JP2003340923A - Optical-forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical forming apparatus capable of forming at a high speed and to provide a light forming apparatus capable of forming at a high definition. <P>SOLUTION: Though a micromirror line, wherein 800 pieces of micromirrors are arranged in a main scanning direction, is arranged by 600 sets in a subscanning direction for a DMD 50 to be used in an exposure head, control is carried out so that only a part of the micromirror line (for example, 800 pieces × 100 lines) is driven with a controller. Since there is a limit in a data processing speed of the DMD 50 and a modulating speed per line is determined in proportion to the number of pixels to be used, the modulating speed line is increased by using only a part of the micromirror line. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereolithography apparatus, and more particularly to a stereolithography apparatus for exposing a photocurable resin with a light beam modulated by a spatial light modulator according to image data to produce a three-dimensional model. Regarding the device.

[0002]

2. Description of the Related Art In recent years,
With the spread of the three-dimensional CAD (Computer Aided Design) system, a three-dimensional model created by a three-dimensional CAD in a virtual space on a computer is exposed to a photocurable resin with a light beam based on CAD data, and a three-dimensional model is created. An optical molding system for molding is used. In this stereolithography system, CAD data is sliced at a predetermined interval on a computer to create a plurality of cross-section data, and the surface of a liquid photo-curable resin is scanned with laser light based on each cross-section data to be cured in layers. Then, the resin cured layers are sequentially laminated to form a three-dimensional model. As a stereolithography method, a liquid photocurable resin is stored in an open-type tank, and a molding table placed near the liquid surface of the photocurable resin is sequentially submerged from the free liquid surface of the resin while the resin is sinking. A free liquid level method for laminating a hardened layer is widely known.

Conventionally, the stereolithography apparatus used in this stereolithography system includes "Yoji Marutani: Basics / Current Situations / Problems of Stereolithography System, Mold Technology, Vol. 7, No. 10, pp 18-2.
No. 3, 1992 ”, there are some which perform scanning by the laser plotter system and those which perform scanning by the movable mirror system.

FIG. 28 shows an optical molding apparatus using a laser plotter system. In this device, the laser light emitted from the laser light source 250 reaches the XY plotter 256 through the optical fiber 254 provided with the shutter 252, and the liquid surface 266 of the photocurable resin 262 in the container 260 from the XY plotter 256. Is irradiated. Also, the X positioning mechanism 258a
The position of the XY plotter 256 in the X direction and the Y direction is controlled by the XY positioning mechanism 258 including the Y positioning mechanism 258b and the Y positioning mechanism 258b. Therefore, while moving the XY plotter 256 in the X and Y directions, the X
The photocurable resin 262 on a predetermined portion of the liquid surface 266 can be cured by controlling the on / off of the laser light emitted from the Y plotter 256 according to the cross-sectional data.

However, the laser plotter type optical modeling apparatus has a problem that the shutter speed and the moving speed of the plotter are limited, and that it takes a long time for modeling.

Next, FIG. 29 shows an optical modeling apparatus using a movable mirror system using a conventional galvanometer mirror.
In this device, the laser light 270 is emitted from the X-axis rotating mirror 27.
2. Photocurable resin 2 reflected by the Y-axis rotating mirror 274
62 is irradiated. The X-axis rotation mirror 272 rotates about the Z-axis as a rotation axis to change the irradiation position in the X direction to Y
The axis rotation mirror 274 controls the position of the irradiation position in the Y direction by rotating around the X axis. This movable mirror method can increase the scanning speed as compared with the laser plotter method.

However, even in the stereolithography apparatus using the movable mirror system, even if high-speed scanning of, for example, 2 to 12 m / s is performed in order to scan with a minute laser spot,
8 to 3D modeling of 0 cm cubic
It takes a long time for modeling, such as 24 hours. Further, the laser beam 270 is reflected only when it is incident on the Y-axis rotating mirror 274 at an angle within a predetermined range, so that the irradiation area is limited. Therefore, if the Y-axis rotating mirror 274 is arranged at a high position apart from the photocurable resin 262 in order to widen the irradiation area, the diameter of the laser spot becomes large, the positioning accuracy deteriorates, and the modeling accuracy decreases.
There is a problem. Further, when the rotation angle of the Y-axis rotating mirror 274 is increased, the irradiation range is expanded, but similarly, the positioning accuracy is deteriorated and the pin cushion error is increased. Further, the stereolithography apparatus using the galvanometer mirror has problems that the adjustment of the optical system such as distortion correction and optical axis adjustment is complicated, and the optical system is complicated and the entire apparatus becomes large.

In any of the stereolithography apparatuses of any type, a high-power ultraviolet laser light source is used as a laser light source, and conventionally, a gas laser such as an argon laser or a solid laser by THG (third harmonic) is generally used. However, in addition to troublesome maintenance such as tube replacement, the gas laser is expensive and raises the price of the stereolithography apparatus, and ancillary equipment such as a chiller for cooling is required, and the entire apparatus becomes large. In the THG solid-state laser, it is a pulse operation of the Q switch, the repetition speed is slow, and it is not suitable for high-speed exposure. Further, since the THG light is used, the wavelength conversion efficiency is poor and the output cannot be increased.
A pump laser having a high output must be used, which is very expensive.

In view of this problem, JP-A-11-13864
Japanese Unexamined Patent Application Publication No. 5 has proposed a stereolithography apparatus that includes a plurality of light sources capable of illuminating an exposure area with a spot having a size larger than that of a single pixel, and that multiple-exposes pixels by a plurality of light sources. In this device, since pixels are multiple-exposed by a plurality of light sources, the output of each light source may be small, so that an inexpensive light emitting diode (LED) can be used as a light source.

However, JP-A-11-138645
In the stereolithography apparatus described in the publication, since the spot size of each light source is larger than a single pixel, it cannot be used for high-definition modeling, and multiple exposure of pixels by multiple light sources wastes operation. There are also many problems that it takes a long time to form. There is also a problem that the exposure section becomes large due to the increase in the number of light sources. Furthermore, LED
There is a possibility that sufficient resolution may not be obtained even if multiple exposure is performed with the output light amount of.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an optical molding apparatus capable of high-speed molding. Another object of the present invention is to
An object is to provide an optical modeling apparatus capable of high-definition modeling.

[0012]

In order to achieve the above object, an optical modeling apparatus of the present invention supports a modeling tank containing a photocurable resin and a modeled object that is vertically movable in the modeling tank. And a laser device for irradiating a laser beam, and a large number of pixel portions each of which has a light modulation state that changes in accordance with a control signal are two-dimensionally arranged on a substrate and are radiated from the laser device. A spatial light modulator for modulating laser light,
Control means for controlling each of a plurality of pixel units of a number smaller than the total number of pixel units arranged on the substrate by a control signal generated according to exposure information, and a laser beam modulated by each pixel unit. An exposure head including an optical system for forming an image on the liquid surface of the photocurable resin housed in the molding tank; and a moving means for moving the exposure head relative to the liquid surface of the photocurable resin, It is characterized by having.

In the stereolithography apparatus of the present invention, the laser light modulated by each pixel portion of the spatial light modulator of the exposure head is imaged on the liquid surface of the photocurable resin housed in the molding tank. By moving the exposure head relative to the liquid surface of the photocurable resin by the moving means, the liquid surface of the photocurable resin stored in the modeling tank is scanned and exposed. The exposed resin is cured to form a cured resin layer. After forming one cured resin layer, a support table provided in the modeling tank for supporting the molded article is lowered to form a new resin surface, and the next cured resin layer is similarly formed. In this way, the curing of the resin and the lowering of the support are repeated, and the cured resin layers are sequentially laminated to form a three-dimensional model.

In the stereolithography apparatus of the present invention, with respect to the spatial light modulation element of the exposure head, each of a plurality of pixel units of which the number is smaller than the total number of pixel units arranged on the substrate is determined according to the exposure information. It is controlled by the generated control signal. That is, a part of the pixel parts is controlled without controlling all the pixel parts arranged on the substrate. Therefore, the number of pixel units to be controlled is reduced, and the transfer rate of control signals is shorter than that in the case of transferring control signals for all pixel units. As a result, the modulation speed can be increased and high-speed molding can be performed.

In the above-mentioned stereolithography apparatus, the pixel portion controlled by the control means is a pixel portion included in a region in which the length in the direction corresponding to the predetermined direction is longer than the length in the direction intersecting with the predetermined direction. It is preferable. The number of exposure heads to be used can be reduced by using the pixel portion having a long area in the arrangement direction of the light emitting points of the laser device.

Further, in the above-mentioned optical modeling apparatus, the laser device is provided with a plurality of fiber light sources for emitting the laser light incident from the incident end of the optical fiber from its emission end, and the emission ends of the plurality of fiber light sources. Each of the light emitting points can be composed of a fiber array light source arranged in a one-dimensional or two-dimensional array. Further, each of the light emitting points at the emission ends of the plurality of fiber light sources may be configured by a fiber bundle light source arranged in a bundle. Higher output can be achieved by forming an array or a bundle. As the optical fiber, it is preferable to use an optical fiber having a uniform core diameter and a cladding diameter at the exit end smaller than the cladding diameter at the entrance end.

