Multi-channel laser diode drive control system and control method for photolithography machine

Abstract

The invention relates to a multi-channel laser diode drive control system and a control method for a photolithography machine, wherein an MPU is respectively connected to three LD group drive units, an AND gate two, an AND gate three and a solid-state relay; an output end of an AND gate one is connected to an AND gate two and an AND gate three, an output end of an AND gate two is connected to a multi-channel analog switch, and an output end of an AND gate three is connected to the multi-channel analog switch; an output control end of an analog interface is connected to the multi-channel analog switch; an output port of a digital-to-analog converter is connected to the multi-channel analog switch; an adjustable end of an adjustable resistor is connected to the multi-channel analog switch; output ends of the multi-channel analog switch are respectively connected to the three LD group drive units; one end of a surge protection diode is grounded, and the other end is connected to an input end of a solid-state relay in parallel with a drive power supply output; output ends of the solid-state relay are respectively connected to the three LD group drive units; current sensing voltage output ends of the three LD group drive units are respectively connected to an analog-to-digital converter and an adding amplifier; and the circuit is effectively protected from surge voltage shock.

Description

Technical Field

[0001] The invention relates to a multi-channel laser diode drive control system for a photolithography machine and a control method thereof. Background Art

[0002] At present, in the semiconductor industry, laser applications are involved in photolithography machines, exposure machines, and PCB processing. Due to the limitations of processing materials, laser wavelength, laser power, and cost control, most lasers use multiple low-power laser diodes in cascade to obtain the required higher continuous laser power, and achieve the required processing conditions in the industry through laser beam combination and shaping. However, the corresponding laser drivers often have problems such as burning out the laser diodes when powered on, being unable to detect the current of each channel, and flickering of the light source under a specific current. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a multi-channel laser diode drive control system and method for a photolithography machine.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A multi-channel laser diode drive control system for a photolithography machine, characterized in that: a communication port of a communication interface is connected to a communication port of an MPU, and three I / O pins of the MPU are respectively connected to enable inputs of LD group drive unit 1, LD group drive unit 2, and LD group drive unit 3; two I / O pins of the MPU are respectively connected to inputs of AND gate 2 and AND gate 3; one I / O pin of the MPU is connected to a control pin input of a solid-state relay; an I2C bus port of the MPU is connected to an I2C bus port of an analog-to-digital converter; an SPI bus port of the MPU is connected to an SPI bus port of a digital-to-analog converter; an output of AND gate 1 is connected to inputs of AND gate 2 and AND gate 3; an output of AND gate 2 is connected to a selection port 1 of a multi-channel analog switch, and an output of AND gate 3 is connected to a selection port 2 of the multi-channel analog switch; an output control end of the analog interface is connected to an analog input port 1 of the multi-channel analog switch; an output port of the digital-to-analog converter is connected to an analog input port 2 of the multi-channel analog switch; an adjustable end of an adjustable resistor is connected to an analog input port 3 of the multi-channel analog switch; one end of the adjustable resistor is connected to a ground GND, and the other end is connected to an output end of a reference voltage unit; The output ends of the analog switches are respectively connected to the current setting input ends of the LD group drive unit 1, the LD group drive unit 2, and the LD group drive unit 3; one end of the surge protection diode is grounded GNG, and the other end is connected to the input end of the solid-state relay in parallel with the drive power output; the output ends of the solid-state relay are respectively connected to the power input ends of the LD group drive unit 1, the LD group drive unit 2, and the LD group drive unit 3; the current sensing voltage output end of the LD group drive unit 1 is connected to the analog input port 1 of the analog-to-digital converter and the input port 1 of the adding amplifier; the current sensing voltage output end of the LD group drive unit 2 is connected to the analog input port 2 of the analog-to-digital converter and the input port 2 of the adding amplifier; the current sensing voltage output end of the LD group drive unit 3 is connected to the analog input port 3 of the analog-to-digital converter and the input port 3 of the adding amplifier; the output end of the adding amplifier is connected to the input end of the comparator 1; the output end of the comparator 1 is connected to the input end of the AND gate 1; the output end of the temperature sensor is connected to the input end of the comparator 2, the input end of the analog interface, and the analog input port 4 of the analog-to-digital converter; the output end of the comparator 2 is connected to the input end of the AND gate 1.

[0006] Furthermore, in the above-mentioned multi-channel laser diode drive control system for a photolithography machine, the LD group drive unit 1, the LD group drive unit 2 and the LD group drive unit 3 have the same structure, including an operational amplifier 1, a transistor 1, an operational amplifier 2 and a transistor 2, one end of the capacitor 1 is grounded, and the other end is connected to the current setting end and is connected to the positive input end of the operational amplifier 1; the negative input end of the operational amplifier 1 is connected to the capacitor 2, the resistor 1, one end of the resistor 5 and the output end of the operational amplifier 2; the output end of the operational amplifier 1 is connected to the other end of the capacitor 2, the resistor 2 and one end of the capacitor 3; the other end of the resistor 1 is connected to the other end of the capacitor 3; the positive input end of the operational amplifier 2 is connected to the signal output end of the current sensor and is also connected to the current of the system. The negative input terminal of operational amplifier 2 is connected to the other end of resistor 5 and one end of resistor 6; the other end of resistor 6 is connected to ground; the other end of resistor 2 is connected to the base of transistor 1 and the collector of transistor 2; the collector of transistor 1 is connected to the power input terminal; the emitter terminal of transistor 1 is connected to the positive electrode of LD 1; the negative electrode of LD 1 is connected to the positive electrode of LD 2; the negative electrode of LD 2 is connected to the positive electrode of LD 3; the negative electrode of LD 3 is connected to the positive electrode of LD 4; the negative electrode of LD 4 is connected to the input terminal of the current sensor; the output terminal of the current sensor is grounded; the base of transistor 2 is connected to one end of resistor 3 and one end of resistor 4; the emitter of transistor 2 is grounded; the other end of resistor 3 is connected to the enable terminal; the other end of resistor 4 is connected to the power supply VCC.

[0007] Furthermore, in the above-mentioned multi-channel laser diode drive control system for a lithography machine, the LD 1, LD 2, LD 3, and LD 4 are connected in series.

