Laser system comprising a corner cooler used to cool laser gas within a laser resonator

Abstract

The invention relates to a laser system comprising a corner cooler for cooling laser gas within a laser resonator, wherein the corner cooler comprises a housing (1) with a number of warm insert rows (3) and spaced-apart cold insert rows (2), wherein in the region of the cold insert rows (2) there is no housing cooling through which a cooling fluid flows, but only condensation insulation (6), and in the region of the warm insert rows (3) a housing cooling (5) through which a first cooling fluid flows is formed, wherein the housing cooling (5) is supplied with HTPCW (High Temperature Process Cooling Water), and the ratio of the cold insert rows (2) to the warm insert rows (3) in the corner cooler is at least 3:2.

Description

[0001] The present invention relates to a laser system comprising a corner cooler for cooling laser gas within a laser resonator, wherein the corner cooler comprises a housing with a number of warm insert rows and cold insert rows spaced apart therefrom.

[0002] In the field of laser systems, particularly high-power lasers, cooling the laser gas within the laser resonator is crucial. A common method for efficient heat dissipation is the use of a corner cooler, which cools the laser gas to an optimal operating temperature. The corner cooler typically comprises a housing containing both hot and cold insert rows through which different cooling fluids circulate to bring the laser gas to the desired temperature.

[0003] Prior art laser systems are known in which both the hot and cold insert rows are supplemented by housing cooling, which is also circulated with cooling fluids to support the cooling processes. A common system is used in which the hot insert rows are cooled with a high-temperature cooling fluid (HTPCW - High Temperature Process Cooling Water), while the cold insert rows are cooled with a low-temperature cooling fluid (LTPCW - Low Temperature Process Cooling Water). This arrangement aims to ensure maximum cooling of the laser gas while simultaneously dissipating the heat effectively.

[0004] A significant disadvantage of these conventional laser systems with corner coolers is the parasitic heat flow that can occur between the hot and cold areas of the cooler. Since both areas are typically located in close proximity and the housing is permeated by flow in both the hot and cold zones, there is a risk of heat being transferred from the hot to the cold insert rows. This unwanted heat transfer can significantly impair cooling efficiency, as more energy is required to bring the laser gas to the desired temperature. This results in higher energy consumption and less efficient use of the coolant.

[0005] Another problem with conventional corner coolers is the high pressure drop caused by the serial flow through the insert rows. Especially with long coolant flow paths, the resulting pressure drop can severely stress the cooling water system and thus impair the system's cooling performance. This pressure drop can lead to an inability to supply the required amount of cooling water, further reducing the efficiency of the laser system.

[0006] Furthermore, existing laser systems often exhibit insufficient adaptability to varying operating conditions. Since the housing cooling is typically designed for static operation, fluctuations in load or environmental conditions can lead to over- or under-cooling, impairing the stability and reliability of the laser system. The inability to dynamically adjust the cooling capacity to current requirements can result in suboptimal operating conditions, particularly under varying loads.

[0007] Furthermore, the design of conventional corner coolers is often complex and requires numerous cooling water connections and supply lines, especially when both the hot and cold insert rows have separate cooling circuits. This complexity not only leads to higher manufacturing and maintenance costs but also to a greater need for installation space, which makes it difficult to integrate the laser system into compact machines or systems.

[0008] In summary, conventional laser systems with corner coolers exhibit several weaknesses regarding efficiency, energy consumption, and adaptability. These drawbacks necessitate improvements to the cooling systems to ensure more efficient and reliable cooling of the laser gas without the negative effects described above. In particular, an advanced solution should minimize parasitic heat flows, reduce pressure drop, and increase system flexibility to better adapt to varying operating conditions.

[0009] The object of the invention is therefore to provide a laser system comprising a corner cooler for cooling laser gas within a laser resonator, which avoids or at least reduces the problems known from the prior art.

