JP2000238137A - Apparatus and method for conducting stereolithography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately conduct a stereolithography of a three-dimensional article. SOLUTION: The apparatus 1 for conducting a stereolithography comprises a resin storage tank 21 for storing liquid-like photo-setting resin 23, a light source 11 for emitting a luminous flux 12, a luminous flux scanning means 30 for scanning a luminous flux 14, and a lens 51 for focusing the resin 23 with the luminous flux 14b, and conducts the stereolithography of a desire stereoscopic shape by laminating a resin cured layer by repeating the step of forming the resin cured layer of a predetermined surface-like pattern by scanning the flux 14b by the means 30. In this case, the apparatus comprises a luminous flux power control means 40 for suppressing a change of power of the flux 14b, a focus position detecting means for detecting a focal position of the flux 14b, a focus position control means 50 for moving the focus of the flux to a predetermined position, and a luminous flux scanning speed control means for suppressing a change of the speed, thereby individually controlling the means 40, 50 and the scanning speed control means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resin cured layer having a predetermined planar pattern by irradiating a liquid light curable resin in a resin storage tank with a light beam focused by a lens and scanning the light beam. The present invention relates to an optical shaping apparatus and an optical shaping method for forming a three-dimensional three-dimensional shape by repeating a process and stacking resin cured layers.

[0002]

2. Description of the Related Art Conventionally, it is possible to easily and inexpensively mold a three-dimensional shape designed arbitrarily, and to quickly confirm design specifications. Also, it is difficult to mold using a conventional molding method using a mold. Or, by scanning the liquid photocurable resin while irradiating it with a light beam, the product can be developed quickly and inexpensively in response to complicated three-dimensional shapes that were impossible. An optical shaping device for shaping has been developed.

[0003] Such an optical shaping apparatus has, for example, a structure as shown in FIG. 10.
Liquid photocurable resin 102 that cures when irradiated with ultraviolet light
, A horizontal plate-shaped stage 104 disposed in the resin storage tank 101, an elevator 103 for driving the stage 104 up and down, and a laser beam 107 having a wavelength in the ultraviolet region. Curable resin 102
, And a modeling controller 108 for controlling the operations of the beam scanner 106 and the elevator 103.

Here, shape data (cross-sectional slice data) of each cross section obtained by slicing a desired three-dimensional solid into a plurality of layers with a predetermined thickness is input to the shaping controller 108. Scanner 1
The operation 06 is controlled by the modeling controller 108 based on the slice data.

[0005] In order to form a desired three-dimensional solid by the optical shaping apparatus, first, the stage 104 is moved to an initial position indicated by a solid line in FIG. Here, the initial position of the stage 104 is set at a position lower than the liquid surface 102a of the liquid photocurable resin 102 by a predetermined thickness, that is, a position lower by the unit resin layer thickness, and the laser beam irradiated from the beam scanner 106 is used. 1
07 is regulated by the stage 104 and the liquid level 102
a, the liquid photocurable resin 102 in the region between the stages 104
Is cured to form a first cured layer having a predetermined thickness.

At this time, the beam scanner 106 is controlled by the molding controller 108 to
Is scanned according to the slice data of the first layer, and a first cured resin layer (hereinafter, also simply referred to as a cured layer) is formed in a predetermined shape. Next, the stage 104 is moved downward by a predetermined thickness by the elevator 103.
At this time, the first cured layer moves downward by a predetermined thickness together with the stage 104, so that the liquid photocurable resin 10
2 flows into the first hardened layer, and a region sandwiched between the liquid surface 102a and the upper surface of the first hardened layer is formed as a second hardened layer with a predetermined thickness.

At this time, similarly to the first layer, the laser beam 107 is scanned by the beam scanner 106 in accordance with the slice data of the second layer to form a second hardened layer into a predetermined shape. In this case, the second hardened layer is the first hardened layer.
To the upper surface of the cured layer. Thereafter, each layer is formed based on the cross-sectional slice data in accordance with the above-described procedure, and the stage 104 moves to the final position indicated by the two-dot chain line in the figure to form the uppermost hardened layer and form a three-dimensional structure. The shaping of the shape is completed.