As each fiber light source constituting the fiber array light source or the like, a combined laser light source that combines laser light and makes it enter the optical fiber is preferable. By using the combined laser light source, high brightness and high output can be obtained. Also,
The number of optical fibers to be arrayed to obtain the same light output is small, and the cost is low. Furthermore, since the number of optical fibers is small, the light emitting area when arrayed is further reduced (increased brightness). Even when the spatial light modulator is partially used, by using a high-intensity fiber array light source or fiber bundle light source, it is possible to efficiently irradiate the laser light to the used portion, and irradiate the laser light with high light density. be able to. This enables high-speed and high-definition exposure and modeling. For example, it is possible to form a fine shape on the order of 1 μm.

For example, the fiber light source includes a plurality of semiconductor lasers, a plurality of semiconductor lasers, and one optical fiber.
A condensing optical system that condenses the laser beam emitted from each of the plurality of semiconductor lasers and couples the condensing beam to the incident end of the optical fiber. Further, the fiber light source is a multi-cavity laser having a plurality of light emitting points, one optical fiber, and a laser beam emitted from each of the plurality of light emitting points is focused, and the focused beam is directed to the optical fiber. And a condensing optical system to be coupled to the incident end of. Further, the laser beams emitted from each of the light emitting points of the plurality of multi-cavity lasers may be condensed and combined into one optical fiber.

As the spatial modulation element used in the above-mentioned optical modeling apparatus, a large number of micromirrors whose reflection surface angles can be changed according to control signals are arranged two-dimensionally on a substrate. Digital micromirror device (D
MD) or a liquid crystal shutter array in which a large number of liquid crystal cells capable of blocking transmitted light according to control signals are arranged two-dimensionally on a substrate can be used. By exposing with a large number of channels using a spatial light modulator having a large number of pixels such as DMD, power is dispersed and thermal distortion is prevented.

As the laser device used in the above-mentioned stereolithography device, one that irradiates laser light having a wavelength of 350 to 450 nm is preferable. For example, by using a GaN-based semiconductor laser as the semiconductor laser, it is possible to configure a laser device that emits laser light having a wavelength of 350 to 450 nm. By using the laser light having a wavelength of 350 to 450 nm, the light absorption rate of the photocurable resin can be significantly increased as compared with the case of using the laser light in the infrared wavelength region. Since the laser light having a wavelength of 350 to 450 nm has a short wavelength, it has a large photon energy and can be easily converted into heat energy. Thus, the wavelength of 350 ~
Since 450 nm laser light has a large light absorption rate and is easily converted into heat energy, curing of the photocurable resin, that is, modeling can be performed at high speed. The wavelength band of laser light is preferably 350 to 420 nm. The wavelength of 405 nm is particularly preferable in terms of using a low-cost GaN-based semiconductor laser.

The above-mentioned stereolithography apparatus can be configured as a multi-head type stereolithography apparatus having a plurality of exposure heads. By using multiple heads, the modeling speed can be further increased.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (First Embodiment) [Structure of Stereolithography Apparatus] A stereolithography apparatus according to an embodiment of the present invention is, as shown in FIG.
And a liquid photo-curable resin 1 in the container 156.
50 are accommodated. In addition, a flat plate-shaped lifting stage 152 is arranged inside the container 156, and the lifting stage 152 is provided on the support part 15 arranged outside the container 156.
It is supported by 4. The support portion 154 has a male screw portion 15
4A is provided, and a lead screw 155, which is rotatable by a drive motor (not shown), is screwed into the male screw portion 154A. This lead screw 1
With the rotation of 55, the elevating stage 152 is moved up and down.

Photocurable resin 1 contained in container 156
A box-shaped scanner 162 is arranged above the liquid surface of 52 with its longitudinal direction oriented in the lateral direction of the container 156.
The scanner 162 is supported by two support arms 160 attached to both side surfaces in the lateral direction. In addition,
The scanner 162 is connected to a controller (not shown) that controls the scanner 162.

Guides 158 extending in the sub-scanning direction are provided on both side surfaces in the longitudinal direction of the container 156. The lower ends of the two support arms 160 are attached to the guide 158 so as to be capable of reciprocating along the sub-scanning direction. The support arm 16 is provided in this stereolithography apparatus.
A driving device (not shown) for driving the scanner 162 along with the guide 158 is provided.

The scanner 162, as shown in FIG.
A plurality of (for example, 14) exposure heads 166 arranged in a matrix (for example, 3 rows and 5 columns) are provided. In this example, four exposure heads 166 are arranged in the third row in relation to the width of the container 156 in the lateral direction. When the individual exposure heads arranged in the m-th row and the n-th column are shown, they are referred to as exposure heads 166 _mn .

Exposure area 168 by exposure head 166
Is a rectangular shape having a short side in the sub-scanning direction. Therefore, as the scanner 162 moves, a belt-shaped exposed region (cured region) 170 is formed on the liquid surface of the photocurable resin 152 for each exposure head 166. When the exposure area by the individual exposure heads arranged in the m-th row and the n-th column is shown, it is referred to as an exposure area 168 _mn .

Further, as shown in FIGS. 3 (A) and 3 (B),
In addition, the strip-shaped exposed area 170 is orthogonal to the sub-scanning direction.
Each row arranged in a line so that they are lined up with no gap in the direction
Each of the exposure heads of the
A natural number times the long side of A, twice in this embodiment)
It is arranged. Therefore, the exposure area 168 of the first row
₁₁And exposure area 168₁₂The part that cannot be exposed between
Second row exposure area 168_{twenty one}And exposure area 16 on the 3rd row
8₃₁It can be exposed by.

As shown in FIGS. 4, 5A and 5B, each of the exposure heads 166 _{11 to} 166 _mn is a spatial light modulator that modulates an incident light beam for each pixel according to image data. A digital micromirror device (DMD) 50 is provided as an element. The DMD 50 is connected to a controller (not shown) including a data processing unit and a mirror drive control unit. The data processing unit of this controller generates a control signal for driving and controlling each micromirror in the region to be controlled by the DMD 50 for each exposure head 166 based on the input image data. The area to be controlled will be described later. The mirror drive control unit controls the angle of the reflecting surface of each micro mirror of the DMD 50 for each exposure head 166 based on the control signal generated by the image data processing unit. The control of the angle of the reflecting surface will be described later.

On the light incident side of the DMD 50, there is provided a fiber array light source having a laser emitting section in which the emitting ends (light emitting points) of the optical fibers are arranged in a line along a direction corresponding to the long side direction of the exposure area 168. 66, fiber array light source 66
The lens system 67 that corrects the laser light emitted from the lens and focuses it on the DMD, and the laser light that has passed through the lens system 67 is D
A mirror 69 that reflects toward the MD 50 is arranged.

The lens system 67 is a fiber array light source 66.
A lens 71 that collimates the laser light emitted from the laser beam, a pair of combination lenses 73 that corrects the collimated laser light so that the light amount distribution is uniform, and a DMD that corrects the light amount distribution. It is composed of a condenser lens 75 for converging light on the upper side. With respect to the arrangement direction of the laser emission ends, the combined lens 73 expands the light beam in a portion near the optical axis of the lens and contracts the light beam in a portion away from the optical axis, and in a direction orthogonal to the arrangement direction. Has a function of allowing light to pass through as it is, and corrects the laser light so that the light amount distribution becomes uniform.

On the light reflecting side of the DMD 50, the DMD
Lens systems 54 and 58 for arranging the laser light reflected by 50 on the scanning surface (exposed surface) 56 of the photocurable resin 150 are arranged. The lens systems 54 and 58 are DMD50s.
And the exposed surface 56 are arranged so as to have a conjugate relationship.

The DMD 50, as shown in FIG.
A micro mirror (micro mirror) 62 is disposed on an M cell (memory cell) 60 while being supported by a support, and a large number (for example, 6
This is a mirror device configured by arranging pixels, which are 00 × 800 micromirrors, in a grid pattern. Each pixel has a micromirror 6 supported by a pillar at the top.
2 is provided, and a material having a high reflectance such as aluminum is vapor-deposited on the surface of the micro mirror 62. The reflectance of the micro mirror 62 is 90% or more.
Immediately below the micro mirror 62, a silicon gate CMOS SRAM cell 60 manufactured in a normal semiconductor memory manufacturing line is arranged via a pillar including a hinge and a yoke, and the whole is monolithic (integrated type). )
Is configured.

When a digital signal is written in the SRAM cell 60 of the DMD 50, the micromirrors 62 supported by the pillars are ± α degrees (for example ± 10 degrees) with respect to the substrate side on which the DMD 50 is arranged with the diagonal line as the center. Tilt in range. FIG. 7A shows a state in which the micro mirror 62 is in the ON state and is inclined to + α degrees, and FIG. 7B shows a state in which the micro mirror 62 is in the OFF state and is inclined to −α degrees. Therefore, by controlling the inclination of the micro mirror 62 in each pixel of the DMD 50 according to the image signal as shown in FIG. 6, the light incident on the DMD 50 is reflected in the inclination direction of each micro mirror 62. .

