WO2022142250A1

WO2022142250A1 - Objective lens for correcting distribution state of optical focus points in beam propagation direction

Info

Publication number: WO2022142250A1
Application number: PCT/CN2021/104867
Authority: WO
Inventors: 王雪辉; 温彬; 李曾卓; 王建刚
Original assignee: 武汉华工激光工程有限责任公司
Priority date: 2020-12-30
Filing date: 2021-07-07
Publication date: 2022-07-07
Also published as: CN112305726A; CN112305726B

Abstract

An objective lens for correcting the distribution state of optical focus points in a beam propagation direction. The objective lens comprises a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), a sixth lens (6) and a seventh lens (7), which are sequentially arranged in an incident beam direction, wherein a biconcave lens is used as the first lens (1); a plano-convex lens is used as the second lens (2); a biconvex lens is used as the third lens (3); a convex-plano lens is used as the fourth lens (4); a meniscus lens is used as the fifth lens (5) and the sixth lens (6); and a plano-plano lens is used as the seventh lens (7). The designed objective lens can correct the distribution state of the optical focus points in the beam propagation direction, so as to make light spot energy and the energy concentration of focused light spots at different positions consistent, thereby ensuring the processing precision.

Description

Objective lens for correcting the distribution of optical focus points along the beam propagation direction

technical field

The invention relates to the technical field of ultrafast laser processing, in particular to an objective lens for correcting the distribution state of optical focus points along the beam propagation direction.

Background technique

Glass cutting, wafer hidden cutting, etc. are hot technologies in the industrial field. These cutting technologies require that the section after cutting must be clean and do not require subsequent processing; and the cutting materials are generally relatively fragile, and local changes of materials will also occur during processing. Weak, requiring that laser cracks must be created along the entire depth of the glass sheet. Therefore, considering factors such as timeliness, it is hoped that the formed beam can be distributed in the entire cutting direction, such as a slender Bessel beam, a laser filament beam, or a multifocal distribution based on diffraction theory. In order to maximize the processing, it is necessary to process the entire glass thickness so that the energy density of the beam and the distribution of the beam spot are consistent, but since the required beam spot diameter is very small, the focused spot diameter d = 2*M according to the formula ² *λ/(π*NA), where M ² is the beam quality factor and λ is the laser wavelength, then the required numerical aperture NA of the focusing mirror is very large, therefore, the focus distributed outside the refracting focus of the focusing mirror Due to the influence of aberrations, the light spot distribution and the energy density distribution will deteriorate, as shown in Figure 1.

It can be seen from Figure 1 that the multifocal shaping lens forms different numbers of focal points along the propagation direction of the beam after passing through the focusing lens. Then, due to the different focusing angles of the focusing points, the distribution of the focusing points and the energy concentration will be deteriorated. Since the refraction focus is placed at the center position, the distribution of the light spots is basically symmetrical, and the trend deteriorates, as shown in the dotted line box in Figure 1. The distribution of light spots; if the focus of refraction is placed on the top of multiple foci, the last focus will deteriorate the most, as shown in the distribution of light spots outside the dotted box in Figure 1. In the same way, this phenomenon will occur in other ways of distribution along the Z direction, and it will seriously affect the processing accuracy, and even cause the final device to be unavailable.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides an objective lens for correcting the distribution state of optical focusing points along the beam propagation direction, which can make the spot distribution and energy concentration of focusing spots at different positions consistent.

The present invention is achieved through the following technical solutions:

The objective lens for correcting the distribution of optical focal points along the beam propagation direction, including the first mirror, the second mirror, the third mirror, the fourth mirror, the fifth mirror, the sixth mirror and the seventh mirror arranged in sequence along the direction of the incident beam ; The first mirror adopts a biconcave lens, the second mirror adopts a plano-convex lens, the third mirror adopts a biconvex lens, the fourth mirror adopts a convex-planar lens, and both the fifth mirror and the sixth mirror adopt a curved lens A lunar lens, the seventh lens adopts a flat lens.