[0008] Furthermore, in the above-mentioned multi-channel laser diode drive control system for a lithography machine, the resistance value of the resistor three is 1k ohm, the resistance value of the resistor four is 6.8k ohm, and the voltage of the power supply VCC is 5V.

[0009] Furthermore, in the above-mentioned multi-channel laser diode drive control system for a photolithography machine, the resistance value of resistor one is 1k ohm, the capacitance of capacitor two is 10uF, and the capacitance of capacitor three is 0.01uF.

[0010] The present invention is used for a multi-channel laser diode drive control method for a photolithography machine. After power-on, the MPU performs state initialization. At this time, the solid-state relay control end is not powered, and the driving power supply does not act on the LD group driving unit 1, the LD group driving unit 2, and the LD group driving unit 3. At the same time, because the transient suppression diode has a surge voltage protection, the driving power supply output is overvoltage protected at the moment of power-on to prevent damage to the subsequent circuit. Because the solid-state relay is not turned on, the LD group driving unit 1, the LD group driving unit 2, and the LD group driving unit 3 are not powered at the moment of power-on, thereby protecting each group of laser diodes. After the MPU initialization is completed, the control end of the solid-state relay and the driving power supply output act on the LD group driving unit 1, the LD group driving unit 2, and the LD group driving unit 3 through the solid-state relay to be powered.

[0011] There are three ways to control the driving current of the LD group. The host computer sends instructions to the MPU through the communication interface. The MPU switches the control mode according to the control instructions, so that the two I / Os input to the AND gate 2 and the AND gate 3 of the MPU have different logic combinations. Under normal working conditions, the outputs of comparator 1 and comparator 2 are both high, so the output of AND gate 1 is high, making the input of AND gate 2 and AND gate 3 high, so that the two I / O logic combinations of the MPU directly act on the selection end of the multi-channel analog switch. When the selection end is 00, the multi-channel analog switch input selects the adjustable end voltage of the adjustable resistor, thereby making the output of the multi-channel analog switch consistent with the adjustable end voltage of the adjustable resistor. This mode is the manual adjustment mode and is used for testing; when the selection end is When 01, the multi-channel analog switch input selects the output adjustment voltage of the analog interface, thereby making the output of the multi-channel analog switch consistent with the output voltage of the analog interface. This mode is controlled by an external analog interface and can be adjusted quickly and in real time. This mode is used for processing and is selected by default after the system is powered on. When the selection end is 10, the multi-channel analog switch input selects the output voltage of the digital-to-analog converter, thereby making the output of the multi-channel analog switch consistent with the output voltage of the digital-to-analog converter. This mode is the host computer instruction control mode. The output voltage of the multi-channel analog switch simultaneously acts on the current adjustment input ends of the LD group drive unit 1, the LD group drive unit 2, and the LD group drive unit 3, thereby adjusting the current of the laser to ensure that the output current of each LD group is consistent.

[0012] Furthermore, the above-mentioned multi-channel laser diode drive control method for a lithography machine, wherein, in a manual adjustment mode, the laser current and the laser power are adjusted by adjusting the adjustable resistor through the output high-precision voltage of the reference voltage unit, and when the manual adjustment test is completed, the adjustable end of the adjustable resistor outputs a modulated zero-position voltage; in an external control mode, a predetermined voltage can be directly input through the analog interface to adjust the laser current and power; in a command control mode, the user sends a control current command to the MPU from the host computer, and the MPU converts the corresponding current parameters into digital quantities according to the calibration parameters and the conversion relationship and sends them to the digital-to-analog converter to adjust the laser current and power.

[0013] Furthermore, in the above-mentioned multi-channel laser diode drive control method for a lithography machine, the LD group drive unit 1, the LD group drive unit 2, and the LD group drive unit 3 are built with corresponding current sensors to measure the current size, and the current is output through the voltage quantity. The voltage of each group is output to the analog input terminal of the analog-to-digital converter. The MPU can read the current size of each group of LD in real time, and the host computer can also send instructions for reading; it has each group of LD drive current monitoring and each LD group drive enable control, and the power-on self-check is whether each LD group is normal. After the system is powered on, the MPU automatically switches the control mode to the default mode after completing the initialization. Switch to the command control mode, and send data to the digital-to-analog converter at the same time, so that the digital-to-analog output voltage corresponds to the threshold current of the control LD. When the LD is under the threshold current, the LD group drive unit 1 is enabled to work, and the corresponding current is detected by the analog-to-digital converter. If it is equal to the set current, the LD group drive is working normally; then turn off the LD group drive unit 1 enable, and use the same method to enable the control LD group drive unit 2 and LD group drive unit 3 for channel detection. If there is an abnormal system output alarm, turn off the enable of each group at the same time. If it works normally, the MPU will switch the control mode to external analog interface control;

[0014] Furthermore, in the above-mentioned multi-channel laser diode drive control method for a lithography machine, the output of the temperature sensor is divided into three channels, one of which is directly output through an analog interface, so that users can detect it online in real time; one channel is input into comparator 2 for hardware over-temperature protection; the third channel is connected to the analog-to-digital converter and can read the temperature in real time through the MPU, and the host computer can also send instructions to read the current temperature; when working, the MPU reads the current ambient temperature and the current size of LD group drive unit 1, LD group drive unit 2, and LD group drive unit 3 in real time. When the MPU detects that the ambient temperature is too high, or the total current of each LD group drive exceeds the rated working current of the system, the MPU automatically turns off the enable of LD group drive unit 1, LD group drive unit 2, and LD group drive unit 3, and outputs an alarm at the same time. At this time, there is no current in each LD, so the laser has no power output; when the system is working, the current detection voltage of LD group drive unit 1, LD group drive unit 2, and LD group drive unit 3 is input to Adding amplifier, the output of the adding amplifier corresponds to the total working current of the LD group, and the output voltage is input to comparator 1. During normal operation, the output voltage of the adding amplifier is less than the set voltage of comparator 1, so the output of comparator 1 is high level. When the total working current of the LD group is greater than the rated working current of the system, the output voltage of the adding amplifier is greater than the set voltage of comparator 1. At this time, the output of comparator 1 is low level, resulting in the output of AND gate 1 being low, and then resulting in the output of AND gate 2 and AND gate 3 being low level, thereby forcing the multi-channel analog switch to select the manual control mode. In manual mode, the starting level of the adjustable end of the adjustable resistor is zero potential, and the driving current of each LD group is turned off; under normal circumstances, the output voltage of the temperature sensor is less than the set voltage of comparator 2, and the output of comparator 2 is high level. When the temperature is too high, the output voltage of the temperature sensor is higher than the set voltage of comparator 2, so that the output of comparator 2 is low level, thereby resulting in the output of AND gate 1 being low level, thus turning off the driving current of the LD group and protecting the laser.