[0008] As described above, a method of forming a hardened layer one by one while irradiating a laser beam 107 from above to the liquid photo-curable resin 102 stored in the resin storage tank 101 is generally a free liquid surface. Called the scheme. In addition, in addition to such a free liquid surface type, a conventional stereolithography apparatus includes a liquid photocurable resin in a resin storage tank having a transmission window through which laser light is transmitted at a bottom portion, through a transmission window from below. There is a method called a regulated liquid level method in which a laser beam is irradiated to perform modeling. As an apparatus of the regulated liquid level system, for example, there is an apparatus shown in FIG. 11, and this apparatus is provided with a resin storage tank 111 storing a liquid photo-curable resin 112 and a resin storage tank 111 disposed in the resin storage tank 111 as shown in the figure. Horizontal stage 114
, An elevator 113 having a moving means 113 a to move up and down the stage 114, a light source 119 for irradiating a laser beam 117, and a beam scanner 116 disposed below the resin storage tank 111. .

Here, an opening is provided at the bottom of the resin storage tank 111, and the laser light 117
Window 118 such as a quartz glass plate through which light can pass.
Is installed. Also, the beam scanner 116 is
The deflector 116a is provided with a deflector 116a and a lens 116b.
Through the transmission window 118 by the lens 116b.
Is focused on the liquid photocurable resin 112 via The deflector 116a and the lens 116b can move integrally in the left-right direction, and the laser beam 117 can be scanned by moving the deflector 116a and the lens 116b.

The stereolithography apparatus is provided with a modeling controller (not shown). The modeling controller has a shape of each cross section obtained by slicing a desired three-dimensional solid into a plurality of layers with a predetermined thickness. Data (section slice data) has been input. The operations of the beam scanner 116 and the elevator 113 are controlled by the modeling controller based on the slice data.

Therefore, under the control of the shaping controller, the laser beam 117 is scanned by the beam scanner 116, and a hardened layer having a predetermined shape is formed one by one. At this time, since the laser beam 117 is regulated by the stage 114, the gap 1 between the stage 114 and the transmission window 118 is
20 determines the thickness of the cured layer. Each time the shaping of the hardened layer is completed, the stage 114 is moved to the elevator 1
13 to move the stage 11 up by a predetermined thickness.
By laminating this hardened layer on the lower surface of 4, a desired three-dimensional three-dimensional shape is finally formed.

As described above, in any of the conventional stereolithography apparatuses using the free liquid level system and the regulated liquid level system, a plurality of cured layers are superimposed to form a three-dimensional three-dimensional shape. In order to form an original solid, it is necessary to reduce the thickness of one cured layer and to improve the accuracy of this thickness. Here, the maximum height Zmax of the unit resin layer thickness formed when the liquid photocurable resin is scanned at a constant speed while irradiating the liquid photocurable resin with the power (laser power) P (W) of the light beam and the laser scanning speed ( Hereinafter, it is simply referred to as a scanning speed) v (m / s), the spot diameter w (m) of the laser beam on the liquid surface of the liquid photo-curable resin, the absorption coefficient α (m ^-1 ) of the liquid curable resin, and the critical curing. Energy density u _C (J
/ M ² ) can be analytically determined by the following equation (1).

Zmax = α ⁻¹ {ln [(2 / π) ^0.5 P / (v · w)] · ln (u _C )} (1) Here, each parameter α, P in equation (1) , V,
Assuming that w and u _C are independent of each other, and that the absorption coefficient α and the critical curing energy density u _C that represent the characteristics of the liquid photocurable resin are constant, the maximum height Zmax of the unit resin layer thickness is equal to that of the laser. It depends only on the power P, the laser scanning speed v, and the laser spot diameter w.

Then, by differentiating both sides of the above equation (1), an equation (2) showing the relationship between the parameters P, v, w and the variation δZmax of the unit resin layer thickness maximum height Zmax is obtained. Can be δZmax ≦ α ⁻¹ (| δP / P | + | δv / v | + | δw / w |) (2) As can be seen from the equation (2), the variation δZ
In order to form a three-dimensional solid with high accuracy by reducing max, the absorption coefficient α representing the characteristics of the liquid photocurable resin is increased, or the laser power P, the laser scanning speed v, and the laser spot diameter w. In this case, various techniques for forming a three-dimensional solid with high precision have been developed from this point of view.

For example, by mixing a liquid photocurable resin with a medium capable of absorbing laser light such as ink (hereinafter simply referred to as an absorption medium), the absorption coefficient α is increased, and the maximum height of the unit resin layer thickness is increased. There is a technique for reducing the variation Zmax and suppressing the variation δZmax (prior art 1). By increasing the absorption coefficient α in this manner, the maximum height Zmax of the unit resin layer thickness and its variation δ
Zmax can be suppressed in inverse proportion to the absorption coefficient α.

