Optical system and method for outputting variable light spots

Abstract

The invention discloses an optical system and method for outputting a variable light spot, and the system comprises a laser device, the output optical fiber of which is a multi-clad optical fiber; a plurality of movable parts are arranged on the structure shaping module, an output optical fiber of the laser is sequentially wound on the movable parts and is sequentially connected with a CPS device and an optical fiber output head after being wound, and the CPS device and the optical fiber output head are located outside the structure shaping module; and the circuit control module is used for controlling the moving positions of the plurality of moving parts so as to change the bending radius of the output optical fiber. According to the invention, laser energy is pumped to a specific cladding fiber for transmission by using a mode disturbing effect of bending of the fiber. The CPS device ensures that only light within the target cladding region is output, stripping stray light in the larger cladding and light from a smaller region mode that is not fully suppressed, thereby obtaining a spot having a size corresponding to the target cladding diameter.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light spot output, in particular to an optical system and method for outputting variable light spots. BACKGROUND

[0002] In the field of 3D printing, welding, cutting and other light spot processing, a single size of output light spot is difficult to cope with complex and variable processing conditions, and the processing precision and efficiency are limited.

[0003] To solve the processing problems of single size of output light spot, the current technical route generally adopts Gaussian, annular light spot combination or Gaussian, flat top light spot combination, and the specific implementation modes include two kinds, one is to realize by combining multiple light modules, which cannot output multiple different sizes of light spots, the output power cannot be superimposed, is affected by module aging, and the light path structure is complex and bulky, which is not conducive to wide application due to large volume and weight; the other implementation mode is to realize by optical lens shaping, which needs to use multiple lens groups, needs to be accurately aligned in space, including position, angle, polarization direction, etc., but the matching error and assembly deviation between lenses will cause aberration accumulation, further reducing the light spot quality, and there is a problem of difficult maintenance. SUMMARY

[0004] Therefore, the present application provides an optical system for outputting variable light spots, comprising:

[0005] A laser, wherein the output optical fiber of the laser is a multi-clad optical fiber;

[0006] A structure shaping module, wherein a plurality of movable components are arranged on the structure shaping module, the output optical fiber of the laser is sequentially wound around the plurality of movable components, and is sequentially connected with a CPS device and an optical fiber output head after being wound, and the CPS device and the optical fiber output head are located outside the structure shaping module;

[0007] A circuit control module, wherein the circuit control module is used to control the active positions of the plurality of movable components to change the bending radius of the output optical fiber.

[0008] According to a preferred embodiment, the output optical fiber comprises a core, a first cladding, a second cladding, a third cladding, a fourth cladding and a coating layer, the sizes of the core, the first cladding, the second cladding, the third cladding and the fourth cladding are m1, m2, m3, m4 and m5 in sequence, the refractive indexes are n1, n2, n3, n4 and n5 in sequence, and satisfy the following relationships: m1 < m2 < m3 < m4 < m5, n1 > n2 > n3 > n4 > n5, and the light spot size output by the optical system can be m1, m2, m3 or m4.

[0009] According to a preferred embodiment, the plurality of movable components are cylindrical structures mounted on ball screws to achieve movement through a sliding block.

[0010] Further, the structure shaping module further comprises a stepper motor and a roller screw, the stepper motor provides power for the roller screw to control the movement of the movable components.

[0011] Further, the circuit control module comprises an encoder and a control unit, the encoder is fixed on the stepper motor for reading the rotation angle of the stepper motor, and the control unit is used to control the stepper motor according to the rotation angle.

[0012] According to a preferred embodiment, the plurality of movable components comprises: a first movable component, a second movable component, a third movable component and a fourth movable component, the movement ranges are parallel to each other, and adjacent movable components are located on opposite sides of the output optical fiber.

[0013] The application also provides a method for outputting a variable light spot, using the optical system for outputting a variable light spot as described above, comprising the following steps:

[0014] S1: adjusting a plurality of movable components to a movement starting point;

[0015] S2: calculating the bending radius of the output optical fiber according to requirements;

[0016] S3: adjusting the movement position of the movable components based on the bending radius.

[0017] Further, in S1, the stepper motor outputs direction information to the movable components, and the movement starting point is obtained based on the encoder.

[0018] Further, in S2, the bending radius of the output optical fiber is calculated according to the critical bending radius formula wherein R C represents the bending radius of the output optical fiber, a represents the diameter of the output optical fiber, and NA represents the numerical aperture of the output optical fiber.

[0019] Further, the S3 step is completed based on the circuit control module.

