CN210182775U - Laser modulation drive circuit based on TDLAS - Google Patents
Laser modulation drive circuit based on TDLAS Download PDFInfo
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- CN210182775U CN210182775U CN201921168405.0U CN201921168405U CN210182775U CN 210182775 U CN210182775 U CN 210182775U CN 201921168405 U CN201921168405 U CN 201921168405U CN 210182775 U CN210182775 U CN 210182775U
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Abstract
The utility model discloses a laser modulation drive circuit based on TDLAS, which comprises an MCU circuit, a high-frequency carrier circuit and a low-frequency scanning circuit which are in communication connection with the MCU circuit, a direct current bias circuit and a signal superposition circuit; the high-frequency carrier circuit is used for generating a high-frequency sine wave signal; the low-frequency scanning circuit is used for generating a low-frequency sawtooth wave signal; the direct current bias circuit is used for generating a direct current bias signal; and the signal superposition circuit is used for superposing the high-frequency sine wave signal, the low-frequency sawtooth wave signal and the direct current offset signal to output a driving signal. The utility model discloses simple structure, interference killing feature are strong, stability is high, measurement accuracy is high, with low costs.
Description
Technical Field
The utility model belongs to the semiconductor laser field, concretely relates to laser modulation drive circuit based on TDLAS.
Background
Tunable laser diode absorption spectroscopy (TDLAS) is a technique for measuring gas by using the wavelength scanning and current tuning characteristics of a laser diode, i.e. the narrow line width and wavelength of a tunable semiconductor laser are changed with the injection current to measure the absorption line of a single molecule or a plurality of molecules which are very close to each other and difficult to distinguish, and has the advantages of high selectivity, high resolution, high reaction speed, high sensitivity and the like.
The reliability and accuracy of the laser driving circuit are very critical, the wavelength emitted by the laser can be more stable, the laser can scan around the central wavelength of the gas, the gas can be fully absorbed, and the gas detection precision is improved. When a high-frequency carrier signal is loaded on a low-frequency scanning signal by a traditional laser driving circuit based on the TDLAS technology, an additional signal generator is often needed to be configured, and the cost is high; in addition, the signal synchronization problem is not easy to solve, and is not suitable for online instrument application; in addition, the structure of a laser driving circuit in the existing online instrument is complex, the system is easy to interfere, the stability is not high, the measurement result is not accurate, and the like.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to the problem that exists with not enough above-mentioned, provide a laser modulation drive circuit based on TDLAS, simple structure, interference killing feature are strong, stability is high, measurement accuracy is high, with low costs.
In order to realize the purpose, the utility model discloses a technical scheme is: a laser modulation drive circuit based on TDLAS comprises an MCU circuit, a high-frequency carrier circuit and a low-frequency scanning circuit which are in communication connection with the MCU circuit, a direct current bias circuit and a signal superposition circuit;
the high-frequency carrier circuit is used for generating a high-frequency sine wave signal;
the low-frequency scanning circuit is used for generating a low-frequency sawtooth wave signal;
the direct current bias circuit is used for generating a direct current bias signal;
and the signal superposition circuit is used for superposing the high-frequency sine wave signal, the low-frequency sawtooth wave signal and the direct current offset signal to output a driving signal.
Further perfecting the technical scheme, the circuit also comprises 3 voltage following circuits which are respectively arranged at the rear stages of the direct current bias circuit, the high-frequency carrier circuit and the low-frequency scanning circuit, and the output of each voltage following circuit is respectively connected to the input of the signal superposition circuit.
Further, the voltage follower circuit adopts an OPA2188AIDR operational amplifier to form a voltage follower.
Furthermore, the direct current bias circuit is formed by an OP07CDR operational amplifier and is used for outputting a direct current signal with adjustable amplitude.
Furthermore, the high-frequency carrier circuit is formed by adopting a DDS chip with the model number of AD9833 BRMZ.
Further, the low frequency scanning circuit is formed by using a DAC8830ID chip.
Further, the signal superposition circuit uses an OPA2188AIDR operational amplifier to form an adder.
