Laser temperature measurement circuit
By designing a laser temperature measurement circuit with adjustable bias current, the problems of insufficient compatibility, stability and safety in the existing technology are solved, multi-sensor adaptation and cost reduction are achieved, and the overall performance of laser temperature measurement is improved.
Patent Information
- Application Number
- CN202511336170.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2025-12-16
AI Technical Summary
Existing laser temperature measurement circuits suffer from poor compatibility, insufficient stability, low safety, and high cost, especially in terms of adaptability to different sensors and in terms of driving and signal processing.
A laser temperature measurement circuit was designed, comprising a reference voltage generation module, a differential operation module, a bias current driving module, and a temperature output module. The circuit achieves adjustable bias current through interstage feedback of operational amplifiers, is compatible with various sensors, and automatically shuts off the bias current to protect the laser in case of abnormal output.
This invention achieves high compatibility of laser temperature measurement circuit, improves temperature measurement accuracy and stability, reduces costs, avoids laser damage caused by sensor malfunction, and enhances circuit safety and versatility.
Smart Images
Figure CN121140973A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of laser, and particularly to a laser temperature measurement circuit. BACKGROUND
[0002] In the operation of the laser, the temperature measurement circuit guarantees the stable operation of the laser by monitoring the temperature in the cavity in real time. Currently, the temperature measurement methods mainly include thermocouple, thermistor, integrated circuit, etc. However, there are many technical defects.
[0003] From the adaptability and cost of the sensor, the laser using a specific sensor package excessively depends on the manufacturing process of the sensor, and the cost is high. The laser supporting different sensor packages needs to design corresponding temperature measurement circuits due to different sensor principles and compensation requirements, and the universality is poor. From the perspective of driving and signal processing, when using sensors such as thermistor, resistance temperature detector (RTD) or temperature sensor chip (for example, chip model LM335), a constant current source is needed for driving, but there are obvious deficiencies: first, the constant current source of the thermistor is easily affected by the supply voltage, and the analog voltage is disturbed by the power supply fluctuation, which needs additional compensation or isolation; second, some negative temperature coefficient (NTC) sensors need a large bias current, and if the current is abnormal, the temperature measurement voltage may be too low, which may cause the heating of the temperature control end to be too large and burn out the laser. In addition, for integrated sensors, the sampling resistance value is single or the adjustable range is small, which is only suitable for specific lasers and has poor compatibility.
[0004] In summary, the existing circuit has problems in compatibility, stability, safety and precision, and there is an urgent need for a laser temperature measurement circuit that can support multiple sensors and has an adjustable bias current. SUMMARY
[0005] The present application aims to provide a laser temperature measurement circuit with an adjustable bias current, so as to support multiple sensors and improve the universality of the laser temperature measurement circuit.
[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows: A laser temperature measurement circuit, comprising a reference voltage generation module, a differential operation module, a bias current driving module and a temperature output module, the reference voltage generation module, the differential operation module, the bias current driving module and the temperature output module are connected in sequence, and the bias current driving module provides an adjustable bias current.
[0007] Further, the reference voltage generating module comprises a first operational amplifier, a second operational amplifier, a first resistor, a second resistor, a first end of the first resistor is connected with the first voltage, a second end of the first resistor is connected with a first end of the second resistor and a first input end of the first operational amplifier, a second end of the second resistor is grounded, an output end of the first operational amplifier is connected with a second input end of itself and a first input end of the second operational amplifier, an output end of the second operational amplifier is connected with a second input end of itself, and the output end of the second operational amplifier is also connected to the differential operation module.
[0008] Further, the differential operation module comprises a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first end of the fifth resistor is connected with an output end of the first operational amplifier, a second end of the fifth resistor is connected with a second input end of the third operational amplifier, a first end of the sixth resistor is connected with a first input end of the third operational amplifier, a second end of the sixth resistor is grounded, a first end of the seventh resistor is connected with an output end of the second operational amplifier, a second end of the seventh resistor is connected with a first end of the sixth resistor, a first end of the eighth resistor is connected with a second input end of the third operational amplifier, a second end of the eighth resistor is connected with an output end of the third operational amplifier, and the output end of the third operational amplifier is connected to the bias current driving module.