In the above technical solution, the object-side focal points of different image-side focal points are placed at different object-distance positions, and the infinite-distance object-side distance position can be located at the object side of the central focus of the entire distribution of the multiple focal points, or can be placed at the first focal point. position or the position of the last focus; then set different image distances to match different object distances, each focus position corresponds to the angle of a beam, that is, the numerical aperture value; based on the aforementioned principles, seven groups of lenses are designed. The objective lens can correct the distribution state of the optical focusing points along the beam propagation direction, so that the spot energy and energy concentration of the focusing spots at different positions are consistent, and the processing accuracy is guaranteed.

Further, the first mirror, the second mirror, the third mirror, the fourth mirror, the fifth mirror, the sixth mirror and the seventh mirror are coaxially arranged in sequence along the laser beam propagation direction and along the horizontal direction.

Further, the first lens includes two curved surfaces S1 and S2, the curvature radius of the curved surface S1 is R1=-29.6±10%mm, and the curvature radius of the curved surface S2 is R2=18.3±10%mm; the first The center thickness of a lens is 2±10% mm.

Further, the second lens includes a flat surface S3 and a curved surface S4, and the curvature radius R4 of the curved surface S4 is -29.0±10% mm; the center thickness of the second lens is 5±10% mm.

Further, the third lens includes two curved surfaces S5 and S6, the curvature radius of the curved surface S5 is R5=59.0±10%mm, and the curvature radius of the curved surface S6 is R6=-197.8±10%mm; the first The center thickness of the three lenses is 5±10% mm.

Further, the fourth lens includes a curved surface S7 and a flat surface S8, and the curvature radius R7 of the curved surface S7 is 33.2±10% mm; the center thickness of the fourth lens is 5±10% mm.

Further, the fifth lens includes two curved surfaces S9 and S10, the curvature radius of the curved surface S9 is R9=21±10% mm, and the curvature radius of the curved surface S10 is R10=33±10% mm; the fifth The center thickness of the lens is 4.33±10% mm.

Further, the sixth lens includes two curved surfaces S11 and S12, the curvature radius R11 of the curved surface S11 is 13±10% mm, and the curvature radius R12 of the curved surface S12 is 14±10% mm; the sixth The center thickness of the lens is 4.4±10% mm.

Further, the seventh lens includes two planes S13 and S14, and the center thickness of the seventh lens is 2±10% mm.

Further, the distance between the first mirror and the second mirror is 24.92mm, the distance between the second mirror and the third mirror is 10mm, the distance between the third mirror and the fourth mirror is 1.56mm, and the first mirror The distance between the fourth mirror and the fifth mirror is 0.2mm, the distance between the fifth mirror and the sixth mirror is 0.2mm, and the distance between the sixth mirror and the seventh mirror is 2.657mm.

Compared with the prior art, the beneficial effect of the present invention is that: the present invention places the object-side focal points of different image-side focal points at positions of different object distances, and the position of infinite object distance can be located at the center of the entire distribution of the multiple focal points. The object side can also be placed at the position of the first focus or the position of the last focus; then set different image distances to match different object distances, each focus position corresponds to the angle of a beam, that is, the numerical aperture value; based on the aforementioned principles Seven groups of lenses are designed, and the designed objective lens can correct the distribution of optical focusing points along the beam propagation direction, so that the spot energy and energy concentration of the focusing spots at different positions are consistent, and the processing accuracy is guaranteed.

Description of drawings

FIG. 1 is an effect diagram of light spot distribution in the prior art.

FIG. 2 is a relationship diagram of object distance and image distance according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of an objective lens according to an embodiment of the present invention.

FIG. 4 is an effect diagram of light spot distribution along the Z direction according to an embodiment of the present invention.

In the figure: 1, the first lens; 2, the second lens; 3, the third lens; 4, the fourth lens; 5, the fifth lens; 6, the sixth lens; 7, the seventh lens.

Detailed ways

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

In the description of the present invention, it should be understood that the terms "first" and "second" are only used for description purposes, and cannot be interpreted as indicating or implying relative importance or the number of indicated technical features. Thus, features defined as "first", "second" may expressly or implicitly include one or more of said features. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; it can be a mechanical connection, an electrical connection or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction of two elements relation. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

The present invention provides a special objective lens for correcting the distribution state of optical focal points along the beam propagation direction. The object focal points of different image focal points are placed at different object distance positions, and the infinite object distance position can be located in multiple focal points. The object side of the central focus of the entire distribution can also be placed at the position of the first focus or the position of the last focus, and then set different image distances to match different object distances. Each focus position corresponds to the angle of a beam, that is, the value Aperture value, the numerical aperture angle value of each focal point cannot be higher than the limit value of the numerical aperture angle of the lens itself. This objective is suitable for different laser wavelengths.

