High-pressure gas discharge lamp and laser driving device thereof

Abstract

The invention discloses a high-pressure gas discharge lamp and a laser driving device thereof, and belongs to the technical field of gas discharge lamps, the high-pressure gas discharge lamp comprises a lamp housing, a first lamp post, a second lamp post, an anode, a cathode and a cooling device, the first lamp post and the second lamp post are respectively located at the anode end and the cathode end of the lamp housing, and the anode and the cathode are arranged in a discharge chamber and located in the axial direction of the lamp housing; the first lamp pole and the second lamp pole are communicated with the connecting pieces at the two ends respectively. The center of the plasma is located above the center of the lamp shell, the distance from the anode to the center of the lamp shell is d1, the distance from the cathode to the center of the lamp shell is d2, d1 is larger than d2, preferably, d1 / d2 is larger than 2, and d1 + d2 is larger than 18 mm. The cooling device is of a conical barrel double-layer structure, and a plurality of small holes are formed in the bottom and aligned with the lamp shell around the plasma center for cooling. The gas discharge lamp can be effectively cooled, so that the gas discharge lamp is kept in a safe temperature range in the working process, the reliability of the gas discharge lamp is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of gas discharge lamps, and particularly to a high-pressure gas discharge lamp and its laser driving device. Background Art

[0002] A laser-driven high-pressure gas discharge lamp is a gas discharge lamp widely used in fields such as semiconductor defect detection. It is usually equipped with a dedicated lamp chamber system. The laser beam is diverged and then irradiated on a reflector bowl. After reflection, it is focused on the center of the high-pressure gas discharge lamp, causing the gas inside the high-pressure gas discharge lamp to ionize to form a plasma and emit light. When the high-pressure gas discharge lamp starts, a high voltage is applied between the cathode and the anode, which helps in the formation of the plasma. After the high-pressure gas discharge lamp starts, it relies on the laser to maintain the plasma to emit light, and no high voltage needs to be applied anymore. The light emitted by the plasma is collected by the reflector bowl and then irradiated on a dichroic mirror. After being reflected by the dichroic mirror, it is separated from the laser beam and output.

[0003] The electrodes of this kind of high-pressure gas discharge lamp only play an auxiliary role during the startup stage. There is no emission and reception of electrons between the electrodes during the stable operation process. Therefore, the damage to the electrodes is reduced, and the service life of the high-pressure gas discharge lamp is extended. Since this kind of high-pressure gas discharge lamp provides energy through a laser beam to maintain the plasma to emit light, the plasma is concentrated in a smaller space range. Therefore, the central temperature of the plasma is higher, and the proportion of the ultraviolet component in the emitted light is higher. In addition, since this kind of high-pressure gas discharge lamp is installed vertically with the anode end on top, the hot air flow inside the lamp makes the temperature of the anode and the surrounding lamp shell higher. Therefore, targeted cooling is required. Otherwise, the temperature gradient will exceed the tolerance limit of the material, thereby affecting the performance and life of the high-pressure gas discharge lamp. Summary of the Invention

[0004] The present invention aims to provide a high-pressure gas discharge lamp and a laser driving device.

[0005] To achieve the above object, the technical solution of the present invention is: a high-pressure gas discharge lamp, including a lamp shell, the middle part of the lamp shell encloses to form a discharge chamber; a first lamp rod, the first lamp rod is arranged at the anode end of the lamp shell; an anode, the anode is connected to the first lamp rod and is located inside the discharge chamber; a second lamp rod, the second lamp rod is arranged at the cathode end of the lamp shell; a cathode, the cathode is connected to the second lamp rod and is located inside the discharge chamber; the distance from the anode to the center of the lamp shell is set as d1, the distance from the cathode to the center of the lamp shell is set as d2, and d1 > d2.

[0006] In one embodiment, d1 / d2 > 2 and d1 + d2 > 18 mm.

[0007] In one embodiment, it further includes an air filling port, and the air filling port is arranged at the end of the lamp shell.

[0008] In one embodiment, the inflation port is disposed at the cathode end of the lamp housing.

[0009] In one embodiment, it further includes a sealing member and a connecting member. The first lamp post and the second lamp post are respectively fixedly connected to the lamp housing through the sealing member; the connecting member is connected to the sealing member.

