Optical isolation system and laser drilling system

Abstract

The utility model relates to an optical isolation system and a laser drilling system. The optical isolation system comprises a polarization selective reflector which is arranged on a light path of a first linearly polarized light beam and is used for totally reflecting the first linearly polarized light beam to form a second linearly polarized light beam; the phase delay reflector is arranged on a light path of the second linearly polarized light beam, is used for reflecting the second linearly polarized light beam to form a circularly polarized light beam, and is also used for reflecting a circularly polarized reflected light beam to form a third linearly polarized light beam after receiving the circularly polarized reflected light beam corresponding to the circularly polarized light beam; the vibration direction of the third linearly polarized light beam is parallel to the incident plane of the third linearly polarized light beam incident to the polarization selective reflector; and the polarization selective reflector is also used for absorbing the third linearly polarized light beam. By the adoption of the optical isolation system and the laser drilling system, the laser can be effectively protected.

Description

Technical Field

[0001] This application relates to the field of optical processing technology, and in particular to optical isolation systems and laser drilling systems. Background Technology

[0002] With the rapid development of electronic technology, especially the ever-increasing demand in fields such as portable electronic devices, communication equipment, and automotive electronics, high-density interconnect circuit board (HDPCB) technology has emerged. HDPCB technology significantly improves the wiring density and performance of circuit boards by using micro-wires, microvias, and multilayer structures, meeting the demands of modern electronic devices for high integration, high performance, and miniaturization.

[0003] High-density interconnect circuit boards typically consist of a copper foil layer on the surface and a non-metallic material layer such as epoxy resin sandwiched between the copper foil. Because non-metallic materials have excellent absorption characteristics for 9.4μm wavelength carbon dioxide laser beams, this wavelength is commonly used to create through-holes and blind vias on PCBs. However, the bright copper foil on the surface of high-density interconnect circuit boards has extremely high reflectivity to 9.4μm wavelength laser beams.

[0004] In related technologies, copper foil is typically browned or blackened to improve its light absorption capacity. However, a significant amount of laser beam is still reflected back into the laser, causing instability or damage. Utility Model Content

[0005] Therefore, it is necessary to provide an optical isolation system and a laser drilling system that can protect the laser.

[0006] In a first aspect, this application provides an optical isolation system, the optical isolation system comprising a polarization-selective reflector and a phase-retardant reflector, wherein:

[0007] A polarization-selective reflector is used to reflect vertically polarized light and absorb parallel polarized light. The polarization-selective reflector is disposed in the optical path of a first linearly polarized beam, and the normal of the polarization-selective reflector is perpendicular to the vibration direction of the first linearly polarized beam. The polarization-selective reflector is used to reflect the first linearly polarized beam to form a second linearly polarized beam.

[0008] A phase delay mirror is used to delay the phase of parallel polarized light by a first angle; the phase delay mirror is disposed in the optical path of the second linearly polarized beam, and the angle between the normal of the phase delay mirror and the vibration direction of the second linearly polarized beam is a second angle; the phase delay mirror is used to reflect the second linearly polarized beam to form a circularly polarized beam.

[0009] The phase delay mirror is also used to reflect the circularly polarized reflected beam to form a third linearly polarized beam after receiving the circularly polarized reflected beam corresponding to the circularly polarized beam; the optical path of the third linearly polarized beam overlaps with that of the second linearly polarized beam, and the vibration direction of the third linearly polarized beam is parallel to the incident surface of the third linearly polarized beam when it is incident on the polarization selective mirror.

[0010] The polarization-selective reflector is also used to absorb the third linearly polarized beam.

[0011] In one embodiment, the first angle is 89-91 degrees and the second angle is 59-61 degrees.

[0012] In one embodiment, the polarization-selective reflector includes a metal substrate layer and an absorptive-transmission-reflective coating.

[0013] In one embodiment, the metal substrate layer includes a copper substrate layer.

[0014] In one embodiment, the first linearly polarized beam is incident on the polarization-selective mirror at an angle of 44-46 degrees.

[0015] Secondly, this application also provides a laser drilling system, which includes the optical isolation system described above, and further includes:

[0016] A laser used to emit a first linearly polarized beam;

[0017] A focusing lens is used to drill a hole in a target workpiece by focusing the circularly polarized light beam onto the target workpiece.

