TWI789275B - Laser spatial distribution transformation element and transformation method - Google Patents

Abstract

The present invention discloses a laser spatial distribution transformation element, which an optical channel is defined by a housing, the optical channel includes a light receiving section, a conic section having a wide aperture end and a narrow aperture end and a light output section, the wide aperture end connects to the light receiving section and the narrow aperture end connects to the light output section, wherein the light receiving section and the conic section have a first central axis, and the light output section has a second central axis, and the second central axis and the first central axis are parallel to each other and do not overlap.

Description

Laser light-shape conversion element and conversion method

The invention relates to an optical element for laser transmission, in particular to an optical element and a conversion method for laser light-shape conversion.

The energy of the laser beam has a Gaussian distribution along the radial direction, which means that the energy is the highest at the center of the beam and rapidly weakens radially towards the outer edge of the beam, so that the energy at the edge acts on the surface of the material and is easily converted into excess heat.

According to the current method, the external optical device is arranged at the laser output port, and after the laser light is output, it is converted through the optical device to make the energy distribution in the radial direction more uniform, but the energy loss will be increased.

In view of the consumption problem derived from the above energy distribution, the present invention provides a light shape conversion element, which converts the Gaussian distribution of the laser light shape into a flat-top distribution to make the energy distribution uniform in space and reduce energy loss at the same time.

The present invention provides a light shape conversion element. A housing defines an optical channel, and the optical channel includes: a tapered section with a wide bore end and a narrow bore end; and a light output section connected to the narrow aperture end of the tapered section; Wherein the tapered section has a first central axis, the light output section has a second central axis, and the second central axis and the first central axis are parallel to each other and do not overlap.

The present invention further provides a light-shape conversion method, which includes applying 10-100 psi positive stress to the casing of the aforementioned light-shape conversion element.

The following embodiments are used in conjunction with the drawings to illustrate the spirit of the present invention so that those skilled in the art can clearly understand the technology of the present invention, but are not intended to limit the scope of the present invention. The patent scope of the present invention should be determined by the claims defined. It is especially emphasized that the drawings are only for illustration purposes, and do not represent the actual size or quantity of components, and some details may not be fully drawn for the sake of simplicity of the drawings.

The light shape conversion element of the present invention has a light source section and a light output section. The light exit end of the light source segment forms a tapered shape and is joined to the light exit segment. The optical axis of the cone of the light source segment and the optical axis of the light output segment are parallel to each other and do not coincide. In this way, after the light from the light source section enters the light exit section, the beam has a large light cone and the center is not on the optical axis of the light exit section, and more modes are excited during transmission, which can form a relatively uniform energy distribution. Therefore, the light shape can be converted from a Gaussian distribution to a flat-top distribution.

In some implementations, this light-shape conversion mechanism is implemented with optical fibers. In a certain embodiment, the diameter of the optical fiber is gradually reduced into a tapered shape, so that the numerical aperture (NA) of the optical fiber at the narrow aperture end becomes larger, and the corresponding acceptance angle (θ) of the fiber end face becomes larger, and through the narrow aperture end, the off-axis Connect the output fiber in a central way.

Please refer to FIG. 1 and FIG. 2 , which are schematic diagrams of the optical fiber structure of all and part of the light-shape conversion element of the present invention. The light shape conversion element is formed by the light channel 2 defined by the housing 1. In this embodiment, the cross-sectional profile of the light channel 2 is a circular structure. The light channel 2 includes a light receiving section 5, a tapered section 6 and a light output area. Section 7, understandably, the laser light passes through the light receiving section 5, the tapered section 6 and the light output section 7 in sequence, wherein the tapered section 5 has a wide-aperture end 10 and a narrow-aperture end 11, through which the wide-aperture The end 10 is connected to the light receiving section 5, and through the narrow aperture end 11 to the light output section 7, said connections are preferably welded.

Wherein the light receiving section 5 and the tapered section 6 have the same first central axis 8, the light output section 7 has a second central axis 9, and the second central axis 9 and the first central axis 8 are parallel to each other and do not overlap .

In this embodiment, the tapered section 6 is formed by hot-melt tapering, the length L of the tapered section is 3-25 mm, and the apertures from the wide-aperture end 10 to the narrow-aperture end 11 are gradually reduced, wherein the aperture of the wide-aperture end is d The ratio of ₁ to the aperture _d2 at the narrow aperture end is 1.2:1~4:1, and the corresponding fiber numerical aperture 3 at the wide aperture end or the acceptance angle of the fiber end face θ ₁ and the fiber numerical aperture 4 at the narrow aperture end or the acceptance angle of the fiber end face The ratio of θ ₂ is 1:1.2~1:4.

