Thermopile laser power probe

Abstract

A thermopile laser power probe comprises a laser absorption layer, an insulation substrate, a thermopile layer, an insulation isolation layer and a heat conduction substrate which are sequentially arranged from top to bottom, the thermopile layer is provided with a probe lead, the laser absorption layer is arranged on the front face of the insulation substrate, and the thermopile layer is arranged on the back face of the insulation substrate. The heat conduction substrate and the thermopile layer are separated by an insulation isolation layer. According to the utility model, the position of the thermopile layer is changed, the staggered circular thermopiles are designed, and the sensitivity and response speed of the thermopile laser power probe are improved at the same time.

Description

TECHNICAL FIELD

[0001] The utility model belongs to laser power probe field relates to a thermoelectric pile laser power probe for improving the sensitivity and response speed of thermoelectric pile. BACKGROUND

[0002] Laser has broad application prospects, especially in the field of high-end manufacturing. High-power laser processing has entered the field of electronic devices, and the processing precision has reached the micron level, but the processing yield has been halved. The main reason is that the larger the power of the laser, the more likely it is to drift during use. This drift is unacceptable in precision machining. Therefore, the technical demand for real-time monitoring and rapid detection of high-power lasers is increasingly urgent.

[0003] The probe is the key core of the laser power detector. The mainstream high-power laser detector uses a thermoelectric pile probe to sense the laser power signal (CN202011578264, CN202023212741). Due to the low thermal conductivity of thermoelectric materials, researchers use high-thermal-conductivity substrates to share the heat conduction function of the thermoelectric pile. The laser absorption layer is on the front surface of the substrate, and the thin-film thermoelectric pile is on the back surface of the substrate (CN202020227804). Probes measuring thresholds above 10W often use thicker substrates to increase heat flow to ensure stable operation of the probe. Figure 1 The old structure shown in the figure is the basic structure of such a probe, and the laser absorption layer 1 is on the upper part of the heat-conducting substrate 2 facing the light beam, while the thermoelectric pile layer 4 is generally on the lower part of the heat-conducting substrate 2. This configuration ensures sufficient heat dissipation to stabilize the probe. Figure 2 The isotherm distribution shows that the temperature difference ΔT 正面 of the cold and hot ends of the back surface of the heat-conducting substrate 2 is much smaller than the temperature difference ΔT 背面 of the same position on the back surface of the laser absorption layer 1, and the thicker the heat-conducting substrate, the better the heat dissipation, the smaller the temperature difference, and the smaller the sensitivity of the probe.

[0004] To improve sensitivity, many institutions have proposed placing the thermoelectric pile on the side of a cylindrical probe, increasing the temperature difference between the cold and hot ends (CN201810184299, CN202211594130). However, this method of designing the laser absorption layer and the thermoelectric pile layer on both sides of the heat-conducting substrate makes the heat source far from the high-temperature end of the thermoelectric pile, resulting in a probe response time of up to 9s and a steady-state time of more than 30s, which cannot meet the real-time monitoring needs of high-power laser processing. This obviously limits the application prospects of laser probes. Therefore, a power probe with high sensitivity and response speed needs to be designed and manufactured. SUMMARY

[0005] In order to overcome the prior art, the utility model provides a thermoelectric pile laser power probe, changes the position of thermoelectric pile layer, designs the circular thermoelectric pile of staggered arrangement, improves the sensitivity and response speed of thermoelectric pile laser power probe simultaneously.

[0006] The utility model discloses a technical scheme that solves its technical problem:

[0007] A kind of thermoelectric pile laser power probe, including laser absorption layer, insulating substrate, thermoelectric pile layer, insulating isolation layer and heat-conducting base that are sequentially arranged from top to bottom, the thermoelectric pile layer has probe lead, the laser absorption layer is in insulating substrate front, the thermoelectric pile layer is in insulating substrate back, and heat-conducting base and thermoelectric pile layer are separated by insulating isolation layer.

[0008] Further, in the thermoelectric pile layer, thermoelectric materials are periodically connected in series with each other and form disc-shaped thermoelectric piles in a circular radiation pattern.

[0009] Preferably, the hot end of the thermoelectric pile is arranged with staggered inner diameters.

[0010] The thermoelectric pile layer material is a high cost-effective thermoelectric material that can be selected from nickel-chromium / nickel-copper, nickel-copper / copper, indium oxide doped with tin / indium oxide, etc.

[0011] The thermoelectric pile layer is provided with positive and negative pins, and the probe lead is connected to the positive and negative pins by silver welding.

[0012] The laser absorption layer is made of high-temperature-resistant light-absorbing materials such as silicon and silicon carbide, and is deposited on the insulating substrate by plasma spraying technology.