[0018] In one embodiment, the laser drilling system further includes at least one of the following:

[0019] A silicon total internal reflection mirror is disposed in the optical path of the first linearly polarized light or the circularly polarized beam, and is used to adjust the optical axis of the first linearly polarized light or the circularly polarized beam;

[0020] A variable magnification beam expander is positioned in the optical path of the first linearly polarized light;

[0021] An aperture assembly is positioned on the optical path of the first linearly polarized light;

[0022] A galvanometer system is positioned on the optical path of the circularly polarized beam.

[0023] In one embodiment, the variable magnification beam expander includes at least three focusing lenses, the position of which can be adjusted independently.

[0024] In one embodiment, the aperture assembly includes an aperture absorption component and a variable aperture.

[0025] In one embodiment, the galvanometer system includes galvanometer lenses, each of which is coated with a zero-phase total reflection film.

[0026] The aforementioned optical isolation system and laser drilling system, by setting the angle between the normal of the phase-delay mirror and the vibration direction of the second linearly polarized beam as a second angle, ensure that the vibration direction of the second linearly polarized beam forms a certain angle with the incident surface of the phase-delay mirror. Thus, after reflection by the phase-delay mirror, the amplitude and phase of the perpendicularly polarized component of the second linearly polarized beam remain unchanged, but the phase of the parallel polarized component is delayed by a first angle, forming a circularly polarized beam. When the circularly polarized beam is reflected back to the circularly polarized reflected beam through the original optical path, the parallel polarized component of the circularly polarized reflected beam is further phase-delayed by the phase-delay mirror, resulting in a third linearly polarized beam that overlaps with the optical path of the second linearly polarized beam but with a deflected vibration direction. Therefore, the vibration direction of the third linearly polarized beam is no longer perpendicular to the incident surface of the polarization-selective mirror, allowing at least a portion of the third linearly polarized beam to be absorbed by the polarization-selective mirror instead of being reflected back to the laser. This effectively reduces beam reflection back into the laser, protecting the laser and ensuring its normal operation and long-term stability. Furthermore, the optical isolation system provided in this application only requires a polarization-selective reflector and a phase-delay reflector. By adjusting the position and normal direction of the two reflectors, effective protection of the laser can be achieved. It is simple to operate, requires fewer optical components, and has low hardware investment costs. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an optical isolation system in one embodiment.

[0028] Figure 2 This is a schematic diagram illustrating the change of vibration direction with phase in one embodiment.

[0029] Figure 3 This is a schematic diagram of the structure of a laser drilling system in one embodiment.

[0030] Figure 4 This is a schematic diagram of the laser drilling system in another embodiment. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0037] See Figure 1 , Figure 1 A schematic diagram of an optical isolation system according to an embodiment of this application is shown. The optical isolation system provided in this embodiment includes a polarization selective reflector 102 and a phase delay reflector 104.

[0038] The polarization-selective reflector 102 is a reflector capable of selectively reflecting or absorbing incident light according to its polarization state. In this embodiment, the polarization-selective reflector 102 is capable of total internal reflection of vertically polarized light and total absorption of parallel-polarized light. Vertically polarized light refers to incident light whose vibration direction is perpendicular to the incident surface. Parallel-polarized light refers to incident light whose vibration direction is parallel to the incident surface.

[0039] Since the vibration direction of the linearly polarized beam is perpendicular to the propagation direction of the linearly polarized beam, the position of the polarization-selective reflector 102 can be adjusted so that it is located in the optical path of the first linearly polarized beam. By adjusting the normal direction of the polarization-selective reflector 102 so that its normal is perpendicular to the vibration direction of the first linearly polarized beam, total internal reflection of the first linearly polarized beam can be achieved, forming a second linearly polarized beam. That is, the second linearly polarized beam is the outgoing beam of the first linearly polarized beam after total internal reflection by the polarization-selective reflector 102.

