TDLAS laser head high-precision constant temperature circuit and device

Abstract

The utility model relates to a TDLAS laser head high precision constant temperature circuit and device, the constant temperature circuit comprises a temperature sensor, a temperature acquisition module, two paths of operational amplifiers, a differential amplifier, an integrator, a comparator and a TEC module, the temperature sensor is divided into two paths to output analog temperature signals, and the differential amplifier is connected with the integrator. The digital temperature signals are respectively input to the temperature acquisition module and the first operational amplifier, the temperature acquisition module outputs the digital temperature signals and inputs the digital temperature signals to the second operational amplifier, the output ends of the two operational amplifiers are respectively connected to the differential amplifier, the output end of the differential amplifier is connected to the integrator, and the integrator outputs time voltage signals to the comparator. And the comparator outputs a control signal to the TEC module. Compared with traditional mos tube driving, the TDLAS laser head high-precision constant-temperature circuit and device have the advantages that power consumption and temperature are low, a radiator is not needed, the TEC driving capacity is high, the circuit size is smaller, and performance stability is more reliable.

Description

Technical Field

[0001] The utility model relates to the technical field of spectrum measurement, in particular to a high-precision constant temperature circuit and device for a TDLAS laser head. Background Art

[0002] Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a non-contact spectroscopy method that applies laser technology to absorption spectrum measurement technology. The detection technology has high sensitivity and is increasingly used in various industries. Since the absorption spectra of different gases are specific, it can measure parameters such as temperature, humidity and concentration of the gas to be measured, which can also effectively filter interference signals. TDLAS technology has been widely used in the field of gas detection, and the second harmonic detection and analysis technology has been actually applied online in many fields in gas concentration measurement.

[0003] In TDLAS gas detection technology, in order to obtain a stable gas absorption peak, the constant temperature of the laser diode is indispensable. The laser diode will generate temperature when working, and the unstable temperature change will directly lead to the absorption peak shift. As the TDLAS optical hardware ages, the absorption peak of the gas will also change. It is necessary to adjust the current temperature of the laser diode to calibrate the position of the absorption peak. The temperature shift causes the absorption peak to shift, and the actual concentration value deviation becomes worse as the temperature difference increases.

[0004] Therefore, a high-precision constant temperature circuit and device for a TDLAS laser head is proposed to solve the above problems. Utility Model Content

[0005] In view of the shortcomings of the prior art, the utility model provides a high-precision constant temperature circuit and device for a TDLAS laser head, which has the advantages of precise temperature control, etc., and solves the problem of needing to adjust the current temperature of the laser diode to calibrate the position of the absorption peak, temperature offset, resulting in absorption peak offset, and actual concentration value deviation as the temperature difference increases, and the concentration value data becomes worse and worse.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a high-precision constant temperature circuit for a TDLAS laser head, the constant temperature circuit comprising a temperature sensor, a temperature acquisition module, an operational amplifier, a differential amplifier, an integrator, a comparator and a TEC module, the operational amplifier having two paths, the temperature sensor outputting analog temperature signals in two paths, which are respectively input into the temperature acquisition module and the first operational amplifier, the temperature acquisition module outputting a digital temperature signal, which is input into the second operational amplifier, the output ends of the two operational amplifiers are respectively connected to the differential amplifier, the output end of the differential amplifier is connected to the integrator, the integrator outputs a time voltage signal to the comparator, and the comparator outputs a control signal to the TEC module.

[0007] Furthermore, impedance conversion circuits are provided at the input ends of the two operational amplifiers.

[0008] Furthermore, the TEC module includes a power driver, a cooling plate control chip and a TEC cooling plate connected in sequence, and the power driver is used to drive the TEC cooling plate to cool or heat.

[0009] Furthermore, the constant temperature device includes a fixed sheet metal, a laser emitting diode installed on the fixed sheet metal, and the above-mentioned constant temperature circuit, and the temperature sensor and the TEC cooling plate are built into the laser emitting diode.

[0010] Furthermore, a compressed air inlet connector and a compressed air outlet connector are connected to the bottom of the fixed sheet metal component, and an air path channel connected to the compressed air inlet connector and the compressed air outlet connector respectively is provided in the fixed sheet metal component.

[0011] Furthermore, the constant temperature device also includes a fixed base plate, and the fixed sheet metal part is fixed on the fixed base plate.

[0012] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0013] The TDLAS laser head high-precision constant temperature circuit and device, because TDLAS has strict requirements on the calibration of the laser diode absorption peak, directly affects the output concentration value, and requires high stability and accuracy. This circuit solution can achieve 0.01℃ precision control of the temperature, so that the TDLAS laser diode can achieve a stable output absorption wavelength. Compared with the traditional MOS tube drive, it has the advantages of low power consumption and temperature, no need for a heat sink, strong TEC driving ability, smaller circuit size, and more reliable performance stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the constant temperature circuit of the utility model;

[0015] Figure 2 This is a schematic diagram of the thermostatic device of the utility model;

[0016] Figure 3 This is a schematic diagram of the gas path in the laser diode fixing sheet metal of the utility model.