[0015] Furthermore, in the above-mentioned multi-channel laser diode drive control method for a photolithography machine, the circuit structures of LD group drive unit 1, LD group drive unit 2 and LD group drive unit 3 are the same, and resistors 3 and 4 in the circuit constitute a voltage divider circuit, transistor 2 is used for switching, and when the enable signal is high, the base of transistor 2 is high, at this time, the collector and emitter of transistor 2 are turned on, so that the base of power transistor 1 is pulled down, no matter how much the external set voltage is, transistor 1 cannot be turned on, and no current flows into LD 1, LD 2, LD 3, and LD 4; when the enable signal is low, the base voltage of transistor 2 is less than the PN junction conduction voltage, so transistor 2 is turned off, and the current of the laser can be adjusted by setting the voltage;

[0016] In the circuit, resistor 1 is used for filtering to eliminate the burr noise of the set voltage; resistor 1, capacitor 2 and capacitor 3 form an integral feedback circuit to stabilize the output current of the laser and suppress current jitter;

[0017] The voltage output of the current sensor represents the current working current. The output voltage is amplified by operational amplifier 2 and then output, and input to the negative input terminal of operational amplifier 1. Operational amplifier 1 is used for error amplification, and resistor 2 is used for current limiting. Under the action of the base input current of transistor 1, the amplified current is output at the emitter through the input power supply and flows into each LD, and finally flows into the current sensor. The output voltage of the current sensor is proportional to the current of the LD. The larger the current, the larger the output voltage. The current output voltage of the current sensor is connected to the analog-to-digital converter for collection.

[0018] Operational amplifier 2, resistor 5 and resistor 6 form a phase proportional amplifier circuit with an amplification factor of F=1+R5 / R6. Assuming that the current working current of LD is I, the voltage output of the current sensor is Us=kI, k is the fixed conversion factor of the current sensor, then the output voltage of operational amplifier 2 is Uo=kI(1+R5 / R6). In the stable working state, the positive input terminal voltage and the negative input terminal voltage of the error amplifier are equal. Regardless of the manual adjustment mode, the external analog interface control and the command control mode, the set voltage of the required current is equal to Uo. Assuming that the set voltage is Ui, then Ui=Uo=kI(1+R5 / R6). The resolution of the set voltage and the corresponding range are changed by changing the size of resistor 5 and resistor 6, wherein R5 refers to the resistance value of resistor 5, and R6 refers to the resistance value of resistor 6.

[0019] Compared with the prior art, the present invention has significant advantages and beneficial effects, which are specifically embodied in the following aspects:

[0020] ① The circuit design of the present invention has a compact structure, stable operation, high current accuracy, good reliability, and dual protection functions of software and hardware; at the same time, it can meet the different working mode requirements of users and is very convenient to use;

[0021] ② Realize power-on self-check to see if each LD channel is normal and stable control of LD working current; each channel adopts LD series connection to achieve uniform current and light output of each LD and prevent surge voltage impact; work over-current and over-temperature protection, software monitoring and hardware monitoring dual protection;

[0022] ③ Realize a data communication method that is easy to integrate into the control system, and realize current collection and monitoring of each channel of the system and ambient temperature monitoring through MPU and peripheral A / D;

[0023] ④ Realize various LD working current adjustment modes, including command control, external analog interface control, and manual adjustment control.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by practicing the specific embodiments of the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 : Schematic diagram of circuit principle of the control system of the present invention;

[0027] Figure 2 : Schematic diagram of the circuit principle of the LD group driving unit. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, directional terms and order terms are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0030] The present invention realizes a driving control mode of multiple laser diodes, effectively avoids the circuit from being impacted by surge voltage, realizes power-on self-check to check whether each laser diode channel is abnormal, switches between multiple control modes, stabilizes the output current, and improves the reliability of the controller.

[0031] like Figure 1 , Figure 2As shown, a multi-channel laser diode drive control system for a photolithography machine, the communication port of the communication interface 1 is connected to the communication port of the MPU2, and the three I / O (Input / Output) pins of the MPU2 are respectively connected to the enable input terminals of the LD group drive unit 10, the LD group drive unit 2 11, and the LD group drive unit 3 12; the two I / O pins of the MPU2 are respectively connected to the input terminals of the AND gate 2 5 and the AND gate 3 6; an I / O pin of the MPU2 is connected to the control pin input terminal of the solid-state relay 13; the I2C (Inter-Integrated Circuit Bus) bus port of the MPU2 is connected to the I2C bus port of the analog-to-digital converter 3; the SPI (Serial Peripheral The output end of the AND gate 1 4 is connected to the input end of the AND gate 2 5 and the AND gate 3 6; the output end of the AND gate 2 5 is connected to the selection port 1 of the multi-way analog switch 8, and the output end of the AND gate 3 6 is connected to the selection port 2 of the multi-way analog switch 8; the output control end of the analog interface 17 is connected to the analog input port 1 of the multi-way analog switch 8; the output port of the digital-to-analog converter 7 is connected to the analog input port 2 of the multi-way analog switch 8; the adjustable end of the adjustable resistor 20 is connected to the analog input port 3 of the multi-way analog switch 8; one end of the adjustable resistor 20 is connected to the ground GND, and the other end is connected to the output end of the reference voltage unit 9; the output end of the multi-way analog switch 8 is respectively connected to the current setting input end of the LD group drive unit 10, the LD group drive unit 2 11, and the LD group drive unit 3 12; one end of the surge protection diode 21 is grounded GNG, and the other end is connected to the output of the drive power supply 14 and connected to the input end of the solid-state relay 13; the solid-state relay The output end of the electrical appliance 13 is respectively connected to the power input end of the LD group driving unit 10, the LD group driving unit 2 11, and the LD group driving unit 3 12; the current sensing voltage output end of the LD group driving unit 10 is connected to the analog input port 1 of the analog-to-digital converter 3 and the input port 1 of the adding amplifier 15; the current sensing voltage output end of the LD group driving unit 2 11 is connected to the analog input port 2 of the analog-to-digital converter 3 and the input port 2 of the adding amplifier 15; the current sensing voltage output end of the LD group driving unit 3 12 is connected to the analog input port 3 of the analog-to-digital converter 3 and the input port 3 of the adding amplifier 15; the output end of the adding amplifier 15 is connected to the input end of the comparator 1 16; the output end of the comparator 1 16 is connected to the input end of the AND gate 1 4; the output end of the temperature sensor 18 is connected to the input end of the comparator 2 19, the input end of the analog interface 17, and the analog input port 4 of the analog-to-digital converter 3; the output end of the comparator 2 19 is connected to the input end of the AND gate 1 4.

