CN217034616U

CN217034616U - Laser instrument current control circuit based on V-I conversion

Info

Publication number: CN217034616U
Application number: CN202220963200.7U
Authority: CN
Inventors: 吕代兵
Original assignee: Chengdu Rongbo Communication Technology Co ltd
Current assignee: Chengdu Rongbo Communication Technology Co ltd
Priority date: 2022-04-25
Filing date: 2022-04-25
Publication date: 2022-07-22
Anticipated expiration: 2032-04-25

Abstract

The utility model discloses a laser current control circuit based on V-I conversion, and relates to the technical field of laser current control. The laser device comprises a PID controller, a laser device transmitting circuit and a sampling circuit, wherein the laser device transmitting circuit is connected with a plurality of proportional resistors, the working current application of different laser devices can be realized by adjusting the proportional resistors, and the stable work of the laser devices can be realized by adjusting the output voltage in real time through the PID controller in combination with the characteristics of the stable work of the laser devices. The laser current control circuit is low in cost, the voltage is output through the DAC port of the PID controller, the current with the corresponding magnitude can be obtained by being supplemented with the corresponding proportional resistor, and the application of lasers with different working currents and the corresponding APC control can be realized by adjusting the magnitude of the current.

Description

Laser instrument current control circuit based on V-I conversion

Technical Field

The utility model relates to the technical field of laser current control, in particular to a laser current control circuit based on V-I conversion.

Background

In the field of photoelectricity, when a laser works in a locked state, the working power condition of the laser needs to be detected in real time, the traditional detection mode is that a PD light receiver is matched with the laser, the PD light receiver senses laser emitted by the laser, the laser is converted into an electric signal and fed back to a controller, and the controller calculates according to the electric signal fed back by the PD light receiver, so that the power of the laser is obtained, and whether the voltage output by the laser needs to be adjusted or not is judged.

In the application of the optical module, the laser cannot work, and the light emitting size of the laser has a close relation with the current. Generally, a laser can output bias current by adopting a special IC to enable the laser to work, but with the rise of localization and cost control, the function of a special chip can be realized by peripheral simple current, namely, the special chip is realized by a voltage (V) and current (I) conversion circuit, the accurate supply of the current can be realized by adjusting the output voltage in combination with the peripheral circuit, and then the stable working characteristic of the laser is added, and the output voltage can be dynamically adjusted in real time through the detected signal size, which is called APC (automatic power control) for short.

Most of the existing chips can directly control a chip register to achieve a current output function, such as an ADUCM320 chip of ADI (advanced design integration) and have a special IDAC (idle digital control access) output port, the chip is mainly used for a laser requiring large current output, the laser working at low current, such as a VCSEL (vertical cavity surface emitting laser), is not preferred, a proper chip needs to be selected additionally, and the cost of the chip integrating the current output is usually higher.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problems that the cost is high when a special chip is adopted and a proper chip needs to be selected for lasers working at different low currents in the prior art. The laser control circuit based on the V-I conversion comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein the laser transmitting circuit is connected with a plurality of proportional resistors, the working current application of different lasers can be realized by adjusting the proportional resistors, and the stable work of the lasers can be realized by adjusting the output voltage in real time through the PID controller in combination with the characteristic of the stable work of the lasers. The laser current control circuit is low in cost, the voltage is output through the DAC port of the PID controller, the current with the corresponding magnitude can be obtained by being supplemented with the corresponding proportional resistor, and the application of lasers with different working currents and the corresponding APC control can be realized by adjusting the magnitude of the current.

In order to solve the problems in the prior art, the utility model is realized by the following technical scheme.

