CN112292627A

CN112292627A - Telecentric lens and laser processing equipment

Info

Publication number: CN112292627A
Application number: CN201880094741.7A
Authority: CN
Inventors: 陈玉庆; 周朝明; 彭金明; 高云峰
Original assignee: Han s Laser Technology Industry Group Co Ltd
Current assignee: Han s Laser Technology Industry Group Co Ltd
Priority date: 2018-07-11
Filing date: 2018-07-11
Publication date: 2021-01-29
Anticipated expiration: 2038-07-11
Also published as: WO2020010538A1; CN112292627B

Abstract

The utility model provides a telecentric lens for ultraviolet laser, includes the first lens, the second lens, the third lens, the fourth lens and the fifth lens that arrange in proper order along the incident direction of light, the first lens is biconcave negative lens, the second lens is the falcate negative lens, the third lens is the falcate positive lens, the fourth lens is plano-convex positive lens, the fifth lens is the plano-convex positive lens, telecentric lens's focal length is 254mm, the tolerance is 10%, the upper deviation is + 5%, the lower deviation is-5%, the angle of vision is 42.

Description

Telecentric lens and laser processing equipment

Technical Field

The invention relates to the technical field of optical lenses, in particular to a telecentric lens and laser processing equipment.

Background

The rapid development of the ultraviolet laser in recent years has been from 0.2w to 0.5w at the beginning to the laser power density higher than 10w at present. Due to the improvement of the power of the laser, the application field of the ultraviolet laser not only stays on the product mark, but also is widely applied in the fields of wafer cutting, flexible circuit board cutting, thin plate cutting and the like.

However, the telecentric lens for the high-power ultraviolet laser at present cannot meet the application of a large focal length range, so that the scanning range is small and the processing efficiency is low.

Disclosure of Invention

In view of the foregoing, it is desirable to provide a telecentric lens and a laser processing apparatus with a larger focal length.

The utility model provides a telecentric lens for ultraviolet laser, includes first lens, second lens, third lens, fourth lens and the fifth lens that the incident direction of following light arranged in proper order, first lens is biconcave negative lens, the second lens is meniscus negative lens, the third lens is the positive lens of meniscus, the fourth lens is plano-convex positive lens, the fifth lens is plano-convex positive lens, telecentric lens's focus is 254mm, and the tolerance is 10%, and the upper deviation is + 5%, and the lower deviation is-5%, and the angle of vision is 42.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a telecentric lens system in one embodiment;

FIG. 2 is a graph of the geometric aberration of a telecentric lens in one embodiment;

FIG. 3 is a distortion plot of a telecentric lens in one embodiment;

FIG. 4 is a graph of the optical transfer function O.T.F of a telecentric lens in one embodiment;

FIG. 5 is an M.T.F. plot of the transfer function of a telecentric lens in one embodiment;

FIG. 6 is a schematic diagram of a diffuse spot of a telecentric lens in one embodiment;

FIG. 7 is a schematic diagram of the energy concentration of a telecentric lens in one embodiment.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "inner", "outer", "left", "right" and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

It should be noted that, when light travels from left to right, the curvature radius is negative with respect to the intersection point of the spherical surface and the main optical axis, and the center of the spherical surface is left at this point. Conversely, if the center of the sphere is to the right of the point, the radius of curvature is positive. In addition, in this document, incident light propagates from left to right, and the object side is located on the left side of the lens, and the image side is located on the right side of the lens.

As shown in fig. 1, a telecentric lens 100 comprises a first lens 10, a second lens 20, a third lens 30, a fourth lens 40 and a fifth lens 50 which are sequentially arranged along the incident direction of light rays, wherein the first lens 10 is a double-concave negative lens, the second lens 20 is a meniscus negative lens, the third lens 30 is a meniscus positive lens, the fourth lens 40 is a plano-convex positive lens, the fifth lens 50 is a plano-convex positive lens, the focal length of the telecentric lens 100 is 254mm, the allowable tolerance is 10%, the upper deviation is + 5%, the lower deviation is-5%, and the field angle is 42 °.

To obtain a larger processing area, the scan field of view of telecentric lens 100 needs to be increased. The focal length of the telecentric lens 100 is designed to be 254mm, the field angle is 42 degrees, and under the condition that a processing object or a workbench is not moved, the scanning field range of the telecentric lens 100 reaches 120mm to 120mm, so that the requirement of a processing area with a larger breadth can be met, and the production efficiency is effectively improved.

According to the telecentric lens 100, due to the design of the shapes and relative positions of the first lens 10, the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50, astigmatism and distortion are effectively corrected, the energy concentration ratio is high, a telecentric light path at a large focal length stage is realized, high-quality imaging marking can be realized, and the imaging quality is improved. And the lens has simple structure and convenient design, and is suitable for being widely applied to various laser processing devices.

