TW201620658A - Laser focusing optical module and laser focusing method - Google Patents

Abstract

Disclosed is a laser focusing optical module, including an adjustable convertor cylinder, a laser beam expander, and a planar-convex lens subsequently from a light incident end to a light out end. The adjustable convertor cylinder includes a converter and an aspheric lens, and the converter is connected to a fiber which outputs a laser beam. Disclosed is also a laser focusing method.

Description

Laser focusing optical module and laser focusing method

The present invention relates to a laser focusing optical module and a laser focusing method, and more precisely, to a spot size reduction of a near-infrared fiber laser at a high power, and having a low total output power loss and a long working distance. The advantage of the laser focusing optical module.

In general, the types of lasers vary with the choice of luminescent materials, and the power and characteristics of different types of laser light enable them to be used in different applications. Lasers have been widely used in the industry. In the industrial world, the range of laser applications mainly includes cutting, drilling, machining, welding and hard surface treatment.

At present, the traditional optical focusing lens design, the laser spot size can be reduced to a limited extent, the total output power loss is often too high, and the laser working distance can not be adjusted according to user preferences. Generally, the size of the spot output by the fiber laser will be diverged as the distance of the imaging increases, and the high-power near-infrared fiber laser cannot directly output a small spot.

Therefore, there is a need for a laser focusing optical module design that can greatly reduce the size of a laser spot while maintaining the original high power and having a laser working distance that can be easily adjusted.

In order to solve the above problems, the present invention is a laser focusing optical module capable of reducing the spot size of a near-infrared fiber laser at a high power and having the advantages of low total output power loss and long working distance.

According to an aspect of the invention, a laser focusing optical module is provided, which comprises an adjustable focal length adapter cylinder, a beam expander and a plano-convex lens sequentially from an optical end to an optical end of an optical output end. The adjustable focal length transfer cylinder sequentially includes a adapter and an aspherical mirror, wherein the adapter is connected to one of the optical fibers for outputting the laser beam, and the adapter is connected to the light in the adjustable focal length adapter cylinder The displacement of the shaft causes one of the output beams of the laser beam to correspond to a focus of the aspherical mirror, and the laser beam of the optical fiber passes through the aspherical mirror to form a parallel collimated laser beam. The beam expander is disposed between the aspherical mirror and the light exiting end, and expands the parallel collimated laser beam that is emitted through the aspherical mirror. The plano-convex lens is disposed at the light-emitting end, and the beam-expanded parallel collimated laser beam emitted from the beam expander is focused and outputted to the optical end.

Preferably, the beam expander can be a 4x beam expander.

Preferably, the laser beam outputted by the optical fiber can be near-infrared light, and the power loss of the laser beam outputting the lens barrel can be 6% to 10% of the laser beam output from the optical fiber.

Preferably, the spot of the laser beam output by the fiber is at least 8 times the spot of the laser beam outputting the lens barrel.

Preferably, the working distance of the laser focusing optical module can be in the range of about 100 mm to about 150 mm.

According to another aspect of the present invention, a laser focusing method is provided. The method includes: setting an adjustable focal length transfer cylinder along an optical axis at an optical entrance end, which sequentially includes a adapter and an aspherical mirror, wherein the adapter system Connected to the fiber for outputting the laser beam, the laser beam provided by the fiber is passed through the adapter, and the adapter is displaceable along the optical axis in the adjustable focal length adapter; adjusting the adapter to make the laser The beam is output from the focal point of the aspherical mirror to the aspherical mirror to form a parallel collimated laser beam; a beam expander is provided between the aspherical mirror and the light exiting end; and the parallel collimated laser beam is passed through the beam expander to be parallel The collimated laser beam is expanded; a plano-convex lens is provided at the light-emitting end; and the beam-expanded parallel collimated laser beam emerging from the beam expander is focused by a plano-convex lens and outputted to the optical end.

Preferably, the beam expander in the laser focusing method can be a 4x beam expander.

Preferably, the laser beam output from the laser focusing method can be a near-infrared light, and the power loss of the laser beam at the output lens can be 6% to 10% of the laser beam output from the fiber.

Preferably, the spot of the laser beam output by the fiber in the laser focusing method may be at least 8 times the spot of the laser beam outputting the lens barrel.

Preferably, the laser focusing method has a working distance in the range of from about 100 mm to about 150 mm.