Japanese Patent No. 2676838 discloses a deflector for scanning a laser beam, a focus corrector for focusing a laser beam on a liquid surface of a liquid photocurable resin,
There is disclosed an optical shaping apparatus including an AOM (acoustic optical modulation element) for adjusting a laser power P of a laser beam and control means for controlling the AOM (Prior Art 2).

Here, the deflector is composed of, for example, a galvanometer mirror, and scans the laser beam in an arbitrary direction by moving the angle of the deflector to deflect the irradiation direction of the laser beam. Therefore, the changing speed of the angle of the deflector determines the scanning speed v of the laser beam. Further, the focus corrector performs laser beam focusing to focus on the liquid surface of the liquid photocurable resin in accordance with the change in the angle of the deflector. That is, the diameter (spot diameter) w of the laser light on the liquid surface of the liquid photocurable resin is adjusted.

The control of the scanning speed v (the angle control of the deflector), the focusing of the laser beam (the control of the spot diameter w), and the control of the laser power P are respectively feedback-controlled by the control means. . That is, regarding the angle control of the deflector, the angle of the deflector is adjusted so that the laser beam scans at a predetermined scanning speed on a scanning line based on the three-dimensional solid cross-sectional slice data input to the control means in advance. Are sequentially detected to confirm the current position (position information) of the laser light, and the current position of the laser light is compared with a predetermined scanning line, so that the angle of the deflector is feedback-controlled. .

In focusing of the laser beam, the XY coordinate values (the liquid surface position of the liquid photocurable resin) of the laser beam are sequentially calculated from the angle information of the deflector, The data on the focus correction value at each point of the -Y coordinate is compared, and the feedback control is performed by driving the focus corrector based on the data.

Further, the laser power P is controlled by the AOM so that the product of the laser power P and the scanning speed v is always constant. Here, the scanning speed v
Calculates the XY coordinate value of the laser beam from the angle information of the deflector, and sequentially calculates the XY coordinate value from the change amount of the XY coordinate value in a predetermined time.

[0021]

However, the above-mentioned prior art 1 and prior art 2 have the following problems, respectively. That is, in the prior art 1, as described above, the maximum height Zmax of the unit resin layer thickness and the variation δZma
In order to reduce x, the absorption coefficient α is increased by mixing an absorbing medium with the liquid photocurable resin. According to this, the maximum height Zmax and the variation δZmax are calculated by the above-mentioned equation ( As shown in (1) and (2), both decrease in inverse proportion to the absorption coefficient α, so that the ratio (δZmax / Zmax) between the maximum height Zmax and the variation δZmax does not change.
That is, even if the fluctuation amount δZmax is suppressed, the maximum height Zmax is also reduced, and the desired three-dimensional three-dimensional shape is formed by being divided into more layers. Therefore, the improvement in the accuracy of each layer is offset by the increase in the number of layers, and the fluctuation amount of the entire three-dimensional solid derived by multiplying the number of layers forming the three-dimensional three-dimensional shape by the fluctuation amount δZmax does not change. There is a problem that the accuracy does not improve without the need.

Further, the liquid photocurable resin generally has a high viscosity in general, and it is difficult to uniformly mix the absorbing medium with the liquid photocurable resin. For this reason, there is also a problem that unevenness occurs in the concentration of the absorbing medium and the absorption coefficient of the liquid photocurable resin varies. Further, in the prior art 2, unlike the prior art 1, by controlling the laser power P of the laser beam, the laser scanning speed v, and the laser spot diameter w,
It is possible to independently control the maximum height Zmax and the variation δZmax of the unit resin layer thickness. Therefore, the ratio (δZmax / Z) between the maximum height Zmax and the variation δZmax
max), thereby substantially improving the accuracy of the three-dimensional solid.

However, in the prior art 2, AO
There is a problem that a large amount of time is required for the calculation time required for the feedback control between the M and the focus corrector, which causes a control delay and deteriorates the modeling accuracy of the three-dimensional shape.
That is, the control of the laser spot diameter w is performed by calculating the X-Y coordinate value of the laser beam being irradiated from the angle information of the deflector as described above, and performing focus correction according to a correction value created in advance based on the result. Since the deflector is driven, it takes a long time from when the angle of the deflector is detected to when the focus corrector is driven. Therefore, when the focus is corrected by the focus corrector, the laser light has already moved largely from the XY coordinate values used for the calculation for this correction. Therefore, there is a considerable difference between this correction and the correction that should be performed when the focus corrector is actually driven and the laser beam is focused.

