A device for detecting the thermal expansion coefficient matching of a laser material and a heat sink

Abstract

The application discloses a kind of laser material and heat sink's thermal expansion coefficient matching detection device, comprising: temperature control device (1) is provided with the light transmission side (4) for light passing through;Laser material (3) is installed in temperature control device (1), and high reflection film is plated on laser material (3);First heat sink (2) is installed in temperature control device (1), and first heat sink (2) is fixedly connected with laser material (3);Laser light source (5) is used to provide standard light (a), and standard light (a) passes through light transmission side (4) and is shot to the surface of the side that laser material (3) is plated with high reflection film, and standard light (a) forms reflected light (b) after passing through the surface of the side that laser material (3) is plated with high reflection film;Light spot measuring device (6) is installed on the path of forming reflected light (b).The present application amplifies the slight deformation of laser material surface at different temperatures caused by the mismatch of thermal expansion coefficient with first heat sink by optical method, so that it can be measured and utilized.

Description

Technical Field

[0001] This invention relates to the field of solid-state laser technology, and more specifically to a device for detecting the matching coefficient of thermal expansion of laser materials and heat sinks. Background Technology

[0002] Solid-state laser technology uses solid-state laser materials as the working medium and has wide applications in military, scientific, and commercial fields. These widespread applications place high demands on the power and beam quality of solid-state lasers. However, high-power laser output inevitably generates waste heat, which can cause thermal lensing and thermal birefringence in the laser material, thus reducing the output power and quality. To mitigate the adverse effects of heat during laser generation, heat sinks are often welded to the surface of the laser material to increase heat dissipation. When welding the laser material to the heat sink at high temperatures, the laser material initially exhibits no stress or strain. However, as the laser material cools to room temperature and into low temperatures (temperature variations of several hundred degrees Celsius), a mismatch in the thermal expansion coefficients between the laser material and the heat sink can lead to stress and strain in the crystalline material. This stress and strain not only reduce laser output power and beam quality but can also cause the laser material to fracture if excessive, increasing the risk and cost of use. Therefore, selecting a suitable heat sink material based on specific operating conditions is crucial to reduce stress caused by the mismatch in thermal expansion coefficients between the laser material and the heat sink. To meet diverse needs, a simple, wide-temperature-range thermal expansion coefficient matching test system is of great importance. Summary of the Invention

[0003] The purpose of this invention is to provide a laser material and heat sink matching detection device that is simple in structure, easy to use, and can effectively test the matching between laser materials and heat sinks.

[0004] To solve the above problems, the following technical solution is adopted:

[0005] A device for detecting the thermal expansion coefficient matching between a laser material and a heat sink includes: a temperature control device having a light-transmitting side for light to pass through, the temperature control device being used to control the temperature inside the temperature control device; a laser material installed inside the temperature control device, the laser material being coated with a high-reflectivity film; a first heat sink installed inside the temperature control device, the first heat sink being fixedly connected to the laser material; a laser source for providing standard light, the standard light passing through the light-transmitting side and striking the surface of the laser material on the side coated with the high-reflectivity film, the standard light forming reflected light after striking the surface of the laser material on the side coated with the high-reflectivity film, the reflected light passing through the light-transmitting side and exiting the temperature control device; and a spot measurement device installed on the path of the reflected light, the spot measurement device being used to collect and measure the spot of the reflected light.

[0006] Optionally, it also includes: a fixing bracket, which is fixedly installed inside the temperature control device, and is fixedly connected to the first heat sink, leaving a portion of the first heat sink suspended relative to the temperature control device. Specifically, a support shaft is installed on the fixing bracket, and a deep hole parallel to the axis of the support shaft is opened at the end of the first heat sink, or a through hole perpendicular to the axis of the support shaft is opened near the end. The deep hole or through hole is fitted onto the support shaft to fix the first heat sink.

[0007] Optionally, the laser material is fixedly connected to the suspended portion of the first heat sink by welding or bonding.

[0008] Optionally, the laser material is in the form of a long strip, the first heat sink is in the form of a long strip, and the widths of the laser material and the first heat sink are equal.

[0009] Optionally, a second heat sink is also included. The second heat sink is identical to the first heat sink in terms of method, material, and size. The second heat sink is set up independently and is used to observe the influence of factors other than the matching of thermal expansion coefficients on the light spot.