[0010] This problem is solved by a laser system comprising a corner cooler for cooling laser gas within a laser resonator, wherein the corner cooler includes a housing with a number of warm insert rows and spaced-apart cold insert rows, wherein in the region of the cold insert rows there is no housing cooling through which a cooling fluid flows, but only condensation insulation, and in the region of the warm insert rows a housing cooling through which a first cooling fluid flows is provided, wherein the housing cooling is supplied with HTPCW High Temperature Process Cooling Water, and the ratio of the cold insert rows to the warm insert rows in the corner cooler is at least 3:2.

[0011] This laser system offers the advantage of more efficient laser gas cooling by eliminating the need for additional housing cooling in the cold insert rows. This prevents parasitic heat flows that could otherwise occur from the hot to the cold side. Condensation insulation further reduces condensation problems without compromising efficiency. The use of HTPCW in the hot insert rows enables targeted cooling, while a minimum cold-to-warm insert row ratio of 3:2 ensures optimized cooling performance within the system. This configuration results in improved energy efficiency due to reduced LTPCW consumption, which in turn reduces the need for cooling water connections and optimizes build space utilization.

[0012] First, the individual elements of the claimed invention are explained in the order in which they are mentioned in the claim set, and subsequently, particularly preferred embodiments of the invention are described. laser system

[0013] For the purposes of this patent application, a laser system is a technical device comprising a laser resonator and all components necessary for the operation of the laser. The laser system serves to generate coherent light radiation, which is used for various industrial, medical, or scientific applications. A key feature of the laser system is the use of a corner cooler, which serves to selectively cool the laser gas within the laser resonator in order to ensure the efficiency and stability of the laser.

[0014] The laser system consists of a laser resonator in which the laser gas oscillates between two mirrors, generating coherent light through the amplification of light waves. To achieve optimal performance, the laser gas must be cooled to a precisely controlled temperature. This is accomplished, among other things, by the corner cooler integrated into the laser system housing. The corner cooler comprises a housing with cold and hot insert rows, through which different cooling fluids flow. The cold insert rows are preferentially cooled with LTPCW (low-temperature process cooling water) to cool the laser gas to the desired operating temperature, while the hot insert rows are cooled with HTPCW (high-temperature process cooling water) to ensure targeted heat dissipation.

[0015] The function of the laser system is closely linked to the precise temperature control of the laser gas. A stable temperature ensures constant laser power and prevents thermal distortions or power fluctuations that could impair the quality of the generated laser beam. Efficient cooling of the laser gas also contributes to the system's longevity by preventing excessive thermal stress on the components.

[0016] Preferred embodiments of the laser system include a control device that regulates the flow of cooling fluid in the insert arrays to adapt the cooling performance to the current operating conditions. This control allows for flexible adjustment of the cooling parameters, which is particularly advantageous under changing load conditions. Another advantageous embodiment provides that the insert arrays are designed as finned tubes to maximize the heat transfer surface area and increase cooling efficiency. Possible embodiments of the laser system include systems of varying power classes, which can vary depending on the application, from compact laser systems for precise micromachining to high-power lasers for industrial use. All these systems benefit from the advanced cooling technology described in this patent application, which ensures high efficiency and reliability. Corner cooler

[0017] For the purposes of this patent application, a corner cooler is a component within a laser system specifically designed to cool the laser gas within a laser resonator. The corner cooler is designed to cool the laser gas to a desired temperature to ensure optimal function of the laser resonator and to increase the efficiency of the entire laser system. The corner cooler comprises a housing equipped with several rows of inserts. These insert rows consist of hot and cold inserts, each cooled by different cooling fluids. The hot insert rows are located in the area of ​​the housing cooled by HTPCW (High Temperature Process Cooling Water), while the cold insert rows feature condensation insulation instead of housing cooling to prevent unwanted condensation effects.

