconductor laser, by The relationship between the current control signal solidified inside the microcontroller and the working parameters is obtained to obtain the current control signal to stabilize the output optical power of the semiconductor laser.

The optical power controller proposed by Regev et al. can only make the semiconductor laser work in a single mode, that is, the corresponding current can only be obtained by detecting the working parameters of the semiconductor laser and then through the internal algorithm solidified in the storage device. Its working current cannot output the driving current of user-defined parameters according to the needs of users, which limits its application occasions.

In the optical power controller proposed by Regev et al., the relationship algorithm between the operating parameters of the semiconductor laser (including the operating temperature of the semiconductor laser) and the driving current control signal is solidified in the storage device, and the user cannot easily modify it through the input unit.

In the optical power controller proposed by Regev et al., the algorithm for the relationship between the operating parameters of the semiconductor laser (including the operating temperature of the semiconductor laser) and the driving current control signal is obtained through a complex mathematical model, using a combination of discrete measurement and mathematical interpolation. The implementation of the method is complicated and the reliability is not high.

Contents of the invention

In order to overcome the defect in the prior art that the traditional semiconductor laser drive power supply cannot guarantee the stability of the output optical power without temperature control, or has to add a complex and energy-consuming temperature control system to ensure the stability of the output optical power; To overcome the shortcomings of the optical power source controller proposed by Regev et al., the algorithm is complex, the reliability is not high, the working mode is single, and it is inconvenient to modify the relationship list between the working parameters of the semiconductor laser and the driving current, the present invention proposes a method of driving the current of the semiconductor laser The control method is characterized in that: the output characteristics of the semiconductor laser at different temperatures are obtained by using the experimental test calibration method, that is, the required driving current value for the semiconductor laser to reach a certain output power, so as to obtain the one-to-one correspondence between the temperature and the driving current value , input the above corresponding relationship into the microcontroller in the form of a list through the keyboard input unit; use the temperature sensor to monitor the operating temperature of the semiconductor laser in real time, and determine the corresponding driving current value according to the above corresponding relationship, and the semiconductor laser drive power supply adaptively outputs the Current, to ensure that the semiconductor laser has a stable output power at different temperatures.

The present invention also provides a multi-mode drive power supply with temperature self-adaptive adjustment function for realizing the drive current control method, including an LD composed of a control circuit, a drive switch circuit, a monitoring circuit, a protection circuit and an energy storage capacitor Drive circuit, the LD drive circuit is powered by an external DC power supply, characterized in that: the drive power supply also includes a microcontroller and a keyboard input unit connected to it, a display unit, a control voltage output circuit and a temperature sensor group composed of the main control circuit, and the voltage reference circuit connected to the control voltage output circuit; wherein, a mode selection switch is integrated in the microcontroller for the user to select the required working mode; the temperature sensor group is fixed on the semiconductor On the laser, the working temperature of the semiconductor laser is monitored in real time, and the temperature signal is sent to the microcontroller.

The microcontroller of the present invention is a single-chip microcomputer, a single-board computer, a DSP, a field programmable gate array (FPGA), a complex programmable logic device (CPLD), a computer, an embedded system or an application-specific integrated circuit.

A specific form of microcontroller according to the present invention includes LD protection logic circuit 10, LD protection signal input port, frequency divider, keyboard decoder, bouncing elimination circuit, keyboard scanning circuit, current parameter register, mode selection switch , current and temperature relationship register, temperature data register, temperature signal digital filter, control voltage signal output controller, and display controller;

Among them, the frequency divider generates multiple clock signals, which are respectively connected with the LD protection logic circuit, the bounce elimination circuit, the keyboard scanning circuit, the control voltage signal output controller, the display controller and the temperature sensor group fixed on the semiconductor laser, which is the above circuit The unit provides timing control;

The LD drive circuit is connected to the LD protection logic circuit through the LD protection signal input port, and at the same time, the LD protection logic circuit protection enabling signal output terminal is connected to the current parameter register;