In some embodiments, the light receiving section 5, the wide aperture end 10 and the light output section 7 have the same aperture, and the aperture of the light output section 7 is larger than the narrow aperture end aperture d ₂ , when the light output section 7 passes through When the narrow-aperture end 11 is connected to the tapered section 6, under the condition of avoiding light reflection, the wall edge 13 of the narrow-aperture end and the wall edge 12 of the light output section have the same point of tangency, which means that the second central axis 9 and the first A central axis 8 is at a maximum distance apart.

In a preferred embodiment, the cross-sectional profile of the optical channel 2 is a polygonal structure, such as an octagon. In another preferred embodiment, a 10-100 psi forward stress (fiber stress) is applied to at least one of the light-receiving section 5, the tapered section 6 or the light output section 7, and the range of the force-applying section is 5mm or more, or bending the light-to-shape conversion element until the radius of curvature is less than 3 cm can also increase the stress by 10~50psi. The aforementioned preferred embodiments can increase the internal light disturbance and generate more modes, so that the output light energy distribution is more uniform.

In terms of laser energy distribution, Figure 3A shows the general laser energy distribution, the energy is concentrated in the center of the beam, and the energy gradually decreases radially toward the edge, showing a Gaussian distribution; on the contrary, Figure 3B shows the laser energy distribution of the present invention, the energy distribution It is relatively average, with low energy only near the edge, showing a flat-top distribution.

1: housing 2: light channel 3: fiber numerical aperture at wide aperture end 4: fiber numerical aperture at narrow aperture end 5: light receiving section 6: tapered section 7: light output section 8: first central axis 9: Second central axis 10: wide aperture end 11: narrow aperture end 12: wall edge of narrow aperture end 13: wall edge of light output section _d1 : wide aperture end aperture _d2 : narrow aperture end aperture L: tapered section Length θ ₁ : Acceptance angle of the fiber end face at the wide aperture end θ ₂ : Acceptance angle of the fiber end face at the narrow aperture end

Fig. 1 is a schematic diagram of the structure of the optical shape conversion optical fiber of the present invention.

Fig. 2 is a schematic diagram of the optical fiber structure of part of the light shape conversion element of the present invention.

3A and 3B are energy distribution diagrams of a Gaussian spot and a flat-hat spot, respectively.

1: Shell

2: Optical channel

5: Light receiving section

6: Conical section

7: Optical output section

8: The first central axis

9: Second central axis

12: Wall edge at narrow aperture end

13: Wall edge of light output section

d ₁ : Aperture diameter at wide aperture end

d ₂ : Aperture diameter of narrow aperture end

Claims (11)

A light shape conversion element, a housing defines an optical channel, the optical channel includes: a tapered section with a wide aperture end and a narrow aperture end, wherein the aperture ratio of the wide aperture end to the narrow aperture end is 1.2:1~4:1; and a light output section connected to the narrow aperture end of the tapered section; wherein the tapered section has a first central axis, and the light output section has a second The central axis, and the second central axis and the first central axis are parallel to each other and do not overlap. The optical shape conversion element as described in Claim 1, wherein the ratio of the numerical aperture (NA) of the fiber or the acceptance angle (θ) of the fiber end face of the wide aperture end to the narrow aperture end is 1:1.2~1:4. The light-shape conversion element according to claim 1, wherein the length of the tapered section is 3-25mm. The light shape conversion element as claimed in claim 1, wherein the wide aperture end and the light output section have the same aperture. The light shape conversion element as claimed in claim 1, wherein the aperture of the light output section is larger than the aperture of the narrow aperture end. The optical shape conversion element as claimed in claim 1, wherein the optical channel is a polygonal structure. The light-shape conversion element as claimed in claim 1, wherein the light channel has a radius of curvature, and the radius of curvature is less than 3 cm. The optical shape conversion element as claimed in item 1, wherein the light channel further includes a light receiving section connected to the wide aperture end of the tapered section, and the light receiving section and the tapered section have a the first central axis. The light-shape converting element as claimed in claim 8, wherein the light-receiving section and the wide-aperture end have the same aperture. A light-shape conversion method, comprising applying 10-100 psi positive stress to the housing of the light-shape conversion element as described in Claim 1. The light-shape conversion method as described in Claim 10, wherein the range of the section to which the positive stress is applied is more than 5mm.

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