[0018] The corner cooler's function is to efficiently dissipate the heat generated by the laser gas, thereby reducing the gas temperature to an optimal level. The laser gas is first passed through the warm insert rows, where it is pre-cooled to a moderate temperature. It then flows through the cold insert rows, which are cooled with LTPCW (Low Temperature Process Cooling Water) to further cool the gas to a temperature of preferably 10-15°C. This two-stage cooling process ensures precise temperature control while minimizing energy consumption for cooling.

[0019] The corner cooler is designed so that the insert rows are arranged parallel to each other to ensure a uniform cooling flow. Housing cooling in the area of ​​the hot insert rows minimizes pressure loss in the cooling circuit, while condensation insulation in the area of ​​the cold insert rows prevents parasitic heat flows and ensures efficient cooling. The corner cooler can also include a control device that regulates the flow of the HTPCW to adjust the cooling capacity according to the operating conditions of the laser system.

[0020] Possible embodiments of the corner cooler include variants with varying numbers of insert rows, where the ratio of cold to warm insert rows can be varied to meet different cooling requirements. Preferably, the ratio is selected to match the requirements of the specific laser system in order to achieve maximum cooling performance. The insert rows can advantageously be designed as finned tubes to maximize the heat transfer surface area and further increase cooling efficiency. Other embodiments could include the integration of additional coolant circuits to increase the flexibility and adaptability of the corner cooler to different operating conditions. Insert series

[0021] For the purposes of this patent application, an insert array is an arrangement of heat exchanger elements within a corner cooler, designed to cool the laser gas in a laser resonator through heat transfer between the gas and a cooling fluid. An insert array preferably consists of several parallel tubes configured as finned tubes, the surface of which is provided with a plurality of fins or lamellae to maximize the contact area with the cooling fluid. These fins increase the heat transfer surface area, thereby significantly improving the efficiency of the heat exchange between the laser gas and the cooling fluid.

[0022] The function of an insert array is to cool the laser gas flowing through the resonator to a predetermined temperature to ensure the stability and efficiency of the laser system. The cooling fluid, which flows through the finned tubes of the insert array, absorbs and dissipates the heat from the laser gas. The temperature of the cooling fluid can be either higher or lower than the ambient temperature of the laser gas, depending on whether it is a hot or cold insert array. Hot insert arrays use a higher-temperature cooling fluid (HTPCW), while cold insert arrays use a lower-temperature cooling fluid (LTPCW) to allow for precise temperature control of the laser gas.

[0023] Advantageously, the insert rows are designed to be arranged parallel to each other, ensuring a uniform cooling flow and a homogeneous temperature distribution in the laser gas. The design of the insert rows can be varied with regard to the number of tubes, their diameter, and the arrangement and density of the fins or lamellae to meet the specific requirements of the laser system. Preferably, insert rows are designed to offer an optimal balance between cooling capacity and pressure drop in order to maximize system efficiency without unduly impairing the cooling fluid flow rate.

[0024] Possible embodiments of the insert arrays include those with varying numbers of parallel finned tubes, comprising either a larger number of small fins for precise temperature control or a smaller number of larger fins for robust cooling. Another possible embodiment could involve the use of materials with high thermal conductivity to improve heat exchange efficiency, or the integration of sensors to monitor the temperature and flow rate of the cooling fluid within the insert arrays, enabling adaptive control of the cooling process. All these embodiments contribute to optimizing the overall performance of the laser system and allowing it to be flexibly adapted to different operating conditions. Condensation insulation

[0025] For the purposes of this patent application, condensation insulation is an insulating layer that serves to prevent the formation of condensation on the surface of the cold insert arrays or the surrounding housing. The condensation insulation forms a thermal barrier between the cold surface, which is cooled by the use of LTPCW, and the warmer ambient air. This insulation prevents direct contact between the cold surface and the air, thereby preventing the formation of condensation that could otherwise impair the function and efficiency of the laser system.

