Laser pumping plasma light source
By introducing beam expansion collimation device, reflector, focus lens and power detector into the laser pump plasma lamp, the laser power is detected in the split-channel, and the problem of lack of effective power monitoring of the laser pump plasma lamp is solved, real-time Status monitoring and laser usage increase.
Patent Information
- Application Number
- CN202420917549.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-28
- Publication Date
- 2025-01-07
- Estimated Expiration
- 2034-04-28
AI Technical Summary
The existing laser pump plasma lamps lack effective power monitoring, cannot understand the working status of the light source in real time and make adjustments, and the abandoned pump laser has residual energy, resulting in waste heat treatment problems.
A laser pump plasma light source is designed, including a beam expansion collimation device, a reflector, a focus lens, a plasma lamp, a first power detector and a second power detector, which is divided into a transmitting light path and a pumping light path. The first power detector and the second power detector are used to detect the laser power in real time to realize power detection and absorption analysis of the plasma lamp.
It realizes effective power detection of laser pump plasma lamps, understands the light source status in real time, improves laser usage, and reduces waste heat treatment problems.
Smart Images
Figure CN222320180U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of laser application technology, and in particular to a laser pumped plasma light source. Background Art
[0002] Against the backdrop of the rapid development of laser technology, laser-pumped plasma lamps have been widely used in instruments such as spectroscopic ellipsometers, spectroscopic scatterometers, and white light interferometers due to their wide spectrum and high brightness. They are used to measure the thickness of thin films on wafer surfaces, detect defects in patterned wafers, and measure optical critical dimensions.
[0003] Existing laser pumped plasma lamps usually include laser pump source, optical path system and plasma lamp etc. The laser pump source generates a high energy laser beam which is transmitted through the optical path system and focused on the plasma lamp to excite the plasma to generate a high brightness light source.
[0004] However, the existing laser-pumped plasma lamps lack effective power monitoring, and are unable to detect the attenuation of the laser power, understand the working status of the light source in real time, and make corresponding adjustments. At the same time, the discarded pump lasers often have residual energy, which can easily cause waste heat treatment problems. Therefore, how to use the originally discarded pump lasers to effectively detect the power of laser-pumped plasma lamps has become a technical problem to be solved. Utility Model Content
[0005] The present application provides a laser pumped plasma light source to solve the technical problem that the existing laser pumped plasma lamps lack effective power detection.
[0006] The embodiment of the present application provides a laser pumped plasma light source, comprising: a beam expansion and collimation device, a reflector, a focusing lens, a plasma lamp, a first power detector and a second power detector;
[0007] The incident laser is transmitted to the reflector through the first lens in the beam expansion and collimation device, and the incident laser is reflected to the pump light path and transmitted to the transmission light path through the reflector;
[0008] The transmission light path is provided with a first power detector for detecting the power of the transmitted laser on the transmission light path;
[0009] The second lens in the beam expansion and collimation device, the focusing lens, the plasma lamp and the second power detector are arranged in sequence on the pump light path; the pump light reflected on the pump light path is transmitted to the focusing lens through the second lens, and is focused on a preset point of the plasma lamp by the focusing lens, and the second power detector is used to detect the power of the pump light after passing through the preset point.
[0010] Optionally, the first lens in the beam expansion and collimation device is a plano-convex lens or a concave lens; and the second lens is a plano-convex lens.
[0011] Optionally, the preset point is located in a central area between two poles of the plasma lamp.
[0012] Optional, including:
[0013] The plasma lamp is ignited by an electrodeless method or an electrode method, and the pump light on the pump light path is transmitted to the plasma lamp to maintain the plasma luminescence.
[0014] Optionally, the electrodeless ignition is pulsed laser ignition, the plasma lamp is ignited by the pulsed laser, and the continuous pumping laser on the pumping light path is transmitted to the plasma lamp to maintain the plasma luminescence.
[0015] Optionally, the electrode ignition method is arc discharge ignition, the plasma lamp is ignited by arc discharge, and the continuous pump laser on the pump light path is transmitted to the plasma lamp to maintain plasma luminescence.
[0016] Optionally, the focusing lens is a biconvex lens.
[0017] Optionally, the first power detector is a photodetector, and the second power detector is a power meter.
[0018] Optionally, the plasma lamp is a short arc lamp.
[0019] Optionally, the reflector is a high-reflection mirror with a reflectivity greater than or equal to 99.5%.