[0010] Optionally, it also includes: a protective box, a temperature control device (1) installed inside the protective box, a window mirror installed on the protective box, the window mirror being used to allow standard light (a) and reflected light (b) to pass through; a vacuum pumping device connected to the protective box, used to extract the air inside the protective box to achieve a vacuum environment.

[0011] Optionally, it also includes: a protective gas input device, which is connected to the protective box and is used to input protective gas into the protective box.

[0012] Optionally, the laser material is a laser gain medium material used for laser generation, preferably Nd:YAG, Yb:YAG or Nd:YLF, and the material type of the laser material is crystal or ceramic.

[0013] Optionally, the material of the first heat sink is a heat sink material used to cool the laser gain medium, preferably Cu, Fe, Mo or an alloy material.

[0014] Optionally, the standard light provided by the laser source has an incident angle greater than 30°.

[0015] Optionally, the spot measurement device can be grid paper, a coordinate ruler, or a photoelectric detector.

[0016] The above-mentioned technical solution of the present invention has the following beneficial technical effects: The device disclosed in the present invention is simple to operate, provides accurate and obvious results, and also has the advantages of simplicity, feasibility, high safety, and low cost. It amplifies the minute deformation on the surface of the laser material caused by the mismatch in thermal expansion coefficients with the first heat sink using optical methods, making it measurable and usable. A typical measurement and utilization method involves adjusting the temperature within the temperature control device to measure the changes in the reflected light spot obtained by the laser material and a specific first heat sink material at different temperatures, thereby obtaining the matching of the thermal expansion coefficients of the laser material and the specific first heat sink material at different temperatures. Specifically, after selecting the laser material, by changing the material of the first heat sink and conducting multiple experiments, the most suitable first heat sink material for the laser material at a specific temperature and / or temperature range can be selected, thereby reducing the stress on the laser material during laser generation and improving the quality of laser output. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Figure 2 yes Figure 1 A schematic diagram of the cc section.

[0019] Figure 3 This is a schematic diagram of the laser material and the first heat sink in the present invention, from left to right, in the states of a convex mirror, a normal state, and a concave mirror.

[0020] Figure 4 yes Figure 3 The diagrams, from left to right, show the reflected light spots from a convex mirror, a normal mirror, and a concave mirror.

[0021] Wherein: 1-Temperature control device, 2-First heat sink, 3-Laser material, 4-Light-transmitting side, 5-Laser source, 6-Spot measuring device, 7-Fixed bracket, 8-Second heat sink, a-Standard light, b-Reflected light. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0023] like Figure 1 and Figure 2As shown, a device for detecting the thermal expansion coefficient matching between a laser material and a heat sink includes: a temperature control device 1 with a light-transmitting side 4 for light to pass through, used to control the temperature inside the temperature control device 1; a laser material 3 installed inside the temperature control device 1, coated with a high-reflectivity film; a first heat sink 2 installed inside the temperature control device 1 and fixedly connected to the laser material 3; a laser source 5 providing standard light a, which passes through the light-transmitting side 4 and is incident on the surface of the laser material 3 coated with the high-reflectivity film, forming reflected light b after entering the surface of the laser material 3 coated with the high-reflectivity film, and exiting the temperature control device 1 through the light-transmitting side 4; and a spot measuring device 6 installed on the path of the reflected light b, used to collect and measure the spot of the reflected light b. This device is simple to operate, provides accurate and clear results, and has advantages such as simplicity, feasibility, high safety, and low cost. The minute deformations on the surface of the laser material caused by the mismatch in thermal expansion coefficients with the first heat sink are magnified using optical methods, making them measurable and usable. A typical measurement and utilization method involves adjusting the temperature within the temperature control device 1 to measure the changes in the reflected light spot obtained by the laser material 3 and a specific first heat sink 2 at different temperatures, thereby obtaining the matching of the thermal expansion coefficients of the laser material and the specific first heat sink material at different temperatures. Specifically, after selecting the laser material 3, by changing the material of the first heat sink 2 and conducting multiple experiments, the most suitable first heat sink 2 material for the laser material 3 at a certain temperature can be selected, thereby reducing the stress on the laser material 3 during laser generation and improving the quality of laser output.