[0013] The insulating substrate layer material can be selected from one of alumina ceramic, silicon carbide, and glass fiber epoxy resin composite according to the laser power threshold measured by the detector, and the thickness is 300-500 microns.

[0014] The insulating isolation layer can be made of alumina or silicon oxide film, or heat-conducting silicone grease, and the thickness is 20-100 microns.

[0015] The heat-conducting base is in the form of a flat thick disc.

[0016] The heat-conducting base is an anodized aluminum plate with a thickness of 1-10 mm.

[0017] The utility model has the advantages of improving the sensitivity and response speed of the thermoelectric pile laser power probe. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the structure diagram of the prior art laser power probe.

[0019] Figure 2 is a thermoelectric layer structure design drawing of the prior art.

[0020] Figure 3 is a laser power probe steady-state isotherm distribution schematic diagram.

[0021] Figure 4 is a laser power probe structure diagram of the utility model.

[0022] Figure 5 is a thermoelectric layer structure design schematic diagram.

[0023] Figure 6 is a laser power response of the probe manufactured by the utility model and an old structure comparison diagram, wherein, (a) indicates the old structure, and (b) indicates the utility model.

[0024] The reference signs are: 1 laser absorption layer;2 heat-conducting base;3 insulation isolation layer;4 thermoelectric layer;5 insulation protective layer;6 insulation base;7 probe lead;8 laser incidence direction. DETAILED DESCRIPTION

[0025] The utility model is further described below in combination with the drawings.

[0026] Referring to Figures 1-5 , a thermoelectric laser power probe comprises laser absorption layer 1, insulation base 6, thermoelectric layer 4, insulation isolation layer 3 and heat-conducting base 2 arranged in sequence from top to bottom, thermoelectric layer 4 is provided with probe lead 7, laser absorption layer 1 is on the front surface of insulation base 6, thermoelectric layer 4 is on the back surface of insulation base 6, and insulation isolation layer 5 is arranged between heat-conducting base 2 and thermoelectric layer 4.

[0027] In the utility model, as Figure 3 Indicated, the radial temperature difference between laser absorption layer and heat-conducting base is greater than the radial temperature difference of the lower part of heat-conducting base at the same position. Therefore, as Figure 4 Indicated, the new structure of the utility model, the thermoelectric layer of the probe is not immediately located between laser absorption layer and heat-conducting base. Laser absorption layer is on the front surface of insulation base 6, and thermoelectric layer is on the back surface of insulation base. Insulation isolation layer 3 is arranged between heat-conducting base and thermoelectric layer. The design increases the temperature difference of the cold and hot ends of thermoelectric layer, and also utilizes the good heat dissipation of heat-conducting base to the cold end of thermoelectric layer to make the temperature difference steady-state time shorter.

[0028] Further, in thermoelectric layer 4, thermoelectric materials are periodically connected in series and form disc-shaped thermoelectric piles in a circular radial pattern.

[0029] Preferably, the hot end of the thermoelectric pile is arranged in an inner diameter with staggered sizes.

[0030] In order to further increase the sensitivity of the probe, make full use of the temperature difference caused by the laser, the utility model uses the thermoelectric element pattern shown in the new design of Figure 5 Thermoelectric materials are periodically connected in series and form a disc-shaped thermoelectric element in a circular radial pattern. Compared with the existing design, the hot end of the thermoelectric element in the new design uses staggered inner diameter arrangement, which improves the hot end temperature of part of the thermocouple, fully utilizes the high temperature of the hot end space, and further improves the sensitivity of the probe.

[0031] The thermoelectric element layer 4 material is a high cost-effective thermoelectric material such as nickel-chromium / nickel-copper, nickel-copper / copper, indium tin oxide / indium oxide, etc. The number of thermocouples in the thermoelectric element is selected as needed.

[0032] The thermoelectric element layer 4 is provided with positive and negative pins, and the probe lead 7 is welded with silver material to connect the positive and negative pins.

[0033] The laser absorption layer 1 uses high-temperature resistant light-absorbing materials such as silicon and silicon carbide deposited on the insulating substrate by plasma spraying technology, and the thickness of the laser absorption layer is 50-200 microns.

[0034] The insulating substrate 2 material is selected from one of alumina ceramic, silicon carbide and glass fiber epoxy resin composite according to the high and low of the laser power threshold measured by the detector, and the thickness is 300-500 microns.

[0035] The insulating isolation layer 3 is an optional alumina or silicon oxide film, which can also be a heat-conducting silicone grease, and the thickness is 20-100 microns.

[0036] The heat-conducting substrate 2 is a flat thick disc.