[0020] The application utilizes the mode disturbance effect of fiber bending to pump laser energy into a specific cladding optical fiber for transmission. The CPS device ensures that only the light energy in the target cladding area is output, and the stray light in the larger cladding and the light from the smaller area mode that is not completely suppressed are stripped, thereby obtaining a relatively pure light spot with a size corresponding to the diameter of the target cladding. The application has a simple structure, a small volume, is beneficial to wide application, is not affected by the matching error between lenses and assembly deviation, has excellent light spot quality, and is easy to maintain as a whole. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of an optical system for outputting variable light spots in the present application;

[0022] Figure 2 is a cross-sectional view of a multi-clad optical fiber in the present application;

[0023] Figure 3 is a schematic diagram of the structural shaping module in the present application, in which each movable component is in a zero position;

[0024] Figure 4 is a structural schematic diagram of the structural shaping module in the present application;

[0025] Figure 5 is a diagram of light spots of different sizes output by an embodiment of the present application. DETAILED DESCRIPTION

[0026] In the fields of 3D printing, welding, cutting and other light spot processing, a single size of output light spot is difficult to cope with complex and variable processing conditions, and the processing precision and processing efficiency are limited.

[0027] To solve the processing problems of single-size output light spots, the current technical route generally adopts a combination of Gaussian and ring-shaped light spots or a combination of Gaussian and flat-top light spots. The specific implementation modes include two kinds. One is to realize it by combining multiple light modules. This mode cannot output multiple light spots of different sizes, the output power cannot be superimposed, is affected by module aging, and has a complex and bulky light path structure, which is large in volume and weight and is not conducive to wide application. The other implementation mode is to realize it by optical lens shaping. This mode needs to use multiple lens groups, needs to be accurately aligned in space, including position, angle, polarization direction, etc. However, the matching error between lenses and assembly deviation will cause aberration accumulation, further reducing the quality of the light spot, and there is a problem of difficult maintenance.

[0028] Therefore, the present application provides an optical system for outputting variable light spots. To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that in the embodiments of the present application, many technical details are proposed in order to make the reader better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed by the present application can be implemented.

[0029] In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. It will be appreciated, however, that embodiments can be practiced in other ways without one or more of the specific details.

[0030] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an open, inclusive sense, as

[0031] The embodiments of the present application will be described in detail with reference to the drawings, so as to make clear the purpose, features and advantages of the present application. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present application, but merely to illustrate the essential spirit of the technical solutions of the present application.

[0032] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0033] Specifically, as shown in the application embodiment, an optical system outputting variable light spots comprises: Figure 1

[0034] a laser, an output fiber of the laser being a multi-clad fiber;

[0035] a structure shaping module, a plurality of movable components are arranged on the structure shaping module, the output fiber of the laser is sequentially wound around the plurality of movable components, and is sequentially connected with a CPS device and a fiber output head after being wound, the CPS device and the fiber output head being located outside the structure shaping module;

[0036] a circuit control module, the circuit control module being used for controlling active positions of the plurality of movable components, so as to change a bending radius of the output fiber.

[0037] Preferably, the output fiber is a QBH fiber, and the output end is a multi-clad fiber assembly adopting a QBH joint.

[0038] In one embodiment, as shown in the application embodiment, an optical system outputting variable light spots comprises: Figure 2 ​As shown, the output fiber includes a core, a first cladding, a second cladding, a third cladding, a fourth cladding and a coating layer, the core, the first cladding, the second cladding, the third cladding and the fourth cladding have sizes of m1, m2, m3, m4 and m5 in sequence, and have refractive indexes of n1, n2, n3, n4 and n5 in sequence, and satisfy the following relationships: m1 < m2 < m3 < m4 < m5, and n1 > n2 > n3 > n4 > n5, and the spot size output by the optical system can be m1, m2, m3 or m4.

[0039] Based on the total reflection and mode coupling principle of the fiber, the spot size output can be changed from m1 to m2, m3 or m4.

[0040] When the spot size of m1 is needed, the moving distance of the plurality of movable components relative to the zero point is l1, and the light is mainly limited in the core to be transmitted in the fundamental mode. The CPS device removes any light that may leak to the larger cladding, and the output spot size is the core diameter m1. Wherein, as shown, the zero point refers to the position of each movable component when the output fiber is flat. Figure 3

[0041] When the spot size of m2 is needed, the moving distance of the plurality of movable components relative to the zero point is l2 (l2 < l1), and the bending mode effect will couple part of the light energy from the core to the mode of the first cladding. At the same time, the bending loss will suppress the core mode. The CPS device effectively removes the light that leaks to the larger cladding.