The keyboard scanning signal output terminal of the keyboard scanning circuit is connected to the keyboard input unit, and the bounce elimination circuit is connected to the keyboard input unit at the same time, and is used to receive and process the keyboard scanning signal passing through the keyboard input unit, and its output terminal is connected to the keyboard decoding device connected;

The keyboard decoder is connected to the mode selection switch to transmit corresponding control signals, and is also connected to the current parameter register to transmit data signals;

The mode selection switch is selected by the switch, one of its output ends is directly connected to the current parameter register, and the other is connected to the current parameter register through the current and temperature relationship register;

The temperature sensor group is connected to the temperature data register through a temperature signal digital filter, and the output terminals of the temperature data register are respectively connected to the current-temperature relationship register and the display controller;

The current parameter register is connected to the control voltage output circuit through the control voltage output controller, and transmits display data to the display unit through the display controller.

The present invention is based on the traditional LD driving power supply, and the microcontroller outputs the corresponding driving current at the temperature according to the temperature of the semiconductor laser detected by the temperature sensor group in real time.

The LD drive power supply realized by the present invention has two kinds of operating modes, and the mode selection is carried out by the mode selection switch. The first mode is to input current parameters with a keyboard in a traditional way, including current frequency, pulse width, and current size (continuous current as long as the The current frequency is set to 1), so that the LD drive power supply realizes the control of the drive current according to the preset requirements; the second working mode is that the temperature sensor group monitors the working temperature of the semiconductor laser (or each semiconductor laser in the laser array) in real time, Send temperature signal to microcontroller. According to the operating temperature, the microcontroller obtains the operating current value that can make the semiconductor laser meet the requirements of use after compensating the influence of temperature, and controls the driving power supply to generate this operating current, so that the semiconductor laser can output laser radiation that meets the requirements. Moreover, the driving power supply of the present invention can also conveniently expand the functions to realize the driving and control of multiple semiconductor lasers.

The LD driving power supply of the present invention can not only realize the above-mentioned functional requirements, output the required stable operating current, but also protect the LD from damage, the LD protection circuit of the LD driving power supply of the present invention can make the LD driving power supply under various failure conditions , to protect the LD from damage.

The LD drive power supply of the present invention can display LD temperature and current parameters including current frequency, current pulse width and current magnitude in real time. So that users can keep abreast of the working conditions of LD.

The beneficial effect of the present invention is: because the control method of the driving current of the present invention and the driving power supply based on the control method do not strictly control the temperature of the semiconductor laser or do not carry out temperature control, but are self-adaptive according to the operating temperature of the semiconductor laser Adjust its driving current accordingly to obtain the required laser radiation. The driving power supply can not only reduce energy loss and improve efficiency, but also make the LD driving power supply partly intelligent, which represents the future development direction of the LD driving power supply.

The invention can make the driven LD (array) work normally in a relatively large temperature range, avoid the complicated temperature control system, reduce unnecessary energy loss, improve the efficiency of the laser, and broaden the working environment range of the laser , so that the laser can operate with optimized current parameters in a complex temperature environment, ensuring the stability of the optical power output.

The difference between the present invention and the optical power source controller proposed by Regev etc. mentioned in the background technology lies in the following points:

First, the semiconductor laser drive power supply developed by the present invention can be based on multi-mode operation. The user can select the operating mode, which can be defined by the user. Parameters that define the drive current. So that the power supply has a wide range of applications.

Second, the main control circuit developed in the present invention can be conveniently modified by the user at any time through the keyboard input unit to the relationship list between the working parameters of the semiconductor laser and the driving current parameters.