FIG. 6 shows an example of a state in which a part of the DMD 50 is enlarged and the micromirror 62 is controlled to + α degrees or −α degrees. Each micro mirror 6
The on / off control of No. 2 is performed by a controller (not shown) connected to the DMD 50. A light absorber (not shown) is arranged in the direction in which the light beam is reflected by the micro mirror 62 in the off state.

Further, it is preferable that the DMD 50 is disposed so as to be slightly inclined so that its short side makes a predetermined angle θ (for example, 1 ° to 5 °) with the sub-scanning direction. 8 (A) is D
8 shows scanning trajectories of the reflected light image (exposure beam) 53 by each micromirror when the MD 50 is not tilted, and FIG.
(B) is the exposure beam 53 when the DMD 50 is tilted
The scanning locus of is shown.

In the DMD 50, a large number (for example, 600) of micromirror rows in which a large number (for example, 800) of micromirrors are arranged in the longitudinal direction are arranged in the lateral direction. As shown in B), by tilting the DMD 50, the pitch P ₁ of the scanning locus (scanning line) of the exposure beam 53 by each micromirror is set to the DMD.
The pitch is narrower than the scanning line pitch P ₂ when 50 is not tilted, and the resolution can be greatly improved. on the other hand,
Since the tilt angle of the DMD 50 is small, the scan width W ₂ when the DMD 50 is tilted and the scan width W ₁ when the DMD 50 is not tilted are substantially the same.

Further, the same scanning line is overlapped and exposed (multiple exposure) by different micromirror rows.
By performing multiple exposure in this way, it is possible to control a very small amount of the exposure position and realize high-definition exposure. Further, the joint between the plurality of exposure heads arranged in the main scanning direction can be connected without a step by controlling the exposure position with a very small amount.

Instead of tilting the DMD 50,
The same effect can be obtained by arranging the micromirror rows in a zigzag pattern with a predetermined gap in the direction orthogonal to the sub-scanning direction.

As shown in FIG. 9, the fiber array light source 66 includes a plurality of (six in this embodiment) laser modules 64, and each laser module 64 has one end of the multimode optical fiber 30. Are combined. At the other end of the multimode optical fiber 30, an optical fiber 31 having the same core diameter as the multimode optical fiber 30 and a cladding diameter smaller than the multimode optical fiber 30 is coupled, and as shown in FIG. The laser emitting portion 68 is configured by arranging the emitting ends (light emitting points) of the optical fibers 31 in one line along the main scanning direction orthogonal to the sub scanning direction. As shown in FIG. 9D, the light emitting points can be arranged in two rows along the main scanning direction.

The emission end of the optical fiber 31 is shown in FIG.
As shown in FIG. 7, the support plate 65 is sandwiched and fixed by two support plates 65 having flat surfaces. A transparent protective plate 63 such as glass is arranged on the light emitting side of the optical fiber 31 to protect the end face of the optical fiber 31. Protection plate 63
May be arranged in close contact with the end face of the optical fiber 31, or may be arranged so that the end face of the optical fiber 31 is sealed. Although the emission end of the optical fiber 31 has a high light density and easily collects dust and easily deteriorates, by disposing the protective plate 63, it is possible to prevent dust from adhering to the end face and delay the deterioration.

In this example, in order to arrange the output ends of the optical fibers 31 having a small clad diameter in one row without a gap, the multimode optical fibers 30 are adjacent to each other in the portion having a large clad diameter. The fibers 30 are stacked, and the output end of the optical fiber 31 coupled to the stacked multi-mode optical fibers 30 is two of the optical fibers 31 coupled to the two multi-mode optical fibers 30 adjacent to each other in the portion where the cladding diameter is large. It is arranged so as to be sandwiched between two emission ends.

Such an optical fiber is shown in FIG.
As shown in FIG. 3, the length of the multimode optical fiber 30 having a large cladding diameter is
It can be obtained by coaxially coupling optical fibers 31 having a small clad diameter of cm. The two optical fibers are fused and coupled so that the incident end face of the optical fiber 31 is connected to the emitting end face of the multimode optical fiber 30 so that the central axes of the both optical fibers coincide with each other. As described above, the diameter of the core 31a of the optical fiber 31 is the same as the diameter of the core 30a of the multimode optical fiber 30.

Further, a short optical fiber in which an optical fiber having a small clad diameter is fused to an optical fiber having a short length and a large clad diameter is coupled to the emission end of the multimode optical fiber 30 via a ferrule or an optical connector. You may.
By detachably coupling with a connector or the like, the tip portion can be easily replaced when the optical fiber having a small clad diameter is damaged, and the cost required for maintenance of the exposure head can be reduced. In the following, the optical fiber 31
May be referred to as the exit end of the multimode optical fiber 30.

As the multimode optical fiber 30 and the optical fiber 31, a step index type optical fiber,
Either a graded index type optical fiber or a composite type optical fiber may be used. For example, a step index type optical fiber manufactured by Mitsubishi Cable Industries, Ltd. can be used. In the present embodiment, the multimode optical fiber 30 and the optical fiber 31 are step index type optical fibers, and the multimode optical fiber 30 has a cladding diameter = 125 μm, a core diameter = 25 μm, and NA = 0.
2, the transmittance of the incident end face coat = 99.5% or more,
The optical fiber 31 has a clad diameter of 60 μm and a core diameter of 2
5 μm, NA = 0.2.

In general, with laser light in the infrared region, the propagation loss increases when the cladding diameter of the optical fiber is reduced.
Therefore, a suitable cladding diameter is determined according to the wavelength band of laser light. However, the shorter the wavelength is, the smaller the propagation loss becomes, and in the laser light having a wavelength of 405 nm emitted from the GaN-based semiconductor laser, the cladding thickness {(clad diameter-core diameter) / 2} is the infrared light in the wavelength band of 800 nm. Of about 1/2 when propagating infrared light, and about 1 when propagating infrared light in the wavelength band of 1.5 μm for communication.
Even at / 4, the propagation loss hardly increases. Therefore, the cladding diameter can be reduced to 60 μm.

However, the cladding diameter of the optical fiber 31 is 60
It is not limited to μm. The clad diameter of the optical fiber used in the conventional fiber light source is 125 μm,
The smaller the clad diameter, the higher the brightness and the deeper the depth of focus. Therefore, the clad diameter of the multimode optical fiber is preferably 80 μm or less, more preferably 60 μm or less, and further preferably 40 μm or less. On the other hand, since the core diameter needs to be at least 3 to 4 μm, the cladding diameter of the optical fiber 31 is preferably 10 μm or more.

The laser module 64 is composed of a combined laser light source (fiber light source) shown in FIG. This combined laser light source is a plurality (eg, 7) of chip-shaped lateral multimode or single mode GaN-based semiconductor lasers L arranged and fixed on the heat block 10.
D1, LD2, LD3, LD4, LD5, LD6 and LD7, and collimator lenses 11, 12 and 1 provided corresponding to each of the GaN-based semiconductor lasers LD1 to LD7.
It comprises 3, 14, 15, 16, and 17, one condenser lens 20, and one multimode optical fiber 30. The number of semiconductor lasers is not limited to seven. Clad diameter = 60 μm, core diameter = 50 μm,
As many as 20 semiconductor laser beams can be incident on the multimode optical fiber with NA = 0.2, the required amount of light of the exposure head can be realized, and the number of optical fibers can be further reduced.

The GaN semiconductor lasers LD1 to LD7 are
The oscillation wavelengths are all common (for example, 405 nm), and the maximum outputs are also all common (for example, 1 for a multimode laser).
00 mW, and 30 mW for a single mode laser). The GaN-based semiconductor lasers LD1 to LD7 have a wavelength range of 350 nm to 450 nm and the above 40
A laser having an oscillation wavelength other than 5 nm can be used. The wavelength band of the laser light is more preferably 350 to 420 nm. The wavelength of 408 nm is particularly preferable in that a low-cost GaN-based semiconductor laser is used.

The above-mentioned combined laser light source is shown in FIGS.
As shown in FIG. 3, it is housed together with other optical elements in a box-shaped package 40 having an upper opening. The package 40 includes a package lid 41 formed so as to close the opening thereof, and introduces a sealing gas after the degassing process,
By closing the opening of the package 40 with the package lid 41, the combined laser light source is hermetically sealed in the closed space (sealing space) formed by the package 40 and the package lid 41.

A base plate 42 is fixed to the bottom surface of the package 40, and the heat block 10, a condenser lens holder 45 for holding the condenser lens 20, and a multimode light are provided on the upper surface of the base plate 42. A fiber holder 46 that holds the entrance end of the fiber 30 is attached. The exit end of the multimode optical fiber 30 is
It is pulled out from the package through an opening formed in the wall surface of the package 40.

A collimator lens holder 44 is attached to the side surface of the heat block 10 and holds the collimator lenses 11 to 17. An opening is formed on the lateral wall surface of the package 40 and G
A wiring 47 for supplying a drive current to the aN semiconductor lasers LD1 to LD7 is drawn out of the package.