In order to enable the reviewing committee to have a further understanding and understanding of the features, objects and functions of the present invention, the related detailed structure of the device of the present invention and the concept of the design are explained below so that the reviewing committee can understand the present invention. Features, detailed descriptions are as follows:

Please refer to FIG. 1 , which is a schematic view of a first embodiment of a laser focusing optical module of the present invention. In this embodiment, the laser focusing optical module 1 sequentially includes an optical fiber 10, a lens barrel 110, an adjustable focal length adapter cylinder 120, a beam expander 130, and a plano-convex lens 140 from the light incident end to the light exit end. . Fiber 10 provides a laser beam 100. In the present embodiment, the laser beam 100 produced by the optical fiber 10 has a variable wavelength range of 780-1100 nm, which is a near-infrared light range, and the numerical aperture NA of the optical fiber 10 is 0.22. Further, in one embodiment, the laser beam produced by the optical fiber 10 has a beam diameter of 400 μm and a wavelength of 808 nm.

The adjustable focal length adapter cylinder 120 includes a adapter 121 and an aspherical mirror 122. Please refer to FIG. 2 and FIG. 3, which are respectively a perspective view of a fiber laser adapter and an aspherical mirror cross-sectional view of an exemplary embodiment of a laser focusing optical module according to the present invention. The optical fiber 10 is connected to the light incident end of the adapter 121, and the laser beam 100 is output from one end thereof through the adapter 121. The adjustable focal length adapter cylinder 120 can be used to adjust the position of the adapter 121 on the optical axis such that the output point of the laser beam 100 from one end of the adapter 121 corresponds to the focus of the aspherical mirror 122. It is intended to transform the laser beam 100 passing through the aspherical mirror 122 into a parallel collimated beam 100a. The parallel collimated beam 100a passing through the aspherical mirror 122 is again received by the beam expander 130. It is to be noted that the adapter 121 used herein is a Ferrule Converter of Model 77670 manufactured by Newport Corporation, and has an outer diameter R1 of about 11 mm and a length L1 and a length L2 of about 10 mm and about 6.3 mm, respectively. The non-spherical mirror 122 is Mounted Molded Glass Aspheric Lens of the model KGA220-B-MT manufactured by Newport Corporation, and has an outer diameter D3 of about 9.24 mm, an effective light incident inner diameter D2 of about 5.75 mm, and an effective focal length EFL1 of about 11 mm. . The working distance WD is about 7.96 mm, so the beam diameter of the parallel collimated beam 100a can be calculated by the following Equation 1:

Equation 1: Beam diameter = 2 * EFL1 * NA = 2 * 11 * 0.22 = 4.84 mm

The beam expander 130 further expands the parallel collimated beam 100a to form a larger parallel collimated beam 100b. It is to be noted that the beam expander 130 is an optical element capable of changing the diameter of the laser beam and the divergence angle. The adjustment of the beam expander 130 allows the output parallel collimated beam 100b to be obtained by using the plano-convex lens 140 afterwards. The high power density spot, in addition, preferably, if the beam expander 130 is used in conjunction with the spatial rate light sheet, the asymmetric beam profile can be adjusted to a symmetric beam profile to make the light energy distribution more uniform. Reference is made to Fig. 4, which is a cross-sectional view of a beam expander shown in an exemplary embodiment of a laser focusing optical module in accordance with the present invention. Here, the beam expander 130 uses a high-energy laser beam expander of the model HB-4XAR.16 manufactured by Newport Corporation, wherein as shown in FIG. 4, the length L4 is approximately 127.0 mm, and the outer diameter D4 of the light exit end of the beam expander 130 is about 44.5 mm. The beam diameter of the larger parallel collimated beam 100b can be calculated by the beam diameter of Equation 1 and Equation 2 below:

Equation 2: Beam diameter (mm) = 4.84 *4 = 19.36 mm

After passing through the beam expander 130, the plano-convex lens 140 receives the larger parallel collimated beam 100b that is expanded from the beam expander 130, and further focuses the parallel collimated beam 100b onto the plano-convex lens 140 to form a focused laser beam. 100c. As shown in Fig. 5, there is shown a plano-convex lens cross-sectional view of an exemplary embodiment of a laser focusing optical module in accordance with the present invention. Here, the plano-convex lens 140 uses a plano-convex lens (Plano-Convex Lens) of the model SPX022AR.16 manufactured by Newport Corporation, and has an effective focal length EFL2 of about 100 mm, a radius of curvature R of about 45.90 mm, and a thickness P2 of about 3.28 mm. The thickness Tc and the thickness Te are about 3 mm and 1 mm, respectively. The beam diameter of the focused laser beam 100c can be calculated from the beam diameter calculated by Equation 2 and Equation 3 below:

