Thermoelectric laser energy measurement circuit

Abstract

The present application relates to the technical fields of laser energy measurement, and discloses a thermoelectric laser energy measurement circuit, comprising: an excitation circuit for amplifying, comparing and then outputting an input signal to a sampling circuit; the sampling circuit is used for processing the signal output by the excitation circuit and sending the processed signal to the MCU circuit; the MCU circuit is used for processing the signal sent by the sampling circuit, converting it into an energy value and interacting with the outside through the communication circuit and the energy value; the power supply circuit is used for power supply. The present application has the advantages of low noise, low power consumption, high measurement precision and the like.

Description

Technical Field

[0001] This invention relates to the field of laser energy measurement technology, and in particular to a thermoelectric laser energy measurement circuit. Background Technology

[0002] Laser energy measurement mainly employs methods such as photoelectric, thermoelectric, and pyroelectric methods. The photoelectric method utilizes the photoelectric conversion principle of photoelectric sensors (such as Si, InGaAs, and Ge photodiodes) to convert optical signals into electrical signals, thereby measuring laser energy. The thermoelectric method measures the temperature change caused by the absorption of laser energy in the absorption cavity of an energy meter, which is then converted into an electrical signal by a thermocouple. The pyroelectric method utilizes the pyroelectric effect of a pyroelectric sensor to convert optical signals into electrical signals, thus measuring laser energy. However, existing measurement methods often suffer from low accuracy and large errors when measuring weak signals, high peak energy, and short pulse duration pulsed lasers. Therefore, improvements are needed. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides a thermoelectric laser energy measurement circuit.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a thermoelectric laser energy measurement circuit, comprising:

[0005] The excitation circuit is used to amplify and compare the input signal and then output it to the sampling circuit.

[0006] The sampling circuit is used to process the signal output by the excitation circuit and send the processed signal to the MCU circuit.

[0007] The MCU circuit is used to process the signal sent by the sampling circuit, convert it into energy value, and exchange the energy value with the outside world through the communication circuit.

[0008] Power supply circuit, used to supply power.

[0009] Preferably, it also includes an ESD protection circuit and an EMC circuit, wherein the ESD protection circuit is used to protect the sampling circuit; the ESD protection circuit includes an ESD diode of model PESD15VS2UT.

[0010] Preferably, it also includes a filtering circuit to block high-frequency noise signals and prevent the sampling circuit from being interfered with by external noise and noise from the circuit itself.

[0011] Preferably, it also includes a voltage reference source circuit for providing a reference source voltage to the sampling circuit; the voltage reference source circuit includes a CLREF0525 chip.

[0012] Preferably, the sampling circuit includes an MS1242 chip.

[0013] Preferably, the power supply circuit includes an FC-LX1D series EMC filter.

[0014] Preferably, the MCU circuit includes an STM32F103 microcontroller chip.

[0015] Preferably, the communication circuit includes an RS422 / RS485 serial communication module, a USB communication module, and an RS232 serial communication module.

[0016] This invention also includes other components that enable the normal operation of a thermoelectric laser energy measurement circuit, all of which are conventional techniques in the art. Furthermore, any devices or components not specified in this invention employ conventional techniques in the art.

[0017] This invention is used to measure pulsed lasers with high peak energy and very short pulse duration. It uses a platinum wire as the front-end sensor and employs a thermoelectric method to measure the laser energy. Platinum wire, as a high-precision and stable resistance wire, has wide applications in temperature measurement. The input of this invention is a platinum wire, and a high-precision measurement circuit based on an ARM microcontroller converts the temperature change value, thermal compensation value, and correction coefficient of the platinum wire into a laser energy value.

[0018] This invention is a high-precision laser energy measurement circuit designed with an ARM microcontroller as the core processing and control unit. It fully considers the effects of external interference, system noise, and switching noise. It uses power supply filtering devices, RC low-pass filtering devices, 24-bit AD analog-to-digital converter devices, precision constant current sources, precision differential amplifier modules, and ultra-low temperature drift precision resistors. Through a reasonable circuit layout, it is used to accurately measure the change in resistance of platinum wire, thereby realizing the conversion and output of laser energy value.

[0019] Compared with existing technologies, the present invention has advantages such as low noise, low power consumption, and high measurement accuracy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the principle of this embodiment.

[0021] Figure 2 This is a circuit diagram of the ESD protection circuit, EMC circuit, and power supply circuit in this embodiment.

[0022] Figure 3 This is a circuit diagram of the filtering circuit and the sampling circuit in this embodiment.

[0023] Figure 4 This is a circuit diagram of the voltage reference source circuit in this embodiment.

[0024] Figure 5 This is a circuit diagram of the excitation circuit in this embodiment.

[0025] Figure 6 This is a circuit diagram of the MCU circuit in this embodiment.

[0026] Figure 7 This is a circuit diagram of the communication circuit in this embodiment.