[0010] In one embodiment, it further includes a cooling device, and the cooling device is installed at the anode end of the lamp housing.

[0011] In one embodiment, the cooling device includes an inner housing, an outer housing, an air duct and an air outlet. The outer housing is sleeved outside the inner housing. The top and bottom of the inner housing and the outer housing are connected to each other. The diameter of the bottom of the outer housing is the same as the maximum lateral diameter of the discharge chamber; the gap between the inner housing and the outer housing forms the air duct, and a plurality of the air outlets are evenly opened at the bottom of the inner housing and the outer housing, and are aligned with the lamp housing around the plasma center.

[0012] In one embodiment, the cooling device further includes an air inlet and a mounting portion. The air inlet is opened on the outer housing and communicates with the air duct; the mounting portion is arranged at the top of the inner housing and the outer housing; the cooling device is installed at the anode end of the lamp housing through the mounting portion.

[0013] The present invention also provides a laser driving device, including the high-pressure gas discharge lamp described in any one of the above.

[0014] In one embodiment, the laser driving device further includes a lamp chamber system. The lamp chamber system includes a laser, a beam expander, a reflector, a dichroic mirror and a reflector bowl. The laser, the beam expander and the reflector are arranged on a horizontal straight line. The reflector, the dichroic mirror and the reflector bowl are arranged on a vertical straight line in sequence. The high-pressure gas discharge lamp is installed in the reflector bowl along the vertical direction through the connecting member. The inner surface of the reflector bowl is an ellipsoidal surface, and the center of the high-pressure gas discharge lamp coincides with the focus of the ellipsoidal surface.

[0015] A high-pressure gas discharge lamp proposed by the present invention reduces the burning of the anode by the plasma and lowers the temperature of the anode by adjusting the distance between the anode and the cathode and the asymmetric layout; and a cooling device is configured to precisely cool the lamp housing around the plasma center, effectively reducing the temperature of the high-pressure gas discharge lamp, keeping the high-pressure gas discharge lamp within a safe temperature range during operation, improving the reliability of the high-pressure gas discharge lamp, and extending the service life of the gas discharge lamp.

[0016] To make the above features and advantages of the invention more obvious and understandable, specific embodiments are given below and described in detail in conjunction with the accompanying drawings. Description of the Drawings

[0017] Figure 1 Schematic diagram of the laser driving device of the present invention; Figure 2 Schematic cross-sectional view of the high-pressure gas discharge lamp of the present invention; Figure 3 Schematic diagram of the cooling device.

[0018] 1 - Laser driving device; 11 - Lamp chamber system; 111 - Laser; 112 - Beam expander; 113 - Reflecting mirror; 114 - Dichroic mirror; 115 - Reflector bowl; 12 - High-pressure gas discharge lamp; 121 - Lamp housing; 1211 - Discharge chamber; 1212 - First side tube; 1213 - Second side tube; 122 - Gas filling port; 123 - First lamp rod; 124 - Second lamp rod; 125 - Anode; 126 - Cathode; 127 - Sealing member; 128 - Fixing member; 129 - Cooling device; 1291 - Inner housing; 1292 - Outer housing; 1293 - Air duct; 1294 - Air inlet; 1295 - Air outlet; 1296 - Mounting portion.

[0019] In the drawings, like reference numerals refer to the same elements of the drawings. Detailed Embodiments

[0020] To make the objectives and technical solutions of the embodiments of the present invention clearer, the following will combine the accompanying drawings of the embodiments of the present invention Figure 1 - Accompanying Figure 3 , and clearly and completely describe the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0021] In the present invention, for clear description, the following explanations are made: When the observer observes facing the accompanying Figure 1 , the upper end of the discharge lamp is the "anode end" and the lower end is the "cathode end". For ease of explanation, the up, down, left, and right directions in the specification respectively correspond to the up, down, left, and right directions when the observer observes facing the accompanying Figure 1 . The above explanations are only for clearly describing the present invention, rather than indicating or implying that the structures or components referred to must have a specific orientation or be constructed in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0022] As Figure 1As shown, a laser driving device 1 is used to detect defects with micro and nano-scale dimensions. The laser driving device 1 includes a lamp chamber system 11 and a high-pressure gas discharge lamp 12. The high-pressure gas discharge lamp 12 is used to detect nano-scale defects on a semiconductor wafer. The high-pressure gas discharge lamp 12 is installed vertically in the lamp chamber system 11. The lamp chamber system 11 emits a laser beam, which after reflection and focusing, causes the high-pressure gas discharge lamp 12 to emit light. The light emitted by the high-pressure gas discharge lamp 12 is output after reflection again.