[0024] In practical operation, the laser material 3 is fixedly connected to the first heat sink 2. After the connection, the entire experimental sample is placed in the temperature control device, with the side of the laser material 3 coated with a high-reflectivity film facing the light-transmitting side 4. The collimated standard light a provided by the laser source 5 is incident from the light-transmitting side 4 onto the outer surface of the experimental sample coated with the high-reflectivity film. At different temperatures, the laser material 3 deforms due to the mismatch in thermal expansion coefficients with the first heat sink 2. This deformation causes changes in the size and offset of the reflected light b spot. The optical testing system amplifies the minute surface deformation of the laser material 3 caused by the mismatch in thermal expansion coefficients with the first heat sink, thus reflecting the matching of the thermal expansion coefficients of the laser material 3 and the first heat sink 2 within a certain temperature range. If the thermal expansion coefficient of the laser material 3 is lower than that of the first heat sink 2, during the heating process, the expansion of the first heat sink 2 is greater than that of the laser material 3. This causes the surface of the laser material 3 to undergo a deformation similar to a concave mirror, resulting in a convergence and reduction of the light spot. If the coefficient of thermal expansion of the laser material 3 is relatively high, then during the heating process, the expansion of the laser material 3 will be less than that of the first heat sink 2. This will cause the surface of the laser material 3 to undergo a deformation similar to a convex mirror, resulting in a divergence and magnification effect on the light spot. Similarly, the degree of linear expansion matching between the laser material 3 and the first heat sink 2 when the temperature decreases can also be read from the change in the light spot. Furthermore, by changing the temperature of the temperature control device, the degree of matching between the thermal expansion coefficients of the laser material 3 and the first heat sink 2 at different temperatures can be measured. The light-transmitting side 4 can be designed as an open-type or lens-type optical element to allow light to pass through, depending on actual needs.

[0025] In an optional embodiment, the device further includes a fixing bracket 7, which is fixedly installed inside the temperature control device 1. The fixing bracket 7 is fixedly connected to the first heat sink 2, and a portion of the first heat sink 2 is suspended relative to the temperature control device 1. During the experiment, if the first heat sink 2 is directly placed inside the temperature control device 1, one entire surface of the first heat sink 2 will inevitably be in contact with the inner wall of the temperature control device 1. The temperature control device 1 itself will undergo some deformation during different temperature changes, and this deformation, combined with the deformation caused by the thermal expansion coefficient of the first heat sink 2, will make it more difficult to calculate the thermal expansion coefficient of the first heat sink 2 independently. To solve this problem, we need to separate the deformation caused by the temperature control device 1 itself from the deformation caused by the thermal expansion coefficient of the first heat sink 2. A portion of the first heat sink 2 is fixed using the fixing bracket 7, which is fixed inside the temperature control device 1, while the other portion of the first heat sink 2 is suspended relative to the temperature control device 1. This changes the fixing method between the first heat sink 2 and the temperature control device 1 from direct fixing to indirect fixing via the fixing bracket, thereby reducing their mutual influence by changing the contact method between them. Specifically, the fixed bracket 7 has a support shaft, and a deep hole parallel to the axis of the support shaft is opened at the end of the first heat sink 2, or a through hole perpendicular to the axis of the support shaft is opened near the end. The deep hole or through hole is fitted onto the support shaft to fix the first heat sink 2. This method minimizes the interference of external factors on the expansion of the first heat sink 2, helping to achieve more ideal experimental results.

[0026] In an optional embodiment, the laser material 3 is fixedly connected to the suspended portion of the first heat sink 2 by welding or bonding. This indirect connection, with a portion of the first heat sink 2 suspended, significantly reduces the impact of the deformation of the temperature control device 1 during different temperature changes on the expansion of the first heat sink 2. However, even so, the deformation of the temperature control device 1 during different temperature changes still has a slight impact on the calculation of the expansion of the first heat sink 2. To prevent this impact from being carried over, or to a very small extent, to the matching experiment between the laser material 3 and the first heat sink 2, the suspended position of the laser material 3 is positioned as far away as possible from the indirect fixing position between the first heat sink 2 and the temperature control device 1. This minimizes or negligibly reduces the impact of the deformation of the temperature control device 1 during different temperature changes on the matching experiment between the laser material 3 and the first heat sink 2. Furthermore, when irradiating the suspended end away from the fixed end, the beam deformation caused by the mismatch in the thermal expansion coefficients of the laser material and the heat sink material is more pronounced, which is beneficial to the accuracy of the experiment.