The control of the laser power P is performed so that the product of the laser power P and the laser beam scanning speed v is always constant as described above. Therefore, first, the XY coordinate value of the laser light is calculated based on the position (angle) information of the deflector, and the laser light scanning speed v is calculated from the displacement amount of the XY coordinate value in a predetermined time. After calculating the laser power P from the laser beam scanning speed v,
Control is performed by the AOM. Therefore, as in the case of the focus corrector, a great amount of time is required from when the angle of the deflector is detected to when the laser power P is corrected, and this correction and the time when the control is actually performed by the AOM are performed. Therefore, there is still a difference from the correction that should be performed.

In order to solve such a problem of the prior art 2, Japanese Patent Application Laid-Open No. 9-99490 discloses that data of a laser beam scanning speed v at an arbitrary intermediate point is calculated in advance from cross-sectional slice data. There is disclosed a technology (prior art 3) for predictively controlling each control target (focus corrector, AOM) based on the data of the laser beam scanning speed v to prevent a control delay. However, even if each control target is predictively controlled in this way, when an environmental disturbance such as a vibration or a temperature change occurs during the formation of a three-dimensional solid, correction for such a sudden disturbance is performed. And the modeling accuracy may be reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical shaping apparatus and an optical shaping method capable of forming a three-dimensional solid with high accuracy. .

[0027]

According to the first aspect of the present invention, there is provided an optical forming apparatus according to the present invention, wherein a resin storage tank storing a liquid photocurable resin, a light source for emitting a light beam, and the light beam are scanned. A light beam scanning unit; and a lens for focusing the light beam on the liquid photocurable resin in the resin storage tank. The light beam converged by the lens and irradiated on the liquid photocurable resin is scanned with the light beam. The step of forming a resin cured layer having a predetermined planar pattern by scanning by means is repeated, and by laminating the resin cured layers, in an optical shaping apparatus for forming a desired three-dimensional shape, A light beam power control unit that suppresses fluctuations in the power of the light beam based on power detection information; a focus position detection unit that detects a focal position of the light beam focused by the lens; The Focus position control means for moving the focal point of the light beam to a predetermined position based on the information on the point position, and light beam scanning speed control means for suppressing fluctuation in the scanning speed based on detection information of the scanning speed of the light beam. The light beam power control means, the focus position control means, and the light beam scanning speed control means are individually controlled.

According to a second aspect of the present invention, there is provided an optical shaping apparatus according to the first aspect, wherein the light flux power control means is constituted by an acousto-optic element. According to a third aspect of the present invention, there is provided the stereolithography apparatus according to the first or second aspect, wherein the focal position detecting means detects the reflected light of the light flux reflected from the liquid surface of the liquid photocurable resin. A reflected light shape detecting means for detecting a shape is provided, and the focal position is detected by an astigmatism method based on a detection result from the reflected light shape detecting means.

According to a fourth aspect of the present invention, there is provided an optical shaping method according to the present invention, wherein a light beam is focused on a liquid photo-curable resin in a resin storage tank by a lens and irradiated, and the light beam is scanned to form a predetermined planar pattern. By repeating the step of forming a cured resin layer having, by laminating the cured resin layer, in a stereolithography method of molding a desired three-dimensional shape, at the time of irradiation of the light beam, based on detection information of the power of the light beam, Light beam power control for suppressing fluctuations in the light beam power, focus position control for moving the focal point of the light beam focused by the lens to a predetermined position based on detection information of the focus position of the light beam, and scanning speed of the light beam And light beam scanning speed control for suppressing fluctuations in the scanning speed of the light beam based on the detection information.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described. FIGS. 1 to 8 show a stereolithography apparatus and a stereolithography method as a first embodiment of the present invention.
Is a schematic diagram showing the overall configuration of the device, FIG. 2 is a diagram showing control signals output from the host computer, FIG. 3 is a schematic diagram showing the configuration and control blocks of the laser intensity stabilizing section, and FIG. FIG. 5 is a schematic view showing a configuration of a laser scanning unit and a control block, FIG. 5 is a schematic view from a top view showing a configuration of an autofocus unit and a modeling unit, and FIG. 6 is an autofocus unit together with a configuration of the autofocus unit and the modeling unit. FIG. 7 is a schematic diagram showing the control block of FIG.
FIG. 8 is a diagram showing a beam cross-sectional shape detected by the four-segmented photodetector, and FIG. 8 is a diagram showing a relationship between an intensity signal detected by the four-segmented photodetector and a relative position of a focal point with respect to a transmission window.

