阅读说明：本技术 光造型装置用光学系统 (Optical system for optical modeling apparatus ) 是由 大岛英司 铃木久则 于 2021-02-26 设计创作，主要内容包括：提供一种能够通过光造型装置进行高精度的造型的光造型装置用光学系统。光造型装置用光学系统(10)具有：光源(11),光扫描部(16),使从光源(11)出射的光反射并朝向造型面(IM)扫描,以及聚光透镜(17),配置在光扫描部(16)与造型面(IM)之间,将由光扫描部(16)反射的光聚光。在将聚光透镜(17)的焦点距离设为f,将聚光透镜(17)的造型面(IM)侧的面的最大有效直径上的法线角设为A时,光造型装置用光学系统(10)满足以下的条件式：f≤25mm,0.3＜cos(A)。(Provided is an optical system for an optical modeling device, which can perform modeling with high precision by the optical modeling device. An optical system (10) for an optical modeling device comprises: the light source (11), the light scanning unit (16), make the light that is sent out from the light source (11) reflect and scan towards the moulding surface (IM), and the condenser lens (17), dispose between light scanning unit (16) and moulding surface (IM), condense the light reflected by the light scanning unit (16). When the focal length of a condenser lens (17) is f and a normal angle on the maximum effective diameter of a surface on the modeling surface (IM) side of the condenser lens (17) is A, an optical system (10) for an optical modeling device satisfies the following conditional expression: f is less than or equal to 25mm, and cos (A) is more than 0.3.)

1. An optical system for a light shaping apparatus, comprising:

a light source for emitting light from a light source,

a light scanning unit for reflecting the light emitted from the light source and scanning the light toward the modeling surface, an

A condensing lens disposed between the light scanning unit and the molding surface, and condensing the light reflected by the light scanning unit;

when the focal length of the condenser lens is f and a normal angle on the maximum effective diameter of the surface of the condenser lens on the molding surface side is a, the following formula is satisfied:

f≤25mm，

0.3＜cos(A)。

2. the optical system for a light shaping apparatus according to claim 1,

the condenser lens is a double-convex lens,

when the curvature radius of the surface of the condenser lens on the light scanning unit side is R1 and the curvature radius of the surface of the condenser lens on the shaping surface side is R2, the following formula is satisfied:

1.0≤|R1/R2|。

3. the optical system for a light shaping apparatus according to claim 1 or 2,

a beam shaping unit is further provided between the light source and the light scanning section,

the beam shaping unit diffuses light in the short axis direction on the emission side so as to satisfy the following equation, where Da represents the length of the short axis and Db represents the length of the long axis in the cross section of the light beam incident from the light source,

0.9＜Da/Db＜1.2。

4. the optical system for a light shaping apparatus according to claim 3,

the beam shaping unit has a concave surface formed along the long axis on an incident side of the light emitted from the light source, and has a convex surface formed along the long axis on an emission side.

Technical Field

The present invention relates to an optical system for a light shaping apparatus, which is preferably mounted in a light shaping apparatus for shaping a light-curable resin into a desired shape by curing the resin using light emitted from a light source such as a laser light source or an LED light source.

Background

A so-called 3D printer, which is an additive manufacturing technique for the purpose of producing a large number of products in a small amount, shortening a trial production period, reducing development costs, and the like, has attracted attention. The 3D printer can model a three-dimensional object by attaching a material based on a cross-sectional shape of three-dimensional data made by CAD or the like as a design drawing. There are various ways to model a 3D printer. Among them, the liquid tank Photopolymerization (photo-molding) in which a photocurable resin is selectively cured by light such as laser light to perform molding can realize fine and highly precise molding.