[0026] The function of condensation insulation is therefore essentially to minimize heat exchange between the cooled surface and the ambient air. The thermal barrier keeps the surface temperature of the cold insert rows above the dew point of the surrounding air, thus preventing condensation of water vapor. This is particularly important in a laser system, as condensation can lead to short circuits, corrosion, and other undesirable effects that compromise the system's lifespan and reliability.

[0027] The condensation insulation can be constructed from various materials with low thermal conductivity. Preferably, the insulation is made of closed-cell foam or another insulating material that ensures homogeneous and complete coverage of the surfaces to be insulated. Such a structure not only prevents heat exchange but also ensures that no moisture penetrates the insulation. The thickness of the insulation layer is selected to meet the specific requirements of the system, particularly with regard to temperature differences and humidity conditions.

[0028] Possible embodiments of the condensation insulation include, among others, a design made of a flexible foam that conforms to the shape of the insert rows and the housing, thus achieving efficient and complete insulation. Another embodiment could be a multi-layered construction in which an inner layer consists of a hard, insulating material surrounded by an outer, moisture-resistant layer. This layer protects the insulation from mechanical damage and ensures long-lasting insulation performance. It is also conceivable that the condensation insulation could be provided with a reflective coating, which additionally helps to block heat radiation from the surface, further enhancing the insulation effect. Advantageous embodiments of the invention

[0029] According to an advantageous embodiment of the invention, the cold insert arrays can be supplied with LTPCW (low-temperature process cooling water) to cool the laser gas within the laser resonator to a temperature of preferably 10-15°C. This precise temperature control ensures optimal cooling of the laser gas, resulting in increased laser power and improved overall energy efficiency of the system. The use of LTPCW further increases efficiency because less energy is required for cooling, making the operation of the laser system more economical.

[0030] According to a further preferred embodiment of the invention, the number of cold insert rows can also be at least six. This leads to more effective cooling of the laser gas, thereby improving the operational reliability and efficiency of the laser system. A higher number of cold insert rows also makes it possible to lower the laser gas to the desired temperature without excessive pressure drop, thus ensuring compliance with the pressure drop budget.

[0031] Furthermore, according to another advantageous embodiment of the invention, the number of warm insert rows can be limited to a maximum of four. This reduces the pressure drop within the system and enables more efficient use of the HTPCW. Fewer warm insert rows also mean less heat transfer to the cold side, which in turn reduces the need for cooling by LTPCW and thus lowers the overall energy consumption of the system.

[0032] According to a further particularly preferred embodiment of the invention, the cold insert rows and the warm insert rows can be arranged parallel to each other to ensure a uniform cooling flow. This results in a uniform temperature distribution in the laser gas, thereby avoiding hotspots and stabilizing the power of the laser system. Uniform cooling also minimizes component wear and extends the system's service life, contributing to long-term cost efficiency.

[0033] Furthermore, the invention can be further developed such that the corner cooler includes a control device that regulates the flow of the HTPCW in the housing cooling system in order to adjust the cooling capacity according to the operating conditions of the laser system. This offers the advantage that the cooling can be dynamically optimized, leading to a further improvement in energy efficiency. The ability to regulate the cooling flow ensures that the laser system is always optimally cooled under various load conditions, thus increasing the reliability and flexibility of the system.

[0034] In a further preferred embodiment of the invention, the total area of ​​the cold insert rows can also be larger than the total area of ​​the warm insert rows. This configuration maximizes the cooling capacity of the system, since a larger area of ​​the cold insert rows enables more effective heat dissipation. This allows the laser gas to be cooled to the desired temperature more quickly and efficiently, which increases the laser's performance while simultaneously minimizing energy consumption.

[0035] It can also be advantageous to further develop the invention such that the insert rows are designed as finned tubes. Designing the insert rows as finned tubes increases the heat transfer surface area, resulting in more effective cooling. Finned tubes offer the advantage of an increased surface area for heat transfer between the laser gas and the cooling fluid, thereby accelerating cooling and improving temperature control. This contributes to improving the overall performance of the laser system and reducing energy consumption, as more efficient heat dissipation is achieved.