[0040] In some embodiments, the polarization-selective reflector 102 includes a metal substrate layer and an absorptive and transmissive film for reflection (ATRF) coating. The ATRF coating is a multilayer thin-film structure designed by precisely controlling the thickness and number of layers of the material, thereby achieving total internal reflection of perpendicularly polarized light and total absorption of parallelly polarized light. The metal substrate layer can be a base layer made of metals such as copper, silver, aluminum, or gold. The metal material provides a robust foundation structure, ensuring the overall stability and mechanical strength of the reflector. During reflection, the metal substrate layer acts as a good reflector, effectively improving the reflectivity of the polarization-selective reflector 102 and thus enhancing the reflection effect. During absorption, the temperature of the ATRF coating rises rapidly after absorbing laser energy; the metal substrate layer has excellent thermal conductivity, which helps the polarization-selective reflector 102 dissipate heat quickly.

[0041] In some embodiments, the metal substrate layer includes a copper substrate layer. Copper has high reflectivity, which helps to improve the reflection effect of the polarization selective mirror 102, and copper has high thermal conductivity, which helps the polarization selective mirror 102 to dissipate heat quickly. Furthermore, copper is easy to process, has good dimensional stability at high temperatures, and is low in cost.

[0042] The phase-delay reflector 104 refers to a reflector that introduces phase delay when reflecting a light beam. In this embodiment, the phase-delay reflector 104 can delay the phase of parallel polarized light by a first angle without delaying the phase of perpendicularly polarized light. The first angle can be determined based on actual conditions and test results, and this embodiment does not impose any limitations on it. The position of the phase-delay reflector 104 can be adjusted so that it is located on the optical path of the second linearly polarized beam. Furthermore, by adjusting the direction of the normal 1041 of the phase-delay reflector 104, the normal 1041 of the phase-delay reflector 104 can form a second angle with the vibration direction of the second linearly polarized beam. The second angle can also be determined based on actual conditions and test results, and this embodiment does not impose any limitations on it. In this way, the second linearly polarized beam can be incident on the phase delay mirror 104, and the vibration direction of the second linearly polarized beam can form a certain angle with the incident surface. Thus, when the second linearly polarized beam is incident on the phase delay mirror 104, it has a vertical polarization component and a parallel polarization component. After reflection by the phase delay mirror 104, the phase of the vertical polarization component remains unchanged, while the phase of the parallel polarization component is delayed by a first angle, forming a circularly polarized beam. That is, the circularly polarized beam is the outgoing beam after the second linearly polarized beam is reflected by the phase delay mirror 104. The circularly polarized beam can include circularly polarized light and elliptically polarized light. Circularly polarized light refers to a beam whose electric field vector endpoint trajectory traces a circle on a plane perpendicular to the propagation direction. The two orthogonal components of circularly polarized light have the same amplitude but a phase difference of 90 degrees or 270 degrees. Elliptically polarized light refers to a beam whose electric field vector endpoint trajectory traces an ellipse on a plane perpendicular to the propagation direction. The two orthogonal components of elliptically polarized light have different amplitudes, or the phase difference between the two orthogonal components is not strictly 90 degrees.

[0043] A circularly polarized reflected beam refers to the reflected light formed by the reflection of a circularly polarized beam along its original optical path; that is, the optical paths of the circularly polarized reflected beam overlap with those of the original circularly polarized beam. The circularly polarized reflected beam can be formed by the reflection of a circularly polarized beam from a target workpiece during processing, or by the reflection of a circularly polarized beam from other optical elements or other objects. This embodiment does not impose any limitations on this. In some feasible embodiments, the circularly polarized reflected beam and the circularly polarized beam have the same phase but opposite rotation.

[0044] In some feasible embodiments, a circularly polarized light beam can be used to drill a hole in the target workpiece 106, and the circularly polarized reflected light beam can be the reflected light of the circularly polarized light beam after being reflected from the surface of the target workpiece 106 and then propagating in the opposite direction along the original optical path. In some feasible embodiments, the hole diameter range for drilling the target workpiece 106 can be 70μm-200μm.

[0045] In some feasible embodiments, the target workpiece 106 can be a high-density interconnect circuit board, and the first linearly polarized beam can be a 9.4μm band carbon dioxide laser beam. The non-metallic material layer in the high-density interconnect circuit board has good absorption characteristics for the 9.4μm band carbon dioxide laser beam, but the copper foil layer on the surface of the high-density interconnect circuit board has extremely high reflectivity for the 9.4μm band carbon dioxide laser beam. Without optical isolation, at least part of the reflected light from the copper foil layer will propagate back along its original propagation path into the laser, causing instability or damage to the laser, affecting its stable operation, and potentially reducing its lifespan.