As a 3D printer using an optical modeling method, for example, an optical modeling device described in patent document 1 is known. The optical system mounted in the optical modeling apparatus includes a light source, a light intensity modulator, a beam expander, a condenser lens, and 2 Galvanometer mirrors (Galvanometer mirror). Light emitted from the light source sequentially passes through the light intensity modulator, the beam expander and the condenser lens and enters the galvanometer mirror. The galvanometer mirrors each have a mirror and an actuator, and the mirrors rotate in mutually orthogonal directions. The light sequentially reflected by the respective mirrors of the galvanometer mirror is irradiated onto the photocurable resin on the molding surface, and the irradiated portion is cured. Further, the three-dimensional object is modeled by laminating the cured layers.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-94563

Disclosure of Invention

Problems to be solved by the invention

In recent years, with the expansion of the modeling objects of the optical modeling system, higher and finer modeling than ever before is required. For example, in a Diffractive Optical Element (DOE), a higher-definition design than in the past is required in order to faithfully reproduce an uneven structure. In the optical modeling, high-definition modeling can be performed by reducing a light-converging diameter of light rays irradiated to a modeling surface, that is, a so-called spot diameter, but various technical problems exist for realizing the modeling.

In the optical system of the optical modeling apparatus described in patent document 1, the light emitted from the light source is expanded by the beam expander, and the expanded light is incident on the condenser lens. Since the NA (numerical aperture) of the condenser lens is increased by enlarging the beam diameter of the light beam, the spot diameter of the light beam irradiated to the mold surface can be reduced. However, since a galvanometer mirror for scanning a light beam is disposed between the condenser lens and the shaping surface, the distance between the condenser lens and the shaping surface inevitably becomes long. Therefore, in the optical system described in patent document 1, it is difficult to further reduce the spot diameter of the light beam irradiated to the modeling surface, and there is a limitation in improving the modeling accuracy.

The invention aims to provide an optical system for a light modeling device, which can perform high-precision light modeling.

Means for solving the problems

In order to solve the above problem, an optical system for an optical modeling apparatus according to the present invention includes: the light source, the light scanning part, make the light that is emergent from the light source reflect and scan towards the modeling surface, and the condenser lens, dispose between light scanning part and modeling surface, the light that will be reflected by the light scanning part gathers. In such a configuration, when the focal length of the condenser lens is f and the normal angle on the maximum effective diameter of the surface on the modeling surface side of the condenser lens is a, the optical system for an optical modeling apparatus of the present invention satisfies the following conditional expressions (1) and (2).

f≤25mm(1)

0.3＜cos(A)(2)

In the conventional optical system for an optical modeling apparatus, the focal length of the condenser lens is long, and therefore it is difficult to reduce the spot diameter of the light beam irradiated on the modeling surface. On the other hand, in the optical system for an optical modeling apparatus of the present invention, the condenser lens is disposed between the optical scanning unit and the modeling surface. Thus, the condensing lens can be brought close to the molding surface, and the focal length of the condensing lens can be shortened. Further, since the NA of the condenser lens can be reduced, the spot diameter of the light beam irradiated to the mold surface can be made, for example, 10 μm or less by satisfying the above conditional expression (1). Therefore, according to the optical system for an optical modeling apparatus of the present invention, high-definition modeling can be performed in the optical modeling apparatus.

However, in the photo-molding apparatus, since the photo-curable resin is molded by irradiating light to cure the part, even if the spot diameter of the light irradiated to the molding surface can be reduced, there is a possibility that high-definition molding cannot be realized by the distribution state of the light irradiation energy in the molding surface. The resolution of the shaped object changes between a region where the light irradiation energy is low and a region where the light irradiation energy is high. Generally, the peripheral light quantity ratio tends to decrease as the image height of the mold surface increases due to the characteristics of the lens. When the energy required for curing the photocurable resin is not reached by the light irradiation, the contour of the shaped object becomes unclear and it is difficult to perform high-definition shaping.

Therefore, the optical system for an optical modeling apparatus of the present invention further satisfies the conditional expression (2), thereby suppressing a decrease in the peripheral light amount ratio of the light beam irradiated to the modeling surface. This makes it possible to uniformize the distribution of the light irradiation energy in the molding surface, thereby enabling a more precise molding. In the present specification, the normal angle is an angle between a direction perpendicular to the optical axis of the condenser lens and a normal direction of the lens surface.