[0023] The lamp chamber system 11 includes a laser 111, a beam expander 112, a reflector 113, a dichroic mirror 114, and a reflector bowl 115. The laser 111 emits a laser beam. The laser 111, the beam expander 112, and the reflector 113 are arranged on a horizontal straight line, and the reflector 113 is placed obliquely. The dichroic mirror 114 and the reflector bowl 115 are arranged in sequence below the reflector 113 and are on a vertical straight line with the dichroic mirror 114. The dichroic mirror 114 has an opposite inclination direction to the reflector 113. The high-pressure gas discharge lamp 12 is installed vertically in the reflector bowl 115, with the upper end being the anode end and the lower end being the cathode end. The inner surface of the reflector bowl 115 is an ellipsoidal surface, and the center of the high-pressure gas discharge lamp 12 coincides with the focus of the ellipsoidal surface of the reflector bowl 115.

[0024] The laser 111 emits a laser beam. The laser beam diverges at a certain angle after passing through the beam expander 112, is reflected by the reflector 113, passes through the dichroic mirror 114, and irradiates on the inner surface of the reflector bowl 115. The equivalent focus of the laser beam and the center of the high-pressure gas discharge lamp 12 are respectively located at the two foci of the ellipsoidal surface of the reflector bowl 115. The high-power laser beam after focusing ionizes the gas in the high-pressure gas discharge lamp 12 to form a plasma. During the start-up stage within a few seconds, applying a high voltage at both ends of the high-pressure gas discharge lamp 12 helps in the formation of the plasma. During the stable operation stage, the high-temperature plasma continuously emits light with a continuous spectrum. The higher the temperature, the stronger the ultraviolet component of the emitted spectrum. The light emitted by the high-pressure gas discharge lamp 12 is collected by the reflector bowl 115 and output after being reflected by the dichroic mirror 114. Before the emitted light is output, it can also pass through a light homogenizing device, a collimating device, etc.

[0025] Please combine Figure 1 and Figure 2, the upper end of the high-pressure gas discharge lamp 12 is the anode end, and the lower end is the cathode end. The high-pressure gas discharge lamp 12 includes a lamp housing 121, an air filling port 122, a first lamp pole 123, a second lamp pole 124, an anode 125, a cathode 126, a sealing member 127 and a fixing member 128. The lamp housing 121 is a symmetric hollow structure. Both ends of the lamp housing 121 are tubular, and the middle part is bulb-shaped. External laser is focused on the center O of the lamp housing 121.

[0026] Refer to Figure 2 , the air filling port 122 is arranged at the end of the lamp housing 121. Preferably, the air filling port 122 is arranged at the cathode end of the lamp housing 121. The air filling port 122 is used to fill gas into the lamp housing 121, and the air filling port 122 is sealed after filling. Generally, the air filling port 122 is arranged in the middle part of the lamp housing 121. However, this arrangement destroys the continuity of the lamp housing 121, forms stress concentration, and is likely to cause the high-pressure gas discharge lamp 12 to explode under high temperature and high pressure conditions. Transferring the air filling port 122 from the middle part of the lamp housing 121 to the cathode end of the lamp housing 121 maintains the continuity of the lamp housing 121, improves the pressure resistance of the lamp housing 121. At the same time, during the operation of the high-pressure gas discharge lamp 12, the whole is in a high-temperature state, and the temperature of the anode end is relatively higher. The air filling port 122 is located at the cathode end, and the temperature is lower than that of the anode end, reducing the probability of the lamp housing 121 cracking.