Incidentally, in FIG. 13, in order to avoid complication of the drawing, GaN among a plurality of GaN-based semiconductor lasers is used.
Only the system semiconductor laser LD7 is numbered, and only the collimator lens 17 of the plurality of collimator lenses is numbered.

FIG. 14 shows the collimator lenses 11-1.
7 is a front view of a mounting portion of No. 7. Each of the collimator lenses 11 to 17 is formed in a shape in which a region including the optical axis of a circular lens having an aspherical surface is elongated and cut out in parallel planes. The elongated collimator lens can be formed by molding resin or optical glass, for example. The length direction of the collimator lenses 11 to 17 is a GaN-based semiconductor laser LD1.
~ LD7 is closely arranged in the arrangement direction of the light emitting points so as to be orthogonal to the arrangement direction of the light emitting points (the horizontal direction in FIG. 14).

On the other hand, GaN semiconductor lasers LD1 to LD
7 includes an active layer having an emission width of 2 μm, and the divergence angle in the direction parallel to the active layer and the divergence angle in the direction perpendicular to the active layer are, for example, 10
Lasers which emit laser beams B1 to B7 in the respective states of 30 ° and 30 ° are used. These GaN-based semiconductor lasers LD1 to LD7 have an emission point of 1 in the direction parallel to the active layer.
It is arranged so as to line up in a row.

Therefore, the laser beams B1 to B7 emitted from the respective light emitting points diverge with respect to the elongated collimator lenses 11 to 17 as described above, in which the direction where the divergence angle is large coincides with the length direction. The light enters in a state in which the direction with a small angle coincides with the width direction (direction orthogonal to the length direction). That is, each collimator lens 11 to 17 has a width of 1.1 mm and a length of 4.6 mm, and the laser beams B1 to B7 incident on them have horizontal and vertical beam diameters of 0.9 mm and 2. It is 6 mm. Also,
Each of the collimator lenses 11 to 17 has a focal length f ₁ =
3 mm, NA = 0.6, lens arrangement pitch = 1.25 m
m.

In the condenser lens 20, a region including the optical axis of a circular lens provided with an aspherical surface is cut into long and thin parts in parallel planes, and the collimator lenses 11 to 17 are arranged in a long direction, that is, in the horizontal direction, and in a direction perpendicular to it. It has a short shape. This condenser lens 20 has a focal length f ₂ = 23 m
m, NA = 0.2. The condenser lens 20 is also formed by molding resin or optical glass, for example.

[Operation of Stereolithography Apparatus] Next, the operation of the above stereolithography apparatus will be described.

In each exposure head 166 of the scanner 162, laser beams B1, B2, B3, B emitted in a divergent state from each of the GaN semiconductor lasers LD1 to LD7 constituting the combined laser light source of the fiber array light source 66.
4, B5, B6, and B7 are collimated by the corresponding collimator lenses 11 to 17, respectively. The collimated laser beams B1 to B7 are condensed by the condenser lens 20, and the core 30 of the multimode optical fiber 30 is collected.
It converges on the incident end face of a.

In this example, the collimator lenses 11 to 17 and the condenser lens 20 constitute a condenser optical system, and the condenser optical system and the multimode optical fiber 30 constitute a multiplexing optical system. That is, the laser beams B1 to B7 condensed by the condenser lens 20 as described above.
From the optical fiber 31 which is incident on the core 30a of the multimode optical fiber 30, propagates in the optical fiber, is combined with one laser beam B, and is coupled to the emission end of the multimode optical fiber 30. Emit.

In each laser module, the coupling efficiency of the laser beams B1 to B7 to the multimode optical fiber 30 is 0.85, and the GaN semiconductor lasers LD1 to LD7.
Output of 30 mW, the output of each of the optical fibers 31 arranged in an array is 180 mW (= 3
A combined laser beam B of 0 mW × 0.85 × 7) can be obtained. Therefore, the output of the laser emitting section 68 in which the six optical fibers 31 are arranged in an array is about 1 W (= 1
80 mW x 6).

Laser emitting section 6 of fiber array light source 66
As shown in FIG. 8, high-luminance light emitting points are arranged in a line in the main scanning direction. Since the conventional fiber light source that combines the laser light from a single semiconductor laser into one optical fiber has a low output, a desired output could not be obtained without arranging in multiple rows. Since the combined laser light source used in the mode has a high output, a desired output can be obtained even with a small number of rows, for example, one row.

For example, in a conventional fiber light source in which a semiconductor laser and an optical fiber are coupled one-to-one, a laser having an output of about 30 mW (milliwatt) is usually used as the semiconductor laser, and a core diameter of 50 μm is used as the optical fiber. Since a multimode optical fiber with a cladding diameter of 125 μm and an NA (numerical aperture) of 0.2 is used, 48 multimode optical fibers (8 × 6) are required to obtain an output of about 1 W (watt). Must be bundled, the area of the light emitting region is 0.62mm2 (0.675mm × 0.925m
m), the brightness at the laser emitting portion 68 is 1.6 ×
106 (W / m2), the brightness per optical fiber is 3.
It is 2 × 10 6 (W / m 2).

On the other hand, in the present embodiment, as described above, the output of about 1 W can be obtained with the six multimode optical fibers, and the area of the light emitting region at the laser emitting portion 68 is 0.0081 mm 2 (0 .325 mm x 0.025 m
m), the brightness at the laser emitting portion 68 is 123 ×
Since it is 106 (W / m2), it is possible to increase the brightness by about 80 times as compared with the conventional one. In addition, the brightness per optical fiber is 90 × 10 6 (W / m 2), and it is possible to achieve a brightness that is about 28 times higher than the conventional one.

Here, the difference in depth of focus between the conventional exposure head and the exposure head of the present embodiment will be described with reference to FIGS. 15 (A) and 15 (B). The diameter of the light emitting region of the bundle-shaped fiber light source of the conventional exposure head in the sub scanning direction is 0.675 mm, and the diameter of the light emitting region of the fiber array light source of the exposure head of the present embodiment in the sub scanning direction is 0.075 mm.
It is 25 mm. As shown in FIG. 15A, in the conventional exposure head, since the light emitting area of the light source (bundle-shaped fiber light source) 1 is large, the angle of the light beam incident on the DMD 3 is large, and as a result, it is incident on the scanning surface 5. The angle of the luminous flux becomes large. For this reason, the beam diameter tends to be thicker in the focusing direction (shift in the focusing direction).

On the other hand, as shown in FIG. 15B, in the exposure head of this embodiment, since the diameter of the light emitting area of the fiber array light source 66 in the sub-scanning direction is small, it passes through the lens system 67 to the DMD 50. The angle of the incident light beam becomes smaller, and as a result, the angle of the light beam incident on the scanning surface 56 becomes smaller. That is, the depth of focus becomes deep. In this example, the diameter of the light emitting area in the sub-scanning direction is about 30 times that of the conventional one.
It is possible to obtain a depth of focus corresponding to the diffraction limit. Therefore, it is suitable for exposure of a minute spot. The effect on the depth of focus is more remarkable and effective as the required light amount of the exposure head is larger. In this example, 1 projected on the exposure surface
The pixel size is 10 μm × 10 μm. DMD
Is a reflection type spatial modulation element, but FIGS. 15A and 15B are developed views for explaining the optical relationship.

Image data corresponding to the exposure pattern for one layer is input to a controller (not shown) connected to the DMD 50 and temporarily stored in a frame memory in the controller. This image data is data in which the density of each pixel forming the image is represented by a binary value (whether or not dots are recorded).

The scanner 162 is moved along the guide 158 from the upstream side to the downstream side in the sub-scanning direction at a constant speed by a driving device (not shown). When the movement of the scanner 162 is started, the image data stored in the frame memory is sequentially read out by a plurality of lines, and a control signal is sent to each exposure head 166 based on the image data read by the data processing unit. Is generated. Then, each exposure head 16 is controlled by the mirror drive controller based on the generated control signal.
Each of the micromirrors of the DMD 50 is controlled to be turned on / off every 6 times.

When the DMD 50 is irradiated with laser light from the fiber array light source 66, the laser light reflected when the micromirrors of the DMD 50 are in the on state is reflected by the lens system 5.
Liquid level of the photocurable resin 150 (exposed surface) by 4, 58
Imaged on 56. In this way, the laser light emitted from the fiber array light source 66 is turned on and off for each pixel, and the photo-curable resin 150 is exposed and cured in the same number of pixel units (exposure area 168) as the number of pixels used in the DMD 50. To do. Further, by moving the scanner 162 at a constant speed, the liquid surface of the photocurable resin 150 is sub-scanned,
A belt-shaped hardening region 170 is formed for each exposure head 166.

As shown in FIGS. 16A and 16B, in the present embodiment, the DMD 50 has 600 sets of micromirror rows in which 800 micromirrors are arrayed in the main scanning direction and in the subscanning direction. Although arranged, in the present embodiment, the controller 51 controls so that only some of the micromirror rows (for example, 800 rows × 100 rows) are driven.