In the optical system for an optical modeling apparatus configured as described above, it is preferable that the condenser lens is a biconvex lens, and that the following conditional expression (3) is satisfied where R1 represents a radius of curvature of a surface of the condenser lens on the light scanning unit side and R2 represents a radius of curvature of a surface of the condenser lens on the modeling surface side.

1.0≤|R1/R2|(3)

By satisfying the conditional expression (3), it is possible to suppress the maximum normal angle from decreasing on the surface of the condensing lens on the molding surface side, and to appropriately suppress the decrease in the peripheral light amount ratio on the molding surface.

In the optical system for an optical modeling apparatus having the above configuration, it is preferable that a beam shaping unit is further provided between the light source and the light scanning unit. In this case, it is preferable that the beam shaping means diffuses the light in the short axis direction on the emission side so as to satisfy the following conditional expression (4) when Da is the length of the short axis and Db is the length of the long axis in the cross section of the light beam incident from the light source.

0.9＜Da/Db＜1.2(4)

In addition, the cross-sectional shape of the light beam emitted from the light source is not circular in many cases. In particular, semiconductor lasers have a structure in which a light emitting surface is rectangular, and thus the cross-sectional shape of the emitted light beam is elliptical. When the elliptical light beam enters the condenser lens, the spot shape of the light beam irradiated on the molding surface is also formed into an elliptical shape, and thus the molding efficiency is lowered. In addition, even when the spot shape is an elliptical shape, it is difficult to reduce the spot diameter and to form a fine pattern. By satisfying the above conditional expression (4), the light beam emitted from the light source is shaped into a substantially circular shape by the beam shaping means, and therefore, high-definition modeling can be performed.

In the optical system for an optical modeling apparatus having the above configuration, the light scanning unit preferably includes a mirror, and the diameter of the light beam emitted from the beam shaping means is preferably equal to the diameter of the mirror. The light reflected by the mirror is condensed by the condenser lens onto the molding surface. By making the diameter of the light beam incident on the light scanning unit equal to the diameter of the reflecting mirror, the interval and the size of the light spots continuously irradiated onto the modeling surface by the scanning of the light scanning unit can be appropriately maintained, and finer modeling can be performed.

Preferably, the beam shaping unit has a concave surface formed along the long axis on the incident side of the light emitted from the light source, and a convex surface formed along the long axis on the emission side.

According to this configuration, the light on the short axis side of the light beam entering the beam shaping means is enlarged by the concave surface, and is condensed by the convex surface on the emission side. Therefore, the elliptical light incident on the beam shaping means can be emitted as substantially circular parallel light.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the optical system for an optical modeling apparatus of the present invention, high-definition modeling can be performed in the optical modeling apparatus.

Drawings

Fig. 1 is a schematic view of an optical modeling apparatus equipped with an optical system for an optical modeling apparatus according to an embodiment.

Fig. 2 is an optical path diagram showing a schematic configuration of an optical system for a light shaping apparatus according to a first numerical embodiment.

Fig. 3 is a cross-sectional view taken along the long axis of incident light in the shaping unit.

Fig. 4 is a cross-sectional view taken along the short axis of incident light in the shaping unit.

Fig. 5 is a diagram for explaining a normal angle.

Fig. 6 is an optical path diagram showing a schematic configuration of an optical system for a light shaping apparatus of a second numerical embodiment.

Fig. 7 is an optical path diagram showing a schematic configuration of an optical system for a light shaping apparatus according to a third numerical embodiment.

Fig. 8 is an optical path diagram showing a schematic configuration of an optical system for a light shaping apparatus according to a fourth numerical embodiment.

Description of the reference numerals

1: a light shaping device,

10: an optical system for a stereolithography apparatus,

11: a light source,

12: a collimating lens,

13: a beam shaping unit,

14: a first dielectric mirror,

15: a second dielectric mirror,

16: a light scanning unit,

16 a: an MEMS mirror,

17: a condenser lens,

20: a workbench,

30: a groove,

40: a photocurable resin,

50: a platform,

60: a three-dimensional shaped object.