The utility model provides a laser current control circuit based on V-I conversion, which comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein the laser transmitting circuit is connected with a DAC voltage output port of the PID controller, and the sampling circuit is connected with an ADC voltage acquisition port of the PID controller; the laser transmitting circuit comprises an operational amplifier, a field effect transistor and a laser LD, wherein a DAC voltage output port of the PID controller outputs a voltage which is connected to an inverting input end of the operational amplifier after passing through a proportional resistor R2, and a homodromous input end of the operational amplifier is grounded after passing through a proportional resistor R5; wherein R2= R5; the output end of the operational amplifier is connected with a G stage of a field effect tube, and is connected with a laser LD through a current proportional resistor R4 after being output by an S stage of the field effect tube; a branch circuit connected with a proportional resistor R1 is also arranged between the proportional resistor R2 and the laser LD; a branch circuit which is connected with the capacitor C2 and then grounded is arranged on a connecting circuit of a DAC voltage output port of the PID controller and the proportional resistor R2; the D stage of the field effect transistor is grounded after passing through a capacitor C1; a branch circuit which is connected with the capacitor C2 and is grounded is arranged between the field effect transistor and the current proportional resistor R4; the S-stage of the field effect transistor is connected between the reverse input end of the operational amplifier and the proportional resistor R5 through a connecting branch; and a proportional resistor R6 and a capacitor C3 are connected in parallel on the connecting branch, wherein R1= R6.

Furthermore, the resistance value of the current proportional resistor R4 is 0-1 omega.

Furthermore, the sampling circuit comprises a sampling and holding circuit and a light receiver PD, one end of the sampling and holding circuit is grounded, and the other end of the sampling and holding circuit is connected into a circuit between the light receiver PD and the voltage acquisition port of the ADC of the PID controller.

The sample-and-hold circuit comprises a capacitor C5 and a sampling resistor R7 arranged in parallel.

An induction coil L1 is connected in series to the front-end circuit of the laser LD, and the other end of the laser LD is grounded.

The utility model also provides a laser current control circuit based on V-I conversion, which comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein the laser transmitting circuit is connected with a DAC voltage output port of the PID controller, and the sampling circuit is connected with an ADC voltage acquisition port of the PID controller; the laser emitting circuit comprises an operational amplifier, a triode and a laser LD, wherein a DAC voltage output port of the PID controller outputs a voltage which is connected to the inverting input end of the operational amplifier after passing through a proportional resistor R2, and the homodromous input end of the operational amplifier is grounded after passing through a proportional resistor R5; wherein R2= R5; the output end of the operational amplifier is connected to a pin B of the triode through a resistor R3, and is connected with the laser LD through a current proportional resistor R4 after being output by a pin E of the triode; a branch circuit connected with the proportional resistor R1 is also arranged between the proportional resistor R2 and the laser LD; a branch circuit which is connected with the capacitor C2 and then grounded is arranged on a connecting circuit of a DAC voltage output port of the PID controller and the proportional resistor R2; the pin C of the triode is grounded through a capacitor C1; a branch circuit which is connected with the capacitor C2 and is grounded is arranged between the triode and the current proportional resistor R4; the class E of the triode is connected between the inverting input end of the operational amplifier and the proportional resistor R5 through a connecting branch; and a proportional resistor R6 and a capacitor C3 are connected in parallel on the connecting branch, wherein R1= R6.

Furthermore, the sampling circuit comprises a sampling hold circuit and a light receiver PD, one end of the sampling hold circuit is grounded, and the other end of the sampling hold circuit is connected into a circuit between the light receiver PD and the voltage acquisition port of the ADC of the PID controller.

Compared with the prior art, the beneficial technical effects brought by the utility model are as follows:

1. the laser control circuit based on the V-I conversion comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein a plurality of proportional resistors are connected in the laser transmitting circuit, the application of working currents of different lasers can be realized by adjusting the proportional resistors, and the stable work of the lasers can be realized by adjusting output voltage in real time through the PID controller in combination with the characteristic of stable work of the lasers. The laser current control circuit is low in cost, the voltage is output through the DAC port of the PID controller, the current with the corresponding magnitude can be obtained by being supplemented with the corresponding proportional resistor, and the application of lasers with different working currents and the corresponding APC control can be realized by adjusting the magnitude of the current.