[0032] After power-on, MPU2 performs state initialization. At this time, the control end of the solid-state relay 13 is not powered, and the driving power supply 14 does not act on the LD group driving unit 10, the LD group driving unit 2 11, and the LD group driving unit 3 12. At the same time, since the transient suppression diode 21 has a surge voltage protection function, the output of the driving power supply 14 is protected from overvoltage at the moment of power-on to prevent damage to the subsequent circuit. Since the solid-state relay 13 is not opened, the LD group driving unit 10, the LD group driving unit 2 11, and the LD group driving unit 3 12 are not powered at the moment of power-on, thereby effectively protecting each group of laser diodes; when the MPU2 initialization is completed, the control end of the solid-state relay 13 and the output of the driving power supply 14 act on the LD group driving unit 10, the LD group driving unit 2 11, and the LD group driving unit 3 12 through the solid-state relay 13 to be powered.

[0033] There are three ways to control the driving current of the LD group. The upper computer sends instructions to MPU2 through the communication interface 1. MPU2 switches the control mode according to the control instructions, so that the two I / Os input by MPU2 to AND gate 2 5 and AND gate 3 6 have different logic combinations. Under normal working conditions, the outputs of comparator 1 16 and comparator 2 19 are both high level, so the output of AND gate 1 4 is high, so that the input of AND gate 2 5 and one end of AND gate 3 6 is high, so that the two I / O logic combinations of MPU2 directly act on the selection end of the multi-way analog switch 8. When the selection end is 00, the input of the multi-way analog switch 8 selects the adjustable end voltage of the adjustable resistor 20, so that the output of the multi-way analog switch 8 is consistent with the adjustable end voltage of the adjustable resistor 20. This mode is the manual adjustment mode and is used for testing; when ... When it is 01, the multi-way analog switch 8 input selects the output adjustment voltage of the analog interface 17, thereby making the output of the multi-way analog switch 8 consistent with the output voltage of the analog interface 17. This mode is external analog interface control, fast real-time adjustment, and this mode is used for processing. This mode is selected by default after the system is powered on; when the selection end is 10, the multi-way analog switch 8 input selects the output voltage of the digital-to-analog converter 7, thereby making the output of the multi-way analog switch 8 consistent with the output voltage of the digital-to-analog converter 7. This mode is the host computer instruction control mode; the output voltage of the multi-way analog switch 8 simultaneously acts on the current adjustment input ends of the LD group drive unit 10, the LD group drive unit 2 11, and the LD group drive unit 3 12, thereby adjusting the current of the laser and ensuring that the output current of each LD group is consistent.

[0034] In the manual adjustment mode, the laser current and laser power are adjusted by adjusting the adjustable resistor 20 through the output high-precision voltage of the reference voltage unit 9. When the manual adjustment test is completed, the adjustable end of the adjustable resistor 20 outputs a modulated zero-position voltage. In the external control mode, the user directly inputs a predetermined voltage through the analog interface 17 to adjust the laser current and power. In the command control mode, the user sends a control current command to MPU2 from the host computer. MPU2 converts the corresponding current parameters into digital quantities according to the calibration parameters and conversion relationship and sends them to the digital-to-analog converter 7 to adjust the laser current and power.

[0035] During operation, the LD group drive unit 1 10, the LD group drive unit 2 11, and the LD group drive unit 3 12 are built with corresponding current sensors to measure the current size, and the current is output through voltage. Each group of voltage is output to the analog input terminal of the analog-to-digital converter 3. The MPU2 can read the current size of each group of LD in real time, and the host computer can also send instructions to read; it has the functions of monitoring the driving current of each group of LD and enabling the driving of each LD group. It can self-check whether each LD group is normal after powering on the system. After the system is powered on, the MPU2 automatically switches the control mode to the instruction control mode after completing the initialization, and sends data to the digital-to-analog converter 7 at the same time, so that The D / A output voltage corresponds to the threshold current of the controlled LD. Under the threshold current, the output optical power of the LD is very weak and will not cause damage to the external processed products. Then, the LD group drive unit 10 is enabled to work, and the corresponding current is detected by the analog-to-digital converter 3. If it is equal to the set current, the LD group drive is working normally. Then, the LD group drive unit 10 is turned off and enabled. In the same way, the LD group drive unit 2 11 and the LD group drive unit 3 12 are enabled for channel detection. If there is an abnormality, the system outputs an alarm and turns off each group enable at the same time. If it works normally, MPU2 switches the control mode to external analog interface control.

[0036] The output of the temperature sensor 18 is divided into three paths, one of which is directly output through the analog interface 17, which is convenient for users to detect online in real time; one path is input to the comparator 2 19 for hardware over-temperature protection; the third path is connected to the analog-to-digital converter 3 to read the temperature in real time through the MPU2, and the host computer can also send instructions to read the current temperature.