[0027] Please refer to Figure 1 and Figure 2 , the first lamp pole 123 and the second lamp pole 124 are respectively arranged inside the lamp housing 121, on the axis of the lamp housing 121, and are respectively located at the anode end and the cathode end of the lamp housing 121. The first lamp pole 123 is an anode lamp pole, and the second lamp pole 124 is a cathode lamp pole. One end of the first lamp pole 123 close to the center of the lamp housing 121 is provided with the anode 125, and the second lamp pole 124 close to the center of the lamp housing 121 is provided with the cathode 126. The anode 125 and the cathode 126 are arranged facing each other, and the anode 125 and the cathode 126 are located on the axis of the lamp housing 121. When the external laser is focused on the center O of the lamp housing 121, the laser focus coincides with the center O of the lamp housing 121, and the plasma center P is located above the laser focus. The distance from the anode 125 to the center O of the lamp housing 121 is set as d1, and the distance from the cathode 126 to the center O of the lamp housing 121 is set as d2. d1 > d2. Preferably, d1 / d2 > 2 and d1 + d2 > 18 mm. This asymmetric setting can reduce the burning of the plasma on the anode 125, thereby reducing the temperature of the anode 125.

[0028] Refer to Figure 2, the two sealing members 127 are respectively connected to the ends of the first lamp post 123 and the second lamp post 124. The sealing members 127 are installed at the two end ports of the lamp housing 121. The first lamp post 123 and the second lamp post 124 are fixed in the lamp housing 121 through the sealing members 127. The sealing members 127 are used to seal the connection positions between the first lamp post 123, the second lamp post 124 and the lamp housing 121, balance the thermal expansion coefficients between the first lamp post 123, the second lamp post 124 and the lamp housing 121, so as to maintain the seal of the high-pressure gas discharge lamp 12 in the lit and unlit states and prevent the gas filled in the lamp housing 121 from leaking; the fixing member 128 is connected to the sealing member 127, and the fixing member 128 is used to install the high-pressure gas discharge lamp 12 at a specific position in the lamp chamber system 11; the cooling device 129 is installed at the positive end of the lamp housing 121.

[0029] Refer to Figure 2 , the lamp housing 121 includes a discharge chamber 1211, a first side tube 1212 and a second side tube 1213. The discharge chamber 1211 is formed by surrounding the center of the lamp housing 121. The discharge chamber 1211 is filled with a gas of specific components and pressure. The two sides of the discharge chamber 1211 are respectively connected to the first side tube 1212 and the second side tube 1213. The first lamp post 123 passes through the first side tube 1212 and extends out along the direction of the discharge chamber 1211, so that the anode 125 is inside the discharge chamber 1211; the second lamp post 124 passes through the second side tube 1213 and extends out along the direction of the discharge chamber 1211, so that the cathode 126 is located inside the discharge chamber 1211. The gas filling port 122 is arranged on the second side tube 1213; the cooling device 129 is sleeved on the outside of the first side tube 1212. The cooling device 129 can be an air-cooling device. The air outlet position of the cooling device 129 is aligned with the discharge chamber 1211. Further, the air outlet position of the cooling device 129 is aligned with the periphery of the plasma center P.

[0030] Please refer to Figure 2 and Figure 3, the cooling device 129 is a conical cylinder double-layer structure as a whole, including an inner housing 1291, an outer housing 1292, an air duct 1293, an air inlet 1294, an air outlet 1295 and a mounting portion 1296. The outer housing 1292 is sleeved outside the inner housing 1291. The top and bottom of the inner housing 1291 and the outer housing 1292 are connected to each other. The length of the outer housing 1292 in the vertical direction is greater than the length of the inner housing 1291 in the vertical direction. The bottom of the inner housing 1291 and the outer housing 1292 forms a stepped shape, so that the bottom of the inner housing 1291 is aligned with the anode 125. The bottom diameter of the outer housing 1292 is the same as the maximum transverse diameter of the discharge chamber 1211. The bottom of the outer housing 1292 is aligned with the discharge chamber 1211; the gap between the inner housing 1291 and the outer housing 1292 forms the air duct 1293; the air inlet 1294 is opened on the outer housing 1292. The air inlet 1294 is connected to a pipeline (not shown in the figure), and the air inlet 1294 is communicated with the air duct 1293; a plurality of the air outlets 1295 are evenly opened at the bottom of the inner housing 1291 and the outer housing 1292. Cold air is input from the air inlet 1294 and flows out from the air outlet 1295 through the air duct 1293. Since the plasma center P is located above the laser focus, the cold air output from the air outlet 1295 is aligned with the discharge chamber 1211 for cooling. Further, the air outlet 1295 on the inner housing 1291 is aligned with the periphery of the anode 125 for cooling, and the air outlet 1295 on the outer housing 1292 is aligned with the periphery of the plasma center P for cooling. The air outlet 1295 can accurately deliver cold air to the area with the highest temperature of the lamp housing 121. The air outlet 1295 is preferably a small hole with a diameter of 0.5 mm. The air outlet 1295 with a small diameter has a higher flow rate and better cooling effect; the mounting portion 1296 is mounted on the top of the inner housing 1291 and the outer housing 1292. The cooling device 129 is mounted on the anode end of the lamp housing 121 through the mounting portion 1296. Specifically, the mounting method of the cooling device 129 can be, but is not limited to, being threadedly connected to the fixing member 128 through the mounting portion 1296. A high-pressure gas discharge lamp proposed by the present invention reduces the burning of the anode by the plasma and lowers the temperature of the anode by adjusting the distance between the anode and the cathode and the asymmetric layout; and a cooling device is configured to accurately cool the lamp housing around the plasma center, effectively reducing the temperature of the high-pressure gas discharge lamp, keeping the high-pressure gas discharge lamp within a safe temperature range during operation, improving the reliability of the high-pressure gas discharge lamp, and extending the service life of the high-pressure gas discharge lamp.