Equation 3: Beam diameter (μm) = 4/π * λ * EFL2 / beam diameter = 4 / π * 808 * 10 ^-9 * 1.2 * 100 / 19.36mm = 6.377 μm

Further, under the above conditions, the depth of field DOF (Defth of Field, DOF) of the focused laser beam 100c used for material processing or modification may be calculated by the following Equation 4:

Equation 4: DOF=8/π* λ * (EFL2/beam diameter)*2 * 106 = 8/π * 808 * 10 ^-9 * (100 / 19.36)*2 * 106= 54.9 μm

Here, from the above results, the actual output spot size is 6.377 μm, and the depth of field DOF of the focused laser beam 100c can be changed by changing the effective focal length EFL2 of the plano-convex lens 140. Therefore, the working distance of the laser focusing optical module 1 can be improved by this. In another preferred embodiment, if the effective focal length EFL2 of the plano-convex lens 140 is changed to about 150 mm, the depth of field DOF of the larger focused beam and the beam diameter of the other focused laser beam 100c can be obtained as follows:

Equation 3: Beam diameter (μm) = 4/π * λ * EFL2 / beam diameter = 4 / π * 808 * 10 ^-9 * 1.2 * 150 / 19.36mm = 9.57 μm

Equation 4: DOF = 8 / π * λ * (EFL2 / beam diameter) * 2 * 106 = 8 / π * 808 * 10 ^-9 * (100 / 19.36) * 2 * 150 = 123.52 μm

In addition, through actual measurement, the power of the laser beam 100 directly output by the optical fiber 10 is 32.69 W, and the output power after the laser focusing optical module 1 is 30.52 W, and the overall output optical power loss is about 2.17 W (about 6 %), the 400 μm spot output from the focused laser beam 100c of the optical fiber 10 can be reduced by 8 times to 50 μm or less (~20 μm) while maintaining high power, and a working distance of 100 to 150 mm can be achieved. Here, the working distance of the laser focusing optical module is only an example, and the working distance can be changed by changing the lens to achieve a longer focal length, and is not limited to the above range of 100 to 150 mm.

Figure 6 is a flow chart of a laser focusing method in accordance with the present invention.

The laser focusing method of the present invention will now be described with reference to Fig. 6. Firstly, an adjustable focal length transfer cylinder is arranged along the optical axis at the light entrance end, and the adjustable focal length transfer cylinder sequentially includes a adapter and an aspherical mirror (step S61), and the adapter is adjusted to make the laser beam from the focus of the aspherical mirror. Outputting to the aspherical mirror to form a parallel collimated laser beam (step S62), the adjustable focal length adapter cylinder can be used to adjust the position of the adapter on the optical axis to output the laser beam from one end of the adapter The point corresponds to the focus of the aspherical mirror. It is intended to transform the laser beam 100 passing through the aspherical mirror 122 into a parallel collimated beam 100a. The parallel collimated beam 100a passing through the aspherical mirror 122 is again received by the beam expander 130.

Furthermore, a beam expander disposed between the aspherical mirror and the light exiting end is provided (step S63), and the parallel collimated laser beam is passed through the beam expander to expand the parallel collimated laser beam (step S64), and the beam is expanded. The parallel collimated beam is further expanded to form a larger parallel collimated beam, and the beam expander 130 can change the diameter of the laser beam and the divergence angle. The adjustment of the beam expander enables the parallel collimated beam to be utilized after the flat beam. The convex lens obtains a fine high power density spot. Next, a plano-convex lens disposed at the light-emitting end is provided (step S65), and finally, the expanded parallel collimated laser beam emerging from the beam expander is focused by a plano-convex lens, and the light-emitting end is output (step S66). After the laser beam passes through the beam expander, the plano-convex lens receives a larger parallel collimated beam from the beam expander and further focuses the parallel collimated beam onto the focus of the plano-convex lens to form a focused laser beam. In the above steps, the specifications of the adapter, the aspherical mirror, the beam expander, and the plano-convex lens are as described above, and therefore will not be described herein.

In summary, the laser focusing optical module and the laser focusing method of the present invention can greatly reduce the size of the laser spot, and at the same time maintain the original high power, and have a laser working distance that can be easily adjusted. Shooting focusing optical module design.

However, the above is only an embodiment of the present invention, and the scope of the present invention is not limited thereto. It is to be understood that the scope of the present invention is not limited by the spirit and scope of the present invention, and should be considered as a further embodiment of the present invention.