[0009] Further, the bias current driving module comprises a fourth operational amplifier, a first transistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fourteenth resistor, a first end of the ninth resistor is connected with an output end of the third operational amplifier in the differential operation module, a second end of the ninth resistor is connected with a first input end of the fourth operational amplifier, a first end of the tenth resistor is connected with a second input end of the fourth operational amplifier, a second end of the tenth resistor is connected with a source of the first transistor, a first end of the eleventh resistor is connected with an output end of the fourth operational amplifier, a second end of the eleventh resistor is connected with a gate of the first transistor, a first end of the fourteenth resistor is connected with a first input end of the third operational amplifier in the differential operation module, a second end of the fourteenth resistor is connected with a source of the first transistor, a drain of the first transistor is connected as a load end, and the load end is connected with the load in one way and connected with the temperature output module in the other way.
[0010] Further, the temperature output module comprises a fifth operational amplifier, a twelfth resistor, a thirteenth resistor and a first interface, the first input end of the fifth operational amplifier is connected with the drain of the first transistor, the first end of the twelfth resistor is the first interface, the second end of the twelfth resistor is connected with the output end of the fifth operational amplifier and the first end of the thirteenth resistor, and the second end of the thirteenth resistor is connected with the second input end of the fifth operational amplifier.
[0011] Specifically, the drain of the first transistor is connected with a load.
[0012] More specifically, the load comprises a fifteenth resistor, the first end of the fifteenth resistor is connected with the drain of the first transistor, and the second end of the fifteenth resistor is grounded.
[0013] More specifically, the fifteenth resistor is a thermistor, a resistance temperature detector or a temperature sensor chip.
[0014] In an embodiment, the bias current driving module comprises a second capacitor, the first end of the second capacitor is connected with the connection point of the second end of the eleventh resistor and the gate of the transistor, and the second end of the second capacitor is connected with the source of the first transistor.
[0015] More specifically, the first transistor is a P-channel metal-oxide-semiconductor field effect transistor.
[0016] The laser temperature measuring circuit provided by the application can realize adjustable bias current, realizes accurate adjustment of the bias current through inter-stage feedback of the operational amplifier, and is compatible with various temperature sensors. In addition, when the output voltage of the operational amplifier is abnormal, the temperature measuring circuit can automatically turn off the bias current, prevents sudden temperature voltage change from causing the laser to be suddenly heated too much and damaged.
[0017] To make the above features and advantages of the application more obvious and easy to understand, the following specific embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 A module schematic diagram of the laser temperature measuring circuit provided by the application.
[0019] Figure 2 A circuit schematic diagram of the laser temperature measuring circuit provided by the application. DETAILED DESCRIPTION
[0020] In order to make the technical scheme of the present application clearer, the technical scheme will be described below in connection with the drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.
[0021] The present application provides a laser temperature measurement circuit, and the following will be described in detail. Figure 1 A schematic diagram of a laser temperature measurement circuit module is provided in the present application. As shown in Figure 1 A laser temperature measurement circuit 1 includes a reference voltage generation module 11, a differential operation module 12, a bias current driving module 13 and a temperature output module 14, which are connected in sequence.
[0022] Further, the laser temperature measurement circuit 1 is connected to a load 2, specifically, the load 2 is connected to the bias current driving module 13.
[0023] More specifically, the reference voltage generation module 11 generates a reference voltage to the differential operation module 12; the differential operation module 12 suppresses common-mode interference and purifies the output signal; the bias current driving module 13 provides adjustable bias current; the temperature output module 14 outputs the analog voltage of the laser temperature to the outside of the system; and the load 2 can be connected to different types of sensors.
[0024] Figure 2 A circuit schematic diagram of a laser temperature measurement circuit is shown. As shown in Figure 2 The reference voltage generation module 11 includes an operational amplifier U1, an operational amplifier U2, a resistor R1 and a resistor R2, the voltage VCC is connected to the first end of the resistor R1, the second end of the resistor R1 is connected to the first end of the resistor R2 and the first input end of the operational amplifier U1, the second end of the resistor R2 is grounded, the output end of the operational amplifier U1 is connected to its own second input end and the first input end of the operational amplifier U2, the output end of the operational amplifier U2 is connected to its own second input end, and the output end of the operational amplifier U2 is also connected to the differential operation module 12.
[0025] Further, the first input ends of the operational amplifier U1 and the operational amplifier U2 are the same phase input ends, and the second input ends of the operational amplifier U1 and the operational amplifier U2 are the opposite phase input ends.
[0026] More specifically, the operational amplifier U1 and the operational amplifier U2 are used as voltage followers.
[0027] More specifically, the operational amplifier U1 and the operational amplifier U2 are rail-to-rail field effect transistor (FET) operational amplifiers.
[0028] Optionally, the reference voltage generating module 11 further comprises a capacitor C1 connected in parallel to the resistor R2. The capacitor C1 functions as a filter.