Thirdly, the driving power source developed by the present invention can conveniently enable users to perform experimental calibration on the relationship between the operating temperature of the semiconductor laser and the driving current. That is to say, using the first working mode, the user inputs the driving current through the keyboard, and simultaneously detects the output optical power and the operating temperature of the semiconductor laser, and obtains a series of corresponding relationship lists between the operating temperature of the semiconductor laser and the operating current of the semiconductor laser, and passes this list through the keyboard. The input unit inputs into the microcontroller. When the user selects the second working mode, the main control circuit of the power supply can work according to the relationship list between the working temperature of the semiconductor laser and the driving current measured by calibration. Since the power source used for calibration and the power source used for work belong to the same power source, the reliability of the calibration data is guaranteed.

The present invention can be used in various fields where semiconductor lasers are used as continuous or pulsed pumping sources or light sources.

Description of drawings

Figure 1 is a structural block diagram of a traditional LD drive power supply.

Fig. 2 is a structural block diagram of the driving power supply of the present invention.

FIG. 3 is a structural block diagram of an embodiment of the microcontroller of the present invention.

Fig. 4 is a structural block diagram of an embodiment of the DC power supply of the present invention.

FIG. 5 is a circuit diagram of an embodiment of the protection circuit of the LD driving power supply of the present invention.

FIG. 6 is a circuit diagram of an embodiment of the temperature sensor group of the present invention.

FIG. 7 is a circuit diagram of an embodiment of the control voltage output circuit of the present invention.

FIG. 8 is a circuit diagram of an embodiment of a voltage reference circuit of the present invention.

FIG. 9 is a circuit diagram of an embodiment of the LD driving circuit of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The control method of the driving current of the semiconductor laser according to the present invention uses the experimental test calibration method to obtain the required driving current value for the semiconductor laser to reach a certain output power at different temperatures, thereby obtaining the one-to-one correspondence between the temperature and the driving current value, Input the above-mentioned corresponding relationship into the microcontroller in the form of a list through the keyboard input unit; the experimental test calibration method is to test the driving current value required for the output of a certain power of the semiconductor laser at different temperatures, and form the relationship between the temperature and the driving current value. Correspondence (such as the temperature and drive current value correspondence table).

The temperature sensor is used to monitor the working temperature of the semiconductor laser in real time, and the corresponding driving current value is determined according to the above correspondence, and the semiconductor laser driving power supply is output adaptively to ensure that the semiconductor laser has a stable output power at different temperatures.

The first mode of operation of the semiconductor laser drive power supply of the multi-mode work of the present invention is: input current parameters with a keyboard in a traditional manner, including current frequency, pulse width, and current size (continuous current as long as the current frequency is set to 1 ), so that the LD drive power can control the drive current according to the preset requirements.

The second mode of operation of the semiconductor laser drive power supply of the multi-mode operation of the present invention is: 1. The user presets the required current parameters for input through the keyboard input unit, outputs the required current value, and simultaneously detects the operation of the semiconductor laser Temperature and output optical power, get the corresponding relationship between the two, and form a list. The user inputs the above list into the microcontroller through the keyboard input unit. 2. Through the mode selection switch, the user selects the second working mode of the multi-mode semiconductor laser drive power supply, which is to monitor the working temperature of the semiconductor laser. Through the temperature sensor or temperature sensor group fixed on the semiconductor laser, the working temperature of the semiconductor laser is monitored in real time, and the temperature signal is fed back to the control unit. Calculate the required current value from the corresponding temperature measured. According to the measured temperature signal, the micro-controller obtains the required driving current value by using the predetermined correspondence between temperature and driving current value (that is, the above-mentioned corresponding list of temperature and driving current value). 3. Output the control voltage signal corresponding to the driving current. The control unit outputs a control voltage signal through a corresponding output unit, and the signal is amplified to obtain the required driving current. At the same time, the temperature sensor or the temperature sensor group inputs the measured temperature signal into the control unit.