Detailed Description

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The optical system for an optical modeling apparatus of the present embodiment is assumed to be mounted in an optical modeling apparatus that employs a liquid tank photopolymerization (optical modeling) method in which a photocurable resin is selectively cured by light such as laser light to perform modeling.

First, a schematic configuration of the optical modeling apparatus will be described. As shown in fig. 1, the optical modeling apparatus 1 includes an optical system 10 for the optical modeling apparatus, a table 20, a tank 30 placed on the table 20, a photocurable resin 40 stored in the tank 30, and a stage 50 disposed above the tank 30. The table 20 is provided with an opening having a size approximately equal to the modeling surface IM of the table 50 at a position facing the modeling surface IM with the bottom surface of the groove 30 interposed therebetween. The optical system 10 for an optical modeling apparatus is disposed below the opening of the stage 20.

In the molding, the stage 50 is immersed in the photocurable resin 40 in the tank 30. The modeling surface IM of the stage 50 is scanned by the light emitted from the light source 11 of the optical system 10 for the optical modeling apparatus, and the portion irradiated with the light is solidified on the modeling surface IM. Then, the platform 50 is continuously raised at a predetermined pitch, and the solidified layers are laminated to form the three-dimensional shaped object 60. The state of curing of the photocurable resin 40 depends on the spot size of the irradiated light, the intensity of the light energy, the distribution thereof, and the like. The shape of the light beam emitted from the optical system 10 for an optical modeling apparatus determines the accuracy of modeling in the optical modeling apparatus 1.

Fig. 2 and 6 to 8 are optical path diagrams showing the schematic configuration of the optical system for an optical modeling apparatus according to the first to fourth numerical examples of the present embodiment. Since the basic structure is the same in all the numerical examples, the optical system for a light modeling apparatus of the present embodiment will be described herein with reference to the optical path diagram of the first numerical example.

As shown in fig. 2, the optical system 10 for an optical modeling apparatus of the present embodiment includes a collimator lens 12, a beam shaping unit 13, a first dielectric mirror 14, a second dielectric mirror 15, an optical scanning unit 16, and a condenser lens 17 in this order from the light source 11 toward the modeling surface IM.

As the light source 11, various light sources can be applied, but a laser light source having high light emission efficiency, a semiconductor light source such as an LED light source, or the like is preferably used. Among them, the laser light source is excellent in monochromaticity and directivity, and can improve energy density by condensing light through a lens. In the present embodiment, a laser light source having a wavelength of 405nm, which has a large market throughput and high reliability, is used as the light source 11. The collimator lens 12 converts the light incident from the light source 11 into parallel light, and emits the parallel light toward the beam shaping unit 13.

As shown in fig. 3 and 4, the beam shaping unit 13 in the present embodiment has a shape in which the plano-concave cylindrical lens and the plano-convex cylindrical lens are joined to each other on the plane side so that the directions of formation of the convex surface and the concave surface are aligned. The beam shaping unit 13 may be configured by 2 cylindrical lenses having concave and convex portions.

In the present embodiment, since the laser light source is used as the light source 11, the collimator lens 12 emits parallel light having a substantially elliptical shape. The beam shaping unit 13 shapes the light of the substantially elliptical shape incident from the collimator lens 12 into a substantially circular shape. In detail, when the length of the short axis in the cross section of the incident light beam is Da and the length of the long axis is Db, the beam shaping unit 13 enlarges the light in the short axis direction on the emission side so as to satisfy the following conditional expression,

0.9＜Da/Db＜1.2。

in the present embodiment, the half-value width is used as the values of Da and Db.