The light rays pass through the telecentric lens 100 to obtain an image space telecentric light path, and the telecentric degree of the telecentric lens 100 is less than 5 degrees. When the non-telecentric lens is used for punching, a certain inclination angle is formed between the image side chief ray and the focal plane, so that the machined hole has a certain inclination. In addition, when the object to be processed and the non-telecentric lens have a certain defocus, additional distortion is caused, and the processing precision is reduced. The telecentric lens 100 of the invention is specially designed, so that the exit pupil is at infinity in the image space, the chief ray of the focused light beam is perpendicular to the focal plane under the condition of any field angle, the perforation inclination can be avoided, the distortion caused by slight defocusing of the processed object is reduced, and the processing precision is ensured.

The wavelength of the incident beam of telecentric lens 100 is 355 nm.

According to the judgment of the Airy Disk (Airy Disk judgment), the theoretical resolution distance of the dispersed light spot after laser focusing is as follows:

d＝2.44λf/D

wherein: d is the diameter of the airy disk (i.e., the focused dispersed light spot);

λ is the laser wavelength of the processing beam;

f is the focal length of telecentric lens 100;

d is the entrance pupil diameter of telecentric lens 100.

From the above, cutting with an ultra-short wavelength laser beam results in a finer kerf. The wavelength λ of the currently commonly used uv laser is 355nm, and its resolution is theoretically three times larger than that of a laser with a wavelength of 1064 nm. Because the materials of the first lens 10, the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50 of the telecentric lens 100 are all fused quartz, the telecentric lens 100 can be applied to a laser λ of an ultraviolet band which is 355nm, and a high-resolution point distance can be obtained, that is, a hyperfine focused dispersion light spot can be obtained, and the telecentric lens is suitable for high power density and can be applied to a 20w ultraviolet laser.

The entrance pupil diameter of the telecentric lens 100 is 16mm, which can effectively increase the light flux amount in unit time, so that the telecentric lens 100 has the advantage of large aperture, thereby enhancing the imaging effect in dark environment while reducing the aberration of the marginal field.

The first lens 10 is composed of a first curved surface 11 and a second curved surface 12, the second lens 20 is composed of a third curved surface 21 and a fourth curved surface 22, the third lens 30 is composed of a fifth curved surface 31 and a sixth curved surface 32, the fourth lens 40 is composed of a seventh curved surface 41 and an eighth curved surface 42, the fifth lens 50 is composed of a ninth curved surface 51 and a tenth curved surface 52, wherein the first curved surface 11 to the tenth curved surface 52 are sequentially arranged along the direction of incident light, the curvature radius of the first curved surface 11 is-355.5 + -5% mm, the curvature radius of the second curved surface 12 is 272.5 + -5% mm, the curvature radius of the third curved surface 21 is-46.25 + -5% mm, the curvature radius of the fourth curved surface 22 is-59.5 + -5% mm, the curvature radius of the fifth curved surface 31 is-75 + -5% mm, the curvature radius of the sixth curved surface 32 is-75.5 + -5% mm, the curvature radius of the seventh curved surface 41 is infinity, the radius of curvature of the eighth curved surface 42 is-128.5 + -5% mm, the radius of curvature of the ninth curved surface 51 is 252.5 + -5% mm, and the radius of curvature of the tenth curved surface 52 is infinity.

The center thickness d1 of the first lens 10 on the optical axis is 4.5 + -5% mm, the center thickness d2 of the second lens 20 on the optical axis is 14 + -5% mm, the center thickness d3 of the third lens 30 on the optical axis is 14 + -5% mm, the center thickness d4 of the fourth lens 40 on the optical axis is 20 + -5% mm, and the center thickness d5 of the fifth lens 50 on the optical axis is 13 + -5% mm.

The distance S1 between the second curved surface 12 and the third curved surface 21 on the optical axis is 23 + -5%, the distance S2 between the fourth curved surface 22 and the fifth curved surface 31 on the optical axis is 0.5 + -5%, the distance S3 between the sixth curved surface 32 and the seventh curved surface 41 on the optical axis is 0.5 + -5%, and the distance S4 between the eighth curved surface 42 and the ninth curved surface 51 on the optical axis is 0.5 + -5%.

The proportion of the refractive index to the Abbe number of the first lens 10 is 1.4585/67.82 +/-5%, the proportion of the refractive index to the Abbe number of the second lens 20 is 1.4585/67.82 +/-5%, the proportion of the refractive index to the Abbe number of the third lens 30 is 1.4585/67.82 +/-5%, the proportion of the refractive index to the Abbe number of the fourth lens 40 is 1.4585/67.82 +/-5%, and the proportion of the refractive index to the Abbe number of the fifth lens 50 is 1.4585/67.82 +/-5%.

In one embodiment, the structural parameters of telecentric lens 100 are as follows:

as can be seen from fig. 2 and 3, the astigmatism and curvature of the telecentric lens 100 have reached the ideal correction state, and the image plane is significantly flattened. That is, the image plane in the whole cutting range is very flat, and no obvious difference exists between the on-axis and the off-axis. The astigmatism is small, and high-precision processing can be met.