The drive power supply with the multi-mode work of the present invention's self-adaptive temperature regulation function, its structure as shown in Figure 2, comprises LD drive circuit 4 (this circuit is identical with existing circuit structure by control circuit, drive switch circuit, monitoring circuit, protection circuit and energy storage capacitor, not shown in the figure), the LD drive circuit is powered by an external DC power supply 5, and on this basis also includes a microcontroller 3 and a keyboard input unit connected to it respectively 2. The main control circuit composed of the display unit 21, the control voltage output circuit 6 and the temperature sensor group 1, and the voltage reference circuit 7 connected to the control voltage output circuit 6; wherein, a mode selection switch is integrated in the microcontroller 15, for the user to select the required working mode; the temperature sensor group 1 is fixed on the semiconductor laser, monitors the working temperature of the semiconductor laser in real time, and sends the temperature signal to the microcontroller 3.

Wherein, the microcontroller can be any one of single-chip microcomputer, single-board computer, DSP, field programmable gate array (FPGA), complex programmable logic device (CPLD), computer, embedded system or application-specific integrated circuit.

The working principle of the present invention is as follows: the temperature sensor group 1 is connected with the semiconductor laser, monitors the working temperature of the semiconductor laser in real time, and sends the temperature signal to the microcontroller 3 . The microcontroller 3 receives the user's operation through the keyboard input unit 2, sets the working state and working parameters of the system, and obtains the working current value of the semiconductor laser that meets the use requirements after compensating the influence of the temperature according to the working temperature, and outputs it by controlling the voltage The circuit 6 generates a corresponding control voltage to control the LD drive circuit 4 powered by an external DC power supply, and generates this operating current to make the semiconductor laser emit laser output. The real-time working status is output and displayed through the display unit for users to check at any time. Wherein, the voltage reference circuit 7 provides an accurate and stable reference voltage for the control voltage output circuit 6 . The invention has a real-time display function, can display current parameters, and temperature collection values of a temperature sensor, and can timely reflect the ambient temperature and the working state of the LD.

In the present invention, microcontroller 3 is described with FPGA chip as an example, as shown in Figure 3, specifically includes LD protection logic circuit 10, LD protection signal input port 8, frequency divider 9, keyboard decoder 11, bounce Elimination circuit 12, keyboard scanning circuit 13, current parameter register 14, mode selection switch 15, current-temperature relationship register 16, temperature data register 17, temperature signal digital filter 18, control voltage signal output controller 19, and display controller 20;

The above circuits are all digital logic units, which are described by VHDL hardware description language, and then compiled, simulated and logically verified by Sysnopsys software, and the netlist representing the connection relationship is extracted; the back-end layout and wiring of the layout are completed by using Cadence software and the circuit Inspection; use T-Spice software for circuit simulation.

Wherein, frequency divider 9 produces multi-channel clock signal, respectively with LD protection logic circuit 10, bouncing elimination circuit 12,

The keyboard scanning circuit 13, the control voltage signal output controller 19, the display controller 20 and the temperature sensor group 1 fixed on the semiconductor laser are connected to provide timing control for these circuit units;

The LD drive circuit 4 is connected to the LD protection logic circuit 10 through the LD protection signal input port 8, and the LD protection logic circuit 10 protection enable signal output terminal is connected to the current parameter register 14;

The keyboard scanning signal output end of keyboard scanning circuit 13 is connected with described keyboard input unit 2, and described bouncing elimination circuit 12 is connected with keyboard input unit 2 simultaneously, is used for receiving and processing the keyboard scanning signal through keyboard input unit 2, and its output End links to each other with keyboard decoder 11;

The keyboard decoder 11 is connected to the mode selection switch 15 to transmit corresponding control signals, and is also connected to the current parameter register 14 to transmit data signals;

The mode selection switch 15 is selected by the switch, and one of its output terminals is directly connected to the current parameter register 14, and the other is connected to the current parameter register 14 through the current and temperature relationship register 16;

The temperature sensor group 1 is connected to the temperature data register 17 through a temperature signal digital filter 18, and the output terminals of the temperature data register 17 are respectively connected to the current-temperature relationship register 16 and the display controller 20;

The current parameter register 14 is connected to the control voltage output circuit 6 through the control voltage output controller 19 , and transmits display data to the display unit 21 through the display controller 20 .

