WO2025180439A1

WO2025180439A1 - Optical device and laser processing device

Info

Publication number: WO2025180439A1
Application number: PCT/CN2025/079500
Authority: WO
Inventors: Keyou Chen; Feng Feng; Daniel FLAMM
Original assignee: Trumpf China Co Ltd
Current assignee: Trumpf China Co Ltd
Priority date: 2024-02-27
Filing date: 2025-02-27
Publication date: 2025-09-04
Anticipated expiration: 2026-08-27
Also published as: CN119247637A

Abstract

The present disclosure discloses an optical device for splitting an input laser pulse into two sub-pulses with an adjustable time interval, the optical device comprising: a polarizer, which is adapted to decompose a laser pulse into a first polarization component and a second polarization component; and an adjustment unit, which is adapted to reflect at least one of the first polarization component and the second polarization component towards the polarizer and adjust a propagation distance of at least one of the first polarization component and the second polarization component such that the first polarization component and the second polarization component are combined again through the polarizer to obtain the two sub-pulses. According to certain exemplary embodiments, an optical device for splitting time pulses within a picosecond time scale can be provided, which is simple and compact in structure and also at low cost, with good compatibility and wide application. The present disclosure further provides a laser processing device having the optical device.

Description

OPTICAL DEVICE AND LASER PROCESSING DEVICE

TECHNICAL FIELD

This disclosure relates to the field of laser processing technology, and in particular to an optical device capable of temporally modulating laser pulses within a picosecond time scale and a laser processing device having the optical device.

BACKGROUND ART

Ultrashort laser pulses have good application results in the field of precision machining due to their extremely short pulse width and extremely high single-pulse peak power. Compared with conventional single-pulse processing, a pulse train-based processing mode can not only obtain better processing quality but also ensure higher processing efficiency. Currently, laser sources of the prior art can generate pulse sequences with time delays ranging from nanoseconds to hundreds of picoseconds, with the delay time being fixed depending on different laser sources. In addition, designs of temporal pulses below 1000 picoseconds have been proven beneficial in various processing and research work, such as laser ablation, laser-induced breakdown microscopy, soft X-ray generation, etc. However, as a result of the complexity of implementation, the parameter range of time delay below 1000 picoseconds is rarely used in industry. Therefore, a new optical device is needed to facilitate implementing designs of the temporal sequence pulses within this parameter range.

SUMMARY OF THE INVENTION

A purpose of the present disclosure is to provide an optical device and a laser processing device having the optical device, which can temporally modulate laser pulses within a picosecond time scale to at least partially overcome the deficiencies in the prior art.

According to a first aspect of the present disclosure, there is provided an optical device, comprising:

a polarizer, which is adapted to decompose an input laser pulse into a first polarization component and a second polarization component; and

an adjustment unit, which is adapted to change a polarization state, a propagation direction and a propagation distance of at least one of the first polarization component and the second polarization component, and to cause the first polarization component and the second polarization component to obtain two sub-pulses with a time interval after being combined again through the polarizer.

According to an optional embodiment of the disclosure, the polarizer is adapted to decompose a laser pulse into a transmitted first polarization component and a reflected second polarization component, which have polarization states orthogonal to each other.

According to an optional embodiment of the disclosure, the adjustment unit is configured to change a polarization direction of the incident first polarization component and/or second polarization component and to reflect it or them towards the polarizer.

According to an optional embodiment of the disclosure, the adjustment unit comprises a plurality of adjustment assemblies, each of which is configured to change a polarization direction of the corresponding incident polarization component from the polarizer by π/2 and to reflect it back to the polarizer.

According to an optional embodiment of the disclosure, each of the adjustment assemblies comprises a quarter-wave plate and a reflective mirror arranged along an incident direction of the corresponding polarization component of respective adjustment assembly.

According to an optional embodiment of the disclosure, at least the reflective mirror of at least one of the adjustment assemblies is configured as a movable part being capable of changing a distance from the polarizer by movement.

According to an optional embodiment of the disclosure, the reflective mirror of at least one of the adjustment assemblies is configured that its normal axis has a predetermined angle relative to the incident polarization component, or the reflective mirror is configured as a parabolic reflective mirror with a predetermined focal length.