Different image distance settings correspond to different object distances, and the corresponding relationship is: x*x'=-f ² , as shown in Figure 2, x is the distance from the focal position of the refracting lens to the object point, and x' is the distance refraction The image distance value of the focal position of the lens, f is the object focal length of the focusing objective.

As shown in FIG. 3, the objective lens of the present invention includes a first mirror 1, a second mirror 2, a third mirror 3, a fourth mirror 4, a fifth mirror 5, a sixth mirror 6 and a seventh mirror 7 arranged in sequence along the incident beam direction. ; The first mirror 1 adopts a biconcave lens, the second mirror 2 adopts a plano-convex lens, the third mirror 3 adopts a biconvex lens, the fourth mirror 4 adopts a convex-planar lens, the fifth mirror 5 and the first mirror The six mirrors 6 are all meniscus lenses, and the seventh mirror 7 is a flat lens. The first mirror 1, the second mirror 2, the third mirror 3, the fourth mirror 4, the fifth mirror 5, the sixth mirror 6 and the seventh mirror 7 are coaxially arranged in turn along the laser beam propagation direction and the horizontal direction. . After the incident light beam is shaped by the objective lens of the present invention, the distribution state of the optical focus points along the beam propagation direction can be corrected, so that the light spot energy and energy concentration of the focused light spots at different positions are consistent, and the processing accuracy is ensured.

The distance d ₁₂ between the first mirror 1 and the second mirror 2 is 24.92mm, the distance d ₂₃ between the second mirror 2 and the third mirror 3 is 10mm, and the distance between the third mirror 3 and the fourth mirror 4 d ₃₄ is 1.56mm, the distance d ₄₅ between the fourth mirror 4 and the fifth mirror 5 is 0.2mm, the distance d ₅₆ between the fifth mirror 5 and the sixth mirror 6 is 0.2mm, and the sixth mirror 6 The distance d ₆₇ from the seventh mirror 7 is 2.657 mm.

The first lens 1 includes two curved surfaces S1 and S2, the curvature radius of the curved surface S1 is R1=-29.6±10%mm, and the curvature radius of the curved surface S2 is R2=18.3±10%mm; the first lens The central thickness d ₁ of 1 is 2±10% mm; material Nd (refractive index)=1.51637, Vd (Abbé number)=64.1160.

The second lens 2 includes a flat surface S3 and a curved surface S4, the curvature radius R4 of the curved surface S4=-29.0±10%mm; the central thickness d2 of the second lens ₂ is 5+10%mm; the material Nd ( Refractive index) = 1.51637, Vd (Abbé number) = 64.1160.

The third lens 3 includes two curved surfaces S5 and S6, the curvature radius of the curved surface S5 is R5=59.0±10%mm, and the curvature radius of the curved surface S6 is R6=-197.8±10%mm; the third lens The central thickness d ₃ of 3 is 5+10% mm; material Nd (refractive index) = 1.51637, Vd (Abbé number) = 64.1160.

The fourth lens 4 includes a curved surface S7 and a flat surface S8, the curvature radius R7 of the curved surface S7=33.2±10%mm; the center thickness d4 of the fourth lens ₄ is 5±10%mm; the material Nd (refractive rate) = 1.51637, Vd (Abbé number) = 64.1160.

The fifth lens 5 includes two curved surfaces S9 and S10, the curvature radius of the curved surface S9 is R9=21±10% mm, and the curvature radius of the curved surface S10 is R10=33±10% mm; the fifth lens 5 The central thickness d5 of 4.33+ ₁₀ % mm; material Nd (refractive index)=1.51637, Vd (Abbé number)=64.1160.

The sixth lens 6 includes two curved surfaces S11 and S12, the curvature radius R11 of the curved surface S11 is 13±10% mm, and the curvature radius R12 of the curved surface S12 is 14±10% mm; the sixth lens 6 The central thickness d6 of 4.4+ ₁₀ % mm; material Nd (refractive index)=1.51637, Vd (Abbé number)=64.1160.