[0020] Compared with the prior art, this application has the following advantages:
[0021] The present application provides a laser pumped plasma light source, comprising: a beam expansion and collimation device, a reflector, a focusing lens, a plasma lamp, a first power detector and a second power detector; an incident laser is transmitted to the reflector via the first lens in the beam expansion and collimation device, and the incident laser is reflected to a pump light path via the reflector, and the incident laser is transmitted to a transmission light path; a first power detector for detecting the power of the transmitted laser on the transmission light path is provided on the transmission light path; the second lens in the beam expansion and collimation device, the focusing lens, the plasma lamp and the second power detector are sequentially provided on the pump light path; the pump light reflected on the pump light path is transmitted to the focusing lens via the second lens, and is focused on a preset point of the plasma lamp by the focusing lens, and the second power detector is used to detect the power of the pump light after passing through the preset point.
[0022] In this type of laser pumped plasma light source, the incident laser is divided into two optical paths through a reflector, namely, a transmission optical path and a pump optical path, wherein the light beam of the transmission optical path is detected by the first power detector, and the pump optical path is detected by the second power detector after passing through the plasma lamp, so that the power value before laser pumping and the power value after laser pumping are obtained in real time through the first power detector and the second power detector on different optical paths, and then the absorption rate of the plasma lamp to the laser is obtained, and effective power detection is realized, which provides data support for analyzing its wide-spectrum ultra-bright light source characteristics, and facilitates real-time understanding of the working status of the light source and corresponding adjustments. In addition, the attenuation of the laser power can be obtained based on this, the laser utilization rate can be improved, and the problem of waste heat treatment can be solved. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of the structure of a laser pumped plasma light source provided in an embodiment of the present application.
[0024] Figure 2 This is a first schematic diagram of a laser-pumped plasma light source igniting plasma through an electrode provided in an embodiment of the present application.
[0025] Figure 3 This is a second schematic diagram of a laser-pumped plasma light source igniting plasma through an electrode provided in an embodiment of the present application.
[0026] Figure 4 This is a first schematic diagram of a laser-pumped plasma light source provided in an embodiment of the present application igniting plasma through a pulsed laser.
[0027] Figure 5 This is a second schematic diagram of a laser-pumped plasma light source provided in an embodiment of the present application igniting plasma through a pulsed laser.
[0028] Figure 6 This is a timing diagram of pulsed laser and continuous laser when a plasma is pumped by a pulsed laser, provided in an embodiment of the present application.
[0029] Reference numerals:
[0030] A first lens 1; a reflector 2; a first power detector 3; a second lens 4; a focusing lens 5; a plasma lamp 6; and a second power detector 7. DETAILED DESCRIPTION
[0031] Many specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application, so the present application is not limited by the specific implementation disclosed below.
[0032] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
[0034] The present application provides a laser pumped plasma light source, such as Figure 1-Figure 5 As shown, Figure 1 is a schematic diagram of the structure of a laser pumped plasma light source provided in an embodiment of the present application, Figure 2 is a first schematic diagram of a laser-pumped plasma light source provided in an embodiment of the present application igniting plasma through an electrode, Figure 3 is a second schematic diagram of a laser-pumped plasma light source igniting plasma through an electrode provided in an embodiment of the present application, Figure 4 This is a first schematic diagram of a laser-pumped plasma light source provided in an embodiment of the present application igniting plasma through a pulsed laser. Figure 5 1 is a second schematic diagram of a laser-pumped plasma light source provided in an embodiment of the present application igniting plasma by pulsed laser. For clarity, Figure 1-Figure 5 In the figure, the straight line with arrow represents the transmission path of the laser.
[0035] The laser pumped plasma light source comprises: a beam expansion and collimation device, a reflector 2, a focusing lens 5, a plasma lamp 6, a first power detector 3 and a second power detector 7.
[0036] The incident laser is transmitted to the reflector 2 through the first lens 1 in the beam expansion and collimation device, and the incident laser is reflected to the pump light path and transmitted to the transmission light path through the reflector 2; the transmission light path is provided with a first power detector 3 for detecting the power of the transmitted laser on the transmission light path; the pump light path is provided with a second lens 4, a focusing lens 5, a plasma lamp 6 and a second power detector 7 in the beam expansion and collimation device in sequence; the pump light reflected on the pump light path is transmitted to the focusing lens 5 through the second lens 4, and is focused on a preset point of the plasma lamp 6 through the focusing lens 5, and the second power detector 7 is used to detect the power of the pump light after passing through the preset point.