According to an optional embodiment of the disclosure, the movable part is configured to be movable and positionable relative to the polarizer within a range of 0 to 5000 mm, in particular within a range of 0 to 150 mm.

According to an optional embodiment of the disclosure, the movable part is configured in such a manner that a length difference between an optical path of the first polarization component and an optical path of the second polarization component is 0 to 1000 mm, in particular 60 mm.

According to an optional embodiment of the disclosure, the adjustment unit comprises a first adjustment assembly and a second adjustment assembly which are arranged on an optical path of the second polarization component, such that the second polarization component initially reflected away from the polarizer is incident on the first adjustment assembly and thus reflected back to the polarizer by the first adjustment assembly, and, after transmitting through and away from the polarizer, it is incident on the second adjustment assembly and thus reflected back to the polarizer by the second adjustment assembly, and then combines with the first polarization component after being reflected again by the polarizer.

According to an optional embodiment of the disclosure, the adjustment unit comprises a first adjustment assembly and a second adjustment assembly which are arranged on an optical path of the first polarization component, such that the first polarization component initially transmitting through and away from the polarizer is incident on the first adjustment assembly and thus reflected back to the polarizer by the first adjustment assembly, and, after being reflected and away from the polarizer, it is incident on the second adjustment assembly and thus reflected back to the polarizer by the second adjustment assembly, and then combines with the second polarization component after transmitting through the polarizer again.

According to an optional embodiment of the disclosure, the adjustment unit comprises a first adjustment assembly arranged on an optical path of the first polarization component and a second adjustment assembly arranged on an optical path of the second polarization component, such that the first polarization component initially transmitting through and away from the polarizer is incident on the first adjustment assembly and thus reflected back to the polarizer by the first adjustment assembly, and then is reflected by the polarizer, and that the second polarization component initially reflected away from the polarizer is incident on the second adjustment assembly and thus reflected back to the polarizer by the second adjustment assembly, and then transmits through the polarizer so as to combine with the first polarization component that is reflected by the polarizer.

According to an optional embodiment of the disclosure, the polarizer is a polarization beam splitter cube, in particular with a side length of approximately 30 mm, and in particular with a refractive index of 1.4 to 1.6, preferably 1.5.

According to an optional embodiment of the disclosure, an optical 4f device is provided in an optical path of the first polarization component or the second polarization component.

According to a second aspect of the present disclosure, there is provided a laser processing device, comprising: at least one laser radiation source for providing laser pulses; an optical device according to the first aspect of the present disclosure, which is optically connected to the laser radiation source; and a focusing module for applying laser light from the optical device to a workpiece to be processed.

According to an optional embodiment of the disclosure, the at least one laser radiation source is an ultrashort pulse laser, in particular a femtosecond laser and/or a picosecond laser and/or a nanosecond laser.

According to an optional embodiment of the disclosure, the optical device is configured to generate a pulse delay of 0 to 20 ns, in particular 0 to 1000 ps.

According to an optional embodiment of the disclosure, the focusing module comprises a reflective mirror, a beam shaping unit, a lens set and/or a scanning mirror.

According to an optional embodiment of the disclosure, pulses generated by the laser radiation source have a duration of 100 fs to1000 ps.

According to an optional embodiment of the disclosure, laser pulses output by the laser radiation source are in a wavelength range of 200 nm to 2000 nm, in particular 1030 ± 30 nm.

According to an optional embodiment of the disclosure, a beam configuration module is provided between the laser radiation source and the optical device, which is adapted to configure a propagation angle, a divergence, a beam diameter and/or a polarization state of the laser pulses.

According to an optional embodiment of the disclosure, the laser processing device is a laser ablation device, a laser cutting device, a laser drilling device, a laser induced breakdown spectrometer, a soft X-ray generation device, a surface treatment device or a surface cleaning device.

According to certain exemplary embodiments of the present disclosure, an optical device capable of temporal pulse splitting within a picosecond time scale is provided, which is simple and compact in structure and also at low cost, with good compatibility and wide application.