As shown in FIG. 16 (A), a micromirror array arranged at the center of the DMD 50 may be used, or as shown in FIG. 16 (B), a micromirror array arranged at the end of the DMD 50. Mirror rows may be used. Further, when a defect occurs in some of the micromirrors, the micromirror array used may be appropriately changed depending on the situation, such as using a micromirror array in which no defect has occurred.

The data processing speed of the DMD 50 is limited, and the modulation speed per line is determined in proportion to the number of pixels used. Therefore, by using only some micromirror rows The modulation speed becomes faster. on the other hand,
In the case of the exposure method in which the exposure head is continuously moved relative to the exposure surface, it is not necessary to use all the pixels in the sub-scanning direction.

For example, when only 300 of the 600 sets of micromirror arrays are used, the modulation can be performed twice as fast per line as compared with the case where all 600 sets are used. Also, of the 600 pairs of micromirrors,
When only 200 sets are used, modulation can be performed three times faster per line than when all 600 sets are used. That is, an area of 500 mm in the sub-scanning direction can be exposed in 17 seconds. Also, when using only 100 pairs,
Modulation can be performed 6 times faster per line. That is, an area of 500 mm in the sub scanning direction can be exposed in 9 seconds.

The number of micromirror rows used, that is, the number of micromirrors arrayed in the sub-scanning direction is preferably 10 or more and 200 or less, and 10 or more and 100 or more.
The following is more preferable. Since the area per micromirror corresponding to one pixel is 15 μm × 15 μm, DM
Converted to the usage area of D50, 12 mm x 150 μm
It is preferable that the area is not less than 12 mm × 3 mm and not less than 1
A region of 2 mm × 150 μm or more and 12 mm × 1.5 mm or less is more preferable.

If the number of micromirror rows used is within the above range, as shown in FIGS. 17A and 17B, the laser light emitted from the fiber array light source 66 is converted into substantially parallel light by the lens system 67. Then, the DMD 50 can be irradiated. It is preferable that the irradiation area where the DMD 50 irradiates the laser light coincides with the usage area of the DMD 50.
If the irradiation area is wider than the usage area, the utilization efficiency of the laser light is reduced.

On the other hand, the diameter of the light beam focused on the DMD 50 in the sub-scanning direction needs to be reduced according to the number of micro mirrors arranged in the sub-scanning direction by the lens system 67. If the number of rows is less than 10, the angle of the light beam incident on the DMD 50 becomes large and the depth of focus of the light beam on the scanning surface 56 becomes shallow, which is not preferable. Further, it is preferable that the number of micromirror rows used is 200 or less from the viewpoint of modulation speed. In addition,
The DMD is a reflective spatial light modulator, which is shown in FIG.
(B) is a developed view for explaining the optical relationship.

When the curing of one layer is completed by one sub-scanning by the scanner 162, the scanner 162 is returned to the origin on the most upstream side along the guide 158 by the driving device (not shown). Next, the lead screw 155 is rotated by a drive motor (not shown) to move the lifting stage 1
52 is lowered by a predetermined amount, the cured portion of the photocurable resin 150 is sunk below the liquid surface, and the upper portion of the cured portion is a liquid photocurable resin 1
Fill with 50. Then, the image data of the next layer is DMD.
When input to a controller (not shown) connected to 50, the sub-scanning by the scanner 162 is performed again. In this way, the exposure (curing) by the sub-scanning and the descending of the stage are repeated, and the cured portions are stacked to form a three-dimensional model.

As described above, the stereolithography apparatus according to the present embodiment is provided with the DMD in which the micromirror array in which 800 micromirrors are arranged in the main scanning direction and the 600 sets in the subscanning direction are arranged. , The controller controls so that only some of the micromirror rows are driven, so compared to the case of driving all the micromirror rows,
The modulation speed per line becomes faster. This enables high-speed exposure and modeling.

Further, as the light source for illuminating the DMD, since the high-intensity fiber array light source in which the emitting ends of the optical fibers of the combined laser light source are arranged in an array is used, a high output and a deep focal depth can be obtained. Since it is possible to obtain a high optical density output, high-speed and high-definition modeling can be performed. Furthermore, since the output of each fiber light source increases, the number of fiber light sources required to obtain the desired output decreases, and the cost of the optical modeling apparatus can be reduced.

In particular, in the present embodiment, the clad diameter at the exit end of the optical fiber is made smaller than the clad diameter at the entrance end, so the diameter of the light emitting portion becomes smaller and the brightness of the fiber array light source is further increased. Is planned. This enables higher-definition modeling.

In the above embodiment, an example in which the DMD micromirrors are partially driven has been described. However, a substrate whose length in the direction corresponding to the predetermined direction is longer than the length in the direction intersecting with the predetermined direction. Even if an elongated DMD in which a large number of micromirrors whose reflecting surface angles can be changed according to control signals are arranged two-dimensionally is used, the number of micromirrors that control the reflecting surface angles is reduced. Therefore, the modulation speed can be increased.

Next, a modification of the above-described embodiment will be described. [Other Spatial Modulators] In the above embodiment, an example in which the micromirrors of the DMD are partially driven has been described, but the length in the direction corresponding to the predetermined direction is smaller than the length in the direction intersecting with the predetermined direction. On a long board,
Even if an elongated DMD in which a large number of micromirrors whose reflecting surface angles can be changed according to control signals are arranged in a two-dimensional array is used, the number of micromirrors that control the reflecting surface angles is reduced. The speed can be increased.

In the above-described embodiment, the exposure head provided with the DMD as the spatial modulation element has been described. However, for example, a MEMS (Micro Electro Mechanical Systems) type spatial modulation element (SLM; Spatial Light Modulato) is used.
r), an optical element (PLZT element) that modulates the transmitted light by an electro-optical effect, a liquid crystal optical shutter (FLC), etc.
Even when a spatial modulation element other than the MS type is used, by using a part of the pixel parts with respect to all the pixel parts arranged on the substrate, the modulation speed per pixel and one main scanning line can be increased. Therefore, the same effect can be obtained.

The MEMS is a general term for a micro system in which micro-sized sensors, actuators, and control circuits based on the micromachining technology based on the IC manufacturing process are integrated, and the MEMS type spatial modulator is It means a spatial modulation element driven by electromechanical operation using electrostatic force.

[Laser Driving Method] Each GaN semiconductor laser included in the fiber array light source may be continuously driven or pulse driven. By exposing with pulse-driven laser light, thermal diffusion is prevented, and high-speed and high-definition modeling is possible. The shorter pulse width is preferable, 1psec to 100nsec is preferable, and 1psec to 3
00 psec is more preferable. It should be noted that the GaN-based semiconductor laser has high reliability because the light emitting end face, which is called COD (Catastrophic Optical Damage), is unlikely to be damaged and has high reliability.
A pulse width of ec to 300 psec can be easily realized.

[Other Exposure Methods] As shown in FIG. 18, the entire surface of the liquid surface of the photocurable resin 150 may be scanned by the scanner 162 once in the X direction, as in the above embodiment. As shown in FIGS. 19A and 19B, after scanning the scanner 162 in the X direction, the scanner 162 is moved in the Y direction by one step, and the scanning is performed in the X direction. Repeatedly, the entire liquid surface may be scanned by scanning a plurality of times. In this example, the scanner 162 has 18 exposure heads 166.

In general, in the stereolithography method for molding a three-dimensional model, polymerization shrinkage due to hardening of the resin and hardening shrinkage due to distortion of the resin heated to a high temperature due to the heat of polymerization when the resin is cooled to room temperature are caused. However, there is a problem that the molded article is distorted due to the shrinkage caused by the curing and the molding accuracy is lowered. In particular, when a region including a plurality of pixels is exposed (surface exposure) at the same time to form a flat plate, the formed article warps downward in the stacking direction. In order to prevent such distortion due to curing shrinkage, it is preferable to divide the exposure region into a plurality of regions and perform exposure sequentially.

For example, the same liquid surface of the photo-curable resin is scanned a plurality of times, and the contour line of the modeling shape is exposed by the first scan to cure the photo-curable resin, and then the second and subsequent scans. By exposing the inside of the contour line to cure the photocurable resin, the occurrence of distortion can be prevented.

Further, as shown in FIG. 30A, the exposure area is divided into a large number of pixels, and the large number of pixels are divided into a first group composed of pixels 102 which are not adjacent to each other. Alternatively, the scanning exposure may be performed for each group by dividing into two groups of the second group configured by the pixels 104 that are not adjacent to each other. The pixels 102 and the pixels 104 are alternately arranged so as to form a checkered pattern. A part of the exposure area is shown in FIG.
When the exposure head including D is used, the exposure area can be divided into 1 million pixels according to the number of pixels of the DMD.

First, the first scan exposes the pixels 102 belonging to the first group as shown in FIG. 30 (B), and the second scan exposes the pixels 102 as shown in FIG. 30 (C). Two
The pixels 104 belonging to the group are exposed. As a result, the gaps between the pixels are filled, and the entire exposure area of the liquid surface of the photocurable resin is exposed.