[0037] When the system is working, MPU2 reads the current ambient temperature and the current of LD group drive unit 10, LD group drive unit 2 11, and LD group drive unit 3 12 in real time. When MPU2 detects that the ambient temperature is too high, or the total current of each LD group drive exceeds the rated working current of the system, MPU2 automatically turns off the enable of LD group drive unit 10, LD group drive unit 2 11, and LD group drive unit 3 12, and outputs an alarm at the same time. At this time, there is no current in each LD, so the laser has no power output; when the system is working, the current detection voltage of LD group drive unit 10, LD group drive unit 2 11, and LD group drive unit 3 12 is input to the adding amplifier 15, and the output of the adding amplifier 15 corresponds to the total working current of the LD group, and the output voltage is input to the comparator 16. When working normally, the output voltage of the adding amplifier 15 is less than the set voltage of the comparator 16, so the output of the comparator 16 is a high level. When the total working current of the LD group is greater than the rated working current of the system, the output voltage of the adding amplifier 15 is greater than the set voltage of the comparator 1 16. At this time, the output of the comparator 1 16 is low, which causes the output of the AND gate 1 4 to be low, and then causes the outputs of the AND gate 2 5 and the AND gate 3 6 to be low, thereby forcing the multi-channel analog switch 8 to select the manual control mode. In the manual mode, the starting level of the adjustable end of the adjustable resistor 20 is zero potential, and the LD group drive current is turned off; under normal circumstances, the output voltage of the temperature sensor 18 is less than the set voltage of the comparator 2 19, and the output of the comparator 2 19 is high. When the temperature is too high, the output voltage of the temperature sensor is higher than the set voltage of the comparator 2 19, so that the output of the comparator 2 19 is low, thereby causing the output of the AND gate 4 to be low, thereby turning off the LD group drive current to protect the laser; hardware protection as a redundant design effectively plays a laser protection function when the system program runs away or the system crashes.

[0038] The structures of the LD group driving unit 10, the LD group driving unit 2 11 and the LD group driving unit 3 12 are the same. Figure 2, each includes an operational amplifier 1 23, a transistor 1 28, an operational amplifier 2 34 and a transistor 2 39, one end of the capacitor 1 22 is grounded, and the other end is connected to the current setting end and is connected to the positive input end of the operational amplifier 1 23; the negative input end of the operational amplifier 1 23 is connected to the capacitor 2 24, the resistor 1 25, one end of the resistor 5 36 and the output end of the operational amplifier 2 34; the output end of the operational amplifier 1 23 is connected to the other end of the capacitor 2 24, the resistor 2 27 and one end of the capacitor 3 26; the other end of the resistor 1 25 is connected to the other end of the capacitor 3 26; the positive input end of the operational amplifier 2 34 is connected to the signal output end of the current sensor 33 and is also connected to the current and voltage output end; the negative input end of the operational amplifier 2 34 is connected to the other end of the resistor 5 36 and the output end of the resistor 6 35 One end is connected; the other end of resistor six 35 is connected to ground; the other end of resistor two 27 is connected to the base of transistor one 28 and the collector of transistor two 39; the collector of transistor one 28 is connected to the power input terminal; the emitter terminal of transistor one is connected to the positive electrode of LD one 29; the negative electrode of LD one 29 is connected to the positive electrode of LD two 30; the negative electrode of LD two 30 is connected to the positive electrode of LD three 31; the negative electrode of LD three 31 is connected to the positive electrode of LD four 32; the negative electrode of LD four 32 is connected to the input terminal of current sensor 33; the output terminal of current sensor 33 is grounded; the base of transistor two 39 is connected to one end of resistor three 37 and one end of resistor four 38; the emitter of transistor two 39 is grounded; the other end of resistor three 37 is connected to the enable terminal; the other end of resistor four 38 is connected to the power supply VCC.

[0039] Resistor three 37 and resistor four 38 form a voltage divider circuit, the resistance value of resistor three 37 is 1k ohm, the resistance value of resistor four 38 is 6.8k ohm, the voltage of power supply VCC is 5V, transistor two 39 is used for switching, when the enable signal is high, the base of transistor two 39 is high, at this time, the collector and emitter of transistor two 39 are turned on, so that the base of power transistor one 28 is pulled down, no matter how much the external set voltage is, transistor one 28 cannot be turned on, and no current flows into laser diodes LD one 29, LD two 30, LD three 31, and LD four 32; when the enable signal is low, the base voltage of transistor two 39 is less than the PN junction conduction voltage, so transistor two 39 is turned off, and the current of the laser can be adjusted by setting the voltage.

[0040] Capacitor 1 22 in the circuit is used for filtering to eliminate burr noise of the set voltage; resistor 1 25, capacitor 2 24 and capacitor 3 26 constitute an integral feedback circuit, the resistance value of resistor 1 25 is 1k ohm, the capacitance of capacitor 2 24 is 10uF, and the capacitance of capacitor 3 26 is 0.01uF, which are used to stabilize the output current of the laser and suppress current jitter. Compared with the traditional current control method, the circuit of the present invention will not cause the problem of output laser jitter when setting the LD threshold current.

[0041] The voltage output of the current sensor 33 represents the current working current. The output voltage is amplified by the operational amplifier 2 34 and then output, and is input to the negative input terminal of the operational amplifier 1 23, forming a negative feedback structure and working stably. In the circuit, the operational amplifier 1 (23) is used for error amplification, and the resistor 2 27 is used for current limiting to prevent damage to the power transistor 1 28. Under the action of the base input current of the transistor 1 28, the amplified current is output at the emitter through the input power supply and flows into each LD, and finally flows into the current sensor 33. The output voltage of the current sensor 33 is proportional to the current of the current LD. The larger the current, the larger the output voltage. The current output voltage of the current sensor is connected to the analog-to-digital converter for collection.

[0042] The operational amplifier 2 34, the resistor 5 36 and the resistor 6 35 form a phase proportional amplifier circuit with an amplification factor of F=1+R5 / R6. Assuming that the current working current of the LD is I, the voltage output of the current sensor 33 is Us=kI, k is the fixed conversion factor of the current sensor, then the output voltage of the operational amplifier 2 34 is Uo=kI(1+R5 / R6). In the stable working state, the positive input terminal voltage and the negative input terminal voltage of the error amplifier 23 are equal. Regardless of the manual adjustment mode or the external analog interface control and command control mode, the set voltage of the required current is equal to Uo. Assuming that the set voltage is Ui, Ui=Uo=kI(1+R5 / R6). The resolution of the set voltage and the corresponding range can be changed by changing the size of the resistor 5 and the resistor 6; wherein R5 refers to the resistance value of the resistor 5 36, and R6 refers to the resistance value of the resistor 6 35.