[0037] The heat-conducting substrate 2 is an anodized aluminum plate with a thickness of 1-10 mm.

[0038] A manufacturing method of a thermoelectric element laser power probe, comprising the following steps:

[0039] (1) Use an alumina plate, a silicon carbide plate or a glass fiber epoxy resin composite plate as the insulating substrate according to the high and low of the laser power threshold measured by the detector;

[0040] (2) Use plasma spraying method to prepare the laser absorption layer on the front surface of the insulating substrate;

[0041] (3) Use magnetron sputtering method to prepare the positive material and negative material of the thermoelectric element layer on the back surface of the insulating substrate with the laser absorption layer prepared in step (2);

[0042] (4) Use electrochemical method to make an aluminum plate into an anodized aluminum plate as the heat-conducting substrate;

[0043] (5) According to the laser power threshold measured by the detector, the insulating isolation layer is prepared on the front surface of the heat-conducting substrate prepared in step (4) by coating heat-conducting silica gel, spin-coating aluminum oxide or spin-coating silicon oxide;

[0044] (6) In the preparation of the insulating isolation layer in step (5) above, the insulating substrate prepared in step (3) is placed on the insulating isolation layer before annealing and forming the insulating isolation layer, and then the thermoelectric pile layer and the insulating isolation layer are annealed to form good thermal contact;

[0045] (7) The probe lead wire is led out for the thermoelectric pile layer on the insulating substrate.

[0046] In this embodiment, the insulating substrate 6 material is optionally one of aluminum oxide ceramic, silicon carbide (high power) and glass fiber epoxy resin composite (low power) according to the laser power threshold measured by the detector, and the thickness is 300-500 microns.

[0047] High-temperature resistant light-absorbing materials such as powdered silicon and silicon carbide are sprayed on the insulating substrate 6 as the laser absorption layer 1 using plasma spraying technology. The spraying power is 20-80 kW, the spraying time is 15-30 s, and the thickness of the laser absorption layer is controlled to be 50-200 microns.

[0048] High-performance thermoelectric materials such as optional nickel-chromium / nickel-copper, nickel-copper / copper, indium tin oxide / indium oxide are deposited on the back surface of the insulating substrate to form the thermoelectric pile layer 4 using magnetron sputtering technology. The thermoelectric pile pattern is shown in the new design of Figure 4 , the number of thermocouples in the thermoelectric pile is selected as needed, and is optionally 3 to 40 pairs. Thus, the photo-thermal electric conversion unit is completed.

[0049] An anodized aluminum plate with a thickness of 1-10 mm is selected as the heat-conducting substrate 2. For a high-power probe, an aluminum oxide and silicon oxide film is prepared as the insulating isolation layer 3 on the front surface of the heat-conducting substrate 2 by multiple repeated spin-coating, and the thickness is 20-40 microns. For a low-power probe, heat-conducting silica gel can be used instead of spin-coating aluminum oxide and silicon oxide as the insulating isolation layer 2, and the thickness is controlled to be 40-100 microns. For a high-power probe, the photo-thermal electric conversion unit thermoelectric pile prepared in steps (2)-(4) is placed on the insulating isolation layer with the thermoelectric pile facing down before the spin-coated aluminum oxide and silicon oxide are annealed and formed, and then the photo-thermal electric conversion unit and the insulating isolation layer are annealed to form good thermal contact. For a low-power probe, the photo-thermal electric conversion unit can be directly placed on the heat-conducting substrate coated with heat-conducting silica gel, and the silica gel is solidified.

[0050] Example 1: In this embodiment, a probe with a power threshold of 350 W is manufactured, and the process is as follows:

[0051] 1. The thickness of the SiC ceramic sheet is 0.5mm, which is selected as the insulating substrate according to the laser power threshold measured by the detector.

[0052] 2. The Si powder with a particle size of 45μm is sprayed on the SiC ceramic sheet as the laser absorption layer using the plasma spraying technology. The spraying power is 50kW, the spraying time is 30s, and the thickness of the laser absorption layer is controlled to be 200μm.

[0053] 3. The optional NiCr / NiCu is deposited on the back of the insulating substrate to form the thermoelectric pile using the direct current magnetron sputtering technology. The thermoelectric pile pattern is shown in the new design of Figure 3 , and the number of thermocouples in the thermoelectric pile is selected to be 34 pairs. The deposition conditions are: base vacuum 8x10 -4 , direct current sputtering power 70W, argon (purity 99.99%) flow rate 50sccm, sputtering gas pressure 0.6Pa, and sputtering time 40min.