[0029] Optionally, the reference voltage generating module 11 further comprises a resistor R3, a capacitor C3 and a resistor R4, the first end of the resistor R3 is connected to the second input end of the operational amplifier U2, the first end of the resistor R4 and the first end of the capacitor C3, the output end of the operational amplifier U2 is connected to the second end of the resistor R3 and the second end of the capacitor C3, and the second end of the resistor R4 is grounded. The resistor R3 and the resistor R4 participate in the operation of outputting a fixed voltage value, and the capacitor C3 suppresses self-oscillation of the operational amplifier U2, improves the stability of the circuit, filters out high-frequency noise, and prevents interference to the subsequent stage.
[0030] More specifically, the voltage VCC functions as a power supply.
[0031] In a specific embodiment, the voltage VCC can be 5V.
[0032] Further, the differential operation module 12 comprises an operational amplifier U3, a resistor R5, a resistor R6, a resistor R7, and a resistor R8, the first end of the resistor R5 is connected to the output end of the operational amplifier U1, the second end of the resistor R5 is connected to the second input end of the operational amplifier U3, the first end of the resistor R6 is connected to the first input end of the operational amplifier U3, the second end of the resistor R6 is grounded, the first end of the resistor R7 is connected to the output end of the operational amplifier U2, the second end of the resistor R7 is connected to the first end of the resistor R6, the first end of the resistor R8 is connected to the second input end of the operational amplifier U3, the second end of the resistor R8 is connected to the output end of the operational amplifier U3, and the output end of the operational amplifier U3 is connected to the bias current driving module 13.
[0033] Further, the first input end of the operational amplifier U3 is a non-inverting input end, and the second input end of the operational amplifier U3 is an inverting input end.
[0034] Specifically, the operational amplifier U3 and the resistor R8 constitute a feedback loop, which can suppress common-mode interference of the voltage reference signal, thereby effectively solving the influence of common-mode noise on the circuit.
[0035] Further, the bias current driving module 13 comprises an operational amplifier U4, a transistor Q1, a resistor R9, a resistor R10, a resistor R11, and a resistor RS. The first end of the resistor R9 is connected to the output end of the operational amplifier U3 in the differential operation module, the second end of the resistor R9 is connected to the first input end of the operational amplifier U4, the first end of the resistor R10 is connected to the second input end of the operational amplifier U4, the second end of the resistor R10 is connected to the source of the transistor Q1, the first end of the resistor R11 is connected to the output end of the operational amplifier U4, the second end of the resistor R11 is connected to the gate of the transistor Q1, the first end of the resistor RS is connected to the first input end of the operational amplifier U3 in the differential operation module, the second end of the resistor RS is connected to the source of the transistor Q1, and the drain of the transistor Q1 is connected as a load end, which is connected to the load 2 in one way and to the temperature output module 14 in the other way.
[0036] Further, the first input end of the operational amplifier U4 is a non-inverting input end, and the second input end of the operational amplifier U4 is an inverting input end.
[0037] Specifically, the operational amplifier U3, the operational amplifier U4, the transistor Q1, the resistor R10, and the resistor RS constitute an inter-stage feedback, so as to realize adjustable bias current and avoid noise transmission from the differential operation module 12 to the bias current driving module 13, and further guarantee the stability of the bias current.
[0038] More specifically, the resistor RS is a potentiometer, which is used as an inter-stage feedback resistor.
[0039] More specifically, when the output voltage of the operational amplifier U3 and the operational amplifier U4 is normal, the transistor Q1 is in a conductive state, and the bias current can flow through the load 2 smoothly; when the output voltage is abnormal, the transistor Q1 is cut off, so as to achieve the function of cutting off the bias current, and prevent the sudden temperature and voltage change from causing the laser to heat too much and be damaged.
[0040] Optionally, the transistor Q1 is a metal oxide semiconductor field effect transistor (MOSFET).
[0041] More specifically, the transistor Q1 is a P-channel MOSFET.
[0042] Optionally, the bias current driving circuit 13 further comprises a capacitor C2, the first end of the capacitor C2 is connected to the output end of the operational amplifier U4 and the first end of the resistor R11, the second end of the capacitor C2 is connected to the source of the transistor Q1, the capacitor C2 is between the source and the gate of the transistor Q1, so as to prevent the transistor Q1 from being mis-conducted and have a filtering effect.
[0043] Further, the temperature output module 14 comprises an operational amplifier U5, a resistor R12, and a resistor R13, the first input terminal of the operational amplifier U5 is connected to the drain of the transistor Q1, the first terminal of the resistor R12 is the interface J1, the second terminal of the resistor R12 is connected to the output terminal of the operational amplifier U5 and the first terminal of the resistor R13, and the second terminal of the resistor R13 is connected to the second input terminal of the operational amplifier U5.