[0043] Four laser diodes, namely LD 1 29, LD 2 30, LD 3 31 and LD 4 32, are connected in series. If the laser needs higher power, more LDs can be connected in series by simply increasing the input voltage. Compared with the traditional LD ​​driving structure, the present invention does not adopt the LD parallel mode. Although the parallel mode can reduce the input power supply voltage requirement, and when a certain LD is damaged, other LDs can continue to work. Although the total current output by the emitter of the power transistor 1 28 can be guaranteed by setting the voltage, due to the influence of factors such as the wiring on the circuit board and the factors of the LD itself, it cannot be guaranteed that the current flowing through each LD is uniform and equal, and the inconsistent current will cause the optical characteristics of the laser diode to deviate, thereby resulting in poor processing effect. Therefore, the present invention adopts the LD series mode for driving, which can fully ensure that the current flowing through each LD is consistent, and the optical characteristics of the LD are consistent, thereby ensuring the processing effect.

[0044] The measured laser power is stable and the temperature drift is small. The Agilent oscilloscope model is DSO9254A, with a bandwidth of 2.5GHz and a sampling rate of 20G Sa / S to measure the signal after photoelectric conversion. The signal is stable. Good results have been achieved on mass-produced models.

[0045] In summary, the circuit design of the present invention has a compact structure, stable operation, high current accuracy, good reliability, and dual protection functions of software and hardware; at the same time, it can meet the different working mode requirements of users and is very convenient to use. It can realize power-on self-check to see if each LD (laser diode) channel is normal, and stable control of the LD working current. Each channel adopts LD series connection to achieve uniform current and light output of each LD, and prevent surge voltage shock; it has working overcurrent and overtemperature protection, software monitoring and hardware monitoring dual protection; it realizes a data communication method that is easy to integrate into the control system, and realizes current collection and monitoring of each channel of the system through MPU (Micro Process Unit) and peripheral A / D, and environmental temperature monitoring; it realizes a variety of LD working current adjustment methods, pass command control, external analog interface control, and manual adjustment control.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0047] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0048] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A multi-channel laser diode drive control system for a photolithography machine, characterized in that: The communication port of the communication interface (1) is connected to the communication port of the MPU (2); the three I / O pins of the MPU (2) are respectively connected to the enable input terminals of the LD group drive unit 1 (10), the LD group drive unit 2 (11), and the LD group drive unit 3 (12); the two I / O pins of the MPU (2) are respectively connected to the input terminals of the AND gate 2 (5) and the AND gate 3 (6); an I / O pin of the MPU (2) is connected to the control pin input terminal of the solid-state relay (13); the I2C bus port of the MPU (2) is connected to the I2C bus port of the analog-to-digital converter (3); the SPI bus port of the MPU (2) is connected to the SPI bus port of the digital-to-analog converter (7); the output of the AND gate 1 (4) is connected to the I2C bus port of the analog-to-digital converter (3); the SPI bus port of the MPU (2) is connected to the SPI bus port of the digital-to-analog converter (7); and ... and the SPI bus port of the MPU (2) is connected to the SPI bus port of the digital-to-analog converter (7). The end is connected to the input end of AND gate 2 (5) and AND gate 3 (6); the output end of AND gate 2 (5) is connected to the selection port 1 of the multi-way analog switch (8), and the output end of AND gate 3 (6) is connected to the selection port 2 of the multi-way analog switch (8); the output control end of the analog interface (17) is connected to the analog input port 1 of the multi-way analog switch (8); the output port of the digital-to-analog converter (7) is connected to the analog input port 2 of the multi-way analog switch (8); the adjustable end of the adjustable resistor (20) is connected to the analog input port 3 of the multi-way analog switch (8); one end of the adjustable resistor (20) is connected to the ground GND, and the other end is connected to the output end of the reference voltage unit (9); the output ends of the multi-way analog switch (8) are respectively connected to the LD group The first drive unit (10), the second drive unit (11) of the LD group, and the third drive unit (12) of the LD group are connected to the current setting input terminal; one end of the surge protection diode (21) is grounded to GNG, and the other end is connected to the output of the driving power supply (14) and connected to the input terminal of the solid-state relay (13); the output terminal of the solid-state relay (13) is respectively connected to the power input terminal of the first drive unit (10), the second drive unit (11) of the LD group, and the third drive unit (12); the current sensing voltage output terminal of the first drive unit (10) of the LD group is connected to the analog input port 1 of the analog-to-digital converter (3) and the input port 1 of the summing amplifier (15); the current sensing voltage output terminal of the second drive unit (1 ... The output end is connected to the analog input port 2 of the analog-to-digital converter (3) and the input port 2 of the adding amplifier (15); the current sensing voltage output end of the LD group driving unit 3 (12) is connected to the analog input port 3 of the analog-to-digital converter (3) and the input port 3 of the adding amplifier (15); the output end of the adding amplifier (15) is connected to the input end of the comparator 1 (16); the output end of the comparator 1 (16) is connected to the input end of the AND gate 1 (4); the output end of the temperature sensor (18) is connected to the input end of the comparator 2 (19), the input end of the analog interface (17) and the analog input port 4 of the analog-to-digital converter (3); the output end of the comparator 2 (19) is connected to the input end of the AND gate 1 (4).