BRIEF DESCRIPTION OF THE DRAWINGS

The principles, characteristics and advantages of the present disclosure can be better understood through the detailed description below with reference to the accompany drawings, in which:

FIG. 1 shows main parts of an optical device according to an exemplary embodiment of the present disclosure;

FIGS. 2A and 2B illustrate an optical device according to an exemplary embodiment of the present disclosure, each showing propagation paths of respective polarization components;

FIGS. 3A and 3B illustrate an optical device according to another exemplary embodiment of the present disclosure, each showing propagation paths of respective polarization components;

FIGS. 4A and 4B illustrate an optical device according to yet another exemplary embodiment of the present disclosure, each showing propagation paths of respective polarization components; and

FIG. 5 shows main parts of a laser processing device according to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

For clearer understanding of the technical problems to be solved, technical solutions and advantageous technical effects of the present disclosure, the disclosure will be described below in greater detail in conjunction with the accompany drawings and a number of exemplary embodiments. It is to be understood that specific embodiments described herein are merely for explaining the disclosure, rather than limiting scope thereof. In addition, for the sake of clarity, some reference signs are omitted in some of the drawings, which certainly does not mean to exclude the unmarked parts from the corresponding embodiments.

FIG. 1 shows main parts of an optical device 1 according to an exemplary embodiment of the present disclosure. As shown in FIG. 1, the optical device 1 according to an exemplary embodiment of the present disclosure comprises a polarizer 11, which is adapted to decompose a laser pulse into a first polarization component and a second polarization component; and an adjustment unit 12, which is adapted to change a polarization state, a propagation direction and a propagation distance of at least one of the first polarization component and the second polarization component such that the first polarization component and the second polarization component are combined again through the polarizer 11 to obtain two sub-pulses with a time interval.

As shown in FIG. 2A to FIG. 4B, the polarizer 11 is, for example, a polarization beam splitter cube or a polarization beam splitter prism, which is a substantially symmetrical optical device with a side length a preferably of approximately 30 mm, and a refractive index n which may be 1.4 to 1.6, preferably n = 1.5. The polarizer 11 can decompose a laser pulse into a transmitted first polarization component, i.e., a p-polarized light beam, and a reflected second polarization component, i.e., an s-polarized light beam, which have polarization states orthogonal to each other. In other words, after transmitting through the polarizer 11, the p-polarized component contained in the laser pulse becomes an independent p-polarized light beam, as shown in FIG. 2A; and after being reflected by the polarizer 11, the s-polarized component contained in the laser pulse becomes an independent s-polarized light beam, as shown in FIG. 3A, wherein the s-polarized light beam is preferably reflected at an angle of 45 degrees such that its outgoing direction is substantially at an angle of 90 degrees to the transmitted p-polarized light beam, thereby constructing optical paths of the first polarization component and the second polarization component in different propagation directions. The adjustment unit 12 is arranged on the optical path of at least one of the first polarization component and the second polarization component to change the polarization state of the corresponding polarization component and then reflect it towards the polarizer 11, and is capable of adjusting the propagation distance of the corresponding polarization component, so that a time delay exists between the two polarization components finally combined through the polarizer 11 due to different propagation distances, thereby obtaining two sub-pulses with a time interval.

Specifically, the adjustment unit 12 comprises a plurality of adjustment assemblies (for example, two adjustment assemblies 120a and 120b are provided in the examples shown in the drawings) , each of which is configured to change a polarization direction of the corresponding incident polarization component coming from the polarizer 11 by π/2 and reflect it back to the polarizer 11. More specifically, each of the adjustment assemblies comprises a quarter-wave plate 121 and a reflective mirror 122 arranged along an incident direction of the corresponding polarization component of the adjustment assembly; the p-polarized light beam or the s-polarized light beam incident on the corresponding adjustment assembly passes through the quarter-wave plate 121 and reaches the reflective mirror 122, and, after being reflected by the reflective mirror 122, passes through the quarter-wave plate 121 again, so that the p-polarized light beam or the s-polarized light beam that has passed through the quarter-wave plate 121 twice has its polarization direction deflected by π/2 to become an s-polarized light beam or a p-polarized light beam, and it is emitted from the adjustment assembly towards the polarizer 11 again and then is reflected by or transmits through the polarizer 11 again. In this process, at least the reflective mirror 122 of at least one of the adjustment assemblies is configured as a movable part capable of changing a distance to the polarizer 11 by movement, thereby changing the propagation distance, i.e., the length of the optical path, of the corresponding polarization component. Optionally, at least one of the adjustment assemblies can be moved and positioned as a whole as a movable part relative to the polarizer 11. Alternatively, it is also possible to configure each of the adjustment assemblies to be a movable part or have a movable part such that the propagation distance of the corresponding polarization component can be adjusted more flexibly.