Further, the device also comprises a driving amplifying circuit which is used for amplifying and outputting the driving signal output by the signal superposition circuit.
The utility model has the advantages that: the utility model forms the driving signal by the superposition of the direct current bias signal, the high frequency sine wave signal and the low frequency sawtooth wave signal, reduces the system interference and improves the reliability of the system operation; the high-frequency sine wave signal and the low-frequency sawtooth wave signal are generated through the MCU circuit and a specific functional chip, an additional signal generator is not needed, the structure is simple, and the cost is low; meanwhile, voltage follower circuits are respectively arranged at the rear stages of the direct current bias circuit, the high-frequency carrier circuit and the low-frequency scanning circuit so as to reduce the output impedance of the 3 signal generating circuits and improve the loading capacity.
Drawings
Fig. 1 is a block diagram of the circuit structure of the present invention;
FIG. 2 is a circuit diagram of a portion of the MCU circuit of FIG. 1;
FIG. 3 is a circuit diagram of the high frequency carrier circuit of FIG. 1;
FIG. 4 is a circuit diagram of the low frequency scanning circuit of FIG. 1;
FIG. 5 is a circuit diagram of the DC bias circuit of FIG. 1;
FIG. 6 is a circuit diagram of the 3-way voltage follower circuit of FIG. 1;
fig. 7 is a circuit diagram of the signal superimposing circuit in fig. 1.
Detailed Description
In order to make the disclosure of the present invention clearer, the following detailed description of the embodiments of the present invention is made with reference to the accompanying drawings. It should be noted that for the sake of clarity, the figures and the description omit representation and description of parts not relevant to the present invention, known to a person skilled in the art.
Example 1:
the utility model provides a laser modulation drive circuit based on TDLAS, as shown in figure 1, comprising an MCU circuit, a high frequency carrier circuit and a low frequency scanning circuit which are connected with the MCU circuit in communication, a DC bias circuit and a signal superposition circuit;
the high-frequency carrier circuit is used for generating a high-frequency sine wave signal;
the low-frequency scanning circuit is used for generating a low-frequency sawtooth wave signal;
the direct current bias circuit is used for generating a direct current bias signal;
and the signal superposition circuit is used for superposing the high-frequency sine wave signal, the low-frequency sawtooth wave signal and the direct current offset signal to output a driving signal.
The circuit also comprises 3 voltage following circuits which are respectively a first following circuit, a second following circuit and a third following circuit and are respectively arranged at the rear stages of the direct current bias circuit, the high-frequency carrier circuit and the low-frequency scanning circuit, and the output of each voltage following circuit is respectively connected to the input of the signal superposition circuit.
The laser device also comprises a driving amplifying circuit which is used for amplifying and outputting the driving signal output by the signal superposition circuit so as to drive the laser.
As shown in fig. 2, the MCU circuit adopts STM32F103ZET6 chip, the kernel is 32-bit Cortex-M3CPU, its FLASH512K, SRAM 64K; there are 3 groups of configurable SPI communication channels, wherein, the SPI1 channel is used for the communication of MCU and DDS chip, and the SPI2 channel is used for the communication of MCU and DAC chip.
As shown in FIG. 3, the high frequency carrier circuit includes an external clock circuit U12 and a DDS chip U11 with model number AD9833BRMZ, and the power supply range of the DDS chip U11 is 2.3V-5.5V. The concrete connection mode is as follows: the 3 feet of an external clock circuit U12 are connected with the 5 feet of a DDS chip U11, the 1 foot of the DDS chip U11 is connected with a 3.3V power supply through a capacitor C27, the 2 feet of the DDS chip U11 are connected with a 3.3V power supply, the 3 feet of the DDS chip U11 are grounded through a capacitor C25, the 4 feet of the DDS chip U11 are grounded, the 6 feet of the DDS chip U11 are connected with the 43 feet of an STM32F103ZET6 chip, the 7 feet of the DDS chip U11 are connected with the 41 feet of the STM32F103ZET6 chip, the 8 feet of the DDS chip U11 are connected with the 40 feet of the STM32F103ZET6 chip, the 9 feet of the DDS chip U11 are grounded, and the 10 feet of the DDS chip. The working principle is as follows: the DDS chip U11 communicates with the MCU circuit through the SPI, so that the frequency and phase of the sine wave signal can be adjusted. The DDS adopts an external active crystal oscillator of 20MHZ, and the DSS register is operated by the single chip microcomputer to output 1/3 times of the frequency of the active crystal oscillator, so that signal superposition can be facilitated and no distortion is ensured. When the output frequency is 20KHz, the amplitude is 600 mV.