2. The multi-channel laser diode drive control system for a photolithography machine according to claim 1, characterized in that: The LD group driving unit 1 (10), the LD group driving unit 2 (11) and the LD group driving unit 3 (12) have the same structure, including an operational amplifier 1 (23), a transistor 1 (28), an operational amplifier 2 (34) and a transistor 2 (39); one end of the capacitor 1 (22) is grounded, and the other end is connected to the current setting end and connected to the positive input end of the operational amplifier 1 (23); the negative input end of the operational amplifier 1 (23) is connected to the capacitor 2 (24), the resistor 1 (25), one end of the resistor 5 (36) and the output end of the operational amplifier 2 (34); the output end of the operational amplifier 1 (23) is connected to the other end of the capacitor 2 (24), the resistor 2 (27) and one end of the capacitor 3 (26); the other end of the resistor 1 (25) is connected to the other end of the capacitor 3 (26); the positive input end of the operational amplifier 2 (34) is connected to the signal output end of the current sensor (33) and is also connected to the current and voltage output end of the system; the negative input end of the operational amplifier 2 (34) is connected to the signal output end of the current sensor (33) and is also connected to the current and voltage output end of the system; The input end is connected to the other end of resistor five (36) and one end of resistor six (35); the other end of resistor six (35) is connected to ground; the other end of resistor two (27) is connected to the base of transistor one (28) and the collector of transistor two (39); the collector of transistor one (28) is connected to the power input end; the emitter end of transistor one is connected to the positive electrode of LD one (29); the negative electrode of LD one (29) is connected to the positive electrode of LD two (30); the negative electrode of LD two (30) is connected to L The positive electrode of D3 (31) is connected; the negative electrode of LD3 (31) is connected to the positive electrode of LD4 (32); the negative electrode of LD4 (32) is connected to the input end of the current sensor (33); the output end of the current sensor (33) is grounded; the base of transistor 2 (39) is connected to one end of resistor 3 (37) and one end of resistor 4 (38); the emitter of transistor 2 (39) is grounded; the other end of resistor 3 (37) is connected to the enable end; the other end of resistor 4 (38) is connected to the power supply VCC.

3. The multi-channel laser diode drive control system for a photolithography machine according to claim 2, characterized in that: The LD 1 (29), LD 2 (30), LD 3 (31), and LD 4 (32) are connected in series.

4. The multi-channel laser diode drive control system for a photolithography machine according to claim 2, characterized in that: The resistance value of the resistor three (37) is 1k ohm, the resistance value of the resistor four (38) is 6.8k ohm, and the voltage of the power supply VCC is 5V.

5. The multi-channel laser diode drive control system for a photolithography machine according to claim 2, characterized in that: The resistance value of the resistor 1 (25) is 1k ohm, the capacitance of the capacitor 2 (24) is 10uF, and the capacitance of the capacitor 3 (26) is 0.01uF.

6. A multi-channel laser diode drive control method for a photolithography machine is implemented based on the system of claim 1, characterized in that: After power-on, the MPU (2) performs state initialization. At this time, the control end of the solid-state relay (13) is not powered, and the drive power supply (14) does not act on the LD group drive unit 1 (10), the LD group drive unit 2 (11), and the LD group drive unit 3 (12). At the same time, because the transient suppression diode (21) prevents surge voltage, the output of the drive power supply (14) is protected from overvoltage at the moment of power-on to prevent damage to the subsequent circuit. Because the solid-state relay (13) is not turned on, the LD group drive unit 1 (10), the LD group drive unit 2 (11), and the LD group drive unit 3 (12) are not powered at the moment of power-on, thereby protecting each group of laser diodes. After the MPU (2) is initialized, the control end of the solid-state relay (13) and the output of the drive power supply (14) act on the LD group drive unit 1 (10), the LD group drive unit 2 (11), and the LD group drive unit 3 (12) through the solid-state relay (13) to be powered; There are three ways to control the size of the LD group drive current. The host computer sends instructions to the MPU (2) through the communication interface (1). The MPU (2) switches the control mode according to the control instruction, so that the two I / Os input to the AND gate 2 (5) and the AND gate 3 (6) of the MPU (2) have different logic combinations. Under normal working conditions, the outputs of the comparator 1 (16) and the comparator 2 (19) are both high level, so the output of the AND gate 1 (4) is high, so that the input of the AND gate 2 (5) and the AND gate 3 (6) is high, so that the two I / O logic combinations of the MPU (2) directly act on the selection end of the multi-channel analog switch (8). When the selection end is 00, the multi-channel analog switch (8) input selects the adjustable end voltage of the adjustable resistor (20), thereby making the output of the multi-channel analog switch (8) consistent with the adjustable end voltage of the adjustable resistor (20). This mode is a manual adjustment mode and is used to measure Test; when the selection end is 01, the multi-channel analog switch (8) input selects the output adjustment voltage of the analog interface (17), thereby making the output of the multi-channel analog switch (8) consistent with the output voltage of the analog interface (17). This mode is external analog interface control, fast real-time adjustment, and this mode is used for processing. This mode is selected by default after the system is powered on; when the selection end is 10, the multi-channel analog switch (8) input selects the output voltage of the digital-to-analog converter (7), thereby making the output of the multi-channel analog switch (8) consistent with the output voltage of the digital-to-analog converter (7). This mode is the host computer instruction control mode; the output voltage of the multi-channel analog switch (8) simultaneously acts on the current adjustment input terminals of the LD group drive unit 1 (10), the LD group drive unit 2 (11), and the LD group drive unit 3 (12), thereby adjusting the current of the laser to ensure that the output current of each LD group is consistent.

7. The multi-channel laser diode driving control method for a photolithography machine according to claim 6, characterized in that: In the manual adjustment mode, the laser current and the laser power are adjusted by adjusting the adjustable resistor (20) through the output high-precision voltage of the reference voltage unit (9). When the manual adjustment test is completed, the adjustable end of the adjustable resistor (20) outputs a modulated zero-position voltage. In the external control mode, a predetermined voltage can be directly input through the analog interface (17) to adjust the laser current and power. In the command control mode, the user sends a control current command to the MPU (2) from the upper computer. The MPU (2) converts the corresponding current parameter into a digital quantity according to the calibration parameter and the conversion relationship and sends it to the digital-to-analog converter (7), thereby adjusting the laser current and power.