By using the adjustment unit 12 to change the polarization state of the corresponding polarization component and causing the polarization component, with its polarization state changed, to be incident on the polarizer 11 again, and meanwhile by changing the propagation distance of the corresponding polarization component, it is possible to construct a propagation path of the laser pulse with an adjustable length within a small spatial dimension by utilizing the size of the polarizer 11 itself, so that a length difference between the optical paths of the two polarization components can be adjusted using a more compact structure with a higher resolution, thereby achieving a more precise temporal modulation of laser pulses. A more detailed description will be given below in conjunction with specific embodiments.

As shown in FIGS. 2A and 2B, according to an exemplary embodiment of the present disclosure, the adjustment unit 12 comprises a first adjustment assembly 120a and a second adjustment assembly 120b arranged on an optical path of the second polarization component, wherein a distance between a reflecting surface of the reflective mirror 122 of the first adjustment assembly 120a and the polarizer 11 is D1, and a distance between a reflecting surface of the reflective mirror 122 of the second adjustment assembly 120b and the polarizer 11 is D2.

As shown in FIG. 2A, the p-polarized light beam as the first polarization component in the laser pulse incident on the polarizer 11 (the p-polarized light beam is indicated by a dotted line in FIGS. 2A to 4B) can transmit through the polarizer 11 to propagate substantially along its original optical path, and its propagation distance L1 through the optical device 1 is:

L1 = a × 1 × n,

where, as mentioned above, n is the refractive index of the polarizer 11, and a is the side length of the polarizer 11.

As shown in FIG. 2B, the s-polarized light beam as the second polarization component in the same laser pulse (the s-polarized light beam is indicated by a solid line in FIGS. 2A to 4B) is reflected by the polarizer 11, so its optical path is changed clockwise by approximately 90 degrees and incident on the first adjustment assembly 120a. The s-polarized light beam is reflected in the first adjustment assembly 120a by the reflective mirror 122 so as to pass through the quarter-wave plate 121 twice, having its polarization direction deflected by π/2 and thus becoming a p-polarized light beam, and enters the polarizer 11 again and then transmits therethrough. Then, the p-polarized light beam as the second polarization component transmitting through the polarizer 11 is incident on the second adjustment assembly 120b, and after being reflected in the second adjustment assembly 120b by the reflective mirror 122 so as to pass through the quarter-wave plate 121 twice, having its polarization direction deflected further by π/2 and thus becoming an s-polarized light beam again, enters the polarizer 11 and is reflected thereby again. The s-polarized light beam as the second polarization component, which has been reflected by the polarizer 11 this time and emitted therefrom, has a propagation direction substantially the same as the propagation direction of the optical path of the laser pulse originally incident on the polarizer 11, so that it can combine with the transmitted p-polarized light beam as the first polarization component. A propagation distance L2 of the second polarization component passing through the optical device 1 via the first adjustment assembly 120a and the second adjustment assembly 120b is: L2 = a × 3 × n + D1 ×2 + D2 ×2.

A time interval TD between the combined first polarization component and second polarization component is:

TD = (L2 -L1) /c, where c represents a speed of light in vacuum.

In this way, one laser pulse can be split into two sub-pulses with a time interval TD.

In this case, the distances D1 and D2 can be set as any value according to the actual need for the time interval TD, which may be selected, as an example, from a range of 0 to 5000 mm, in particular a range of 0 to 150 mm. To this end, each adjustment assembly or its movable part is configured to be movable and positionable relative to the polarizer 11 at least within this range, for example, by means of sliding modules such as a slide rail.

