CN213764516U - Telecentric lens for laser cutting processing - Google Patents

Abstract

The utility model provides a telecentric lens for laser cutting processing, include first lens, second lens, third lens, fourth lens and the fifth lens that sets gradually from the object space to the image space, first lens is biconcave negative lens, second lens, third lens and fourth lens are meniscus negative lens, the fifth lens is biconvex positive lens, and wherein first lens includes first incident end face and first emergent terminal surface, and the second lens includes second incident end face and second emergent terminal surface, and the third lens includes third incident end face and third emergent terminal surface, and the fourth lens includes fourth incident end face and fourth emergent terminal surface, and the fifth lens includes fifth incident end face and fifth emergent terminal surface. The utility model provides a there is not inclination before telecentric lens's image space chief ray and focal plane, can not lead to the hole skewness of processing, and processing object does not have out of focus before the perspective core telescope, can not form the distortion that leads to the machining precision to reduce.

Description

Telecentric lens for laser cutting processing

Technical Field

The utility model relates to a laser beam machining field especially relates to a telecentric lens for laser cutting processing.

Background

For the laser processing field, the fineness of the focusing spot has a great relationship with the wavelength of the laser and the focal length of the focusing lens, and the smaller the wavelength of the laser and the shorter the focal length of the focusing lens, the higher the fineness of the focusing spot. The main wave band of the current ultraviolet laser is 355nm, the technology is mature, and the power is improved all the time, so that the ultra-fine processing becomes possible.

However, in the current technical scheme, a common lens is mainly used for punching, so that a certain inclination angle exists between an image side chief ray and a focal plane, the existence of the inclination angle enables a certain inclination angle to exist in a machined hole, and an extra distortion is caused by defocusing existing before a machined object and the common lens, so that the machining precision is reduced.

Disclosure of Invention

To the above-mentioned defect of prior art, the utility model provides an aim at provides a telecentric lens for laser cutting processing forms telecentric lens through arranging a plurality of lenses, compares with ordinary camera lens, and this telecentric lens's image side chief ray does not have the inclination before with the focal plane, and there is the inclination in the hole that can not lead to processing, and the simultaneous processing object does not have out of focus before with the perspective core telescope, can not form the distortion that leads to the machining precision to reduce.

In order to achieve the above object, the present invention provides a telecentric lens for laser cutting processing, comprising a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged from an object space to an image space, wherein the first lens is a biconcave negative lens, the second lens is a meniscus negative lens, the third lens is a meniscus negative lens, the fourth lens is a meniscus negative lens, the fifth lens is a biconvex positive lens, the first lens comprises a first incident end surface and a first emergent end surface, the second lens comprises a second incident end surface and a second emergent end surface, the third lens comprises a third incident end surface and a third emergent end surface, the fourth lens comprises a fourth incident end surface and a fourth emergent end surface, the fifth lens comprises a fifth incident end surface and a fifth emergent end surface, the first incident end surface is a concave surface with a curvature radius of-53.725 mm, first emergence terminal surface is curvature radius 6873.918 mm's convex surface, second incident terminal surface is curvature radius-164.855 mm's concave surface, second emergence terminal surface is curvature radius-84.489 mm's convex surface, third incident terminal surface is curvature radius-4038.184 mm's convex surface, third emergence terminal surface is curvature radius-141.062 mm's convex surface, fourth incident terminal surface is curvature radius-453.138 mm's concave surface, fourth emergence terminal surface is curvature radius-173.782 mm's convex surface, fifth incident terminal surface is curvature radius 852.215 mm's convex surface, fifth emergence terminal surface is curvature radius-419.019 mm's convex surface.

Further, the center thickness of the first lens is 8.800mm, the center thickness of the second lens is 16.815mm, the center thickness of the third lens is 34.535mm, the center thickness of the fourth lens is 34.535mm, and the center thickness of the fifth lens is 32.830 mm.

Further, the distance between the first emergent end face and the second incident end face is larger than the distance between the second emergent end face and the third incident end face.

Further, the distance between the second emergent end surface and the third incident end surface is smaller than the distance between the third emergent end surface and the fourth incident end surface.

Further, the distance between the third emergent end surface and the fourth incident end surface is larger than the distance between the fourth emergent end surface and the fifth incident end surface.

Further, the focal length of the telecentric lens is 230mm, and the diameter of the entrance pupil is 12 mm.

Further, the first lens, the second lens, the third lens, the fourth lens and the fifth lens are all made of fused silica.

The utility model provides a beneficial effect that technical scheme brought is: a plurality of lenses are arranged to form a telecentric lens for replacing a common lens, the image space chief ray and the focal plane of the telecentric lens have no inclination angle, the processed hole has inclination, and the processed object and the telecentric lens have no defocusing phenomenon, so that the distortion and astigmatism which cause the reduction of the processing precision can not be formed.

Drawings

Fig. 1 is a schematic structural view of a telecentric lens for laser cutting processing according to the present invention.

Fig. 2 is a schematic view of an astigmatism curve of a telecentric lens for laser cutting processing according to the present invention.