2. The PID controller mainly realizes the functions of voltage output and voltage acquisition; the resistors R1, R2, R5 and R6 are proportional resistors, and R1= R6 and R2= R5, and the respective proportions are achieved mainly by the size of the resistors, i.e. the amplification factor a = R2/R1. The operational amplifier realizes the calculation of the V-I conversion ratio, and the field effect tube can improve the current output capability; since the current output capability of the operational amplifier is usually small, the field effect transistor is required to improve the current output capability. R4 is a current proportional resistor, voltage is output through a DAC voltage output port of the PID controller, corresponding proportion (proportional coefficient obtained by the proportional resistor) is supplemented, corresponding current size can be obtained by dividing the current size by the resistance value of R4 (the current size calculation formula is I = V/A/R4), and the current proportional resistor R4 is usually a resistor with the size of 0-1 omega.

3. Under the condition of open-loop working, a voltage is output from a DAC voltage output port of the PID controller, the voltage is calculated through an operational amplifier ratio and then divided by a resistance value of R4 to obtain a current with a corresponding magnitude, the current is input to the laser LD, the laser LD correspondingly emits light, the output current is increased, the output light power of the laser LD is increased, when the output value of the adjusted voltage reaches the optimal working light power of the laser, the light of the laser is irradiated onto a light receiver PD, the light receiver PD forms a photocurrent which flows through a resistor R7 to form a voltage, an ADC voltage acquisition port of the PID controller acquires the voltage and performs a corresponding calibration function with the light emitting magnitude of the laser LD to realize the light power magnitude corresponding to the acquired voltage, and then the light power magnitude serves as a reference for adjusting the output voltage of the DAC voltage output port, because the laser can work at different temperatures, the light power fluctuates, after the voltage acquired by the ADC port of the PID controller, and comparing the voltage value with the voltage value obtained by the ADC port obtained by the original calibration, judging whether the output voltage needs to be adjusted, and adjusting the output voltage of the DAC port in real time after the acquired value is different from the original calibration value so as to realize the stable work of the laser, namely Automatic Power Control (APC).

4. In the utility model, the field effect transistor can be equivalently replaced by a triode, and as the triode is a current device, the resistor R3 is required to be added to realize current control.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a laser current control circuit according to the present invention.

Detailed Description

To make the objects, technical solutions and advantages of the present invention clearer and more complete, the technical solutions of the present invention are described below clearly, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

As a preferred embodiment of the present invention, referring to the accompanying drawing 1 of the specification, the embodiment discloses a laser current control circuit based on V-I conversion, which comprises a PID controller, a laser emitting circuit and a sampling circuit, wherein the laser emitting circuit is connected with a DAC voltage output port of the PID controller, and the sampling circuit is connected with an ADC voltage acquisition port of the PID controller; the laser transmitting circuit comprises an operational amplifier, a field effect transistor and a laser LD, wherein a DAC voltage output port of the PID controller outputs a voltage which is connected to an inverting input end of the operational amplifier after passing through a proportional resistor R2, and a homodromous input end of the operational amplifier is grounded after passing through a proportional resistor R5; wherein R2= R5; the output end of the operational amplifier is connected with a G-stage field effect transistor and is connected with a laser LD through a current proportional resistor R4 after being output by an S-stage field effect transistor; a branch circuit connected with a proportional resistor R1 is also arranged between the proportional resistor R2 and the laser LD; a branch circuit which is connected with the capacitor C2 and then grounded is arranged on a connecting circuit of a DAC voltage output port of the PID controller and the proportional resistor R2; the D stage of the field effect transistor is grounded after passing through a capacitor C1; a branch circuit which is connected with the capacitor C2 and is grounded is arranged between the field effect tube and the current proportional resistor R4; the S-stage of the field effect transistor is connected between the reverse input end of the operational amplifier and the proportional resistor R5 through a connecting branch; and a proportional resistor R6 and a capacitor C3 are connected in parallel on the connecting branch, wherein R1= R6. In the present embodiment, the corresponding proportional factor is realized mainly by the size of the resistor, i.e., the amplification factor a = R2/R1. R4 is a current proportional resistor, voltage is output through a DAC voltage output port of the PID controller, corresponding proportion (proportional coefficient obtained by the proportional resistor) is added, and the current is divided by the resistance value of R4 to obtain corresponding current size (the current size calculation formula is I = V/A/R4).