[0042] When the spot size of m3 is needed: the moving distance of the plurality of movable components relative to the zero point is l3 (l3 < l2 < l1), and stronger mode coupling will couple more energy to the mode of the second cladding, and at the same time, the bending loss further suppresses the core and the first cladding mode. The CPS removes the light that leaks to the larger cladding.

[0043] When the spot size of m4 is needed: the moving distance of the plurality of movable components relative to the zero point is l4 (l4 < l3 < l2 < l1), and the severe mode coupling will couple most of the energy to the mode of the third cladding. At the same time, the strong bending loss almost completely suppresses the core and the smaller cladding mode. The CPS still effectively removes the light that leaks to the fourth cladding. The output spot size reaches m4.

[0044] It can be understood that the four movable components are generally selected based on the general situation, and the number of movable components can be changed by those skilled in the art to achieve more flexible or more accurate purposes.

[0045] In the above, the moving distance of each movable component refers to the moving distance towards the output fiber. It can be understood that the larger the spot size is, the smaller the bending diameter of the corresponding output fiber is. ​

[0046] The present application utilizes the bending mode coupling effect to transfer the laser energy from the fiber core to a specific inner cladding. The controllable conversion from the fiber core fundamental mode to the first cladding mode, the second cladding mode, and the third cladding mode is achieved. The output spot size is no longer only the mode size of the fiber core, but the size of the specific cladding that is currently carrying most of the laser energy. The CPS device ensures that only the light energy in the target cladding region is output, stripping the stray light in the larger cladding and the light from the smaller area mode that is not completely suppressed, thereby obtaining a relatively pure spot corresponding to the diameter of the target cladding.

[0047] Further, the plurality of movable components are cylindrical structures mounted on a ball screw to achieve movement through a sliding block. The zero position can be determined according to the position of the center of the circle.

[0048] Further, as shown in Figure 4 The structure shaping module is composed of a structure shaping module base 1, a fiber expansion protection device 2, a fiber clamp 3, a stepper motor 4, a main bearing seat 5, a profile cover plate 6, a ball screw 7, a secondary bearing seat 8, and a cover plate 9. The entire structure shaping module is connected to the circuit control module through the power supply interface 11 to control the structure shaping module to achieve different bending radii of the output fiber 13 after being connected to the power supply through the signal interface 10.

[0049] The structure shaping module base 1 and the cover plate 9 provided thereon provide installation reference and structural support for other components; the main bearing seat 5 and the secondary bearing seat 8 cooperate with the ball screw 7 to realize a mechanical movement mechanism, ensuring movement stability and precision.

[0050] The fiber expansion protection device 2 is used to regulate the bending shape and buffer length change of the fiber to avoid damage caused by excessive bending of the fiber; the fiber clamp 3 bears the function of fixing and positioning the fiber to ensure the stability of the fiber position during the shaping process. It is annular and can provide accommodation space for the output fiber. Through the clamping groove and the support, the positioning of the structure shaping module base is realized.

[0051] The stepper motor 4 serves as a power source to realize the precise displacement of the movable components by driving the ball screw 7, thereby changing the bending state of the fiber. The number of stepper motors 4 corresponds to the number of movable components; the signal interface 10 is responsible for establishing a connection with the circuit control module and receiving control instructions to jointly control the structure shaping module to adjust the fiber bending radius as required, thereby achieving precise control of different bending shapes of the fiber. The profile cover plate 6 plays a protective role for the workbench 12 and reduces external interference such as dust and debris, thereby improving overall reliability and maintenance convenience.

[0052] Further, the circuit control module comprises an encoder fixed on the stepper motor 4 for reading the rotation angle of the stepper motor 4 and a control unit for controlling the stepper motor 4 according to the rotation angle.

[0053] Further, the application adopts the optical system for outputting variable light spots and proposes a method for outputting variable light spots, comprising the following steps:

[0054] S1: adjusting a plurality of movable components to a motion starting point;

[0055] Specifically, the direction information of the movable components is output by the stepper motor, and the motion starting point is obtained based on the encoder.

[0056] The operation logic is that the 4-way stepper motor first outputs a pulse and a direction signal, each way judges whether there is a zero position determination instruction, if it is "N", the signal is continuously output and waiting; if it is "Y", the corresponding encoder position information is read, and the zero positions are stored as Z1, Z2, Z3 and Z4 respectively, so as to realize the determination and recording of the zero positions of the 4-way stepper motor.