The use of FPGA chips can reduce the use of discrete components, and FPGA adopts a parallel operation mode, which has the advantages of stronger anti-interference ability and higher time control accuracy than single-chip microcomputers to a certain extent. Its working principle is: the frequency divider 9 receives an external crystal oscillator signal (not shown in the figure), and generates clock signals of different frequencies required by different parts of the entire circuit, which are the bounce elimination circuit 12, the keyboard scanning circuit 13, and the LD protection Logic circuit 10, control voltage signal output controller 19, display controller 20 provides timing control. The user can complete the setting of current parameters such as current frequency, pulse width and current magnitude through the keyboard just like operating the traditional LD drive power supply, and control the current in this way. The keyboard scanning circuit 13 continuously scans the rows and columns of the keyboard. After the keyboard signal passes through the bounce elimination circuit 12, it enters the keyboard decoder 11. After decoding, the FPGA chip will set the current frequency value and pulse width under timing control. The value is sent to the current parameter register 14, so that it generates a square wave signal with a certain frequency and pulse width for controlling the DA converter, so as to achieve the purpose of controlling the current size, pulse width and frequency.

The user can select the control mode of the current size through the mode selection switch 15. One, directly input the current size through the keyboard to control (as mentioned above), this mode is the control mode of the traditional LD drive power supply, and the present invention is the largest The characteristic lies in the second control method. The microcontroller detects the temperature of the LD in real time, and obtains the current corresponding to the temperature through the current-temperature relationship register 16, thereby realizing the self-adaptive adjustment of the temperature of the LD output current. Among them, the current and temperature relationship register 16, the user will input the current value corresponding to the temperature through the keyboard to form a numerical table, and the microprocessor will obtain the corresponding current value through the temperature signal obtained by the temperature sensor, and then obtain the corresponding current value through the corresponding code. The control signal and data signal of the controller 19 are output to the control voltage signal, so that the self-adaptive adjustment of temperature is realized. At the same time, in order to protect the LD from damage, the microcontroller detects the working status of the LD in real time. Once it detects that the LD has a short circuit signal (not marked in the figure), an open circuit signal (not marked in the figure), an overload signal (not marked in the figure), output), the temperature is too high signal (not marked in the figure), and the signal of exceeding the maximum set current value (not marked in the figure), the microcontroller will quickly cut off the power supply of the LD to realize the function of protecting the LD.

The embodiment of the power supply DC power supply 5 adopted by the present invention is a switching power supply conversion circuit with active power factor correction, and its structure is as shown in Figure 4, consisting of a full-wave rectifier, an inductor L, a diode D, a switching device MOSFET, and an input voltage detector , comparator, multiplier, input current detector, high frequency triangle wave generator, output voltage comparator and error amplifier. The function it realizes is: 220V, 50Hz single-phase AC input, after using the transformer to boost or decompress, pass through the rectifier bridge rectifier, enter the energy storage inductor L, high-frequency high-power switch MOS tube, one-way diode D and filter The boost switching converter circuit composed of the capacitor C together. The input voltage is sampled and detected by the R1 and R2 voltage dividers and then added to the input of the multiplier. In addition, the output voltage is sampled and detected by the R3 and R4 voltage dividers, and the output error signal is also added to the multiplier after participating in the voltage comparison. The multiplier is the key link of the power factor controller. When the sine wave AC input voltage rises from 0 to the peak voltage, the output voltage of the multiplier controls the threshold level of the current sampling comparator, and the comparator is modulated by a high-frequency triangular wave signal, thereby generating a controlled pulse width modulated PWM signal. to the gate of the MOSFET, so that the conduction time of the main switch of the MOSFET can be quickly adjusted, so that it can track the change of the grid input voltage in time. Through the control of various feedback signals, the peak envelope of the inductive current in the inductor L can always closely follow the unidirectional sine wave AC input voltage wave and change, thus realizing the high power factor value of the system. In order to realize the adjustable output voltage, the DC output voltage can be changed by adjusting the sampling resistance of R4.