[0027] like Figure 3 and 4 As shown, in an optional embodiment, the laser material 3 is a long strip, and the first heat sink 2 is also long, with the widths of the laser material 3 and the first heat sink 2 being equal. Under normal conditions, the surface of the laser material is smooth and undeformed, such as... Figure 3 Schematic diagram of group M2, normal size of light spot, as shown. Figure 4 Schematic diagram of group N2. If the coefficient of thermal expansion of the laser material is relatively high, then during the heating process, the expansion of the laser material is less than that of the first heat sink. Consequently, the surface of the laser material will undergo a deformation similar to a convex mirror, such as... Figure 3 The schematic diagram of group M1 shows that it has a diverging and magnifying effect on the light spot, such as... Figure 4 Schematic diagram of group N1. If the coefficient of thermal expansion of the laser material is low and the coefficient of thermal expansion of the first heat sink is high, during the heating process, the expansion of the first heat sink is greater than that of the laser material. Therefore, the surface of the laser material will undergo a deformation similar to a concave mirror, such as... Figure 3 The schematic diagram of group M3 shows that it has a converging and shrinking effect on the light spot, such as... Figure 4 Schematic diagram of group N3. To make the convergence and shrinkage effects more pronounced and the divergence and amplification effects more pronounced, the contact surface between the laser material 3 and the first heat sink 2 is elongated (i.e., the length is several times the width). To make the convergence and shrinkage effects more accurate and the divergence and amplification effects more precise, the widths of the laser material 3 and the first heat sink 2 are equal. For example... Figure 4 As shown, the spot of reflected light b is magnified under the action of a convex mirror and reduced under the action of a concave mirror. Given a fixed ratio, the propagation distance of reflected light b directly affects the degree of this change. In other words, the propagation distance of reflected light b can be reasonably arranged according to actual experimental conditions and specific needs to capture the spot of reflected light b at a suitable position.

[0028] In an optional embodiment, a second heat sink 8 is further included. The second heat sink 8 is identical to the first heat sink 2 in terms of method, material, and size. The second heat sink 8 is independently set up to observe the influence of factors other than the matching of thermal expansion coefficients on the light spot. Since many factors may affect the light spot of the reflected light b during the experiment, such as the deformation of the temperature control device itself during different temperature changes, causing a partial shift in the light spot of the reflected light b, a second heat sink 8 of the same size is fixed in the temperature control device. Its surface is ground and gold-plated. The reflected light from the surface of the second heat sink 2 is used as the reflected reference light to observe the influence of factors other than the matching of thermal expansion coefficients on the light spot. In subsequent calculations, the influence of these other factors is processed, the deformation of the temperature control device itself at different temperatures is calibrated, systematic errors are eliminated, and accuracy is improved.

[0029] In an optional embodiment, the device further includes: a protective box, in which the temperature control device 1 is installed, and a window mirror is mounted on the protective box for the standard light a and reflected light b to pass through; and a vacuum pumping device connected to the protective box for extracting air from the protective box to create a vacuum environment. During temperature changes, the temperature control device 1 and its components are at risk of corrosion or oxidation at high temperatures and frost formation at low temperatures, which could affect light reflection. To avoid these risks caused by temperature changes, extracting air from the temperature control device 1 to create a vacuum environment effectively suppresses this phenomenon and improves the accuracy of the thermal expansion coefficient matching test between the laser material and the heat sink.

[0030] In an optional embodiment, it further includes: a protective gas input device, which is connected to a temperature control device and is used to input protective gas into the temperature control device to compensate for the lack of protection during vacuum venting.

[0031] In an optional embodiment, the laser material 3 is a laser gain medium material used for laser generation, preferably Nd:YAG, Yb:YAG or Nd:YLF, etc., and the material type of the laser material 3 is crystal or ceramic, etc.

[0032] In an optional embodiment, the material of the first heat sink 2 is a heat sink material used to cool the laser gain medium, preferably Cu, Fe, Mo or an alloy material.

[0033] In an optional embodiment, the spot measuring device 6 is a grid paper, a coordinate ruler, or a photoelectric detector, etc.