Fig. 3 is a schematic diagram of a distortion curve of a telecentric lens for laser cutting processing according to the present invention.

Fig. 4 is a schematic diagram of a modulus transfer function MFT curve of a telecentric lens for laser cutting processing according to the present invention.

Fig. 5 is a schematic view of a dispersed light spot of a telecentric lens for laser cutting processing according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, embodiments of the present invention will be further described below with reference to the accompanying drawings.

Referring to fig. 1, an embodiment of the present invention provides a telecentric lens for laser cutting processing, including a first lens 1, a second lens 2, a third lens 3, a fourth lens 4 and a fifth lens 5 sequentially arranged from an object space to an image space, wherein the first lens 1 is a biconcave negative lens, the second lens 2 is a meniscus negative lens, the third lens 3 is a meniscus negative lens, the fourth lens 4 is a meniscus negative lens, the fifth lens 5 is a biconvex positive lens, the first lens includes a first incident end surface 11 and a first emergent end surface 12, the second lens 2 includes a second incident end surface 21 and a second emergent end surface 22, the third lens 3 includes a third incident end surface 31 and a third emergent end surface 32, the fourth lens 4 includes a fourth incident end surface 41 and a fourth emergent end surface 42, and the fifth lens 5 includes a fifth incident end surface 51 and a fifth emergent end surface 52.

In this embodiment, incident light propagates from left to right to the crossing point of each curved surface and principal optical axis is the standard, and when the centre of a circle of curved surface was located the crossing point left side of principal optical axis and curved surface, then radius of curvature was the negative value, when the centre of a circle of curved surface was located the crossing point right side of principal optical axis and curved surface, then radius of curvature was the positive value. That is, the positive and negative of the radius of curvature indicate the direction of curvature of the curved surface, and the magnitude of the radius of curvature indicates the degree of curvature of the curved surface. The first incident end face 11 is a concave face with a curvature radius of-53.725 mm, the first emergent end face 12 is a convex face with a curvature radius of 6873.918mm, the second incident end face 21 is a concave face with a curvature radius of-164.855 mm, the second emergent end face 22 is a convex face with a curvature radius of-84.489 mm, the third incident end face 31 is a convex face with a curvature radius of-4038.184 mm, the third emergent end face 32 is a convex face with a curvature radius of-141.062 mm, the fourth incident end face 41 is a concave face with a curvature radius of-453.138 mm, the fourth emergent end face 42 is a convex face with a curvature radius of-173.782 mm, the fifth incident end face 51 is a convex face with a curvature radius of 852.215mm, the fifth emergent end face 52 is a convex face with a curvature radius of-419.019 mm, and the allowable tolerance of the curvature radii of the first incident end face 11 to the fifth incident end face 51 and the first emergent end face 12 to the fifth emergent end face 52 are 10%, and the upper deviation is + 5%, the lower deviation was-5%.

In this embodiment, the distance between the first exit end face 12 and the second incident end face 21 is greater than the distance between the second exit end face 22 and the third incident end face 31, the distance between the second exit end face 22 and the third incident end face 31 is smaller than the distance between the third exit end face 32 and the fourth incident end face 41, and the distance between the third exit end face 32 and the fourth incident end face 41 is greater than the distance between the fourth exit end face 42 and the fifth incident end face 51.

The center thickness of the first lens 1 is 8.800mm, the center thickness of the second lens 2 is 16.815mm, the center thickness of the third lens 3 is 34.535mm, the center thickness of the fourth lens 4 is 34.535mm, and the center thickness of the fifth lens 5 is 32.830 mm; and the allowable tolerance of the central thickness of the first lens 1 to the fifth lens 5 is 10%, the upper deviation is + 5%, and the lower deviation is-5%.

In the present embodiment, the allowable tolerance of the refractive index and abbe ratio of the first lens 1 to the fifth lens 5 may be 10%, the upper deviation may be + 5%, the lower deviation may be-5%, and the first lens 1 to the fifth lens 5 may all be made of the same material, wherein the refractive index and abbe ratio of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 may all be 1.46/67.82 ± 5%. It is understood that the first lens 1, the second lens 2, the third lens 3, the fourth lens 4 and the fifth lens 5 are made of the same material, and the same refractive index and the same dispersion system (abbe number) are obtained by using the same material, so that the same ratio of the refractive index to the abbe number is obtained.

Because fused silica has advantages such as durable, high temperature resistant, radiation protection, it can be understood that first lens 1, second lens 2, third lens 3, fourth lens 4 and fifth lens 5 all adopt fused silica to make.

In this embodiment, the focal length F of the telecentric lens is 230mm, and the entrance pupil diameter is 12 mm.

The wavelength of incident light of the currently commonly used ultraviolet laser is λ 355nm, and theoretically, the resolution of the incident light with the wavelength of 355nm is three times larger than that of the incident light with the wavelength of 1064 nm. Since the materials of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4 and the fifth lens 5 in this embodiment may all be fused silica, the telecentric lens can be applied to an ultraviolet laser with a wavelength λ of 355nm, a very high resolution point distance can be obtained, that is, a hyperfine focused dispersed light spot can be obtained, and the telecentric lens is suitable for high power density due to the characteristics of the fused silica, and can be applied to a 20w ultraviolet laser. Further, the entrance pupil diameter is set to 12mm, so that the light flux per unit time can be ensured, and the telecentric lens can obtain a smaller volume.