The stereolithography apparatus 1 according to the present embodiment is shown in FIG.
As shown in FIG. 1, a modeling part 20 having a resin storage tank 21 storing a liquid photo-curable resin 23 and a three-dimensional solid is formed.
A laser light source (light source) 11 that emits a laser beam (light beam) 12; a fold mirror 13 that reflects the laser beam 12 to be incident on a laser intensity stabilizing unit (light beam power control unit) 40; A first-order diffracted light 14a of a predetermined laser power (light flux power) from the laser beam (that is, to stabilize the laser power); and a beam diameter of the first-order diffracted light 14a from the laser intensity stabilizer 40 Beam expander 15
A fold mirror 16 that reflects the first-order diffracted light 14b whose beam diameter has been enlarged by the beam expander 15 and makes the first-order diffracted light 14b incident on an autofocus unit (focal position control means) 50; An autofocus unit 50 that focuses on the liquid photocurable resin 23 (that is, adjusts the focal position of the laser beam); an objective lens (lens) 51 disposed above the autofocus unit 50; And objective lens 5
1 is provided with a laser scanning unit (light beam scanning means) 30 on which the light emitting device 1 is mounted.

The objective lens 51 is a high-precision convex lens which removes the aberration of the lens to the utmost.
Can be condensed at one point (focal point) with high precision (to be focused on the liquid photo-curable resin 23).
Further, a beam expander 15 is provided, and the first-order diffracted light 1
The beam diameter of 4a is enlarged.
When the first-order diffracted light 14b is focused on the liquid photocurable resin 23 in the resin storage tank 21 by the objective lens 51 at the subsequent stage, the larger the beam diameter of the first-order diffracted light 14b, the more the first-order diffracted light 14b is converted by the objective lens 51. This is because it can be narrowed down.

As shown in FIG. 1, the X-axis, Y-axis and Z-axis directions are defined in the horizontal direction of the drawing, the direction perpendicular to the plane of the drawing, and the vertical direction, respectively. The axis, the Y axis, and the Z axis indicate this axial direction. As shown in FIG. 2, a host computer 67 is connected to the optical shaping apparatus 1 according to the present embodiment, and the host computer 67 has an arbitrarily set three-dimensional solid cross-sectional slice data (plane). Shape pattern) is stored. Then, control signals Rx, Ry, Sp0, and S0 based on the slice data are input from the host computer 67 to the laser scanning unit 30, the laser intensity stabilizing unit 40, and the autofocus unit 50.

The laser scanning unit 30 has a laser scanning speed v
Stage control devices (light beam scanning speed control means) 63X and 63Y (see FIG. 4) for suppressing the fluctuation of the position are provided with a position command signal Rx from the host computer 67. , Ry, the laser beam scanning speed v is controlled.

The laser intensity stabilizing section 40 is provided with a laser power control device 61 for controlling the laser power P (see FIG. 3).
1 is a reference power signal S from the host computer 67.
The laser power P is controlled based on p0. The autofocus unit 50 is provided with a comparator 66 (see FIG. 6) for controlling the focal position of the laser light (that is, for controlling the laser spot diameter w). The focal position of the first-order diffracted light 14b is controlled based on the reference focal position signal S0.

Further, as shown in FIG.
A target plate 24 is provided in the resin storage tank 21. The target plate 24 is controlled based on a control signal from a host computer 67, and moves up and down to a predetermined position. In addition, resin storage tank 2
1 has a transmission window 2 through which the first-order diffracted light 14b can pass.
The liquid photocurable resin 23 existing in a region sandwiched between the upper surface of the transmission window 22 and the lower surface of the target plate 24 is irradiated with the first-order diffracted light 14b to be cured. Therefore, by moving the target plate 24 to a predetermined position, a hardened layer having a predetermined thickness can be formed.