The beam shaping unit 13 is explained in further detail. Light rays satisfying the above conditional expression "0.9 < Da/Db < 1.2" are emitted from the beam shaping unit 13. For example, when the length of the minor axis in the cross section of the light input to the beam shaping unit 13 is Da equal to 0.47mm and the length of the major axis is Db equal to 1.01mm, the light in the minor axis direction is amplified by about 2.13 times. As a result, the length of the minor axis on the emission side of beam shaping unit 13 is 1.00mm, the length of the major axis is 1.01mm, and light "Da/Db is 1.0" is emitted from beam shaping unit 13.

As shown in fig. 3, in the beam shaping unit 13, a surface on which light is incident (hereinafter referred to as "incident surface") is formed in a concave shape along the long axis, and a surface on which light is emitted (hereinafter referred to as "emission surface") is formed in a convex shape along the long axis. Fig. 3 shows a schematic shape of incident light on the incident side of the beam shaping unit 13 and a schematic shape of outgoing light on the outgoing side (the same applies to fig. 4). Of the light entering the beam shaping unit 13, the light in the short axis direction is diffused by the concave-shaped entrance surface and is emitted as parallel light by passing through the convex-shaped exit surface.

On the other hand, as shown in fig. 4, when the cross-sectional shape of the beam shaping means 13 is viewed along the short axis direction, the radii of curvature of the incident surface and the exit surface are infinite, that is, formed as a plane. Of the light entering the beam shaping unit 13, the light in the longitudinal direction is directly emitted as parallel light without being condensed or diffused.

As described above, in the beam shaping unit 13, only the light in the short axis direction of the incident light is diffused, and thus substantially circular parallel light is emitted from the beam shaping unit 13.

The first dielectric mirror 14 and the second dielectric mirror 15 are flat mirrors. The light exiting from the beam shaping unit 13 is first reflected by the first dielectric mirror 14 and then reflected by the second mirror 15. Since the optical path can be bent by the dielectric mirrors 14 and 15, the optical system 10 for the optical modeling apparatus can be downsized. One or both of the dielectric mirror 14 and the dielectric mirror 15 can be omitted. The fourth numerical embodiment is an example in which the configurations of both the dielectric mirror 14 and the dielectric mirror 15 are omitted. By omitting the dielectric mirror 14 and the dielectric mirror 15, the manufacturing cost of the optical system 10 for an optical modeling apparatus can be suppressed.

The light scanning unit 16 scans the light beam incident from the dielectric mirror 15. The optical scanning unit 16 includes a two-dimensional MEMS (Micro Electro Mechanical System) mirror 16a as a mirror. The two-dimensional MEMS mirror 16a is an electromagnetically driven mirror plate and can move in two dimensions. The light reflected by the two-dimensional MEMS mirror 16a is scanned as the two-dimensional MEMS mirror 16a moves.

Since the dielectric mirrors 14 and 15 are plane mirrors, the shape of the light incident on the light scanning unit 16 is substantially the same as the shape of the light emitted from the beam shaping unit 13. In the present embodiment, by adjusting the diameter of the light beam emitted from the beam shaping unit 13 to be substantially equal to the diameter of the MEMS mirror 16a, high-definition modeling can be achieved.

Further, as a reference, an example of the MEMS mirror 16a is cited. When the rotation angle of the MEMS mirror 16a is ± 11.1 ° in the horizontal direction and ± 6.86 ° in the vertical direction, the scanning range is 44.4 ° in the horizontal direction and 27.44 ° in the vertical direction. The resolution of the image is determined according to the driving frequency of the MEMS mirror 16 a. For example 720P (effective vertical resolution 720).

The condenser lens 17 of the present embodiment is a biconvex lens. The condenser lens 17 satisfies the following conditional expressions.

f≤25mm，

0.3＜cos(A)，

1.0≤|R1/R2|，

Wherein the content of the first and second substances,

f: the focal distance of the condenser lens 17 is,

a: the normal angle on the maximum effective diameter of the face on the molding face IM side of the condenser lens 17,

r1: the radius of curvature of the surface of the condenser lens 17 on the light scanning section 16 side,

r2: the radius of curvature of the surface of the condenser lens 17 on the molding surface IM side.