[0031] Although the present invention has been disclosed above by way of examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the appended patent application scope.

Claims

1. A high pressure gas discharge lamp, characterized in that: include A lamp housing, the middle portion of which is surrounded to form a discharge chamber; A first lamp pole, which is arranged at the anode end of the lamp housing; an anode, the anode being connected to the first lamp pole and being located in the discharge chamber; A second lamp pole, the second lamp pole being arranged at the cathode end of the lamp housing; a cathode, the cathode being connected to the second lamp pole and being located in the discharge chamber; The anode and the cathode are arranged facing each other, the distance from the anode to the center of the lamp housing is set to d1, the distance from the cathode to the center of the lamp housing is set to d2, and d1>d2.

2. A high pressure gas discharge lamp as claimed in claim 1, characterized in that: The d1 / d2>2 and d1+d2>18mm.

3. A high pressure gas discharge lamp as claimed in claim 1, characterized in that: It also includes an air filling port, which is arranged at the end of the lamp housing.

4. A high pressure gas discharge lamp as claimed in claim 3, characterized in that: The gas filling port is arranged at the cathode end of the lamp housing.

5. A high pressure gas discharge lamp as claimed in claim 1, characterized in that: It also includes a sealing member and a connecting member, wherein the first lamp pole and the second lamp pole are respectively fixedly connected to the lamp housing through the sealing member; and the connecting member is connected to the sealing member.

6. A high pressure gas discharge lamp as claimed in claim 1, characterized in that: It also includes a cooling device, which is installed at the anode end of the lamp housing.

7. A high pressure gas discharge lamp as claimed in claim 6, characterized in that: The cooling device comprises an inner shell, an outer shell, an air duct and an air outlet, wherein the outer shell is sleeved on the outer side of the inner shell, the inner shell and the outer shell are connected to each other at the top and the bottom, and the bottom diameter of the outer shell is the same as the maximum transverse diameter of the discharge chamber; the gap between the inner shell and the outer shell forms the air duct, and a plurality of the air outlets are evenly arranged at the bottom of the inner shell and the outer shell, and are aligned with the lamp shell around the center of the plasma.

8. A high pressure gas discharge lamp as claimed in claim 7, characterized in that: The cooling device also includes an air inlet and a mounting portion, wherein the air inlet is provided on the outer shell and connected to the air duct; the mounting portion is arranged on the top of the inner shell and the outer shell; and the cooling device is mounted on the anode end of the lamp housing through the mounting portion.

9. A laser driving device, characterized in that: The invention comprises the high pressure gas discharge lamp as described in any one of claims 1 to 8.

10. The laser driving device according to claim 9, characterized in that: It also includes a lamp house system, which includes a laser, a beam expander, a reflector, a dichroic mirror and a reflective bowl. The laser, the beam expander and the reflector are arranged on a horizontal line, and the reflector, the dichroic mirror and the reflective bowl are arranged in sequence on a vertical line. The high-pressure gas discharge lamp is installed in the reflective bowl along the vertical direction, and the inner surface of the reflective bowl is an ellipsoidal surface. The center of the high-pressure gas discharge lamp coincides with the focus of the ellipsoidal surface.

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