As shown in fig. 4, the low frequency scanning circuit is formed by a DAC8830ID chip U14, and the specific circuit connection mode is as follows: a pin 1 of a DAC8830ID chip U14 is an output end, and an output signal is a sawtooth wave signal LFSW; the 2 pin of the DAC8830ID chip U14 is grounded, the 3 pin of the DAC8830ID chip U14 is connected with a reference voltage source of 2.5V, the 4 pin of the DAC8830ID chip U14 is connected with the 73 pin of the STM32F103ZET6 chip, the 5 pin of the DAC8830ID chip U14 is connected with the 74 pin of the STM32F103ZET6 chip, the 6 pin of the DAC8830ID chip U14 is connected with the 76 pin of the STM32F103ZET6 chip, the 7 pin of the DAC8830ID chip U14 is grounded, and the 8 pin of the DAC8830ID chip U14 is connected with a 3.3V power supply. The working principle is as follows: the DAC8830ID chip is adopted, the chip is powered by a 5V power supply, a reference voltage source is 2.5V, the output voltage is 0-2.5V adjustable, and the output sawtooth wave voltage is changed by operating a register through the SPI of the MCU circuit.
As shown in fig. 5, the dc bias circuit is formed by an OP07CDR operational amplifier, and is configured to output a dc voltage signal with an adjustable amplitude. The specific circuit connection mode is as follows: the 4-pin of the operational amplifier U13A is connected with a-15V power supply, the 8-pin of the operational amplifier U13A is connected with a +15V power supply, the 3-pin of the operational amplifier U13A is respectively connected with one end of a resistor R45 and one end of a resistor R48, the other end of the resistor R45 is grounded, the other end of the resistor R48 is connected with a reference voltage source of 2.5V, the 2-pin of the operational amplifier U13A is connected with the resistor R47 which is grounded, a variable resistor R57 is arranged between the 1-pin and the 2-pin of the operational amplifier U13A, the 1-pin of the operational amplifier U13A is an output end, and the output signal. The working principle is as follows: the signal position is shifted by amplifying the voltage of 0-5 times by the operational amplifier U13A after dividing the voltage of the reference voltage source by 2.5V, and the displacement is changed by adjusting the adjustable resistor to change the voltage.
As shown in fig. 6, the voltage follower circuit adopts an OPA2188aid dr operational amplifier to form a voltage follower, and the specific connection manner is as follows: the non-inverting input end of the OPA2188AIDR operational amplifier is a signal input end, the output end of the OPA2188AIDR operational amplifier is connected with the inverting input end, 4 pins of the OPA2188AIDR operational amplifier are connected with a-15V power supply, and 8 pins of the OPA2188AIDR operational amplifier are connected with a 15V power supply; the output DCS of the DC bias circuit, the output SINW of the high-frequency carrier circuit and the output LFSW of the low-frequency scanning circuit are respectively connected to the signal input end of the 3-path voltage follower circuit, and the output end of the 3-path voltage follower circuit outputs corresponding signals. The working principle is as follows: the OPA2188AIDR operational amplifier is adopted, the operational amplifier power supply voltage is +/-15V, the output impedance of the signal generating circuit in the circuit 3 is reduced through the voltage follower circuit, and the load carrying capacity is improved.