[0017] In the figure: 1. Laser emitting diode; 2. Compressed air inlet connector; 3. Compressed air outlet connector; 4. Fixed sheet metal; 5. Fixed base plate. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] See also Figure 1 In this embodiment, a high-precision constant temperature circuit of a TDLAS laser head is provided. The constant temperature circuit includes a temperature sensor, a temperature acquisition module, an operational amplifier, a differential amplifier, an integrator, a comparator and a TEC module. The operational amplifier has two paths. The temperature sensor outputs analog temperature signals in two paths, which are respectively input to the temperature acquisition module and the first operational amplifier. The temperature acquisition module outputs a digital temperature signal and inputs it to the second operational amplifier. The output ends of the two operational amplifiers are respectively connected to the differential amplifier. The output ends of the differential amplifier are connected to the integrator. The integrator outputs a time voltage signal to the comparator. The comparator outputs a control signal to the TEC module. The input ends of the two operational amplifiers are both provided with impedance conversion circuits.

[0020] When in use, two analog temperature signals are output through the temperature sensor, one of which is collected in real time by the temperature acquisition module. The temperature acquisition module outputs a digital temperature signal, and outputs a voltage according to the gas absorption peak. The voltage is input to the second operational amplifier after impedance transformation. The other analog temperature signal output by the temperature sensor is input to the first operational amplifier after impedance transformation. The output signals of the two operational amplifiers are differentially amplified to the negative input terminal of the differential amplifier, and then converted into a time voltage signal by an integrator, and the control signal is output to the TEC module through the comparator.

[0021] The TEC module includes a power driver, a cooling chip control chip and a TEC cooling chip connected in sequence. The power driver of the semiconductor TEC module is used to drive the TEC cooling chip to maintain a constant temperature. The temperature sensor detects the temperature of the laser emitting diode. When the operating temperature deviates from the set temperature, the temperature of the TEC cooling chip will automatically adjust the temperature to achieve a constant temperature as the resistance value of the temperature sensor changes.

[0022] When the temperature control pin CTL of the power driver is less than 1.5V, the control chip of the cooling plate is converted into a polar current signal to drive the TEC cooling plate to cool; when CTL>1.5V, the control chip of the cooling plate is converted into a polar current signal to drive the TEC cooling plate to heat. By controlling the heating or cooling of the TEC cooling plate, the temperature of the laser emitting diode 1 can be kept in a stable state.

[0023] See also Figure 2-3 In this embodiment, a high-precision constant temperature device for a TDLAS laser head is provided. The constant temperature device comprises a fixed sheet metal part 4, a laser emitting diode 1 mounted on the fixed sheet metal part 4, and the above-mentioned constant temperature circuit. The temperature sensor and the TEC cooling plate are built into the laser emitting diode 1.

[0024] The laser emitting diode 1 is fixed on the fixed base plate 5 through a fixed sheet metal part 4. The bottom of the fixed sheet metal part 4 is connected to a compressed air inlet connector 2 and a compressed air outlet connector 3. An air path channel connected to the compressed air inlet connector 2 and the compressed air outlet connector 3 is provided in the fixed sheet metal part 4.

[0025] Compressed air is injected into the air path of the fixed sheet metal 4 through the compressed air inlet connector 2, and the compressed air is then discharged from the compressed air outlet connector 3 through the air path. The high-speed fluidity of the compressed air can be used to take away the heat generated by the laser emitting diode 1 during operation, thereby achieving heat dissipation and maintaining a constant temperature.

[0026] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-precision constant temperature circuit for a TDLAS laser head, characterized in that: The constant temperature circuit includes a temperature sensor, a temperature acquisition module, an operational amplifier, a differential amplifier, an integrator, a comparator and a TEC module. The operational amplifier has two paths. The temperature sensor outputs analog temperature signals in two paths, which are respectively input to the temperature acquisition module and the first operational amplifier. The temperature acquisition module outputs a digital temperature signal, which is input to the second operational amplifier. The output ends of the two operational amplifiers are respectively connected to the differential amplifier. The output end of the differential amplifier is connected to the integrator. The integrator outputs a time voltage signal to the comparator. The comparator outputs a control signal to the TEC module.

2. A TDLAS laser head high-precision constant temperature circuit according to claim 1, characterized in that: Impedance conversion circuits are provided at the input ends of the two operational amplifiers.

3. A TDLAS laser head high-precision constant temperature circuit according to claim 1, characterized in that: The TEC module includes a power driver, a cooling plate control chip and a TEC cooling plate connected in sequence, and the power driver is used to drive the TEC cooling plate to cool or heat.

4. A high-precision constant temperature device for a TDLAS laser head, characterized in that: The constant temperature device comprises a fixed sheet metal part (4), a laser emitting diode (1) mounted on the fixed sheet metal part (4), and the constant temperature circuit according to claim 3, and the temperature sensor and the TEC cooling plate are built into the laser emitting diode (1).

5. A high-precision constant temperature device for a TDLAS laser head according to claim 4, characterized in that: The bottom of the fixed sheet metal part (4) is connected to a compressed air inlet joint (2) and a compressed air outlet joint (3), and an air path passage which is respectively connected to the compressed air inlet joint (2) and the compressed air outlet joint (3) is provided inside the fixed sheet metal part (4).

6. A high-precision constant temperature device for a TDLAS laser head according to claim 4, characterized in that: The constant temperature device also includes a fixed base plate (5), and the fixed sheet metal part (4) is fixed on the fixed base plate (5).

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