The pixels of the first group which are simultaneously exposed in the first scan are not adjacent to each other, and the pixels of the second group which are simultaneously exposed in the second scan are also adjacent to each other. Absent. Since adjacent pixels are not exposed at the same time as described above, distortion due to curing shrinkage does not propagate to adjacent pixels. That is, when the entire exposure area is exposed at the same time, distortion due to curing shrinkage increases as it propagates through the exposure area, and considerable distortion occurs. However, in this example, curing shrinkage is within a range of 1 pixel. Only occurs,
Distortion due to curing shrinkage does not propagate to adjacent pixels. As a result, the occurrence of distortion is significantly suppressed in the layered model, and modeling with high accuracy becomes possible.

In the exposure apparatus of the above embodiment, the liquid surface of the photocurable resin can be exposed in an arbitrary pattern by one scanning with the scanner. Therefore, it is relatively easy to expose each area divided by a plurality of scans.

[Photocurable Resin] As the liquid photocurable resin used for stereolithography, generally, urethane acrylate resin which is cured by photoradical polymerization reaction or epoxy resin which is cured by photocationic polymerization reaction is used. To be done. Also, at room temperature, it is in a gel state, and when heat energy is applied by laser irradiation, it changes to a sol state.
A gel conversion type photocurable resin can be used. In the stereolithography method using the sol-gel conversion type photocurable resin,
Since exposure and curing are performed on the modeling surface in the gel state instead of the liquid state, the molded article is formed in the gel-like resin, and there is an advantage that it is not necessary to model the support portion and the connecting portion for supporting the molded article. .

When performing line exposure or area exposure for simultaneously exposing a predetermined area, it is preferable to use a resin obtained by adding a thermally conductive filler to the above sol-gel conversion type photocurable resin. Addition of a thermally conductive filler exerts thermal diffusivity and prevents thermal distortion in the modeled object. In particular, in the sol-gel conversion type photocurable resin, unlike the ordinary resin, the filler can be uniformly dispersed without settling, so that the thermal diffusivity can be maintained.

[Other Laser Device (Light Source)] In the above embodiment, an example of using a fiber array light source having a plurality of combined laser light sources has been described, but the laser device is an array of combined laser light sources. It is not limited to the fiber array light source. For example, it is possible to use a fiber array light source that is an array of fiber light sources provided with one optical fiber that emits laser light incident from a single semiconductor laser having one light emitting point.

As a light source having a plurality of light emitting points, for example, as shown in FIG.
It is possible to use a laser array in which a plurality (for example, seven) of chip-shaped semiconductor lasers LD1 to LD7 are arranged on the laser diode 0. In addition, as shown in FIG.
A chip-shaped multi-cavity laser 110 in which (five) light emitting points 110a are arranged in a predetermined direction is known. In the multi-cavity laser 110, the light emitting points can be arranged with higher positional accuracy than in the case of arranging chip-shaped semiconductor lasers, and therefore the laser beams emitted from the respective light emitting points can be easily combined. However, as the number of light emitting points increases, the multi-cavity laser 110 is likely to bend during laser manufacturing. Therefore, the number of light emitting points 110a is preferably 5 or less.

In the exposure head of the present invention, the multi-cavity laser 110 and, as shown in FIG. 21B, a plurality of multi-cavity lasers 110 are arranged on the heat block 100 in the arrangement direction of the light emitting points 110a of the respective chips. A multi-cavity laser array arranged in the same direction as can be used as a laser device (light source).

Further, the combined laser light source is not limited to the one that combines laser beams emitted from a plurality of chip-shaped semiconductor lasers. For example, as shown in FIG. 22, a combined laser light source including a chip-shaped multi-cavity laser 110 having a plurality of (for example, three) light emitting points 110a can be used. This combined laser light source includes a multi-cavity laser 110, a single multi-mode optical fiber 130, and a condenser lens 120. The multi-cavity laser 110 can be composed of, for example, a GaN-based laser diode having an oscillation wavelength of 405 nm.

In the above structure, each of the laser beams B emitted from each of the plurality of light emitting points 110a of the multi-cavity laser 110 is condensed by the condenser lens 120 and is incident on the core 130a of the multimode optical fiber 130. . The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.

A plurality of light emitting points 110a of the multi-cavity laser 110 are arranged side by side within a width substantially equal to the core diameter of the multi-mode optical fiber 130, and the condenser lens 1 is provided.
As 20, a convex lens having a focal length substantially equal to the core diameter of the multimode optical fiber 130, or a rod lens for collimating the emitted beam from the multicavity laser 110 only in a plane perpendicular to its active layer is used.
The coupling efficiency of the laser beam B to the multimode optical fiber 130 can be increased.

Further, as shown in FIG. 23, the multi-cavity laser 1 having a plurality of (for example, three) light emitting points is provided.
10, using a plurality of heat blocks 111 (for example,
A combined laser light source including a laser array 140 in which nine (9) multi-cavity lasers 110 are arranged at equal intervals can be used. The plurality of multi-cavity lasers 110 are arranged and fixed in the same direction as the light emitting points 110a of each chip.

The combined laser light source shown in FIG. 23 includes a laser array 140, a plurality of lens arrays 114 arranged corresponding to each multicapability laser 110, and between the laser array 140 and the plurality of lens arrays 114. It is configured to include one rod lens 113 arranged, one multimode optical fiber 130, and a condenser lens 120. The lens array 114 includes a plurality of microlenses corresponding to the light emitting points of the multicapability laser 110.

In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 10a of the plurality of multi-cavity lasers 110 is condensed in a predetermined direction by the rod lens 113, and then the laser beam of the lens array 114 is collected. The light is collimated by each microlens. The collimated laser beam L is condensed by the condenser lens 120 and is incident on the core 130 a of the multimode optical fiber 130.
The laser light that has entered the core 130a propagates in the optical fiber, is combined into one, and is emitted.

An example of still another combined laser light source will be shown. In this combined laser light source, as shown in FIGS. 24A and 24B, a heat block 182 having an L-shaped cross section in the optical axis direction is mounted on a heat block 180 having a substantially rectangular shape, and two heats are provided. A storage space is formed between the blocks. On the upper surface of the L-shaped heat block 182, a plurality of (for example, 2) light emitting points (for example, 5) are arranged in an array.
The individual multi-cavity lasers 110 are arranged and fixed at equal intervals in the same direction as the arrangement direction of the light emitting points 110a of each chip.

A concave portion is formed in the substantially rectangular heat block 180, and a plurality of light emitting points (for example, five light emitting points) (for example, five light emitting points) arranged in an array are formed on the space-side upper surface of the heat block 180. The (two) multi-cavity lasers 110 are arranged such that their light emitting points are located on the same vertical plane as the light emitting points of the laser chips arranged on the upper surface of the heat block 182.

On the laser beam emitting side of the multi-cavity laser 110, a collimating lens array 18 in which collimating lenses are arranged corresponding to the light emitting points 110a of each chip.
4 are arranged. Collimating lens array 184
Is so that the length direction of each collimator lens and the direction where the divergence angle of the laser beam is large (fast axis direction) match, and the width direction of each collimator lens matches the direction where the divergence angle is small (slow axis direction). It is arranged. As described above, by integrating the collimator lenses in an array, the space utilization efficiency of laser light is improved, the output of the combined laser light source is increased, and the number of parts is reduced and the cost can be reduced. .

Further, one multimode optical fiber 13 is provided on the laser beam emitting side of the collimator lens array 184.
0 and a condenser lens 120 that condenses and combines the laser beam at the incident end of the multimode optical fiber 130.

With the above arrangement, the laser block 180,
Multiple multi-cavity lasers 1 arranged on 182
Each of the laser beams B emitted from each of the ten emission points 10a is collimated by the collimator lens array 184 and condensed by the condenser lens 120,
The light enters the core 130a of the multimode optical fiber 130. The laser light that has entered the core 130a propagates in the optical fiber, is combined into one, and is emitted.

As described above, this combined laser light source can achieve a particularly high output by arranging multi-cavity lasers in multiple stages and forming an array of collimator lenses. By using this combined laser light source, a fiber array light source or a bundle fiber light source with higher brightness can be formed, and thus it is particularly suitable as a fiber light source forming the laser light source of the exposure apparatus of the present invention.

It is possible to construct a laser module in which the above-mentioned combined laser light sources are housed in a casing and the emission end of the multimode optical fiber 130 is pulled out from the casing.

In the above embodiment, another optical fiber having the same core diameter as that of the multimode optical fiber and a cladding diameter smaller than that of the multimode optical fiber is provided at the exit end of the multimode optical fiber of the combined laser light source. Although an example in which the fiber diameter of the fiber array light source is increased by combining the above has been described, for example, the cladding diameter is 125 μm, 80 μm, 6
A multimode optical fiber such as 0 μm may be used without coupling another optical fiber to the output end.

[Light Quantity Distribution Correction Optical System] In the above embodiment, the light quantity distribution correction optical system including a pair of combination lenses is used in the exposure head. This light quantity distribution correction optical system changes the light flux width at each emission position so that the ratio of the light flux width of the peripheral portion to the light flux width of the central portion near the optical axis is smaller on the emission side than on the incident side. When the parallel light flux from the light source is applied to the DMD, the light amount distribution on the illuminated surface is corrected so as to be substantially uniform. The operation of this light quantity distribution correction optical system will be described below.