Fig. 4 and 5 show an optical transfer function o.t.f and a transfer function m.t.f of the ultraviolet laser telecentric lens 100, respectively. Therefore, it can be seen that there is no obvious difference between the on-axis point and the off-axis point of the telecentric lens 100 for ultraviolet laser, and the purpose of image field flattening is achieved.

Fig. 6 and 7 show the diffuse spot and the energy concentration of the telecentric lens 100 for ultraviolet laser. The size of the diffuse spot is controlled to be about 10 μm in all the fields of view. "energy concentration" also means that all energy of cleavage is concentrated around 10 μm. The energy concentration is extremely high so that marking or cutting can be performed accurately.

A laser processing apparatus includes an ultraviolet laser and a telecentric lens 100 for focusing the ultraviolet laser. The laser processing equipment can be a laser drilling machine, a laser marking machine or a laser cutting machine.

The light emitting wavelength of the ultraviolet laser is 355nm, and the power of the ultraviolet laser is equal to or more than 20W. The laser processing equipment further comprises a beam expander, an X galvanometer and a Y galvanometer, wherein laser emitted by the ultraviolet laser sequentially passes through the beam expander, the X galvanometer and the Y galvanometer and is finally focused on an image surface through the telecentric lens 100. The scanning field range of the telecentric lens 100 reaches 120mm to 120mm, the requirement of a processing area with a large breadth can be met, and the production efficiency is effectively improved. Further, the principal ray from the telecentric lens 100 to each view field direction is perpendicular to the image plane, so that the perforation inclination is avoided, and meanwhile, the distortion caused by slight defocusing of a processed object can be avoided, so that the processing precision is ensured. Meanwhile, because the astigmatism of the telecentric lens 100 is small, the severe change of the processing shape caused by slight defocusing or inclination of the processing object can be avoided.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

The utility model provides a telecentric lens for ultraviolet laser, includes first lens, second lens, third lens, fourth lens and the fifth lens that the incident direction of following light arranged in proper order, first lens is biconcave negative lens, the second lens is meniscus negative lens, the third lens is the positive lens of meniscus, the fourth lens is plano-convex positive lens, the fifth lens is plano-convex positive lens, telecentric lens's focus is 254mm, and the tolerance is 10%, and the upper deviation is + 5%, and the lower deviation is-5%, and the angle of vision is 42.
A telecentric lens according to claim 1, wherein the first lens is composed of a first curved surface and a second curved surface, the second lens is composed of a third curved surface and a fourth curved surface, the third lens is composed of a fifth curved surface and a sixth curved surface, the fourth lens is composed of a seventh curved surface and an eighth curved surface, and the fifth lens is composed of a ninth curved surface and a tenth curved surface, wherein the first curved surface to the tenth curved surface are arranged in sequence along the direction of the incident light, the radii of curvature of the first curved surface to the tenth curved surface are-355.5 mm, 272.5mm, -46.25mm, -59.5mm, -75mm, -75.5mm, infinity, -128.5mm, 252.5mm, infinity, an allowable tolerance is 10%, an upper deviation is + 5%, and a lower deviation is-5%.
A telecentric lens according to claim 2, wherein the distance between the second curved surface and the third curved surface on the optical axis is 23 ± 5% mm, the distance between the fourth curved surface and the fifth curved surface on the optical axis is 0.5 ± 5% mm, the distance between the sixth curved surface and the seventh curved surface on the optical axis is 0.5 ± 5% mm, and the distance between the eighth curved surface and the ninth curved surface on the optical axis is 0.5 ± 5% mm in this order.
A telecentric lens according to claim 1, wherein the central thicknesses of the first to fifth lenses on the optical axis are respectively 4.5mm, 14mm, 20mm, 13mm, the allowable tolerance is 10%, the upper deviation is + 5%, and the lower deviation is-5%.
A telecentric lens according to claim 1, wherein the first lens, the second lens, the third lens, the fourth lens and the fifth lens have a refractive index to abbe number ratio of 1.4585/67.82, with a tolerance of 10%, an upper deviation of + 5% and a lower deviation of-5%.
A telecentric lens according to claim 1, wherein the telecentric lens has an entrance pupil diameter of 16 mm.
A telecentric lens as recited in claim 1, wherein the rays pass through the telecentric lens to obtain an image-side telecentric beam path, and wherein the telecentric degree of the telecentric lens is less than 5 °.
A telecentric lens as recited in claim 1, wherein the wavelength of the incident beam of the telecentric lens is 355 nm.
A telecentric lens according to claim 1, wherein the materials of the first lens, the second lens, the third lens, the fourth lens and the fifth lens are fused silica.
A laser machining apparatus comprising a telecentric lens according to any one of claims 1 to 9.