[0044] Further, the first input terminal of the operational amplifier U5 is the non-inverting input terminal, and the second input terminal of the operational amplifier U5 is the inverting input terminal.
[0045] Further, the interface J1 is used for external signal acquisition or debugging.
[0046] Specifically, the output terminal of the operational amplifier U5 is connected to the second input terminal of the operational amplifier U5 through the resistor R13, so as to form a voltage follower.
[0047] More specifically, the output terminal of the operational amplifier U5 is used as the output terminal of the temperature analog voltage, and transmits the voltage signal representing the temperature to the outside of the system.
[0048] Further, the load 2 comprises a resistor RL, the first terminal of the resistor RL is connected to the drain of the transistor Q1, and the second terminal is grounded.
[0049] Specifically, the load 2 changes its resistance / voltage characteristics by sensing the temperature change, and is compatible with various sensors, so as to realize temperature measurement in cooperation with the temperature output module 14.
[0050] Optionally, the resistor RL can be a thermistor, a resistance temperature detector (RTD), a temperature sensor chip, or the like, and senses the temperature change by being directly connected to the drain of the transistor Q1.
[0051] Optionally, the resistance of the thermistor can be 100Ω to 100KΩ.
[0052] Optionally, the resistance of the resistance temperature detector can be 100Ω.
[0053] Optionally, the model of the temperature sensor chip can be LM335.
[0054] The working principle of the application will be further introduced below. Figure 2 The working principle of the application will be further introduced below.
[0055] Firstly, the voltage VCC is divided by the resistor R1 and the resistor R2 to obtain the reference voltage Vref, and the reference voltage Vref is stabilized by the operational amplifier U1 to obtain a stable reference voltage signal. One way of the reference voltage signal is connected to the inverting input terminal of the operational amplifier U3 through the resistor R5, and the other way of the reference voltage signal is connected to the non-inverting input terminal of the operational amplifier U3 through the operational amplifier U2 to further suppress current noise. In the reference voltage generating module 11, the high input impedance of the operational amplifier U1 and the operational amplifier U2 is used to reduce current noise and provide a stable reference voltage signal.
[0056] Further, the reference voltage signal enters the differential operation module 12, and the differential operation module 12 can suppress common-mode interference in the reference voltage signal. The output signal of the differential operation module 12 enters the bias current driving module 13 through the resistor R9.
[0057] Further, the output terminal of the operational amplifier U4 is connected to the gate of the transistor Q1 through the resistor R11. The source of the transistor Q1 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R10, and is connected to the non-inverting input terminal of the operational amplifier U3 through the resistor RS in series. The constant voltage is generated between the source and the gate of the transistor Q1 through the inter-stage feedback of the operational amplifier U3 and the operational amplifier U4, that is, the bias current is generated between the resistors RS. By adjusting the resistance value of the resistor RS, the adjustable bias current is formed. Under normal circumstances, the transistor Q1 is in the on state, and the bias current can smoothly flow through the load 2. When the output of the operational amplifier is abnormal, the voltage between the gate and the source of the transistor Q1 cannot meet the on condition of the transistor Q1, and at this time, the transistor Q1 is cut off, thereby shutting off the bias current and protecting the laser. The sensor in the load 2 can sense the temperature change. The drain of the transistor Q1 is connected to the sensor in one way, and is connected to the operational amplifier U5 in the other way, so as to convert the temperature signal sensed by the sensor into an analog voltage output, thereby realizing temperature measurement.
[0058] The laser temperature measuring circuit provided by the application realizes multiple technical effects by optimizing the circuit design, in compatibility, by virtue of the design of adjustable bias current, various sensors such as thermistors, resistance temperature detectors (RTD), temperature sensor chips, etc. in the load 2 can be adapted, without the need to design a circuit for different sensors separately, greatly improving the universality of the circuit, solving the problem of poor adaptability of the traditional circuit. The differential operation module can effectively suppress common-mode interference, and the inter-stage feedback mechanism of the operational amplifier can guarantee the stability of the bias current, reduce the influence of factors such as power supply fluctuation, improve the temperature measurement precision and the stability of the circuit, and overcome the defects of insufficient precision and poor stability of the traditional compatible circuit. In safety, the transistor Q1 will automatically cut off when the output of the operational amplifier is abnormal, and the bias current is turned off, avoiding damage caused by excessive heating of the laser due to abnormal instantaneous temperature measurement voltage, eliminating the safety hazards caused by abnormal sensor bias current in the traditional circuit. In addition, the laser temperature measuring circuit provided by the application does not need to rely on the manufacturing process of a specific sensor, and is compatible with multiple sensors, reducing the dependence on sensors and the cost of circuit design, solving the problem of high cost of traditional specific sensor packaging circuit.