10‧‧‧Fiber
100‧‧‧Laser beam
100a, 100b‧‧‧ parallel collimated beam
100c‧‧‧focus laser beam
110‧‧‧Mirror tube
120‧‧‧Adjustable focal length adapter
121‧‧‧Adapter
122‧‧‧Aspherical mirror
130‧‧‧beam expander
140‧‧‧ Plano-convex lens
R1, D2, D3, D4‧‧‧ OD
L1, L2, L3, L4‧‧‧ length
P2, Tc, Te‧‧‧ thickness
EFL1, EFL2‧‧‧ effective focal length
WD‧‧‧Working distance
R‧‧‧ radius of curvature

1 is a schematic diagram showing an exemplary embodiment of a laser focusing optical module in accordance with the present invention.

2 is a perspective view of a fiber optic laser adapter shown in accordance with an illustrative embodiment of a laser focusing optical module of the present invention.

Figure 3 is a cross-sectional view of an aspherical mirror shown in an exemplary embodiment of a laser focusing optical module in accordance with the present invention.

Figure 4 is a cross-sectional view of a 4x beam beam expander shown in an exemplary embodiment of a laser focusing optical module in accordance with the present invention.

Figure 5 is a cross-sectional view of a plano-convex lens shown in an exemplary embodiment of a laser focusing optical module in accordance with the present invention.

Figure 6 is a flow chart of a laser focusing method in accordance with the present invention.

10‧‧‧Fiber

100‧‧‧Laser beam

100a, 100b‧‧‧ parallel collimated beam

100c‧‧‧focus laser beam

110‧‧‧Mirror tube

120‧‧‧Adjustable focal length adapter

121‧‧‧Adapter

122‧‧‧Aspherical mirror

130‧‧‧beam expander

140‧‧‧ Plano-convex lens

EFL1, EFL2‧‧‧ effective focal length

Claims (10)

A laser focusing optical module includes an adjustable focal length adapter cylinder sequentially including an adapter and an aspherical mirror, wherein the rotation comprises an adapter and an aspherical mirror. The connector is connected to one of the optical fibers for outputting the laser beam, and the adapter is displaceable along the optical axis in the adjustable focal length adapter cylinder such that one of the output points of the laser beam of the optical fiber corresponds to a focus of the aspherical mirror, the laser beam of the optical fiber passes through the aspherical mirror to form a parallel collimated laser beam; a beam expander is disposed between the aspherical mirror and the light exiting end, and the parallel to be emitted through the aspherical mirror A collimated laser beam is expanded; and a plano-convex lens is disposed at the light-emitting end, and the parallel-collimated laser beam that is expanded from the beam expander is focused and outputted to the light-emitting end. The laser focusing optical module of claim 1, wherein the beam expander is a 4x beam expander. The laser focusing optical module of claim 1, wherein the laser beam outputted by the optical fiber is a near-infrared light, and the power loss of the laser beam outputting the lens barrel is the optical fiber. The output of the laser beam is 6% to 10%. The laser focusing optical module of claim 1, wherein the laser beam outputting the laser beam is at least 8 times larger than a spot of the laser beam outputting the lens barrel. The laser focusing optical module of claim 1, wherein the laser focusing optical module has a working distance of about 100 mm to 150 mm. A laser focusing method, the method comprising: arranging an adjustable focal length adapter cylinder along an optical axis at an optical entrance end, which comprises an adapter and an aspherical mirror in sequence, wherein the adapter is connected Outputting an optical fiber of one of the laser beams, the laser beam provided by the optical fiber passing through the adapter, and the adapter is displaceable along the optical axis in the adjustable focal length adapter; adjusting the transfer The head outputs the laser beam from a focus of the aspherical mirror to the aspherical mirror to form a parallel collimated laser beam; providing a beam expander disposed between the aspherical mirror and the light exiting end; Passing a beam of light through the beam expander to expand the parallel collimated laser beam; providing a plano-convex lens disposed at the light exiting end; and expanding the parallel collimated laser beam that is to be emitted from the beam expander The light-emitting end is focused and output by the plano-convex lens. The laser focusing method of claim 6, wherein the beam expander is a 4x beam expander. The laser focusing method of claim 6, wherein the laser beam outputted by the optical fiber is a near-infrared light, and the power loss of the laser beam outputting the lens barrel is the optical fiber output. The laser beam is 6% to 10%. The laser focusing method of claim 6, wherein the laser beam outputting the laser beam is at least 8 times larger than a spot of the laser beam outputting the lens barrel. The laser focusing method of claim 6, wherein the laser focusing method has a working distance of about 100 mm to 150 mm.