[0036] The described features of the invention enable the development of a laser system that offers higher efficiency within the same installation space. By optimizing the cooling circuits and specifically reducing coolant consumption, both operating costs can be lowered and the system's performance increased. This leads to more economical operation and a longer service life for the laser system, making it particularly advantageous for industrial applications where high performance and reliability are crucial.

[0037] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention.

[0038] It shows: Fig. 1 A detailed view of a corner cooler according to the prior art and of a corner cooler according to the invention, each in a schematic sectional view.

[0039] The present invention relates to a laser system comprising a corner cooler for cooling laser gas within a laser resonator. The corner cooler is designed to significantly increase the efficiency of the laser system by implementing specific design modifications to optimize the cooling process and reduce energy consumption, as demonstrated by the Fig. 1 will now be explained in more detail.

[0040] In connection with the invention, unlike in the prior art (Figure a), no cooling of the housing 1 of the corner cooler by a cooling fluid is provided on the cold side (right). Instead, as can be seen in Figure b, the cold side is provided only with a condensation insulation 6, which prevents condensation on the cold insert rows 2. The condensation insulation 6 forms a thermal barrier that minimizes contact between the cold surface and the surrounding air, thereby preventing the formation of condensation. This approach makes it possible to completely eliminate the use of cooling fluids on the cold side, resulting in a significant saving of cooling water.

[0041] By eliminating the housing cooling on the cold side, parasitic heat flows between the hot and cold sides of the corner cooler are prevented. These parasitic heat flows, which occur in conventional systems and are illustrated in Figure a, lead to undesirable heat transfer from the hot to the cold side, reducing the efficiency of the cooling process. Avoiding these heat flows through the condensation insulation 6 thus contributes significantly to optimizing cooling performance.

[0042] The invention further provides that more cold insert rows 2 are used on the cold side of the corner cooler, while an equivalent number of warm insert rows 3 are reduced on the warm side. This redistribution of the insert rows effectively compensates for the cooling capacity lost by eliminating housing cooling on the cold side. Increasing the number of cold insert rows 2 enlarges the cooling surface, which improves heat dissipation and lowers the laser gas temperature more efficiently to the desired level.

[0043] Simultaneously, reducing the number of hot insert rows (3) lowers the pressure drop within the system to an acceptable level. This minimizes the pressure drop, which often leads to inefficient cooling in conventional systems, ensuring the supply of the required cooling water volume and stabilizing the operation of the laser system.

[0044] The measures described—namely, the elimination of housing cooling on the cold side, the use of condensation insulation, and the adjustment of the number of insert rows—significantly improve the laser system's energy efficiency. Saving cooling water and optimizing heat dissipation contribute to reducing the system's energy consumption while simultaneously increasing cooling capacity. This results in increased laser output power and reduced operating costs.

[0045] Previous systems often aimed to provide the maximum possible heat transfer surface area to cool the laser gas down to the temperature of the cooling water. These systems sought to cool the gas as close as possible to the water temperature, which, with a cooling water temperature of approximately 6°C, meant that the laser gas also had to be cooled to this level. However, this strategy resulted in high energy consumption and inefficient use of the coolant.

[0046] In the laser system according to the invention, two types of water with different temperatures are available: HTPCW at a temperature of 32°C and LTPCW at a temperature of 6°C. Both types of water are used in the corner cooler, with the warm insert rows 3 being supplied with HTPCW and the cold insert rows 2 with LTPCW. The corner cooler comprises a housing 1 with warm insert rows 3 and cold insert rows 2 spaced apart from them. While there is no housing cooling in the area of ​​the cold insert rows 2, but only condensation insulation 6, a housing cooling system 5 through which HTPCW flows is provided in the area of ​​the warm insert rows 3.