As shown in fig. 7, the signal superposition circuit uses OPA2188aid dr operational amplifier to form an adder, and the specific connection mode is as follows: the DC bias voltage signal DCS, the high-frequency carrier signal SINW and the low-frequency scanning signal LFSW are respectively connected to a non-inverting input end of an operational amplifier U18A through resistors R52, R51 and R50, a non-inverting input end of the operational amplifier U18A is connected with a resistor R53 and is grounded, an inverting input end of the operational amplifier U18A is connected with resistors R54, R55 and R56 in parallel, a resistor R49 is arranged between an output end and an inverting input end of an operational amplifier U18A, an output end of the operational amplifier U18A is connected with a non-inverting input end of a voltage follower U18B, an output end of the voltage follower U18B is connected with resistors R41 and R39 in series and is grounded, two ends of a resistor R39 are connected with a capacitor C35 in parallel, and a connecting end of the resistors R41 and. The working principle is as follows: the signal superposition circuit adopts OPA188AIDR, three signals are superposed together through the addition circuit, when the resistance R51 input by the sine carrier wave is increased by 10 times, the superposition is carried out, the operational amplification is carried out, the signals are generated by 4 times and then output, and the output 0-2.5 v modulation driving signals can be obviously seen through the oscilloscope.
The above description is only intended to illustrate embodiments of the present invention, and the description is specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (8)
1. The utility model provides a laser instrument modulation drive circuit based on TDLAS which characterized in that: the device comprises an MCU circuit, a high-frequency carrier circuit and a low-frequency scanning circuit which are in communication connection with the MCU circuit, a direct current bias circuit and a signal superposition circuit;
the high-frequency carrier circuit is used for generating a high-frequency sine wave signal;
the low-frequency scanning circuit is used for generating a low-frequency sawtooth wave signal;
the direct current bias circuit is used for generating a direct current bias signal;
and the signal superposition circuit is used for superposing the high-frequency sine wave signal, the low-frequency sawtooth wave signal and the direct current offset signal to output a driving signal.
2. The TDLAS-based laser modulation driver circuit of claim 1, wherein: the circuit also comprises 3 voltage following circuits which are respectively arranged at the rear stages of the direct current bias circuit, the high-frequency carrier circuit and the low-frequency scanning circuit, and the output of each voltage following circuit is respectively connected to the input of the signal superposition circuit.
3. The TDLAS-based laser modulation driver circuit of claim 2, wherein: the voltage follower circuit adopts an OPA2188AIDR operational amplifier to form a voltage follower.
4. The TDLAS-based laser modulation driver circuit of claim 1, wherein: the direct current bias circuit is formed by an OP07CDR operational amplifier and is used for outputting a direct current signal with adjustable amplitude.
5. The TDLAS-based laser modulation driver circuit of claim 1, wherein: the high-frequency carrier circuit is formed by a DDS chip with the model number of AD9833 BRMZ.
6. The TDLAS-based laser modulation driver circuit of claim 1, wherein: the low frequency scanning circuit is formed by using a DAC8830ID chip.
7. The TDLAS-based laser modulation driver circuit of claim 1, wherein: the signal superposition circuit adopts an OPA2188AIDR operational amplifier to form an adder.
8. The TDLAS-based laser modulation driver circuit as claimed in any of claims 1 to 7, wherein: the driving amplifying circuit is used for amplifying and outputting the driving signal output by the signal superposition circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201921168405.0U CN210182775U (en) | 2019-07-23 | 2019-07-23 | Laser modulation drive circuit based on TDLAS |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921168405.0U CN210182775U (en) | 2019-07-23 | 2019-07-23 | Laser modulation drive circuit based on TDLAS |
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| CN210182775U true CN210182775U (en) | 2020-03-24 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113097862A (en) * | 2021-04-16 | 2021-07-09 | 中国科学院长春光学精密机械与物理研究所 | Driving signal generating device |
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2019
- 2019-07-23 CN CN201921168405.0U patent/CN210182775U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113097862A (en) * | 2021-04-16 | 2021-07-09 | 中国科学院长春光学精密机械与物理研究所 | Driving signal generating device |
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