[0037] In the laser pumped plasma light source, the beam expansion and collimation device is a device arranged before the pump light path, and includes a first lens 1 and a second lens 4, and the first lens 1 and the second lens 4 are arranged successively along the light path transmission direction. The first lens 1 is used to diverge the incident laser, and the second lens 4 is used to convert the diverged laser into an approximately parallel beam.
[0038] There are many specific ways to set up the beam expansion and collimation device. For example, Figure 1 , Figure 2 and Figure 4 As shown, the first lens 1 in the beam expansion and collimation device can be set as a plano-convex lens. Figure 3 and Figure 5 As shown, the first lens 1 is configured as a concave lens. The second lens 4 is used to collimate the laser and can be configured as a plano-convex lens, etc. In summary, the cooperation between the first lens 1 and the second lens 4 only needs to achieve the function of beam expansion and collimation.
[0039] A reflector 2 is arranged between the first lens 1 and the second lens 4, so that the incident laser is emitted onto the reflector 2 after passing through the first lens 1, and the laser reflected by the reflector 2 is transmitted to the second lens 4, and the second lens 4 converts the laser reflected by the reflector 2 into approximately parallel laser to pump the plasma lamp 6.
[0040] In order to ensure the divergence effect of the first lens 1 on the incident laser, corresponding to different settings of the first lens 1, the spacing distance between the first lens 1 and the reflector 2 can be set to different preset distances.
[0041] For example, when the first lens 1 is set as a plano-convex lens, the plane of the plano-convex lens can be aligned with the laser light source of the incident laser, the convex surface of the plano-convex lens can be aligned with the reflecting surface of the reflector 2, and the focus of the incident laser focused by the plano-convex lens can be located between the plano-convex lens and the reflector 2, and then the spacing distance between the plano-convex lens and the reflector 2 can be set to a first preset distance, so that the divergence of the laser by the plano-convex mirror is a focused divergence and achieves a preset divergence effect.
[0042] When the first lens 1 is set as a concave lens, since the concave lens itself will expand the divergence angle of the incident laser, the spacing distance between the concave lens and the reflector 2 should be set to a second preset distance, so as to directly control the divergence of the incident laser by the concave lens through the second preset distance, so as to achieve the preset divergence effect.
[0043] After the incident laser is emitted onto the reflector 2, the incident laser will be reflected and transmitted on the reflector 2, thereby dividing the incident laser into reflected laser and transmitted laser. The installation angle of the reflector 2 can be preset so that the reflected laser is transmitted along the pumping light path and the transmitted laser is transmitted along the transmission light path. The reflector 2 can preferably be set as a high-reflection mirror with a reflectivity greater than or equal to 95% to ensure that the reflected laser as the pump light has sufficient energy to pump the plasma lamp 6. In this embodiment, in order to further enhance the pumping effect, the reflectivity of the reflector 2 is preferably selected to be a high-reflection mirror greater than or equal to 99.5%.
[0044] A first power detector 3 for detecting the power of the transmitted laser on the transmitted light path is provided on the transmitted light path to receive the transmitted laser transmitted through the reflector 2 and detect the power of the transmitted laser.
[0045] In the pumping optical path, a second lens 4, a focusing lens 5, a plasma lamp 6 and a second power detector 7 are sequentially arranged. After the reflected laser is converted into approximately parallel pumping light by the second lens 4, the focusing lens 5 focuses the laser on a preset point of the plasma lamp 6 to achieve pumping of the plasma lamp 6. During the pumping process, the laser passing through the plasma lamp 6 will be transmitted to the second power detector 7, and the second power detector 7 will detect the power of the reflected laser after pumping.
[0046] When the second lens 4 is configured as a plano-convex lens, in order to enable the plano-convex lens to convert the reflected laser into a nearly parallel laser beam, i.e., to achieve the collimation function, the convex surface of the second lens 4, which is a plano-convex lens, is aligned with the reflector 2, and the plane of the second lens 4, which is a plano-convex lens, is aligned with the focusing lens 5.
[0047] The focusing lens 5 is preferably configured as a biconvex lens or a plano-convex lens, and the focusing lens 5 can focus the laser light collimated by the second lens 4 to a preset point of the plasma lamp 6 to pump the ignited plasma.
[0048] The plasma lamp 6 is a transparent container with a plasma filled inner cavity. The plasma lamp 6 can be a short arc lamp or other types of plasma lamps, which are not limited here. The preset point of the plasma lamp 6 is located in the inner cavity of the plasma lamp 6, which can be the focus of the laser, or the target point. In a preferred embodiment, the preset point is located in the central position area between the two poles of the plasma lamp 6 to ensure the pumping effect.