[0027] Figure 8 This is a flowchart of the process of this embodiment. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Example

[0032] See Figure 1-8 A thermoelectric laser energy measurement circuit, comprising:

[0033] The excitation circuit is used to amplify and compare the input signal and then output it to the sampling circuit.

[0034] The sampling circuit is used to process the signal output by the excitation circuit and send the processed signal to the MCU circuit.

[0035] The MCU circuit is used to process the signal sent by the sampling circuit, convert it into energy value, and exchange the energy value with the outside world through the communication circuit.

[0036] Power supply circuit, used for supplying power;

[0037] ESD protection circuit, used to protect the sampling circuit;

[0038] EMC circuit;

[0039] The filter circuit is used to block high-frequency noise signals and prevent the sampling circuit from being interfered with by external noise and noise from the circuit itself.

[0040] A voltage reference source circuit is used to provide a reference source voltage for the sampling circuit.

[0041] The ESD protection circuit includes an ESD diode of model PESD15VS2UT. Due to the usage requirements of the product adapted in this embodiment, an ESD protection circuit needs to be added during the circuit design process. The ESD protection circuit can implement a reverse-biased diode clamping circuit at the input terminal of the sampling circuit chip (i.e., the MS1242 chip in the following text), so that it is in a transparent state during normal operation, without affecting the circuit performance parameters, and can be turned on quickly and promptly under ESD diode stress, so that the ESD diode current can be smoothly discharged through the protection circuit, protecting the electrical signal flowing into the chip within a safe range.

[0042] The voltage reference source circuit includes the CLREF0525 chip. The voltage reference circuit is a crucial component of this embodiment; the stability of the reference voltage directly affects measurement accuracy. Therefore, the selection of the voltage reference source requires extreme caution. After extensive evaluation and testing, the CLREF0525 voltage reference source chip was ultimately selected. This chip can output a 2.5V reference voltage with noise levels as low as 4.8μVpp and a temperature drift of ±5ppm / ℃, meeting the noise-sensitive requirements of the ADC and providing a high-precision, stable, and reliable reference power supply.

[0043] The sampling circuit includes an MS1242 chip. The MS1242 chip is a 24-bit analog-to-digital converter (ADC) used to measure high-precision voltage signals. It is a high-precision, wide dynamic range, Σ-Δ ADC chip with an operating voltage of 2.7V to 5.25V, capable of 24-bit lossless conversion.

[0044] The power supply circuit includes an FC-LX1D series EMC filter. The power supply circuit ensures that the power supply meets EMI and surge level requirements. It includes AC-CDC, DC-CDC, and LDO circuits, capable of generating +12V, +5V, and +3.3V power supplies. Two low-noise ripple isolation circuits supply power to the digital and analog circuits respectively, achieving physical isolation between the digital and analog circuits.

[0045] The MCU circuit includes an STM32F103 microcontroller chip from ARM.

[0046] The communication circuit includes an RS422 / RS485 serial communication module, a USB communication module, and an RS232 serial communication module. These communication modules allow for data exchange with other devices / terminals.

[0047] EMC circuits are used to suppress and eliminate electromagnetic interference in a system, ensuring electromagnetic compatibility.

[0048] The EMC circuit, power supply circuit, and ESD protection circuit are connected in sequence. The ESD protection circuit is connected to the voltage reference source circuit and the MCU circuit. The power reference source circuit, filter circuit, and excitation circuit are all connected to the sampling circuit. The sampling circuit is connected to the MCU circuit. The MCU circuit is connected to the communication circuit.

[0049] In this embodiment, the filtering circuit is an RC low-pass filter. Since the sampling circuit is easily affected by external noise and electrical noise from the circuit itself, and the sampling circuit samples weak signals, the signal quality requirements are very high. If there are signal spikes or glitches in the circuit, they will have a significant impact on the test results. Therefore, a filtering circuit is added to block high-frequency noise signals, remove signal spikes or glitches, and ensure that the signal input to the sampling circuit is as clean as possible. The RC low-pass filter is mainly implemented by using a combination of resistors and capacitors. After theoretical calculations and practical verification and adjustment, a 22Ω resistor and a 100nF capacitor were finally selected to form the filter.

[0050] The excitation circuit is used for amplification, comparison, and output of the input signal. Because the excitation circuit is particularly susceptible to external electromagnetic interference and influence from other circuit modules, it is separately packaged and sealed with a metal casing during the design process. The excitation circuit mainly includes a precision constant current source, a precision differential amplifier module, and ultra-low temperature drift precision resistors, among other related components. The constant current source excites the resistor under test, and the output voltage is compared with the reference voltage of the differential amplifier module, amplified, and then output to the sampling circuit.

[0051] In this invention, the EMC circuit, power supply circuit, and ESD protection circuit are all configured to meet the power requirements of the overall circuit. When the three are connected in series, they can provide a stable power supply for the MCU circuit, sampling circuit, and other related integrated circuits.

[0052] This invention is a circuit designed for laser energy testing based on the thermoelectric method, and its specific working principle is as follows:

[0053] 1) When a platinum wire is attached to K9 glass, the laser emitted onto the glass will be converted into heat. At this time, the platinum wire will sense the change in heat, thus changing the resistance.