According to the optical device 1 of the present embodiment, by appropriately selecting values for each parameter, the time interval TD between the two sub-pulses can reach about 300 picoseconds, and it is easy to reach 1000 picoseconds. In addition, the optical device 1 according to the embodiment substantially does not change the propagation direction of the original laser pulse, so it can be regarded as an optical window or an optical mirror, and owing to its compact structural size, it can also be easily integrated into various existing optical systems directly, exhibiting good compatibility and applicability.

As shown in FIG. 3A and FIG. 3B, according to another exemplary embodiment of the present disclosure, the adjustment unit 12 comprises a first adjustment assembly 120a and a second adjustment assembly 120b arranged on an optical path of the first polarization component, wherein the distance between the reflecting surface of the reflective mirror 122 of the first adjustment assembly 120a and the polarizer 11 is D1, and the distance between the reflecting surface of the reflective mirror 122 of the second adjustment assembly 120b and the polarizer 11 is D2.

As shown in FIG. 3A, the s-polarized light beam as the second polarization component in the laser pulse incident on the polarizer 11 can be reflected by the polarizer 11 to change its optical path by approximately 90 degrees, and its propagation distance through the optical device 1 is:

L2 = a × 1 × n.

As shown in FIG. 3B, the p-polarized light beam as the first polarization component in the same laser pulse transmits through the polarizer 11 and is incident on the first adjustment assembly 120a, and after being reflected in the first adjustment assembly 120a by the reflective mirror 122 so as to pass through the quarter-wave plate 121 twice, having its polarization direction deflected by π/2 and thus becoming an s-polarized light beam, enters the polarizer 11 again and then is reflected. Then, the first polarization component as the s-polarized light beam reflected by the polarizer 11 is incident on the second adjustment assembly 120b, after being reflected in the second adjustment assembly 120b by the reflective mirror 122 so as to pass through the quarter-wave plate 121 twice, having its polarization direction deflected further by π/2 and thus becoming a p-polarized light beam again, enters the polarizer 11 and transmits therethrough again. The first polarization component as the p-polarized light beam after transmitting this time can combine with the reflected second polarization component as the s-polarized light beam. A propagation distance of the first polarization component via the first adjustment assembly 120a and the second adjustment assembly 120b is:

L1 = a × 3 × n + D1 ×2 + D2 ×2.

A time interval existing between the combined first polarization component and second polarization component is:

TD = (L2 -L1) /c.

Similar to the embodiments shown in FIG. 2A and FIG. 2B, the optical device 1 according to the present embodiment can also split one laser pulse into two sub-pulses with a time interval TD, which can be adjusted as appropriate by suitably selecting values for each parameter. In addition, unlike the embodiments shown in FIG. 2A and FIG. 2B, the optical device 1 according to the present embodiment is capable of changing the propagation direction of the laser pulse by a certain angle, such as by approximately 90 degrees as described above; thus, it can also be handily and cleverly applied to various optical path designs due to its functionality as a reflective mirror, which helps to further reduce the number of optical devices in the corresponding optical path design and make the corresponding optical path arrangement more compact.

As shown in FIG. 4A and FIG. 4B, according to yet another exemplary embodiment of the present disclosure, the adjustment unit 12 comprises a first adjustment assembly 120a arranged on the optical path of the first polarization component and a second adjustment assembly 120b arranged on the optical path of the second polarization component, wherein the distance between the reflecting surface of the reflective mirror 122 of the first adjustment assembly 120a and the polarizer 11 is D1, and the distance between the reflecting surface of the reflective mirror 122 of the second adjustment assembly 120b and the polarizer 11 is D2.

As shown in FIG. 4A, the p-polarized light beam as the first polarization component in the laser pulse incident on the polarizer 11 transmits through the polarizer 11 and is incident on the first adjustment assembly 120a, and after being reflected in the first adjustment assembly 120a by the reflective mirror 122 so as to pass through the quarter-wave plate 121 twice, having its polarization direction deflected by π/2 and thus becoming an s-polarized light beam, enters the polarizer 11 and is reflected thereby, wherein its propagation distance through the optical device 1 is:

L1 = a × 2 × n + D1 ×2.