The structure of an embodiment of the protection circuit of the LD driving power supply of the present invention is shown in FIG. 5 , which is mainly composed of a comparator AD1, a comparator AD2, a photocoupler, and several sampling resistors. The function it realizes is that the FPGA chip detects several protection signals in real time. Once a short circuit or open circuit is detected in the LD, the FPGA chip will quickly cut off the power supply of the LD to protect the safety of the LD. As shown in Figure 5, in order to detect the working state of the LD, the voltage across the LD must be detected. The voltage across the LD can be obtained indirectly by measuring the value of U1 and then subtracting U1 from the total voltage (-V_). The sampling resistors R4 and R11 can get the divided voltage of U1. When the voltage is detected to be greater than a certain value (through the voltage comparator AD1), the short-circuit signal SHORT is output through the photocoupler, which is active at low level. When it is working normally, the signal When it detects that the voltage is less than a certain value (through the voltage comparator AD2), the open circuit signal OPEN is output through the photocoupler, and the high level is effective. During normal operation, the signal is low. At the same time, in order to prevent other failures of LD, such as overload protection to prevent excessive current in LD, limit maximum current value protection, temperature overload protection, slow start circuit and power supply allowable work protection, etc., these protection measures will protect LD in various failures safely disconnect the power.

An embodiment of the temperature sensor group 1 according to the present invention is shown in FIG. 6 . The figure shows the connection relationship of the 4-way temperature sensor. Each channel is composed of a temperature sensor chip AD7814, and the four temperature sensor chips are all hung on the pins of the FPGA chip. The FPGA chip selects the work of one of the chips through the CS chip selection signal generated by the decoding circuit. Synchronous clock pulses are sent to each chip through the CLK line, and the DATA port of the FPGA chip reads temperature data from each chip. The connecting wires between each sensor chip and the FPGA chip use shielded cables, which can ensure sufficient transmission distance without errors.

The embodiment of the control voltage output circuit of the present invention is composed of a plurality of digital-to-analog conversion chips MX7548 and a plurality of operational amplifiers AD711, which can control multiple voltage outputs, wherein a single set of control voltage output circuits is shown in Figure 7, each The DB7-DB0 of the digital-to-analog conversion chip is connected to the data output port of the FPGA, and the WR, CSLSB, CSMSB and LDAC are connected to the pins defined by the FPGA chip. VREF is connected to an external -7.5V voltage reference. The current output pin of each digital-to-analog conversion chip is connected to an operational amplifier, and the output terminal of the operational amplifier is the output terminal of the control voltage.

The embodiment of the voltage reference circuit of the present invention, as shown in FIG. 8 , is composed of a reference power supply chip MX584. The -7.5V reference voltage required by the control voltage output module can be generated by the circuit shown in the figure.

An embodiment of the LD driving circuit of the present invention is shown in FIG. 9 , which shows the circuit of a single-channel LD driving module. Wherein, the external DC power supply stores energy in the energy storage capacitors (C2, C3, C4), so as to avoid surges in the current output from the DC power supply to the semiconductor laser during operation. The switching elements U1 and U2 are high-power MOSFETs, and the parallel connection of U1 and U2 can reduce the risk of failure of one of the tubes. The diode D1 plays a protective role and is connected in parallel with the semiconductor laser, which can prevent the reverse overshoot of the discharge current from causing damage to the semiconductor laser. The energy storage capacitor, semiconductor laser, and switching device form a discharge circuit, and the conduction state of the switching element is controlled by the input control voltage, so that the working current of the semiconductor laser meets the requirements. The control input signal first passes through a low-pass filter, and then is amplified by power to obtain the control switch voltage acting between the gate and source of the MOS transistor. In order to stabilize the output current, the current parallel negative feedback is adopted in this circuit.