[0054] 2) Because the present invention requires high testing accuracy, a four-wire testing method is adopted. Four wires led out from the platinum wire are connected to the excitation circuit. The excitation circuit amplifies and compares the signal and then outputs it to the sampling circuit.

[0055] 3) After the configuration of the filter circuit and voltage reference source circuit is completed, the MS1242 chip of the AD analog-to-digital converter in the sampling circuit reads the signal output by the excitation circuit and processes the signal, and then sends the processed signal to the MCU circuit.

[0056] 4. The MCU circuit performs comparative analysis of the signal, energy formula calculation, heat loss compensation, etc., and then outputs the converted energy value and interacts with the outside through the communication circuit.

[0057] This invention is a novel thermoelectric laser energy measurement circuit developed based on projects such as high-energy laser energy measurement. This invention has already been applied in actual products and has advantages such as low noise, low power consumption, and high measurement accuracy. During the design and implementation of this invention, extensive experimental verification and repeated selection of components were conducted, ultimately resulting in this mature circuit. In practical use, this invention can measure high-energy laser energy in the range of 100J to 10000J, with a measurement error of no more than 5%.

[0058] This invention is used to measure pulsed lasers with high peak energy and very short pulse duration. It uses a platinum wire as the front-end sensor and employs a thermoelectric method to measure the laser energy. Platinum wire, as a high-precision and stable resistance wire, has wide applications in temperature measurement. The input of this invention is a platinum wire, and a high-precision measurement circuit based on an ARM microcontroller converts the temperature change value, thermal compensation value, and correction coefficient of the platinum wire into a laser energy value.

[0059] This invention is a high-precision laser energy measurement circuit designed with an ARM microcontroller as the core processing and control unit. It fully considers the effects of external interference, system noise, and switching noise. It uses power supply filtering devices, RC low-pass filtering devices, 24-bit AD analog-to-digital converter devices, precision constant current sources, precision differential amplifier modules, and ultra-low temperature drift precision resistors. Through a reasonable circuit layout, it is used to accurately measure the change in resistance of platinum wire, thereby realizing the conversion and output of laser energy value.

[0060] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A thermoelectric laser energy measurement circuit, characterized by, The application relates to a platinum resistance temperature sensor signal acquisition circuit. The excitation circuit comprises a constant current source, a differential amplification module and an ultralow-temperature-drift precision resistor, the constant current source excites the measured resistor, the output voltage is compared with the reference voltage of the differential amplification module, and then the amplified signal is output to the sampling circuit; The sampling circuit is used for processing the signal output by the excitation circuit and sending the processed signal to the MCU circuit; The MCU circuit is used for processing the signal sent by the sampling circuit, converting the signal into an energy value and performing data interaction with the outside through the communication circuit; The power supply circuit is used for power supply; The ESD protection circuit is used for protecting the sampling circuit, and the ESD protection circuit comprises an ESD diode, the ESD protection circuit is connected to the chip input end of the sampling circuit, is used for forming a reverse-biased diode clamping circuit at the chip input end of the sampling circuit, is in a transparent state to not affect the circuit performance parameters during normal work, is turned on under the stress of the ESD diode, discharges the ESD diode current through the protection circuit, and protects the electric signal flowing into the chip of the sampling circuit in a safe range; The EMC circuit is used for inhibiting and eliminating electromagnetic interference in the system; The filter circuit is used for blocking high-frequency noise signals and avoiding noise interference on the sampling circuit from the outside and the circuit itself; The voltage reference source circuit is used for providing a reference source voltage for the sampling circuit; The EMC circuit, the power supply circuit and the ESD protection circuit are sequentially connected, the ESD protection circuit is connected with the voltage reference source circuit and the MCU circuit, the power supply reference source circuit, the filter circuit and the excitation circuit are connected with the sampling circuit, the sampling circuit is connected with the MCU circuit, and the MCU circuit is connected with the communication circuit. The ESD protection circuit comprises an ESD diode with a model of PESD15VS2UT.

2. A thermoelectric laser energy measurement circuit according to claim 1, wherein: The voltage reference source circuit comprises a CLREF0525 chip.

3. A thermoelectric laser energy measurement circuit according to claim 1, wherein: The sampling circuit comprises an MS1242 chip.

4. A thermoelectric laser energy measurement circuit according to claim 1, wherein: The power supply circuit comprises an EMC filter of an FC-LX1D series.

5. A thermoelectric laser energy measurement circuit according to claim 1, wherein: The MCU circuit comprises an STM32F103 micro-control chip.

6. A thermoelectric laser energy measurement circuit according to claim 1, wherein: The communication circuit comprises an RS422 / RS485 serial communication module, a USB communication module and an RS232 serial communication module.

7. A thermoelectric laser energy measurement circuit according to claim 1, wherein: the thermoelectric laser energy measurement circuit further comprises a laser energy measurement circuit. ​

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