As shown in FIG. 4B, the s-polarized light beam as the second polarization component in the same laser pulse is reflected by the polarizer 11, so its optical path is changed by approximately 90 degrees and incident on the second adjustment assembly 120b. The s-polarized light beam is reflected in the second adjustment assembly 120b by the reflective mirror 122 so as to pass through the quarter-wave plate 121 twice, having its polarization direction deflected by π/2 and thus becoming a p-polarized light beam, and then enters the polarizer 11 and transmits therethrough, and thus combines with the reflected first polarization component as the s-polarized light beam. A propagation distance of the second polarization component through the optical device 1 is:

L2 = a × 2 × n + D2 × 2.

A time interval existing between the first polarization component and the second polarization component of the combined beam is:

TD = (L1 -L2) /c.

According to the optical device 1 of the present embodiment, by appropriately selecting values of D1 and D2 within the range described above, the propagation distances of both the first polarization component and the second polarization component can be adjusted. Thus, by means of the optical device 1 of the embodiment, the time interval between sub-pulses can have a wider range, which is estimated to be -1300 picoseconds to 1300 picoseconds. In this way, it allows a more flexible design of temporal sequence pulses and has greater practicability. Moreover, similar to the embodiments shown in FIG. 3A and FIG. 3B, the optical device 1 of the present embodiment can also change the propagation direction of the laser pulse, for example, by approximately 90 degrees, so it also has the functionality of a reflective mirror and thus can be handily and cleverly applied to various optical path designs to obtain similar effects.

Preferably, in the above exemplary embodiments, the movable part of the adjustment assembly may be configured in such a manner that a length difference between the optical path of the first polarization component and the optical path of the second polarization component is 0 to 1000 mm, in particular 60 mm. In the case of a short optical path length difference of, for example, 60 mm, there will be no large difference in the respective divergences of the two polarization components, so a collimated outgoing light beam can still be obtained. However, in the case of a longer optical path length difference where the issue of beam divergence must be considered, a known optical 4f device, for example, can be inserted into one of the optical paths to compensate for the beam divergence.

In the optical device 1 according to the exemplary embodiments of the present disclosure, spatially modulated laser sub-pulses can be additionally obtained by appropriately configuring the polarizer 11 and/or the reflective mirror 122 of the adjustment assemblies. For example, the polarizer 11 may be configured to have a small angle, in other words, it can change the propagation direction of the reflected second polarization component by an angle slightly deviating of 90 degrees, thereby obtaining two sub-pulses with a small angular deviation. It is also possible to configure as appropriate the reflective mirror 122 of a certain adjustment assembly to have a normal axis at a predetermined angle relative to the incident polarization component, which can also obtain two sub-pulses with a small angle deviation. Alternatively, the reflective mirror 122 of a certain adjustment assembly may be configured as a curved reflective mirror (including a parabolic reflective mirror and a spherical reflective mirror) with a long focal length, so that the two sub-pulses can have different divergences and can be focused onto different positions.

The optical device 1 according to the exemplary embodiments of the present disclosure is composed of simple optical devices only; it is sturdy and stable, having a compact structure and occupying a small space, and, as an adjustable optical device, it can easily obtain a temporally modulated pulse sequence with a time delay of 0 to 1000 picoseconds through proper configuration. For example, if the required time delay is 0 to 400 picoseconds, the size of the optical device 1 can be less than 100×100×50 mm³, and usually even be less than 50×50×50 mm³. In addition, the optical device 1 according to the exemplary embodiments of the present disclosure splits the pulse for temporal modulation by refraction and reflection only, and it is similar to an optical window or an optical mirror in terms of functionality, causing almost no energy loss to the laser pulse. The optical device 1 according to the exemplary embodiments of the present disclosure with the aforementioned advantages is compatible with various lasers, in particular femtosecond and picosecond lasers, and it can be easily integrated into various existing laser devices, and the picosecond pulse sequence obtained by the optical device 1 is highly efficient and beneficial for a variety of laser processing treatment.

According to another aspect of the present disclosure, there is provided a laser processing device 100 having an optical device 1 according to any of the exemplary embodiments of the present disclosure, which further comprises at least one laser radiation source 2 for providing laser pulses and a focusing module 3 for applying laser pulses from the optical device 1 to a workpiece to be processed.