8. The multi-channel laser diode driving control method for a photolithography machine according to claim 6, characterized in that: LD group drive unit 1 (10), LD group drive unit 2 (11), and LD group drive unit 3 (12) are equipped with corresponding current sensors to measure the current size. The current is output through voltage. Each group of voltage is output to the analog input terminal of the analog-to-digital converter (3). The MPU (2) can read the current size of each group of LD in real time, and the host computer can also send instructions to read it. It has the functions of monitoring the driving current of each group of LD and controlling the driving enable of each LD group. It can also self-check whether each LD group is normal after powering on. After the system is powered on, the MPU (2) automatically switches the control mode to the instruction control mode after completing the initialization, and sends data to the analog-to-digital converter (3). The converter (7) makes the digital-to-analog output voltage correspond to the threshold current of the controlled LD. When the LD is under the threshold current, the LD group drive unit 1 (10) is enabled to operate. At the same time, the analog-to-digital converter (3) is used to detect the corresponding current. If the current is equal to the set current, the LD group drive is operating normally. Then, the LD group drive unit 1 (10) is turned off and enabled. In the same way, the LD group drive unit 2 (11) and the LD group drive unit 3 (12) are respectively enabled to perform channel detection. If there is an abnormal system output alarm, each group is turned off at the same time. If the operation is normal, the MPU (2) switches the control mode to external analog interface control.

9. The multi-channel laser diode driving control method for a photolithography machine according to claim 6, characterized in that: The output of the temperature sensor (18) is divided into three paths, one of which is directly output through the analog interface (17) to facilitate real-time online detection by the user; one path is input to the comparator 2 (19) for hardware over-temperature protection; the third path is connected to the analog-to-digital converter (3) to read the temperature in real time through the MPU (2), and the host computer can also send instructions to read the current temperature; when working, the MPU (2) reads the current ambient temperature and the current size of the LD group drive unit 1 (10), the LD group drive unit 2 (11), and the LD group drive unit 3 (12) in real time. When the MPU (2) detects When the ambient temperature is detected to be too high, or the total current of each LD group drive exceeds the rated operating current of the system, the MPU (2) automatically turns off the enable of LD group drive unit 1 (10), LD group drive unit 2 (11), and LD group drive unit 3 (12), and outputs an alarm at the same time. At this time, there is no current in each LD, so the laser has no power output; when the system is working, the current detection voltage of LD group drive unit 1 (10), LD group drive unit 2 (11), and LD group drive unit 3 (12) is input to the summing amplifier (15), and the output of the summing amplifier (15) Corresponding to the total working current of the LD group, the output voltage is input to the comparator 1 (16). During normal operation, the output voltage of the summing amplifier (15) is less than the set voltage of the comparator 1 (16), so the output of the comparator 1 (16) is high level. When the total working current of the LD group is greater than the rated working current of the system, the output voltage of the summing amplifier (15) is greater than the set voltage of the comparator 1 (16). At this time, the output of the comparator 1 (16) is low level, causing the output of the AND gate 1 (4) to be low, and then causing the outputs of the AND gate 2 (5) and the AND gate 3 (6) to be low level, thereby The multi-channel analog switch (8) is forced to select the manual control mode. In the manual mode, the starting level of the adjustable end of the adjustable resistor (20) is zero potential, and the LD group drive current is turned off; under normal circumstances, the output voltage of the temperature sensor (18) is less than the set voltage of the comparator 2 (19), and the output of the comparator 2 (19) is high level. When the temperature is too high, the output voltage of the temperature sensor is higher than the set voltage of the comparator 2 (19), so that the output of the comparator 2 (19) is low level, thereby causing the output of the AND gate 1 (4) to be low level, thereby turning off the LD group drive current to protect the laser.

10. The multi-channel laser diode driving control method for a photolithography machine according to claim 6, characterized in that: The circuit structures of the LD group driving unit 1 (10), the LD group driving unit 2 (11) and the LD group driving unit 3 (12) are the same. The resistor 3 (37) and the resistor 4 (38) in the circuit form a voltage divider circuit. The transistor 2 (39) is used for switching. When the enable signal is high, the base of the transistor 2 (39) is high. At this time, the collector and emitter of the transistor 2 (39) are turned on, so that the base of the power transistor 1 (28) is pulled down. No matter how much the external setting voltage is, the transistor 1 (28) cannot be turned on, and no current flows into LD 1 (29), LD 2 (30), LD 3 (31), and LD 4 (32); when the enable signal is low, the base voltage of the transistor 2 (39) is less than the PN junction conduction voltage, so the transistor 2 (39) is turned off, and the current of the laser can be adjusted by setting the voltage. Capacitor 1 (22) in the circuit is used for filtering to eliminate burr noise of the set voltage; resistor 1 (25), capacitor 2 (24) and capacitor 3 (26) form an integral feedback circuit to stabilize the output current of the laser and suppress current jitter; The voltage output of the current sensor (33) represents the current working current. The output voltage is amplified by the operational amplifier 2 (34) and then output, and input to the negative input terminal of the operational amplifier 1 (23). The operational amplifier 1 (23) is used for error amplification, and the resistor 2 (27) is used for current limiting. Under the action of the base input current of the transistor 1 (28), the amplified current is output at the emitter through the input power supply and flows into each LD, and finally flows into the current sensor (33). The output voltage of the current sensor (33) is proportional to the current of the LD. The larger the current, the larger the output voltage. The current output voltage of the current sensor is connected to the analog-to-digital converter for collection. Operational amplifier 2 (34) and resistor 5 (36) and resistor 6 (35) form a phase proportional amplifier circuit with an amplification factor of F=1+ R5 / R6. Assuming that the current working current of LD is I, the voltage output of the current sensor (33) is Us=kI, k is the fixed conversion factor of the current sensor, then the output voltage of operational amplifier 2 (34) is Uo=kI(1+ R5 / R6). In the stable working state, the positive input terminal voltage and the negative input terminal voltage of the error amplifier (23) are equal. Regardless of the manual adjustment mode, the external analog interface control and the command control mode, the set voltage of the required current is equal to Uo. Assuming that the set voltage is Ui, Ui=Uo=kI(1+ R5 / R6). The resolution of the set voltage and the corresponding range are changed by changing the size of resistor 5 and resistor 6. Among them, R5 refers to the resistance value of resistor 5 (36), and R6 refers to the resistance value of resistor 6 (35).

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