Here, a normal angle is explained. As shown in fig. 5, in the present embodiment, an angle between a direction (perpendicular line) orthogonal to the optical axis and a direction of the normal line is defined as a normal angle a. The normal line is a line perpendicular to a tangent line of the lens surface.

In the present embodiment, both surfaces of the condenser lens 17 are formed to be aspherical. The aspherical surface expression of these aspherical surfaces is expressed by the following formula.

[ formula 1 ]

Wherein the content of the first and second substances,

z: the distance in the direction of the optical axis,

h: a distance from the optical axis in a direction orthogonal to the optical axis,

c: paraxial curvature (1/r, r: paraxial radius of curvature),

k: the constant of the cone is constant and the constant of the cone is constant,

an: aspheric coefficients of nth order.

Next, a numerical example of the optical system for an optical modeling apparatus of the present embodiment is shown. In each numerical embodiment, Co denotes a collimator lens, Bs denotes a beam shaping unit, CL denotes a condenser lens, where S1 denotes a light source side surface, and S2 denotes a molding surface IM side surface. In each numerical example, f represents the focal length of the condenser lens, r represents the radius of curvature, Φ represents the maximum effective diameter, t represents the thickness on the optical axis, and n represents the refractive index.

First numerical embodiment

[ TABLE 1 ]

f＝21.35mm

cos(A)＝0.374，

R1＝160.791mm，

R2＝-11.865mm，

|R1/R2|＝13.551，

Da (incident side) is 0.47mm, Db (incident side) is 1.01mm,

da (emission side) is 0.92mm, Db (emission side) is 0.99mm,

Da/Db＝0.93。

the optical system for an optical modeling apparatus of the first numerical embodiment satisfies each conditional expression.

Second numerical embodiment

[ TABLE 2 ]

f＝7.39mm

cos(A)＝0.622，

R1＝28.893mm，

R2＝-4.193mm，

|R1/R2|＝6.891，

Da (incident side) is 0.47mm, Db (incident side) is 1.01mm,

da (emission side) is 0.92mm, Db (emission side) is 0.99mm,

Da/Db＝0.93。

the optical system for an optical modeling apparatus of the second numerical embodiment satisfies each conditional expression.

Third numerical example

[ TABLE 3 ]

f＝5.70mm

cos(A)＝0.650，

R1＝27.801mm，

R2＝-3.112mm，

|R1/R2|＝8.933，

Da (incident side) is 0.47mm, Db (incident side) is 1.01mm,

da (emission side) is 0.92mm, Db (emission side) is 0.99mm,

Da/Db＝0.93。

the optical system for an optical modeling apparatus of the third numerical embodiment satisfies each conditional expression.

Fourth numerical embodiment

[ TABLE 4 ]

f＝5.84mm

cos(A)＝0.541，

R1＝5.170mm，

R2＝-4.233mm，

|R1/R2|＝1.221，

Da (incident side) is 0.47mm, Db (incident side) is 1.01mm,

da (emission side) is 0.92mm, Db (emission side) is 0.99mm,

Da/Db＝0.93。

the optical system for an optical modeling apparatus according to the fourth numerical embodiment satisfies each conditional expression.

Although the beam shaping means is configured by using 1 cylindrical lens in the present embodiment, the beam shaping means may be configured by using a diffractive optical element instead of the cylindrical lens. With this configuration, the optical path length can be shortened, and therefore the optical system for an optical modeling apparatus can be further miniaturized.

The object to be mounted on the optical system for an optical modeling apparatus of the present embodiment is not limited to the optical modeling apparatus. The optical system for an optical modeling apparatus according to the present invention can be applied to molding machines, processing machines, and measuring machines in which the shape, intensity, and distribution state of light to be irradiated affect the accuracy.

Therefore, when the optical system for an optical modeling apparatus of the above-described embodiment is applied to an optical modeling apparatus, higher and finer modeling can be performed by the optical modeling apparatus than in the related art.

Industrial applicability

The present invention can be used as an optical system mounted on an optical molding apparatus for performing high-definition molding.