[0046] In this embodiment, since the circularly polarized reflected beam overlaps with the optical path of the second linearly polarized beam, the circularly polarized reflected beam can be incident on the phase retardation mirror 104. After reflection by the phase retardation mirror 104, it forms a third linearly polarized beam whose optical path overlaps with that of the second linearly polarized beam. The circularly polarized reflected beam and the circularly polarized beam are in phase; therefore, the parallel polarization component of the circularly polarized reflected beam is delayed by a first angle relative to the vertical polarization component. After reflection by the phase retardation mirror 104, the phase of the parallel polarization component of the circularly polarized reflected beam is delayed by another first angle, while the vertical polarization component remains unchanged. That is, the phase of the parallel polarization component of the third linearly polarized beam is delayed by twice the first angle relative to the vertical polarization component. Thus, the vibration direction of the third linearly polarized beam deviates from the vibration direction of the second linearly polarized beam.

[0047] Since the vibration direction of the second linearly polarized beam is the same as that of the first linearly polarized beam, that is, the vibration direction of the second linearly polarized beam is perpendicular to the normal of the polarization-selective reflector 102, the vibration direction of the third linearly polarized beam, when reflected back to the polarization-selective reflector 102, will form a certain angle with the incident surface, rather than being perpendicular to the incident surface. Thus, at least a portion of the second linearly polarized beam can be absorbed by the polarization-selective reflector 102. This achieves isolation of the reflected light, effectively reducing the backlash of the reflected light along the original optical path back to the laser, thus providing effective protection for the laser. Furthermore, the optical isolation system provided in this embodiment only requires the polarization-selective reflector 102 and the phase-retardant reflector 104. Effective protection of the laser can be achieved by adjusting the position and normal direction of the two reflectors. The operation is simple, requires fewer optical components, and has low hardware investment costs.

[0048] In some embodiments, the first angle is 89-91 degrees and the second angle is 59-61 degrees.

[0049] In this embodiment, when the angle between the normal of the phase delay mirror 104 and the vibration direction of the second linearly polarized beam is 60 degrees, when the second linearly polarized beam is incident on the phase delay mirror 104, the amplitude and phase of its vertical polarization component and parallel polarization component are equal. After reflection by the phase delay mirror 104, the amplitude remains unchanged, the phase of the vertical polarization component remains unchanged, but the parallel polarization component is delayed by 90 degrees, thus forming a circularly polarized beam. In practical applications, under different actual conditions, there may be a certain deviation between the first angle and 90 degrees. Therefore, the first angle can be 89-91 degrees, such as 89 degrees, 89.5 degrees, 90 degrees, 90.5 degrees, 91 degrees, etc., which can still achieve a similar effect. Under different actual conditions, there may be a certain deviation between the second angle and 60 degrees. Therefore, the second angle can be 59-61 degrees, such as 59 degrees, 59.5 degrees, 60 degrees, 60.5 degrees, 61 degrees, etc., which can still achieve a similar effect.

[0050] Since the circularly polarized reflected beam overlaps with the optical path of the second linearly polarized beam, it can be incident on the phase retardation mirror 104. After reflection by the phase retardation mirror 104, it forms a third linearly polarized beam whose optical path overlaps with that of the second linearly polarized beam. The circularly polarized reflected beam and the circularly polarized beam are in phase; therefore, the parallel polarization component of the circularly polarized reflected beam is delayed by 90 degrees. After reflection by the phase retardation mirror 104, the phase of the parallel polarization component of the circularly polarized reflected beam is again delayed by 90 degrees, while the vertical polarization component remains unchanged. That is, the phase of the parallel polarization component of the third linearly polarized beam is delayed by 180 degrees relative to the vertical polarization component. Thus, the vibration direction of the third linearly polarized beam will be perpendicular to the vibration direction of the second linearly polarized beam. In a feasible embodiment, referring to… Figure 2 Assuming the beam's vibration direction is as shown by arrow 202, its vertical polarization component is as shown by arrow 210, and its parallel polarization component is as shown by arrow 204, after the beam is reflected twice by the phase delay mirror 104, the phase of the vertical polarization component remains unchanged, as shown by arrow 210, while the phase of the parallel polarization component is delayed by 180 degrees, as shown by arrow 208. Thus, after the beam is phase-delayed twice by the phase delay mirror 104, its vibration direction will deflect from arrow 202 to arrow 206, and the vibration direction after the two phase delays will be perpendicular to the vibration direction before the two phase delays.