In one embodiment of this embodiment, the resistance value of the current proportional resistor R4 is 0 to 1 Ω.

As another implementation manner of this embodiment, the sampling circuit includes a sample-and-hold circuit and a light receiver PD, one end of the sample-and-hold circuit is grounded, and the other end of the sample-and-hold circuit is connected to a circuit between the light receiver PD and the voltage acquisition port of the PID controller ADC.

Furthermore, the sample-and-hold circuit comprises a capacitor C5 and a sampling resistor R7 which are arranged in parallel.

In another embodiment of the present embodiment, an induction coil L1 is connected in series to the front end circuit of the laser LD, and the other end of the laser LD is grounded.

In this embodiment, the fet may be equivalently replaced by a transistor, and since the transistor is a current device, the resistor R3 needs to be added to implement current control. The specific implementation mode is as follows: a laser current control circuit based on V-I conversion comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein the laser transmitting circuit is connected with a DAC voltage output port of the PID controller, and the sampling circuit is connected with an ADC voltage acquisition port of the PID controller; the laser emitting circuit comprises an operational amplifier, a triode and a laser LD, wherein a DAC voltage output port of the PID controller outputs a voltage which is connected to an inverting input end of the operational amplifier after passing through a proportional resistor R2, and a homodromous input end of the operational amplifier is grounded after passing through a proportional resistor R5; wherein R2= R5; the output end of the operational amplifier is connected to a pin B of the triode through a resistor R3, and is connected with the laser LD through a current proportional resistor R4 after being output by a pin E of the triode; a branch circuit connected with a proportional resistor R1 is also arranged between the proportional resistor R2 and the laser LD; a branch circuit which is connected with the capacitor C2 and then grounded is arranged on a connecting circuit of a DAC voltage output port of the PID controller and the proportional resistor R2; the pin C of the triode is grounded through a capacitor C1; a branch circuit which is connected with the capacitor C2 and is grounded is arranged between the triode and the current proportional resistor R4; the class E of the triode is connected between the reverse input end of the operational amplifier and the proportional resistor R5 through a connecting branch; and a proportional resistor R6 and a capacitor C3 are connected in parallel on the connecting branch, wherein R1= R6.

Furthermore, the resistance value of the current proportional resistor R4 is 0-1 omega. The sampling circuit comprises a sampling holding circuit and a light receiver PD, one end of the sampling holding circuit is grounded, and the other end of the sampling holding circuit is connected into a circuit between the light receiver PD and a voltage acquisition port of the PID controller ADC. The sample-and-hold circuit comprises a capacitor C5 and a sampling resistor R7 arranged in parallel. An induction coil L1 is connected in series to the front end circuit of the laser LD, and the other end of the laser LD is grounded.