First, as shown in FIG. 25A, the entire luminous flux width (total luminous flux width) H of the incident luminous flux and the outgoing luminous flux.
A case where 0 and H1 are the same will be described. Note that, in FIG. 25A, the portions indicated by reference numerals 51 and 52 are
2 is a view virtually showing an entrance surface and an exit surface in a light quantity distribution correction optical system.

In the optical system for correcting light quantity distribution, it is assumed that the luminous flux widths h0 and h1 of the luminous flux incident on the central portion close to the optical axis Z1 and the luminous flux incident on the peripheral portion are the same (h0 = hl). ). The light amount distribution correction optical system expands the luminous flux width h0 of the central incident light flux with respect to the light having the same luminous flux width h0 and h1 on the incident side, and conversely with respect to the peripheral incident light flux. As a result, the light beam width h1 is reduced. That is, regarding the width h10 of the emitted light flux at the central portion and the width h11 of the emitted light flux at the peripheral portion,
Make sure that h11 <h10. Expressed by the ratio of the luminous flux width, the ratio “h11 / h10” of the luminous flux width of the peripheral portion to the luminous flux width of the central portion on the emission side is the ratio (h11 / h10) on the incident side.
It is smaller than (1 / h0 = 1) ((h11 /
h10) <1).

By changing the luminous flux width in this manner, the luminous flux in the central portion where the light amount distribution is normally large can be utilized to the peripheral portion where the light amount is insufficient,
As a whole, the light amount distribution on the irradiated surface is made substantially uniform without lowering the light use efficiency. The degree of homogenization is, for example,
The light amount unevenness in the effective area is set to be within 30%, preferably within 20%.

The operation and effect of such a light quantity distribution correcting optical system is the same when the entire luminous flux width is changed between the entrance side and the exit side (FIGS. 25B and 25C).

FIG. 25B shows the entire luminous flux width H on the incident side.
When 0 is “reduced” to the width H2 and emitted (H0> H
2) is shown. Even in such a case, the light amount distribution correction optical system has the same light flux widths h0 and h on the incident side.
The light having a value of 1 is changed to a luminous flux width h1 at the central portion on the emission side.
0 is made larger than that in the peripheral portion, and conversely, the luminous flux width h11 in the peripheral portion is made smaller than that in the central portion. Considering the reduction ratio of the luminous flux, the reduction ratio of the incident light flux at the central portion is made smaller than that of the peripheral portion, and the reduction ratio of the incident light flux at the peripheral portion is made larger than that of the central portion. Also in this case, the ratio “H11 / H10” of the luminous flux width of the peripheral portion to the luminous flux width of the central portion is
It is smaller than (1 / h0 = 1) ((h11 / h1
0) <1).

FIG. 25C shows the entire luminous flux width H on the incident side.
When 0 is “expanded” to the width Η3 and emitted (H0 <H
3) is shown. Even in such a case, the light amount distribution correction optical system has the same light flux widths h0 and h on the incident side.
The light having a value of 1 is changed to a luminous flux width h1 at the central portion on the emission side.
0 is made larger than that in the peripheral portion, and conversely, the luminous flux width h11 in the peripheral portion is made smaller than that in the central portion. Considering the expansion ratio of the light flux, the expansion ratio for the incident light flux at the central portion is made larger than that at the peripheral portion, and the expansion ratio for the incident light flux at the peripheral portion is made smaller than at the central portion. Also in this case, the ratio “h11 / h10” of the luminous flux width of the peripheral portion to the luminous flux width of the central portion is equal to the ratio (h11 / h10) on the incident side.
It is smaller than (1 / h0 = 1) ((h11 / h1
0) <1).

As described above, the light quantity distribution correcting optical system changes the luminous flux width at each emission position, and the ratio of the peripheral luminous flux width to the central luminous flux width near the optical axis Z1 is larger than that on the incident side. Since the light flux with the same luminous flux width on the incident side has a larger luminous flux width on the exit side, the luminous flux width at the central portion is larger than that at the peripheral portion, and the luminous flux width at the peripheral portion is smaller than that at the central portion. Will be smaller than. This makes it possible to utilize the light flux in the central portion to the peripheral portion, and to form a light flux cross section with a substantially uniform light amount distribution without reducing the light utilization efficiency of the optical system as a whole.

Next, an example of specific lens data of a pair of combination lenses used as a light amount distribution correcting optical system will be shown. This example shows lens data when the light amount distribution in the cross section of the emitted light flux is a Gaussian distribution, as in the case where the light source is a laser array light source. When one semiconductor laser is connected to the incident end of the single mode optical fiber, the light quantity distribution of the light flux emitted from the optical fiber becomes a Gaussian distribution. The present embodiment can be applied to such a case. Further, the present invention is also applicable to the case where the amount of light in the central portion close to the optical axis is larger than the amount of light in the peripheral portion by reducing the core diameter of the multimode optical fiber to approach the configuration of the single mode optical fiber.

Table 1 below shows basic lens data.

[0121]

[Table 1]

As can be seen from Table 1, the pair of compound lenses is composed of two rotationally symmetric aspherical lenses. When the surface on the light incident side of the first lens arranged on the light incident side is the first surface and the surface on the light emitting side is the second surface, the first surface has an aspherical shape. When the surface on the light incident side of the second lens arranged on the light emitting side is the third surface and the surface on the light emitting side is the fourth surface, the fourth surface has an aspherical shape.

In Table 1, the surface number Si is the i-th (i =
1 to 4), the radius of curvature ri represents the radius of curvature of the i-th surface, and the surface distance di represents the surface distance between the i-th surface and the (i + 1) th surface on the optical axis. The unit of the surface distance di value is millimeter (mm). The refractive index Ni represents the value of the refractive index for the wavelength 405 nm of the optical element having the i-th surface.

Table 2 below shows aspherical surface data of the first and fourth surfaces.

[0125]

[Table 2]

The above aspherical surface data is represented by the coefficient in the following expression (A) representing the aspherical surface shape.

[0127]

[Equation 1]

In the above equation (A), each coefficient is defined as follows. Z: The length (mm) of a perpendicular line drawn from a point on the aspherical surface located at a height ρ from the optical axis to the tangent plane (the plane perpendicular to the optical axis) at the apex of the aspherical surface ρ: From the optical axis Distance (mm) K: Cone coefficient C: Paraxial curvature (1 / r, r: Paraxial radius of curvature) ai: Aspheric coefficient of the i-th order (i = 3 to 10) Symbol in the values shown in Table 2 "E" indicates that the number following it is a "base index" with a base of 10. The number represented by an exponential function with a base of 10 is multiplied by the number before "E". Indicates that For example,
If "1.0E-02", it means "1.0x10-2".

FIG. 27 shows the light quantity distribution of the illumination light obtained by the pair of combination lenses shown in Tables 1 and 2. The horizontal axis shows the coordinates from the optical axis, and the vertical axis shows the light amount ratio (%). For comparison, FIG. 26 shows a light amount distribution (Gaussian distribution) of illumination light when no correction is performed. As can be seen from FIGS. 26 and 27, by performing the correction with the light amount distribution correction optical system, a substantially uniform light amount distribution is obtained as compared with the case where the correction is not performed. As a result, it is possible to perform uniform exposure with a uniform laser beam without reducing the light utilization efficiency of the exposure head.

[Other Imaging Optical Systems] In the above-mentioned embodiment, two sets of lenses are arranged as the imaging optical system on the light reflecting side of the DMD used for the exposure head. An image forming optical system for forming an image may be arranged. By enlarging the cross-sectional area of the luminous flux reflected by the DMD, the exposure area area (image area) on the exposed surface can be enlarged to a desired size.

For example, as shown in FIG. 31A, the exposure head DMD 50, the illumination device 144 for irradiating the DMD 50 with the laser beam, and the lens system 454 for enlarging the laser beam reflected by the DMD 50 to form an image. 458, DMD50
, A microlens array 472 in which a large number of microlenses 474 are arranged corresponding to the respective pixels, an aperture array 476 in which a large number of apertures 478 are provided corresponding to the respective microlenses of the microlens array 472, and a laser which has passed through the apertures. It can be configured with lens systems 480 and 482 that image light on the exposed surface 56.

In this exposure head, when laser light is emitted from the illuminating device 144, the cross-sectional areas of the light flux lines reflected in the ON direction by the DMD 50 have lens systems 454 and 458.
Is enlarged several times (for example, twice). The magnified laser light is condensed by each microlens of the microlens array 472 corresponding to each pixel of the DMD 50,
It passes through the corresponding apertures in aperture array 476. The laser light that has passed through the aperture is reflected by the lens system 48.
An image is formed on the exposed surface 56 by 0 and 482.