[0051] Since the vibration direction of the second linearly polarized beam is the same as that of the first linearly polarized beam, that is, the vibration direction of the second linearly polarized beam is perpendicular to the normal of the polarization-selective reflector 102, the vibration direction of the third linearly polarized beam will be parallel to the incident surface when it is reflected back to the polarization-selective reflector 102, and thus it will be completely absorbed by the polarization-selective reflector 102. In this way, the reflected light can be isolated, effectively preventing the reflected light from propagating back to the laser along the original optical path, thus achieving effective protection of the laser. Moreover, the optical isolation system provided in this embodiment only requires the polarization-selective reflector 102 and the phase delay reflector 104. By adjusting the position and normal direction of the two reflectors, effective protection of the laser can be achieved. The operation is simple, the required optical components are few, and the hardware investment cost is low.

[0052] By setting the angle between the normal of the phase delay mirror and the vibration direction of the second linearly polarized beam to 60 degrees, the angle between the vibration direction of the second linearly polarized beam and the incident surface of the phase delay mirror is 45 degrees. In this way, the polarization component of the second linearly polarized beam perpendicular to the incident surface and the polarization component parallel to the incident surface are equal. After reflection by the phase delay mirror, the amplitude remains unchanged, but the phase of the parallel polarization component is delayed by 90 degrees relative to the vertical polarization component, thus forming a circularly polarized beam. Thus, when the circularly polarized beam is reflected back to the circularly polarized reflected beam through the original optical path, the parallel polarization component of the circularly polarized reflected beam is further delayed by 90 degrees by the phase-retardant mirror. This results in a third linearly polarized beam that overlaps with the second linearly polarized beam but has a perpendicular vibration direction. Since the polarization-selective mirror does not change the vibration direction of the beam, the vibration direction of the first linearly polarized beam, which is perpendicular to the incident plane of the polarization-selective mirror, becomes perpendicular to the exit plane of the second linearly polarized beam after reflection. Therefore, the vibration direction of the third linearly polarized beam is parallel to the incident plane of the polarization-selective mirror, and it is completely absorbed by the mirror without being reflected back to the laser. This effectively reduces beam reflection back into the laser, protecting the laser and ensuring its normal operation and long-term stability. Furthermore, the optical isolation system provided in this application only requires a polarization-selective reflector and a phase-delay reflector. By adjusting the position and normal direction of the two reflectors, effective protection of the laser can be achieved. It is simple to operate, requires fewer optical components, and has low hardware investment costs.

[0053] In some feasible embodiments, the angle difference between the first preset angle and 90 degrees can be within a preset angle range, such as ±3 degrees, ±5 degrees, etc. This preset angle range is related to the actual needs and errors of the optical isolation system, and can be set according to the actual situation and test results.

[0054] In some feasible embodiments, the angle difference between the second preset angle and 60 degrees can be within a preset angle range, such as ±3 degrees, ±5 degrees, etc. This preset angle range is related to the actual needs and errors of the optical isolation system, and can be set according to the actual situation and test results.

[0055] The incident angle of the first linearly polarized beam onto the polarization-selective reflector 102 can be determined based on one or more combinations of the characteristics of the polarization-selective reflector 102, the propagation medium of the first linearly polarized beam, the positions of various optical elements in the optical system, and the processing position. The incident angle of the first linearly polarized beam onto the polarization-selective reflector 102 should ensure that the circularly polarized beam is ultimately focused onto the target workpiece 106 for drilling. The reflectivity of the polarization-selective reflector 102 for the first linearly polarized beam is higher than a preset reflectivity threshold, and its absorptivity for the third linearly polarized beam is higher than a preset reflectivity threshold.