[0049] Before laser pumping plasma, the plasma needs to be ignited first. The specific ignition methods include electrodeless ignition and electrode ignition. That is, the plasma lamp 6 is ignited by electrodeless ignition or electrode ignition, and the pump light on the pump light path is transmitted to the plasma lamp 6 to maintain the plasma luminescence. Among them, the pump light is the reflected laser used for pumping.
[0050] When the electrode ignition is arc discharge ignition, such as Figure 2 and Figure 3 As shown, the plasma lamp 6 is provided with discharge electrodes, the plasma lamp 6 is ignited by arc discharge, and the continuous pumping laser on the pumping light path is transmitted into the plasma lamp 6 to maintain plasma luminescence.
[0051] During specific operation, the laser light source always emits continuous laser to preheat the plasma. After preheating to a preset temperature or a preset preheating time, the electrode in the plasma lamp 6 is energized to ignite the plasma through the electrode, and then the plasma can be pumped by continuous laser. Among them, the preset temperature and the preset time can be determined according to specific needs. For example, in order to ensure that the electrode is successfully ignited once, a longer preset time can be set, such as a preset time greater than 60 seconds. In addition, the preset can be preheated by laser or by other means, which is not limited here.
[0052] When the electrodeless ignition is pulsed laser ignition, Figure 4 and Figure 5 As shown, no electrode is required in the plasma lamp 6, the plasma lamp 6 is ignited by a pulsed laser, and the continuous pumping laser on the pumping light path is transmitted to the plasma lamp 6 to maintain the plasma luminescence.
[0053] The specific operation of the laser emission process can be as follows Figure 6 As shown, Figure 6 This is a timing diagram of pulsed laser and continuous laser when the plasma lamp 6 is pumped by pulsed laser provided in an embodiment of the present application. Specifically, the laser light source always emits continuous laser for preheating. When the plasma needs to be ignited, the pulsed laser is emitted. The pulsed laser is incident into the plasma lamp 6, generating a strong thermal effect and ionization effect, causing the temperature and pressure inside the plasma to rise rapidly, thereby causing ignition. After the plasma is ignited, the plasma lamp 6 can continue to be pumped by continuous laser.
[0054] The first power detector 3 and the second power detector 7 are both used to detect laser power, and the first power detector 3 and the second power detector 7 can be the same or different. Exemplarily, a preferred embodiment is that the first power detector 3 is a photoelectric detector, and the second power detector 7 is a power meter.
[0055] The first power detector 3 is used to detect the power of the transmitted laser, and the second power detector 7 is used to detect the power of the reflected laser as pump light after pumping the plasma lamp 6. According to the regular detection or real-time detection of the first power detector 3 and the second power detector 7, the power of the laser can be effectively detected, thereby detecting the dynamic process of the laser pumped plasma.
[0056] Specifically, before the plasma in the plasma lamp 6 is ignited, that is, before the plasma emits light, the laser power is detected by the first power detector 3 and the second power detector 7 respectively. When the plasma is ignited and laser pumping is performed, the laser power is detected by the first power detector 3 and the second power detector 7 respectively, and the laser power is accurately detected, thereby obtaining the absorption rate of the plasma to the laser during the pumping process, and the relationship curve between the absorption rate and the pump laser power can be obtained accordingly, thereby obtaining the attenuation characteristics of the pump laser power with the absorption rate, so as to effectively detect and control the laser pumped plasma lamp 6.
[0057] Exemplarily, before the plasma in the plasma lamp 6 is ignited, such as at the first time t1 when preheating starts but the plasma does not emit light, the first power detector 3 measures the power as P1(t1), and the second power detector 7 measures the power as P2(t1). After the plasma is ignited and at the second time t2 when the plasma is pumped by the continuous laser, the first power detector 3 measures the power as P1(t2), and the second power detector 7 measures the power as P2'(t2).
[0058] Since the absorption rate of plasma to laser is very low in the non-luminous state, if the plasma is not ignited and does not emit light at the second moment t2, its theoretical power P2(t2) should satisfy P2(t2) / P1(t2)=P2(t1) / P1(t1), then P2(t2)=P2(t1)×P1(t2) / P1(t1). At the second moment t2, the absorption rate η of plasma to laser should actually be: η(t2)=1-P2'(t2) / P2(t2)=1-P2'(t2)×P1(t1) / P2(t1)×P1(t2).