Preferably, the laser radiation source 2 is an ultrashort pulse laser capable of providing ultrashort pulses with a duration of, for example, 100 femtoseconds to 1000 picoseconds, and laser pulses output by the laser radiation source 2 are in a wavelength range of 200 nm to 2000 nm, in particular 1030±30 nm.

As described above, with the optical device 1, it is easy to configure a pulse delay of 0 to 1000 picoseconds; certainly, it is also possible to configure a pulse delay of, for example, 0 to 20 nanoseconds as required, and to change the original optical path of the pulse or not as needed.

The focusing module 3 may be selectively composed of a reflective mirror, a beam shaping unit, a lens set and/or a scanning mirror, and be configured to guide and focus the temporally modulated pulse sequence obtained by the optical device 1 onto a target position on the workpiece to be processed in a desired manner.

In a preferred embodiment, a beam configuration module 4 may be provided between the laser radiation source 2 and the optical device 1, and the beam configuration module 4 can configure a propagation angle, a divergence, a beam diameter and/or a polarization state of a laser pulse to be incident on the optical device 1. In other words, various characteristic parameters of the laser pulse to be input to the optical device 1 can be configured in advance by the beam configuration module 4. As an example, two polarization components can be configured in advance in such a manner that the two polarization components have different energy ratios, and that separate sub-pulses with different energy ratios are subsequently obtained by the optical device 1, which can be easily achieved using conventional means such as a half-wave plate and a polarizer.

Through appropriate configurations, the laser processing device 100 according to the exemplary embodiments of the present disclosure can be applied to processing various types of materials in various ways, such as ablation, cutting, and drilling processing of various materials, treatments such as surface treating and cleaning, chamfer edge cutting of glass, X-ray generation, etc. As can be seen, exemplary configurations of the laser processing device 100 according to the exemplary embodiments of the present disclosure include a laser ablation device, a laser cutting device, a laser drilling device, a laser induced breakdown spectrometer, a soft X-ray generation device, a surface treatment device or a surface cleaning device, etc.

For those skilled in the art, it is obvious that the technical idea of the present disclosure is not limited to the above, but can be adjusted according to the actual need of application.

While specific embodiments of the present disclosure have been described in detail here, they have been presented only for the purpose of explanation and should not be construed as limitations on the scope of the disclosure. Various substitutions, changes and modifications can be devised without departing from the spirit and scope of the disclosure.

Claims

An optical device (1) , comprising:

a polarizer (11) , which is adapted to decompose an input laser pulse into a first polarization component and a second polarization component; and

an adjustment unit (12) , which is adapted to change a polarization state, a propagation direction and a propagation distance of at least one of the first polarization component and the second polarization component, and to cause the first polarization component and the second polarization component to obtain two sub-pulses with a time interval after being combined again through the polarizer (11) .
The optical device (1) according to claim 1, wherein

the polarizer (11) is adapted to decompose a laser pulse into a transmitted first polarization component and a reflected second polarization component, which have polarization states orthogonal to each other; and/or

the adjustment unit (12) is configured to change a polarization direction of the incident first polarization component and/or second polarization component and to reflect it or them towards the polarizer (11) .
The optical device (1) according to claim 1 or 2, wherein

the adjustment unit (12) comprises a plurality of adjustment assemblies, each of which is configured to change a polarization direction of the corresponding incident polarization component from the polarizer (11) by π/2 and to reflect it back to the polarizer (11) .
The optical device (1) according to claim 3, wherein

each of the adjustment assemblies comprises a quarter-wave plate (121) and a reflective mirror (122) arranged along an incident direction of the corresponding polarization component of respective adjustment assembly.
The optical device (1) according to claim 4, wherein

at least the reflective mirror (122) of at least one of the adjustment assemblies is configured as a movable part being capable of changing a distance from the polarizer (11) by movement; and/or

the reflective mirror (122) of at least one of the adjustment assemblies is configured that its normal axis has a predetermined angle relative to the incident polarization component, or the reflective mirror (122) is configured as a parabolic reflective mirror (122) with a predetermined focal length.
The optical device (1) according to claim 5, wherein