[0056] In some embodiments, the polarization-selective reflector 102 can reflect vertically polarized light incident at an angle of 45 degrees and absorb parallelly polarized light incident at an angle of 45 degrees. In this case, the angle between the normal of the polarization-selective reflector 102 and the first linearly polarized beam can be adjusted to 45 degrees, so that the angle of incidence of the first linearly polarized beam onto the polarization-selective reflector 102 is 45 degrees, thereby achieving reflection of the first linearly polarized beam and absorption of the third polarized beam. In practical applications, under different circumstances, the angle of incidence of the first linearly polarized beam onto the polarization-selective reflector 102 may deviate from 45 degrees. Therefore, the angle of incidence of the first linearly polarized beam onto the polarization-selective reflector 102 can be 44-46 degrees, such as 44 degrees, 44.5 degrees, 45 degrees, 45.5 degrees, 46 degrees, etc., still achieving a similar effect as described above.

[0057] The incident angle of the second linearly polarized beam onto the phase delay mirror 104 can be determined based on a combination of one or more of the positions of various optical elements in the optical system and the processing position. The incident angle of the second linearly polarized beam onto the phase delay mirror 104 should ensure that the circularly polarized reflected beam can ultimately be focused onto the target workpiece 106 for drilling. In some embodiments, the incident angle of the second linearly polarized beam onto the phase delay mirror 104 can be 45 degrees. In practical applications, under different circumstances, the incident angle of the second linearly polarized beam onto the phase delay mirror 104 may deviate from 45 degrees. Therefore, the incident angle of the second linearly polarized beam onto the phase delay mirror 104 can be 44-46 degrees, such as 44 degrees, 44.5 degrees, 45 degrees, 45.5 degrees, 46 degrees, etc., which can still achieve similar effects.

[0058] The aforementioned optical isolation system and laser drilling system, by setting the angle between the normal of the phase-delay mirror and the vibration direction of the second linearly polarized beam as a second angle, ensure that the vibration direction of the second linearly polarized beam forms a certain angle with the incident surface of the phase-delay mirror. Thus, after reflection by the phase-delay mirror, the amplitude and phase of the perpendicularly polarized component of the second linearly polarized beam remain unchanged, but the phase of the parallel polarized component is delayed by a first angle, forming a circularly polarized beam. When the circularly polarized beam is reflected back to the circularly polarized reflected beam through the original optical path, the parallel polarized component of the circularly polarized reflected beam is further phase-delayed by the phase-delay mirror, resulting in a third linearly polarized beam that overlaps with the optical path of the second linearly polarized beam but with a deflected vibration direction. Therefore, the vibration direction of the third linearly polarized beam is no longer perpendicular to the incident surface of the polarization-selective mirror, allowing at least a portion of the third linearly polarized beam to be absorbed by the polarization-selective mirror instead of being reflected back to the laser. This effectively reduces beam reflection back into the laser, protecting the laser and ensuring its normal operation and long-term stability. Furthermore, the optical isolation system provided in this application only requires a polarization-selective reflector and a phase-delay reflector. By adjusting the position and normal direction of the two reflectors, effective protection of the laser can be achieved. It is simple to operate, requires fewer optical components, and has low hardware investment costs.

[0059] In some embodiments, combined with Figure 3 A laser drilling system is provided, including the aforementioned optical isolation system 302, and also including a laser 304 and a focusing lens 306.

[0060] Laser 304 is used to emit a first linearly polarized beam.

[0061] The optical isolation system 302 includes a polarization-selective reflector 3022 and a phase-delay reflector 3024, which are used to reflect the first linearly polarized beam to form a circularly polarized beam.

[0062] The focusing lens 306 is used to drill a hole in the target workpiece 310 by focusing the circularly polarized light beam onto the target workpiece 310.

[0063] The optical isolation system 302 is also used to isolate the reflected light reflected by the target workpiece 310, reducing the reflected light from propagating back along the original optical path to the laser 304.

[0064] In some embodiments, the laser drilling system further includes at least one of a silicon total reflection mirror, a zoom beam expander, an aperture assembly, and a galvanometer system.