The seventh lens 7 includes two planes S13 and S14, and the central thickness d7 of the seventh lens ₇ is 2+10% mm; material Nd (refractive index)=1.51637, Vd (Abbé number)=64.1160.

Example

In this embodiment, the objective lens for correcting the distribution of optical focus points along the beam propagation direction includes biconcave lenses, plano-convex lenses, biconvex lenses, convex-plano lenses, meniscus lenses, curved For the moon lens and the flat-planar lens, after the incident light is shaped by the objective lens of this embodiment, the spot distribution and energy concentration of the focusing spots at different positions are consistent. The effect of the spot distribution along the Z direction is shown in Figure 3. It can be seen that the spot size of the focused spot at different positions is the same, the energy concentration of the spot is the same, and the distribution state of the spot is the same.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or some or all of the technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

The objective lens for correcting the distribution state of optical focal points along the beam propagation direction is characterized in that it includes a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror, and a sixth mirror arranged in sequence along the direction of the incident beam and the seventh mirror; the first mirror adopts a biconcave lens, the second mirror adopts a plano-convex lens, the third mirror adopts a biconvex lens, the fourth mirror adopts a convex-plano lens, the fifth mirror and the sixth mirror The lenses are all meniscus lenses, and the seventh lens is a flat lens.
The objective lens for correcting the distribution of optical focus points along the beam propagation direction according to claim 1, wherein the first lens comprises two curved surfaces S1 and S2, and the curvature radius of the curved surface S1 is R1=-29.6 ±10% mm, the curvature radius R2 of the curved surface S2 is 18.3 ± 10% mm; the center thickness of the first lens is 2 ± 10% mm.
The objective lens for correcting the distribution of optical focus points along the beam propagation direction according to claim 1, wherein the second lens comprises a plane S3 and a curved surface S4, and the curvature radius of the curved surface S4 is R4=-29.0±29.0± 10%mm; the center thickness of the second lens is 5±10%mm.
The objective lens for correcting the distribution state of optical focal points along the beam propagation direction according to claim 1, wherein the third lens comprises two curved surfaces S5 and S6, and the curvature radius of the curved surface S5 is R5=59.0± 10%mm, the curvature radius R6 of the curved surface S6=-197.8±10%mm; the center thickness of the third lens is 5±10%mm.
The objective lens for correcting the distribution state of optical focal points along the beam propagation direction according to claim 1, wherein the fourth lens comprises a curved surface S7 and a flat surface S8, and the curvature radius of the curved surface S7 is R7=33.2±10 %mm; the center thickness of the fourth lens is 5±10%mm.
The objective lens for correcting the distribution state of optical focal points along the beam propagation direction according to claim 1, wherein the fifth lens comprises two curved surfaces S9 and S10, and the curvature radius of the curved surface S9 is R9=21± 10% mm, the curvature radius R10 of the curved surface S10 = 33±10% mm; the central thickness of the fifth lens is 4.33±10% mm.
The objective lens for correcting the distribution state of optical focal points along the beam propagation direction according to claim 1, wherein the sixth lens comprises two curved surfaces S11 and S12, and the curvature radius of the curved surface S11 is R11=13± 10% mm, the curvature radius R12 of the curved surface S12 is 14±10% mm; the center thickness of the sixth lens is 4.4±10% mm.
The objective lens for correcting the distribution state of optical focal points along the beam propagation direction according to claim 1, wherein the seventh lens includes two planes S13 and S14, and the center thickness of the seventh lens is 2± 10% mm.
The objective lens for correcting the distribution state of optical focal points along the beam propagation direction according to any one of claims 1 to 8, wherein the distance between the first mirror and the second mirror is 24.92 mm, and the first mirror is 24.92 mm. The distance between the second mirror and the third mirror is 10mm, the distance between the third mirror and the fourth mirror is 1.56mm, the distance between the fourth mirror and the fifth mirror is 0.2mm, the fifth mirror and the sixth mirror The distance between the sixth mirror and the seventh mirror is 0.2mm, and the distance between the sixth mirror and the seventh mirror is 2.657mm.