[0034] In an optional embodiment, the standard light a provided by the laser source 5 has an incident angle greater than 30°. The standard light a emitted from the laser source 5 is collimated and then strikes the surface of the experimental sample—the first heat sink 2—with a specific incident angle, facilitating the separation of the incident and outgoing light rays and the placement of optical components. A spot position measuring device collects the outgoing light and measures the changes in spot size and position at different temperatures. These changes are related to the degree of matching between the thermal expansion coefficients of the laser material 3 and the first heat sink 2; the better the matching, the smaller the change.

[0035] During the experiment, a C-shaped groove can be preset inside the temperature control device 1. The groove size is slightly larger than the size of the experimental sample after the laser material and heat sink are connected, or slightly larger than the size of the two groups of experimental samples. The experimental sample can be fixed in the groove of the temperature control device. This device is assembled at room temperature and used at low or high temperatures. It can be used to measure the matching degree between different first heat sink 2 materials and laser material 3 at different temperatures. The purpose is to find a suitable first heat sink 2 material for cooling laser material 3 according to actual usage, thereby reducing the stress caused by the mismatch of thermal expansion coefficients between laser material 3 and first heat sink 2 during laser generation, and improving laser output power and beam quality. The spot measurement device 6 can realize the accurate reading of the spot size or position change, which can be achieved by means of grid paper, coordinate ruler, photoelectric detector, etc. The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A device for detecting the matching coefficient of thermal expansion of laser materials and heat sinks, characterized in that, include: Temperature control device (1), the temperature control device (1) has a light-transmitting side (4) through which light passes, the temperature control device (1) is used to control the temperature inside the temperature control device (1); Laser material (3), the laser material (3) is installed in the temperature control device (1), and the laser material (3) is coated with a high reflectivity film; The first heat sink (2) is installed inside the temperature control device (1) and is fixedly connected to the laser material (3); A laser light source (5) is used to provide standard light (a). The standard light (a) passes through the light-transmitting side (4) and is directed toward the surface of the laser material (3) coated with a high-reflectivity film. After the standard light (a) enters the surface of the laser material (3) coated with a high-reflectivity film, it forms reflected light (b). The reflected light (b) passes through the light-transmitting side (4) and exits the temperature control device (1). A spot measuring device (6) is installed on the path of the reflected light (b) and is used to collect and measure the spot of the reflected light (b). The second heat sink (8) is made of the same material and has the same size as the first heat sink (2). The second heat sink (8) is set up independently and is used to observe the influence of factors other than the matching of thermal expansion coefficients on the light spot. The laser material (3) is fixedly connected to the suspended portion of the first heat sink (2) by welding or bonding. The laser material (3) is in the shape of a long strip, and the first heat sink (2) is in the shape of a long strip. The widths of the laser material (3) and the first heat sink (2) are equal. The material of the first heat sink (2) is a heat sink material used for cooling the laser gain medium, and the heat sink material is Cu, Fe, Mo or an alloy material; The standard light (a) provided by the laser source (5) has an incident angle greater than 30°.

2. The device for detecting the matching coefficient of thermal expansion of laser materials and heat sinks as described in claim 1, characterized in that, Also includes: A fixed bracket (7) is fixedly installed inside the temperature control device (1). The fixed bracket (7) is fixedly connected to the first heat sink (2) and a portion of the first heat sink (2) is suspended relative to the temperature control device (1).

3. The device for detecting the matching coefficient of thermal expansion of laser materials and heat sinks as described in claim 1, characterized in that, Also includes: The protective box contains the temperature control device (1) installed inside it. A window mirror is installed on the protective box, which is used to allow the standard light (a) and the reflected light (b) to pass through. A vacuum pumping device is connected to the protective box and is used to extract the air from the protective box to create a vacuum environment.

4. The device for detecting the matching coefficient of thermal expansion of laser materials and heat sinks as described in claim 3, characterized in that, Also includes: A protective gas input device is connected to the protective box and is used to input protective gas into the protective box.

5. The device for detecting the matching coefficient of thermal expansion of laser materials and heat sinks as described in claim 1, characterized in that, The laser material (3) is a laser gain medium material used for laser generation. The laser gain medium material is Nd:YAG, Yb:YAG or Nd:YLF. The material type of the laser material (3) is crystal or ceramic.

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