[0065] The silicon total internal reflection mirror can be positioned in the optical path of the first linearly polarized light or the circularly polarized light beam. The silicon total internal reflection mirror can be used to adjust the optical axis of the first linearly polarized light or the circularly polarized light beam, so that the laser beam emitted ultimately propagates and focuses onto the target workpiece 310 for processing. The silicon total internal reflection mirror is a zero-phase mirror, meaning that it does not change the phase of the light beam when reflecting it.

[0066] A variable magnification beam expander can be placed in the optical path of the first linearly polarized light. The variable magnification beam expander can adjust the diameter and divergence angle of the laser beam, thereby optimizing the spot size and energy density to meet the needs of different processing tasks. By changing the magnification of the beam expander, the focusing characteristics of the laser beam can be flexibly controlled, improving processing accuracy and efficiency, while reducing the heat-affected zone and ensuring high-quality processing results.

[0067] In some embodiments, the variable magnification beam expander includes at least three focusing lenses, each with an independently adjustable position. The variable magnification beam expander can employ independent three-element lenses, each capable of independent movement to achieve different magnifications and beam control, thereby more precisely controlling the magnification and divergence angle of the laser beam. By changing the distance between the focusing lenses, the input laser beam can be magnified or reduced to the desired diameter. By optimizing the arrangement and spacing of the lenses, the divergence angle of the laser beam can be reduced or increased, thereby controlling the focusing characteristics and transmission distance of the beam.

[0068] An aperture assembly can be positioned in the optical path of the first linearly polarized light. The aperture assembly can precisely control and limit the size of the laser beam. By adjusting the size of the aperture, the quality and energy distribution of the light spot can be optimized, thereby improving processing accuracy and consistency. It can also filter out unnecessary stray light and noise, ensuring that only high-quality light beams can reach the processing surface.

[0069] In some embodiments, the aperture assembly includes an aperture absorption component and a variable aperture. The variable aperture includes multiple circular apertures of different diameters, selectable by computer control, for filtering and energy regulation of the circular laser beam. The aperture absorption component absorbs energy from the laser beam reflected by the aperture, preventing the laser beam from propagating into the laser 304.

[0070] A galvanometer system can be placed in the optical path of the circularly polarized beam. The galvanometer system can quickly and accurately control the scanning path of the laser beam, and change the direction of the beam by means of a high-speed rotating or vibrating mirror, thereby enabling high-precision machining of the target workpiece 310.

[0071] In some embodiments, the galvanometer system includes galvanometer lenses, each coated with a zero-phase total internal reflection film. By coating with the zero-phase total internal reflection film, it can be ensured that the phase of the beam is not altered when the galvanometer system modulates the beam.