[0057] S2: calculating the bending radius of the output optical fiber according to the requirement;

[0058] Specifically, the bending radius of the output optical fiber is calculated according to the critical bending radius formula , wherein R C represents the bending radius of the output optical fiber, a represents the diameter of the output optical fiber, and NA represents the numerical aperture of the output optical fiber.

[0059] During operation, the fiber bending radius is calculated by the formula, and the C1-C4 bits are reset; then the target radius is 4-way respectively, the encoder is read and the movable position of the movable component is determined, the pulse and the direction signal are output, the new position is continuously read and compared, the stepper motor is confirmed to be in place, and the light spot diameter adjustment control is completed.

[0060] S3: adjusting the movable position of the movable component based on the bending radius, which is completed by the circuit control module.

[0061] In one embodiment, the sizes m1, m2, m3 and m4 of the core, the first cladding, the second cladding and the third cladding are respectively 14 um, 25 um, 50 um and 100 um, and the output light spot is as shown in Figure 5 The light spot size corresponds to the sizes of the core, the first cladding, the second cladding and the third cladding, and the shape is uniform, the output quality is excellent, and the stability and expandability are high.

[0062] The above describes in detail the optical system and method for outputting variable light spots provided by the embodiments of the present application. The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be understood by referring to each other. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the relevant parts can be understood by referring to the description of the method. It should be noted that, for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0063] Those skilled in the art will further appreciate that the units and algorithm steps of each example described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been described in general terms above. Whether the functions are performed in hardware or software depends on the particular application and design constraints. Those skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered beyond the scope of the present application.

[0064] The steps of the method or algorithm described in connection with the embodiments disclosed herein can be directly implemented in hardware, software executed by a processor, or a combination of both. The software module can be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

Claims

1. An optical system for outputting a variable light spot, characterized in that: include: A laser, wherein the output optical fiber of the laser is a multi-clad optical fiber; A structural shaping module, wherein the structural shaping module is provided with a plurality of movable parts, and the output optical fiber of the laser is sequentially wound around the plurality of movable parts and, after winding, sequentially connected to a CPS device and an optical fiber output head, wherein the CPS device and the optical fiber output head are located outside the structural shaping module; A circuit control module is used to control the movable positions of the plurality of movable components to change the bending radius of the output optical fiber.

2. The optical system for outputting a variable light spot according to claim 1, characterized in that: The output optical fiber includes a core, a first cladding, a second cladding, a third cladding, a fourth cladding and a coating layer. The sizes of the core, the first cladding, the second cladding, the third cladding and the fourth cladding are m1, m2, m3, m4 and m5 respectively, and the refractive indices are n1, n2, n3, n4 and n5 respectively, and satisfy the following relationship: m1<m2<m3<m4<m5, n1>n2>n3>n4>n5. The spot size output by the optical system can be m1, m2, m3 and m4.

3. The optical system for outputting a variable light spot according to claim 2, wherein: The multiple movable parts are cylindrical structures and are installed on the ball screw to achieve movement through the slider.

4. The optical system for outputting a variable light spot according to claim 3, wherein: The structural shaping module further includes a stepping motor and a roller screw, wherein the stepping motor provides power to the roller screw to control the movement of the movable parts.

5. The optical system for outputting a variable light spot according to claim 4, characterized in that: The circuit control module includes an encoder and a control unit. The encoder is fixed on the stepping motor and is used to read the rotation angle of the stepping motor. The control unit is used to control the stepping motor according to the rotation angle.

6. The optical system for outputting a variable light spot according to claim 1, wherein: The plurality of movable components include: a first movable component, a second movable component, a third movable component and a fourth movable component, whose movable ranges are parallel to each other, and adjacent movable components are located at opposite sides of the output optical fiber.

7. A method for outputting a variable light spot, using the optical system for outputting a variable light spot according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Adjust multiple moving parts to the starting point of movement; S2: Calculate the bending radius of the output optical fiber according to the requirements; S3: Adjusting the movable position of the movable component based on the bending radius.

8. The method for outputting a variable light spot according to claim 7, characterized in that: In S1, the direction information of the movable component is outputted by the stepping motor, and the starting point of the movement is obtained based on the encoder.

9. The method for outputting a variable light spot according to claim 7, wherein: In S2, according to the critical bending radius formula Calculate the bending radius of the output fiber, where R C represents the bending radius of the output optical fiber, a represents the diameter of the output optical fiber, and NA represents the numerical aperture of the output optical fiber.

10. The method for outputting a variable light spot according to claim 7, wherein: The S3 step is completed based on the circuit control module fitting.

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