Claims (3)

1. A driving power supply for semiconductor laser two-mode work, comprising an LD driving circuit (4) composed of a control circuit, a driving switch circuit, a monitoring circuit, a protection circuit and an energy storage capacitor, and the LD driving circuit is powered by an external The DC power supply (5) supplies power, and it is characterized in that: the driving power supply also includes a keyboard input unit (2), a display unit (21), and a control voltage output circuit connected to the microcontroller (3) and the microcontroller respectively. (6) and the main control circuit that temperature sensor group (1) forms, and the voltage reference circuit (7) that is connected with described control voltage output circuit (6); Wherein integrated a mode selection switch in the microcontroller (3) (15), for the user to choose the required two working modes: the first working mode is to input the current parameters with the keyboard input unit in the traditional way, including the current frequency, pulse width and current size, so that the LD drive power can meet the preset requirements Realize the control of the driving current; the second working mode is to use the experimental test calibration method to obtain the required driving current value for the semiconductor laser to reach a certain output power at different temperatures, so as to obtain the one-to-one correspondence between the temperature and the driving current value. Input the above-mentioned corresponding relationship into the microcontroller in the form of a list through the keyboard input unit, the temperature sensor group (1) is fixed on the semiconductor laser, monitors the working temperature of the semiconductor laser in real time, and sends the temperature signal to the microcontroller (3), The corresponding driving current value is determined according to the above corresponding relationship, and the driving power supply of the semiconductor laser adaptively outputs the current to ensure that the semiconductor laser has a stable output power at different temperatures. 2. The drive power supply for two modes of operation of semiconductor lasers according to claim 1, characterized in that: said microcontroller (3) is a single-chip microcomputer, single-board computer, DSP, field programmable gate array, complex programmable logic device, computer, embedded system or application specific integrated circuit. 3. The driving power supply for semiconductor lasers working in two modes according to claim 1 or 2, characterized in that: the microcontroller (3) includes an LD protection logic circuit (10), and the LD protection signal input port (8 ), frequency divider (9), keyboard decoder (11), bounce elimination circuit (12), keyboard scanning circuit (13), current parameter register (14), mode selection switch (15), current and temperature relationship register (16), temperature data register (17), temperature signal digital filter (18), control voltage signal output controller (19), and display controller (20); Wherein, frequency divider (9) produces multi-channel clock signal, respectively with LD protection logic circuit (10), bouncing elimination circuit (12), keyboard scanning circuit (13), control voltage signal output controller (19), display control The device (20) and the temperature sensor group (1) fixed on the semiconductor laser are connected to provide timing control for the above-mentioned circuit units; The LD drive circuit (4) is connected to the LD protection logic circuit (10) through the LD protection signal input port (8), and the LD protection logic circuit (10) protection enabling signal output terminal is connected to the current parameter register (14) ; The keyboard scanning signal output terminal of the keyboard scanning circuit (13) is connected to the keyboard input unit (2), and the bounce elimination circuit (12) is connected to the keyboard input unit (2) at the same time, for receiving and processing the keyboard input unit (2) keyboard scanning signal, its output end links to each other with keyboard decoder (11); The keyboard decoder (11) is connected to the mode selection switch (15) to transmit corresponding control signals, and is also connected to the current parameter register (14) to transmit data signals; The mode selection switch (15) is selected by the switch, one of its output terminals is directly connected to the current parameter register (14), and the other is connected to the current parameter register (14) through the current and temperature relationship register (16); The temperature sensor group (1) is connected with the temperature data register (17) through the temperature signal digital filter (18), and the output end of the temperature data register (17) is respectively connected with the current and temperature relationship register (16) and the display controller ( 20) connected; The current parameter register (14) is connected to the control voltage output circuit (6) through a control voltage signal output controller (19), and transmits display data to a display unit (21) through a display controller (20).

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