[0059] After the plasma is ignited and pumped by a continuous laser, the first power detector 3 and the second power detector 7 can simultaneously detect the power at multiple moments, thereby stably detecting the accurate value of the absorption rate η at multiple moments, thereby obtaining a relationship curve between the absorption rate and the pump laser power, realizing accurate power detection, and thereby always detecting the attenuation of the laser power, and ensuring that the detection is in place and has a high reliability.
[0060] In the laser pumped plasma light source provided in this embodiment, the incident laser is divided into two optical paths through a reflector, namely, a transmission optical path and a pump optical path, wherein the light beam of the transmission optical path is detected by a first power detector, and the pump optical path is detected by a second power detector after passing through a plasma lamp, thereby obtaining the power value before laser pumping and the power value after laser pumping in real time through the first power detector and the second power detector on different optical paths, and then obtaining the absorption rate of the plasma lamp to the laser, realizing effective power detection, providing data support for analyzing its wide-spectrum ultra-bright light source characteristics, and facilitating real-time understanding of the working status of the light source and making corresponding adjustments. In addition, the attenuation of the laser power can be obtained based on this, the laser utilization rate can be improved, and the problem of waste heat treatment can be reduced. This type of laser pumped plasma light source can not only reasonably and effectively utilize the pump laser, but also monitor the laser absorption characteristics of the luminescent plasma, thereby obtaining the luminescence characteristics information of the plasma lamp in real time.
[0061] It should be noted that, although several structures, components or units for realizing related functions are mentioned in the above detailed description, such division is not mandatory. In fact, according to the specific implementation of the present application, the features and functions of two or more structures, components or units described above can be concretized in one structure, component or unit. Conversely, the features and functions of one structure, component or unit described above can be further divided into multiple components, structures or units to be concretized.
[0062] In addition, although the components and the installation methods of the components or devices in the present application are described in a specific order in the drawings, this does not require or imply that the components or devices must be designed according to the specific components or the installation methods of the components, or that all the components shown must be included to achieve the desired results. Additionally or alternatively, some components can be omitted, multiple components can be combined into one component to achieve corresponding functions, and / or one component can be decomposed into multiple components to achieve corresponding functions, etc.
[0063] Although the present application is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present application. Any technical personnel in this field may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.
Claims
1. A laser pumped plasma light source, characterized in that: include: A beam expansion and collimation device, a reflector, a focusing lens, a plasma lamp, a first power detector and a second power detector; The incident laser is transmitted to the reflector through the first lens in the beam expansion and collimation device, and the incident laser is reflected to the pump light path through the reflector, and the incident laser is transmitted to the transmission light path; The transmission light path is provided with the first power detector for detecting the power of the transmitted laser on the transmission light path; The second lens in the beam expansion and collimation device, the focusing lens, the plasma lamp and the second power detector are sequentially arranged on the pump light path; the pump light reflected on the pump light path is transmitted to the focusing lens via the second lens, and is focused on a preset point of the plasma lamp by the focusing lens, and the second power detector is used to detect the power of the pump light after passing through the preset point.
2. The laser pumped plasma light source according to claim 1, characterized in that: The first lens in the beam expansion and collimation device is a plano-convex lens or a concave lens; the second lens is a plano-convex lens.
3. The laser pumped plasma light source according to claim 1, characterized in that: The preset point is located in the central area between the two poles of the plasma lamp.
4. The laser pumped plasma light source according to claim 1, characterized in that: include: The plasma lamp is ignited in an electrodeless manner or an electrode manner, and the pump light on the pump light path is transmitted into the plasma lamp.
5. The laser pumped plasma light source according to claim 4, characterized in that: The electrodeless ignition is pulse laser ignition, the plasma lamp is ignited by the pulse laser, and the continuous pump laser on the pump optical path is transmitted to the plasma lamp.
6. The laser-pumped plasma light source according to claim 4, characterized in that: The electrode ignition method is arc discharge ignition, the plasma lamp is ignited by the arc discharge, and the continuous pumping laser on the pumping light path is transmitted to the plasma lamp.
7. The laser pumped plasma light source according to claim 1, characterized in that: The focusing lens is a biconvex lens.
8. The laser-pumped plasma light source according to claim 1, characterized in that: The first power detector is a photoelectric detector, and the second power detector is a power meter.
9. The laser-pumped plasma light source according to claim 1, characterized in that: The plasma lamp is a short arc lamp.
10. The laser-pumped plasma light source according to claim 1, characterized in that: The reflector is a high-reflection mirror with a reflectivity greater than or equal to 95%.