[0047] The design goal of the laser system according to the invention is no longer to necessarily cool the laser gas down to the temperature of the cooling water (6°C). Instead, for reasons of energy efficiency, the aim is to cool the gas only to a temperature of 10-15°C. This leads to a significant reduction in energy consumption and makes it possible to limit the heat transfer surface to the necessary minimum. Compared to housing cooling, cooling by the insert rows, which are designed as finned tubes, is considerably more efficient, as these offer a larger surface area for heat transfer.

[0048] By eliminating the housing cooling in the area of ​​the cold insert rows 2, 50-80 lpm of LTPCW are saved across all process sections. Instead, slightly more heat is directed to the two additional cold insert rows 2 to ensure the required cooling capacity. This measure also eliminates the parasitic heat flows that, in previous systems, flowed from the hot to the cold housing cooling and impaired cooling performance (see Figure a). These parasitic heat flows were an undesirable side effect of the spatial proximity of hot and cold areas of the corner cooler and led to inefficient cooling processes.

[0049] Overall, the new arrangement leads to an increase in cooling power consumption of approximately 1.6 kW. However, this additional energy for cooling is compensated for by improved cooling performance, which allows the laser gas to be cooled further. This has a positive effect on the laser power, resulting in an increase of approximately 200 W. The system's cooling performance can be further optimized by a control device that regulates the flow of the LTPCW. This allows for an optimal compromise between laser power and cooling power consumption to be selected to meet the specific operational requirements.

[0050] The proposed corner cooler design leads to a significant increase in the laser system's energy efficiency. While the DL efficiency of previous systems was around 6%, the new system achieves an efficiency of 12%, measured as the ratio of input power to laser power. This improvement results from optimized cooling, the reduction of parasitic heat flows, and the adjustment of the pressure drop within the system. By replacing hot insert rows with cold ones, the pressure drop in the hot insert rows can be reduced, allowing the system to continue operating within the specified pressure drop budget.

[0051] The invention is not limited to the embodiments illustrated in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Insofar as the claims and the foregoing description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing any hierarchy. Reference symbol list 1 case 2 insert rows 3 insert rows 5 Case cooling 6 Condensation insulation

Claims

Laser system comprising a corner cooler for cooling laser gas within a laser resonator, wherein the corner cooler comprises a housing (1) with a number of warm insert rows (3) and spaced-apart cold insert rows (2), characterized in that in the region of the cold insert rows (2) there is no housing cooling through which a cooling fluid flows, but only a condensation insulation (6), and in the region of the warm insert rows (3) a housing cooling (5) through which a first cooling fluid flows is formed, wherein the housing cooling (5) is supplied with HTPCW (High Temperature Process Cooling Water), and the ratio of the cold insert rows (2) to the warm insert rows (3) in the corner cooler is at least 3:

2. Laser system according to claim 1, characterized in that the cold insert rows (2) are supplied with LTPCW (Low Temperature Process Cooling Water) to cool the laser gas inside the laser resonator to a temperature of preferably 10-15°C. Laser system according to one of the preceding claims characterized in that the number of cold insert rows (2) is at least six. Laser system according to one of the preceding claims, characterized in that the number of warm insert rows (3) is at most four. Laser system according to one of the preceding claims, characterized in that the cold insert rows (2) and the warm insert rows (3) are arranged parallel to each other to ensure a uniform cooling flow. Laser system according to one of the preceding claims, characterized in that the corner cooler comprises a control device which controls the flow of the HTPCW in the housing cooling (5) in order to adjust the cooling performance according to the operating conditions of the laser system. Laser system according to one of the preceding claims, characterized in that the total area of ​​the cold insert rows (2) is larger than the total area of ​​the warm insert rows (3), Laser system according to one of the preceding claims, characterized in that the insert rows (2,3) are designed as finned tubes.

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