As shown in fig. 1, the principle of the telecentric lens of the embodiment is as follows: incident light having a wavelength of 355nm is incident from the first incident end surface 11 of the first lens 1, the incident light reaching the first incident surface 11 is emitted from the first exit end surface 12 to the second incident end surface 21 after being expanded in the first lens 1, the light reaching the second incident end surface 21 is emitted from the second exit end surface 22 after being converged in the second lens 2, the light converged in the second lens 2 is incident from the third incident end surface 31 of the third lens 3 and is emitted from the third exit end surface 32 after being expanded in the third lens 3, the light converged in the third lens 3 is incident from the fourth incident end surface 41 of the fourth lens 4 and is emitted from the fourth exit end surface 42 after being converged in the fourth lens 4, the light converged in the fourth lens 4 is incident from the fifth incident end surface 51 of the fifth lens 5 and is emitted from the fifth exit end surface 52 after being converged in the fifth lens 5, and the principal light of an image formed by the light finally being refracted through the fifth exit end surface 52 of the fifth lens 5 can be perpendicular to the focal plane, the exit pupil can be positioned at the infinite distance of an object space, and the optical path is an image space telecentric optical path which can ensure that a processed hole is vertical to a processing plane, so that astigmatism and distortion are effectively corrected, and the processing precision is improved.

Referring to fig. 2 and fig. 3, fig. 2 is a graph of astigmatism of the telecentric lens of the present embodiment, and fig. 3 is a graph of distortion of the telecentric lens of the present embodiment. This embodiment provides a telecentric lens having the above-mentioned conditions, in which the degree of curvature of both the astigmatism curve and the distortion curve has reached the ideal correction state, the image plane is significantly flattened, that is, the image plane is very flat throughout the cutting range, and there is no significant difference on-axis from off-axis. The astigmatism and distortion are small, and the ultra-fine and high-precision machining can be achieved.

Referring to fig. 4, fig. 4 is a plot of the modulus transfer function MTF of the telecentric lens of the present embodiment. As can be seen from FIG. 4, the on-axis point and the off-axis point of the incident light after acting on the telecentric lens have no obvious difference, so that the purpose of leveling the image field can be achieved, and the hyperfine and high-precision processing can be realized.

Referring to fig. 5, fig. 5 is a schematic diagram of a dispersed light spot of the telecentric lens of the embodiment. As can be seen from fig. 5, in all the fields of view, the diameter of the dispersed light spot is about 5 μm, and the energy concentration ratio is extremely high, so that high-quality imaging marking is realized, the imaging quality is improved, and further, ultra-fine and high-precision processing, such as precise punching, cutting and the like, can be realized.

In this document, the terms front, back, upper and lower are used to define the components in the drawings and the positions of the components relative to each other, and are used for clarity and convenience of the technical solution. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.

The features of the embodiments and embodiments described herein above may be combined with each other without conflict.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. The utility model provides a telecentric lens for laser cutting processing, its characterized in that includes first lens, second lens, third lens, fourth lens and the fifth lens that set gradually from the object space to the image space, first lens is biconcave negative lens, second lens, third lens and fourth lens are meniscus negative lens, the fifth lens is biconvex positive lens, wherein first lens includes first incident end face and first emergent terminal surface, the second lens includes second incident end face and second emergent terminal surface, the third lens includes third incident end face and third emergent terminal surface, the fourth lens includes fourth incident end face and fourth emergent terminal surface, the fifth lens includes fifth incident end face and fifth emergent terminal surface, the radius of curvature of first incident end face to fifth incident end face is-53.725 mm, -164.855mm in proper order, -4038.184mm, -453.138mm, 852.215mm, the radius of curvature of the first to fifth exit face is 6873.918mm, -84.489mm, -141.062mm, -173.782mm, -419.019mm in sequence.

2. A telecentric lens for laser cutting processing according to claim 1, characterized in that: the center thickness of the first lens is 8.800mm, the center thickness of the second lens is 16.815mm, the center thickness of the third lens is 34.535mm, the center thickness of the fourth lens is 34.535mm, and the center thickness of the fifth lens is 32.830 mm.

3. A telecentric lens for laser cutting processing according to claim 1, characterized in that: the distance between the first emergent end face and the second incident end face is larger than the distance between the second emergent end face and the third incident end face.

4. A telecentric lens for laser cutting processing according to claim 1, characterized in that: and the distance between the second emergent end surface and the third incident end surface is smaller than the distance between the third emergent end surface and the fourth incident end surface.

5. A telecentric lens for laser cutting processing according to claim 1, wherein: and the distance between the third emergent end surface and the fourth incident end surface is greater than the distance between the fourth emergent end surface and the fifth incident end surface.

6. A telecentric lens for laser cutting processing according to claim 1, characterized in that: the focal length of the telecentric lens is 230mm, and the diameter of the entrance pupil is 12 mm.

Images