[0072] In some embodiments, such as Figure 4As shown, a laser drilling system is provided. A laser 401 serves as the light source, generating a 9.4μm wavelength linearly polarized carbon dioxide laser beam. After emission from the laser, the laser beam's diameter is adjusted by a variable magnification beam expander 402. The beam expander 402 employs an independent three-element lens, including focusing lenses 4021, 4022, and 4023. Adjusting the spacing between these lenses allows for continuous magnification, ensuring a properly collimated laser beam of appropriate spot size. The laser beam, after diameter adjustment by the beam expander, is incident directly onto an aperture assembly 403. The aperture assembly 403 includes an aperture absorption component 4031 and a variable aperture 4032. The variable aperture 4032 includes multiple circular apertures of different diameters, which can be formed by PC (Personal) apertures. The selection is controlled by a computer. A variable aperture 4032 is used to filter and regulate the energy of the circular laser beam. An aperture absorption component 4031 absorbs the energy of the laser beam reflected from the variable aperture 4032, preventing the energy from being reflected back into the laser. The circular beam, after being truncated by the aperture, is incident on a silicon total internal reflection mirror 404 at a 45-degree angle. This mirror is a zero-phase mirror, which does not change the vibration direction of the incident beam. Only one mirror is shown in the figure; the number of silicon total internal reflection mirrors 404 can be adjusted according to the actual optical path requirements. The laser beam exiting the silicon total internal reflection mirror 404 is incident on a copper total internal reflection mirror 405 at a 45-degree angle. The vibration direction of the laser beam is perpendicular to the incident surface of the copper total internal reflection mirror 405 to ensure perpendicular polarization and prevent phase shift in the exiting laser beam. The laser beam emitted from the copper total reflection mirror 405 is perpendicular to the exit surface. The laser beam is incident at an angle of 45 degrees and the angle between the laser beam and the normal of the phase delay mirror 406 is 60 degrees. When it is incident on the phase delay mirror 406, the emitted beam changes from linearly polarized light to circularly polarized light. It is then input into the galvanometer system 407. The galvanometer system 407 includes a galvanometer lens 4071 that controls the rotation of the laser beam in the X direction and a galvanometer lens 4072 that controls the rotation of the laser beam in the Y direction. Both galvanometer lenses 4071 and 4072 are coated with a zero-phase total reflection film. The laser beam emitted after passing through the galvanometer system is still circularly polarized light. Finally, it is focused by the subsequent F-theta scanning mirror 408 onto the target workpiece 410 on the platform 409. The target workpiece 410 can be a high-density interconnect circuit board, thereby realizing the drilling processing of the high-density interconnect circuit board. The reflected light from the target workpiece 410 propagates in the opposite direction along the original optical path and is eventually absorbed by the copper total reflection mirror 405, thus preventing it from entering the laser and effectively protecting the laser.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An optical isolation system, characterized in that, The optical isolation system includes a polarization-selective mirror and a phase-delay mirror, wherein: A polarization-selective reflector is used to totally reflect vertically polarized light and totally absorb parallelly polarized light. The polarization-selective reflector is disposed in the optical path of a first linearly polarized beam, and the normal of the polarization-selective reflector is perpendicular to the vibration direction of the first linearly polarized beam. The polarization-selective reflector is used to totally reflect the first linearly polarized beam to form a second linearly polarized beam. A phase delay mirror is used to delay the phase of parallel polarized light by a first angle; the phase delay mirror is disposed in the optical path of the second linearly polarized beam, and the angle between the normal of the phase delay mirror and the vibration direction of the second linearly polarized beam is a second angle; the phase delay mirror is used to reflect the second linearly polarized beam to form a circularly polarized beam. The phase delay mirror is also used to reflect the circularly polarized reflected beam to form a third linearly polarized beam after receiving the circularly polarized reflected beam corresponding to the circularly polarized beam; the optical path of the third linearly polarized beam overlaps with that of the second linearly polarized beam, and the vibration direction of the third linearly polarized beam is parallel to the incident surface of the third linearly polarized beam when it is incident on the polarization selective mirror. The polarization-selective reflector is also used to absorb the third linearly polarized beam.

2. The optical isolation system according to claim 1, characterized in that, The first angle is 89-91 degrees, and the second angle is 59-61 degrees.

3. The optical isolation system according to claim 1, characterized in that, The polarization-selective reflector includes a metal substrate layer and an absorption, transmission, and reflection coating.

4. The optical isolation system according to claim 3, characterized in that, The metal substrate layer includes a copper substrate layer.

5. The optical isolation system according to claim 1, characterized in that, The incident angle of the first linearly polarized beam onto the polarization-selective reflector is 44-46 degrees.

6. A laser drilling system, characterized in that, The laser drilling system includes the optical isolation system according to any one of claims 1 to 5, and further includes: A laser used to emit a first linearly polarized beam; A focusing lens is used to drill a hole in a target workpiece by focusing the circularly polarized light beam onto the target workpiece.

7. The laser drilling system according to claim 6, characterized in that, The laser drilling system also includes at least one of the following: A silicon total internal reflection mirror is disposed in the optical path of the first linearly polarized light or the circularly polarized beam, and is used to adjust the optical axis of the first linearly polarized light or the circularly polarized beam; A variable magnification beam expander is positioned in the optical path of the first linearly polarized light; An aperture assembly is positioned on the optical path of the first linearly polarized light; A galvanometer system is positioned on the optical path of the circularly polarized beam.

8. The laser drilling system according to claim 7, characterized in that, The variable magnification beam expander includes at least three focusing lenses, the position of which can be adjusted independently.

9. The laser drilling system according to claim 7, characterized in that, The aperture assembly includes an aperture absorption component and a variable aperture.

10. The laser drilling system according to claim 7, characterized in that, The galvanometer system includes galvanometer lenses, all of which are coated with a zero-phase total reflection film.

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