[0054] 4. The SiO2 film is deposited on the back of the thermoelectric pile using the alternating current magnetron sputtering technology. The deposition conditions are: base vacuum 8x10 -4 , alternating current sputtering power 120W, argon (purity 99.99%) flow rate 50sccm, sputtering gas pressure 1Pa, and sputtering time 90min. Thus the photo-thermal-electric conversion unit is completed.

[0055] 5. The thickness of the anodized aluminum plate is selected to be 10mm as the heat-conducting substrate. The Al2O3 film is prepared as the insulating isolation layer using the spin coating method. The complete spin coating process includes: the Al2O3 precursor solution is spin coated on the heat-conducting substrate at an average spin speed of 800rpm for each spin coating lasting 30s. After spin coating, the 300℃ nitrogen protection normal pressure annealing is performed. The whole spin coating process is repeated 5 times. The photo-thermal-electric conversion unit is placed on the Al2O3 film to be annealed before the last annealing, and then they are put into the 300℃ nitrogen protection normal pressure annealing together. The overall thickness of the insulating isolation layer is 40μm.

[0056] 6. The lead is welded to the positive and negative pins of the thermoelectric pile through the silver material using the electric welding machine, and the probe is completed.

[0057] Figure 6 (b) shows the laser power response curve of the probe of the present embodiment. As can be seen from the figure, the power response time is less than 2s, and the sensitivity reaches 0.255mV / W. As a comparison, the old structure probe has the structure as shown in Figure 1 , and the geometric configuration and material selection of the laser absorption layer 1, the heat-conducting substrate 2 and the insulating isolation layer 3 are consistent with those of the new structure probe of the present embodiment. The thermoelectric pile layer 4 of the old structure probe uses the new design of Figure 2The shown old design pattern, but the thermoelectric material and the new structure probe are consistent, test results show that its power response time is 7s, and the sensitivity is 0.1mV / W. Therefore, the probe manufactured by the probe design and manufacturing method provided by the utility model has a substantial improvement in response speed and sensitivity. The demand of real-time monitoring of high-power laser processing can be met.

[0058] The content described in the embodiments of the present specification is only a list of implementation forms of the utility model concept, and is only for illustrative purposes. The protection scope of the utility model should not be regarded as being limited to the specific forms stated in the present embodiments, and the protection scope of the utility model also extends to equivalent technical means that can be thought of by those skilled in the art according to the utility model concept.

Claims

1. A thermopile laser power probe, characterized by, The thermoelectric laser power probe comprises, from top to bottom, a laser absorption layer, an insulating base, a thermoelectric layer, an insulating isolation layer and a heat-conducting base, the thermoelectric layer is provided with probe leads, the laser absorption layer is on the front surface of the insulating base, the thermoelectric layer is on the back surface of the insulating base, and the heat-conducting base and the thermoelectric layer are separated by the insulating isolation layer.

2. A thermopile laser power probe as claimed in claim 1, characterized in that In the thermoelectric layer, thermoelectric materials are periodically connected in series and form a circular disc-shaped thermoelectric pile in a circular radial pattern.

3. A thermopile laser power probe as claimed in claim 2, wherein, The hot end of the thermoelectric pile is arranged in a staggered inner diameter.

4. A thermopile laser power probe as described in any one of claims 1 to 3, characterized in that, The thermoelectric layer material is nickel-chromium / nickel-copper, nickel-copper / copper or indium tin oxide / indium tin oxide.

5. A thermopile laser power probe according to any one of claims 1 to 3, wherein the thermopile laser power probe is configured to be used in a wavelength range of 800 nm to 1,100 nm. The thermoelectric layer is provided with positive and negative pins, and the probe leads are connected to the positive and negative pins by silver soldering.

6. A thermopile laser power probe according to any one of claims 1 to 3, wherein The laser absorption layer is deposited on the insulating base by plasma spraying technology using silicon or silicon carbide, and the thickness of the laser absorption layer is 50-200 microns.

7. A thermopile laser power probe according to any one of claims 1 to 3, wherein the thermopile laser power probe is configured to be used in a wavelength range of 800 nm to 1,100 nm. The insulating base layer material uses one of alumina ceramic, silicon carbide and glass fiber epoxy resin composite, and the thickness is 300-500 microns.

8. A thermopile laser power probe according to any one of claims 1 to 3, wherein the thermopile laser power probe is configured to be used in a wavelength range of 800 nm to 1,100 nm. The insulating isolation layer is alumina, silicon oxide film or heat-conducting silicone grease, and the thickness is 20-100 microns.

9. A thermopile laser power probe according to any one of claims 1 to 3, wherein, The heat-conducting base is a flat thick disc.

10. A thermopile laser power probe as claimed in claim 9, wherein, The heat-conducting base is an anodized aluminum plate with a thickness of 1-10 mm.

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