[0059] In summary, the laser temperature measuring circuit provided by the application has breakthroughs in compatibility, precision, stability, safety and cost control, and meets the actual needs of laser temperature measurement.
[0060] Although the application has been disclosed as above, it is not intended to limit the application, and anyone with ordinary knowledge in the art can make some changes and modifications without departing from the spirit and scope of the application, so the protection scope of the application shall be subject to the appended patent application scope.
Claims
1. A laser temperature measuring circuit, characterized by comprising: The reference voltage generating module, the differential operation module, the bias current driving module and the temperature output module are sequentially connected; the bias current driving module provides adjustable bias current. The reference voltage generating module includes a first operational amplifier, a second operational amplifier, a first resistor and a second resistor, a first voltage is connected to a first end of the first resistor, a second end of the first resistor is connected to a first end of the second resistor and a first input end of the first operational amplifier, a second end of the second resistor is grounded, an output end of the first operational amplifier is connected to a second input end of itself and a first input end of the second operational amplifier, an output end of the second operational amplifier is connected to a second input end of itself, and the output end of the second operational amplifier is also connected to the differential operation module.
2. A laser temperature sensing circuit as claimed in claim 1, characterized in that The differential operation module includes a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor, a first end of the fifth resistor is connected to an output end of the first operational amplifier, a second end of the fifth resistor is connected to a second input end of the third operational amplifier, a first end of the sixth resistor is connected to a first input end of the third operational amplifier, a second end of the sixth resistor is grounded, a first end of the seventh resistor is connected to an output end of the second operational amplifier, a second end of the seventh resistor is connected to a first end of the sixth resistor, a first end of the eighth resistor is connected to a second input end of the third operational amplifier, a second end of the eighth resistor is connected to an output end of the third operational amplifier, and the output end of the third operational amplifier is connected to the bias current driving module.
3. A laser temperature sensing circuit as claimed in claim 2, wherein The bias current driving module includes a fourth operational amplifier, a first transistor, a ninth resistor, a tenth resistor, an eleventh resistor and a fourteenth resistor, a first end of the ninth resistor is connected to an output end of the third operational amplifier in the differential operation module, a second end of the ninth resistor is connected to a first input end of the fourth operational amplifier, a first end of the tenth resistor is connected to a second input end of the fourth operational amplifier, a second end of the tenth resistor is connected to a source of the first transistor, a first end of the eleventh resistor is connected to an output end of the fourth operational amplifier, a second end of the eleventh resistor is connected to a gate of the first transistor, a first end of the fourteenth resistor is connected to a first input end of the third operational amplifier in the differential operation module, and a second end of the fourteenth resistor is connected to a source of the first transistor.
4. The laser temperature measurement circuit as described in claim 3, characterized in that, The temperature output module includes a fifth operational amplifier, a twelfth resistor and a thirteenth resistor, a first input end of the fifth operational amplifier is connected to a drain of the first transistor, a first end of the twelfth resistor is a first interface, a second end of the twelfth resistor is connected to an output end of the fifth operational amplifier and a first end of the thirteenth resistor, and a second end of the thirteenth resistor is connected to a second input end of the fifth operational amplifier.
5. A laser temperature sensing circuit as claimed in claim 4, wherein the laser temperature sensing circuit is configured to determine the temperature of the laser by comparing the voltage across the resistor with a predetermined voltage value. The drain of the first transistor is connected to a load.
6. A laser temperature sensing circuit as claimed in claim 4, wherein, 7. A laser temperature measurement circuit as described in claim 6, characterized in that, The load comprises a fifteenth resistor, a first end of the fifteenth resistor is connected to the drain of the first transistor, and a second end of the fifteenth resistor is grounded.
8. The laser temperature measurement circuit as described in claim 7, characterized in that, The fifteenth resistor is a thermistor or a resistance temperature detector or a temperature sensor chip.
9. A laser temperature sensing circuit as claimed in claim 4, wherein, The bias current driving module further comprises a second capacitor, a first end of the second capacitor is connected to the output end of the fourth operational amplifier and the first end of the eleventh resistor, and a second end of the second capacitor is connected to the source of the first transistor.
10. A laser temperature sensing circuit as claimed in claim 3, wherein, The first transistor is a P-channel metal-oxide-semiconductor field-effect transistor.