Claims

1. A laser current control circuit based on V-I conversion comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein the laser transmitting circuit is connected with a DAC voltage output port of the PID controller, and the sampling circuit is connected with an ADC voltage acquisition port of the PID controller; the method is characterized in that: the laser emitting circuit comprises an operational amplifier, a field effect transistor and a laser LD, wherein a DAC voltage output port of the PID controller outputs a voltage which is connected to the inverting input end of the operational amplifier after passing through a proportional resistor R2, and the homodromous input end of the operational amplifier is grounded after passing through a proportional resistor R5; wherein R2= R5; the output end of the operational amplifier is connected with a G stage of a field effect tube, and is connected with a laser LD through a current proportional resistor R4 after being output by an S stage of the field effect tube; a branch circuit connected with a proportional resistor R1 is also arranged between the proportional resistor R2 and the laser LD; a branch circuit which is connected with the capacitor C2 and then grounded is arranged on a connecting circuit of a DAC voltage output port of the PID controller and the proportional resistor R2; the D stage of the field effect transistor is grounded after passing through a capacitor C1; a branch circuit which is connected with the capacitor C2 and is grounded is arranged between the field effect transistor and the current proportional resistor R4; the S-stage of the field effect transistor is connected between the reverse input end of the operational amplifier and the proportional resistor R5 through a connecting branch; and a proportional resistor R6 and a capacitor C3 are arranged on the connecting branch in parallel, wherein R1= R6.

2. The V-I conversion based laser current control circuit of claim 1, wherein: the resistance value of the current proportional resistor R4 is 0-1 omega.

3. A V-I conversion based laser current control circuit as claimed in claim 1 or 2, wherein: the sampling circuit comprises a sampling holding circuit and a light receiver PD, one end of the sampling holding circuit is grounded, and the other end of the sampling holding circuit is connected into a circuit between the light receiver PD and a voltage acquisition port of the PID controller ADC.

4. A V-I conversion based laser current control circuit as claimed in claim 3 wherein: the sample-and-hold circuit comprises a capacitor C5 and a sampling resistor R7 arranged in parallel.

5. A V-I conversion based laser current control circuit as claimed in claim 1, 2 or 4 wherein: an induction coil L1 is connected in series to the front-end circuit of the laser LD, and the other end of the laser LD is grounded.

6. A laser current control circuit based on V-I conversion comprises a PID controller, a laser transmitting circuit and a sampling circuit, wherein the laser transmitting circuit is connected with a DAC voltage output port of the PID controller, and the sampling circuit is connected with an ADC voltage acquisition port of the PID controller; the method is characterized in that: the laser emitting circuit comprises an operational amplifier, a triode and a laser LD, wherein a DAC voltage output port of the PID controller outputs a voltage which is connected to an inverting input end of the operational amplifier after passing through a proportional resistor R2, and a homodromous input end of the operational amplifier is grounded after passing through a proportional resistor R5; wherein R2= R5; the output end of the operational amplifier is connected to a pin B of the triode through a resistor R3, and is connected with the laser LD through a current proportional resistor R4 after being output by a pin E of the triode; a branch circuit connected with the proportional resistor R1 is also arranged between the proportional resistor R2 and the laser LD; a branch circuit which is connected with the capacitor C2 and then grounded is arranged on a connecting circuit of a DAC voltage output port of the PID controller and the proportional resistor R2; the pin C of the triode is grounded through a capacitor C1; a branch circuit which is connected with the capacitor C2 and is grounded is arranged between the triode and the current proportional resistor R4; the class E of the triode is connected between the reverse input end of the operational amplifier and the proportional resistor R5 through a connecting branch; and a proportional resistor R6 and a capacitor C3 are connected in parallel on the connecting branch, wherein R1= R6.

7. A V-I conversion based laser current control circuit as claimed in claim 6 wherein: the resistance value of the current proportional resistor R4 is 0-1 omega.

8. A laser current control circuit based on V-I conversion as claimed in claim 6 or 7, wherein: the sampling circuit comprises a sampling holding circuit and a light receiver PD, one end of the sampling holding circuit is grounded, and the other end of the sampling holding circuit is connected into a circuit between the light receiver PD and a voltage acquisition port of the PID controller ADC.

9. A V-I conversion based laser current control circuit as claimed in claim 8 wherein: the sample-and-hold circuit comprises a capacitor C5 and a sampling resistor R7 arranged in parallel.

10. A V-I conversion based laser current control circuit as claimed in claim 6, 7 or 9 wherein: an induction coil L1 is connected in series to the front-end circuit of the laser LD, and the other end of the laser LD is grounded.