the movable part is configured to be movable and positionable relative to the polarizer (11) within a range of 0 to 5000 mm, in particular within a range of 0 to 150 mm; and/or

the movable part is configured in such a manner that a length difference between an optical path of the first polarization component and an optical path of the second polarization component is 0 to 1000 mm, in particular 60 mm.
The optical device (1) according to any one of claims 1 to 6, wherein

the adjustment unit (12) comprises a first adjustment assembly (120a) and a second adjustment assembly (120b) which are arranged on an optical path of the second polarization component, such that the second polarization component initially reflected away from the polarizer (11) is incident on the first adjustment assembly (120a) and thus reflected back to the polarizer (11) by the first adjustment assembly (120a) , and, after transmitting through and away from the polarizer (11) , it is incident on the second adjustment assembly (120b) and thus reflected back to the polarizer (11) by the second adjustment assembly (120b) , and then combines with the first polarization component after being reflected again by the polarizer (11) .
The optical device (1) according to any one of claims 1 to 6, wherein

the adjustment unit (12) comprises a first adjustment assembly (120a) and a second adjustment assembly (120b) which are arranged on an optical path of the first polarization component, such that the first polarization component initially transmitting through and away from the polarizer (11) is incident on the first adjustment assembly (120a) and thus reflected back to the polarizer (11) by the first adjustment assembly (120a) , and, after being reflected and away from the polarizer (11) , it is incident on the second adjustment assembly (120b) and thus reflected back to the polarizer (11) by the second adjustment assembly (120b) , and then combines with the second polarization component after transmitting through the polarizer (11) again.
The optical device (1) according to any one of claims 1 to 6, wherein

the adjustment unit (12) comprises a first adjustment assembly (120a) arranged on an optical path of the first polarization component and a second adjustment assembly (120b) arranged on an optical path of the second polarization component, such that the first polarization component initially transmitting through and away from the polarizer (11) is incident on the first adjustment assembly (120a) and thus reflected back to the polarizer (11) by the first adjustment assembly (120a) , and then is reflected by the polarizer (11) , and that the second polarization component initially reflected away from the polarizer (11) is incident on the second adjustment assembly (120b) and thus reflected back to the polarizer (11) by the second adjustment assembly (120b) , and then transmits through the polarizer (11) so as to combine with the first polarization component that is reflected by the polarizer (11) .
The optical device (1) according to any one of claims 1 to 6, wherein

the polarizer (11) is a polarization beam splitter cube, in particular with a side length of approximately 30 mm, and in particular with a refractive index of 1.4 to 1.6, preferably 1.5; and/or

an optical 4f device is provided in an optical path of the first polarization component or the second polarization component.
A laser processing device (100) , comprising:

at least one laser radiation source (2) for providing laser pulses;

an optical device (1) according to any one of claims 1 to 10, which is optically connected to the laser radiation source (2) ; and

a focusing module (3) for applying laser light from the optical device (1) to a workpiece to be processed.
The laser processing device (100) according to claim 11, wherein

the at least one laser radiation source (2) is an ultrashort pulse laser, in particular a femtosecond laser and/or a picosecond laser and/or a nanosecond laser; and/or

the optical device (1) is configured to generate a pulse delay of 0 to 20 ns, in particular 0 to 1000 ps; and/or

the focusing module (3) comprises a reflective mirror (122) , a beam shaping unit, a lens set and/or a scanning mirror.
The laser processing device (100) according to claim 11 or 12, wherein

pulses generated by the laser radiation source (2) have a duration of 100 fs to 1000 ps; and/or

laser pulses output by the laser radiation source (2) are in a wavelength range of 200 nm to 2000 nm, in particular 1030 ± 30 nm; and/or

a beam configuration module (4) is provided between the laser radiation source (2) and the optical device (1) , which is adapted to configure a propagation angle, a divergence, a beam diameter and/or a polarization state of the laser pulses.
The laser processing device (100) according to any one of claims 11 to 13, wherein

the laser processing device (100) is a laser ablation device, a laser cutting device, a laser drilling device, a laser induced breakdown spectrometer, a soft X-ray generation device, a surface treatment device or a surface cleaning device.