In this imaging optical system, the laser light reflected by the DMD 50 is magnified several times by the magnifying lenses 454 and 458 and projected on the exposed surface 56, so that the entire image area is widened. At this time, if the microlens array 472 and the aperture array 476 are not arranged, as shown in FIG. 31B, one pixel size (spot size) of each beam spot BS projected on the exposed surface 56 is exposed. The MTF becomes larger according to the size of the area 468 and represents the sharpness of the exposure area 468.
(Modulation Transfer Function) characteristics deteriorate.

On the other hand, when the microlens array 472 and the aperture array 476 are arranged, the DMD50
The laser light reflected by the microlens array 4
The microlenses 72 collect light corresponding to the pixels of the DMD 50. Thereby, as shown in FIG. 31C, even if the exposure area is enlarged, the spot size of each beam spot BS is set to a desired size (for example, 1).
It is possible to reduce the size to 0 μm × 10 μm), prevent deterioration of MTF characteristics, and perform high-definition exposure. The exposure area 468 is tilted because the DMD 50 is tilted in order to eliminate a gap between pixels.

Further, even if the beam is thickened by the aberration of the microlens, the beam can be shaped by the aperture so that the spot size on the exposed surface 56 becomes a constant size, and at the same time, each pixel can be shaped. Crosstalk between adjacent pixels can be prevented by passing through the aperture provided correspondingly.

Furthermore, by using the high-intensity light source for the illumination device 144 as in the above embodiment, the lens 458 is obtained.
Since the angle of the light flux incident on each microlens of the microlens array 472 becomes small, it is possible to prevent a part of the light flux of the adjacent pixel from entering. That is, a high extinction ratio can be realized.

[0137]

The stereolithography apparatus of the present invention has an effect that high-speed molding can be performed.

When a high-brightness light source is used as the light source, there is an effect that high-definition modeling can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a stereolithography apparatus according to a first embodiment.

FIG. 2 is a perspective view showing a configuration of a scanner of the optical modeling apparatus according to the first embodiment.

FIG. 3A is a plan view showing an exposed area formed on a liquid surface, and FIG. 3B is a view showing an arrangement of exposure areas by each exposure head.

FIG. 4 is a perspective view showing a schematic configuration of an exposure head of the stereolithography apparatus according to the first embodiment.

5A is a cross-sectional view taken along the optical axis in the sub-scanning direction, showing the configuration of the exposure head shown in FIG. 4, and FIG.
FIG.

FIG. 6 is a partially enlarged view showing the configuration of a digital micromirror device (DMD).

FIGS. 7A and 7B are explanatory diagrams for explaining the operation of the DMD.

FIGS. 8A and 8B are plan views showing the arrangement of the exposure beam and the scanning line in comparison between the case where the DMD is not tilted and the case where the DMD is tilted.

9A is a perspective view showing a configuration of a fiber array light source, FIG. 9B is a partially enlarged view of FIG. 9A, and FIGS. 9C and 9D show an array of light emitting points in a laser emitting portion. It is a top view shown.

FIG. 10 is a diagram showing a configuration of a multimode optical fiber.

FIG. 11 is a plan view showing a configuration of a combined laser light source.

FIG. 12 is a plan view showing the configuration of a laser module.

13 is a side view showing the configuration of the laser module shown in FIG.

FIG. 14 is a partial side view showing the configuration of the laser module shown in FIG.

15A and 15B are cross-sectional views taken along the optical axis showing the difference between the depth of focus in the conventional exposure head and the depth of focus in the exposure head of the optical modeling apparatus according to the first embodiment. Is.

16A and 16B are diagrams showing an example of a DMD usage area;

FIG. 17A is a side view when the DMD usage area is appropriate, and FIG. 17B is a cross-sectional view in the sub-scanning direction along the optical axis of FIG.

FIG. 18 is a plan view for explaining an exposure method in which the entire liquid surface of the photocurable resin is exposed by one scanning with the scanner.

19A and 19B are plan views for explaining an exposure method in which the entire liquid surface of the photocurable resin is exposed by scanning a scanner a plurality of times.

FIG. 20 is a perspective view showing a configuration of a laser array.

21A is a perspective view showing a configuration of a multi-cavity laser, and FIG. 21B is a perspective view of a multi-cavity laser array in which the multi-cavity lasers shown in FIG.

FIG. 22 is a plan view showing another configuration of the combined laser light source.

FIG. 23 is a plan view showing another configuration of the combined laser light source.

24A is a plan view showing another configuration of the combined laser light source, and FIG. 24B is a sectional view taken along the optical axis of FIG.

FIG. 25 is an explanatory diagram of a concept of correction by a light amount distribution correction optical system.

FIG. 26 is a graph showing a light amount distribution when the light source has a Gaussian distribution and the light amount distribution is not corrected.

FIG. 27 is a graph showing a light quantity distribution after correction by a light quantity distribution correction optical system.

FIG. 28 is a perspective view showing a configuration of a conventional laser scanning type additive manufacturing apparatus.

FIG. 29 is a perspective view showing a configuration of a conventional movable mirror type additive manufacturing apparatus.

30A is a plan view showing an example of an exposure pattern of an exposure region, FIG. 30B is a perspective view showing a state after the pixels of the first group of FIG. (C) is a perspective view showing a state after exposing the pixels of the second group of (A).

FIG. 31 (A) is a sectional view taken along the optical axis showing the configuration of another exposure head having a different coupling optical system, and FIG. 31 (B) is projected onto the exposed surface when a microlens array or the like is not used. FIG. 6C is a plan view showing a light image that is projected, and FIG. 6C is a plan view showing a light image that is projected onto the exposed surface when a microlens array or the like is used.

[Explanation of symbols]

LD1 to LD7 GaN semiconductor laser 10 heat block 11-17 Collimator lens 20 Condensing lens 30 multimode optical fiber 50 Digital Micromirror Device (DMD) 53 Reflected light image (exposure beam) 54, 58 lens system 56 Scanning surface (exposed surface) 64 laser module 66 Fiber array light source 68 Laser emission part 73 Combination lens 150 Light curable resin 152 Lifting stage 156 containers 158 Guide 162 scanner 166 exposure head 168 exposure area 170 Exposed area

Continued front page    (72) Inventor Yoji Okazaki             798 Miyadai, Kaisei-cho, Ashigarakami-gun, Kanagawa Prefecture             Shishi Film Co., Ltd. (72) Inventor Hiromi Ishikawa             798 Miyadai, Kaisei-cho, Ashigarakami-gun, Kanagawa Prefecture             Shishi Film Co., Ltd. (72) Inventor Takeshi Fujii             798 Miyadai, Kaisei-cho, Ashigarakami-gun, Kanagawa Prefecture             Shishi Film Co., Ltd. (72) Inventor Hiromitsu Yamakawa             1-324 Uetakecho, Saitama City, Saitama Prefecture             Fuji Photo Optical Co., Ltd. F-term (reference) 4F213 AA44 AC05 WL03 WL13 WL23                       WL37 WL43 WL50 WL75 WL76                       WL80 WL85 WL87 WL92 WL96

Claims (5)

[Claims] 1. A molding tank for accommodating a photocurable resin, a support stand for supporting a molded object which is provided in the molding tank so as to be able to move up and down, a laser device for irradiating a laser beam, and control signals respectively. A plurality of pixel portions whose light modulation state changes according to the two-dimensionally arranged on the substrate, the spatial light modulator for modulating the laser light emitted from the laser device, and the pixels arranged on the substrate Control means for controlling each of a plurality of pixel parts of which the number is smaller than the total number of parts by a control signal generated according to the exposure information, and a laser beam modulated by each pixel part is stored in the modeling tank. An optical modeling apparatus comprising: an exposure head including an optical system that forms an image on the liquid surface of a curable resin; and a moving unit that relatively moves the exposure head with respect to the liquid surface of the photocurable resin. 2. The pixel section controlled by the control means comprises:
The stereolithography apparatus according to claim 1, wherein the stereolithography device is a pixel unit included in a region having a length in a direction corresponding to a predetermined direction longer than a length in a direction intersecting with the predetermined direction. 3. The laser device is provided with a plurality of fiber light sources for emitting laser light incident from an incident end of an optical fiber from an emission end thereof, each light emitting point at the emission end of the plurality of fiber light sources being an array. The optical modeling apparatus according to claim 1 or 2, comprising fiber array light sources arranged in a matrix or fiber bundle light sources arranged in a bundle. 4. The optical modeling apparatus according to claim 3, wherein the optical fiber is an optical fiber having a uniform core diameter and a cladding diameter at an emitting end smaller than a cladding diameter at an incident end. 5. The fiber light source according to the following (1) to (3)
The optical modeling apparatus according to claim 3, wherein the optical modeling apparatus is configured by any one of the fiber light sources. (1) Condensing optics for condensing a plurality of semiconductor lasers, one optical fiber, and laser beams emitted from each of the plurality of semiconductor lasers, and coupling the condensing beams to an incident end of the optical fiber. The semiconductor laser of the fiber light source (2) (1) provided with the system is a multi-cavity laser having a plurality of emission points, and the fiber light source (3) a multi-cavity laser having a plurality of emission points and one light A fiber light source including a fiber and a condensing optical system that condenses a laser beam emitted from each of the plurality of light emitting points and couples the condensing beam to an incident end of the optical fiber.