Therefore, the optical shaping apparatus 1 according to the present embodiment focuses the first-order diffracted light 14b on the liquid photocurable resin 23 in the resin storage tank 21 by the autofocus unit 50 based on the control signal from the host computer 67. At the same time, the laser beam is scanned by the laser scanning unit 30 at a predetermined speed. Is formed.
Then, each time the cured resin layer is formed, the target plate 24 is moved upward by a predetermined thickness of the resin layer, and the cured resin layer having a predetermined resin layer thickness and a predetermined planar pattern is laminated. The desired three-dimensional shape is formed.

Hereinafter, the modeling section 20, the laser intensity stabilizing section 4
0, the autofocus unit 50, and the laser scanning unit 30 will be described in more detail. First, the modeling part 20 will be described with reference to FIGS. 1, 5, and 6.
As described above, a resin storage tank 21 storing the liquid photocurable resin 23 is provided, and further, a lifting rod 25,
The elevator 26 includes an elevator 26 for raising and lowering the lifting rod 25 and a target plate 24 disposed inside the resin storage tank 21 and fixed to a lower end of the lifting rod 25. The elevator 26 is, for example, a stepping motor. The target plate 24 is moved up and down to a predetermined position based on a control signal from the host computer 67 by being driven by a simple actuator (not shown).

An opening is provided at the bottom of the resin storage tank 21, and a transmission window 22 through which the first-order diffracted light 14b can pass is provided in this opening. Then, the first-order diffracted light 14b from the objective lens 51 passes through the transmission window 22, and the liquid photocurable resin 23 existing in the region between the upper surface of the transmission window 22 and the lower surface of the target plate 24.
Is irradiated to cure.

Next, the laser intensity stabilizing unit 40 will be described. The laser intensity stabilizing unit 40, as shown in FIG.
AOM (acousto-optic modulation element) 41 for generating
Spatial filter 4 for extracting a diffracted light having a predetermined laser power (here, a first-order diffracted light 14a having the largest laser power) from higher-order diffracted lights 14 from M41
4, a half mirror 42 for sampling the power reference beam 14c from the first-order diffracted beam 14a, and a power reference beam 1
Photodetector 4 for detecting power signal Sp from 4c
3, a laser power control device 61, and an AOM drive amplifier 62.
Is used with grounding.

The intensity (laser power) of the high-order diffracted light 14 generated by the AOM 41 can be modulated by the AOM 41. Here, among the diffracted lights 14, one having the largest laser power is used. The next-order diffracted light 14a is extracted by the spatial filter 44. When the required laser power is small, a high-order diffracted light having a smaller laser power than the first-order diffracted light 14a may be extracted from the high-order diffracted light 14 generated by the AOM 41.

The laser power controller 61 receives the power signal Sp from the photodetector 43 and receives the reference power signal Sp0 from the host computer 67 as described above. Then, the laser power control device 61 outputs these signals Sp,
A power fluctuation signal δSp indicating the difference of Sp0 is output to the AOM drive amplifier 62.

The AOM drive amplifier 62 amplifies the power fluctuation signal δSp and outputs it to the AOM 41.
Feedback control is performed based on this signal. That is, the power signal Sp and the reference power signal S
The power fluctuation signal δSp is controlled to be equal to p0 and the power fluctuation signal δSp becomes 0, so that the first-order diffracted light 14a output from the laser intensity stabilizing unit 40 is always stabilized at a predetermined laser power. It is.

Further, by setting the reference power signal Sp0 to zero, the output of the diffracted light 14 from the AOM 41 can be instantaneously turned off. Accordingly, it is possible to perform ON / OFF timing control (switching ON / OFF switching) of the laser power on the order of nano (10 ⁻⁹ ) seconds, and to perform modeling with high accuracy.

AOM 41 is a crystal (lithium niobate or quartz) that can easily convert an electric signal into a surface acoustic wave.
An electrode is attached to one end of the crystal. When an electric signal of about several hundred kHz is applied to this electrode, a standing wave is generated inside the crystal, and this standing wave spatially changes the density inside the crystal. As a result, the AOM 41 can be used as a transmission type diffraction grating, and when the laser beam 12 passes through the AOM 41, a high-order diffracted light 14 is generated. By changing the amplitude of the electric signal applied to the electrode, the contrast of the density change inside the crystal can be adjusted, so that the laser power of the diffracted light 14 emitted from the AOM 41 can be electrically and easily controlled. It is becoming.

Next, the laser scanning unit 30 will be described. As described above, the laser scanning unit 30
1 is mounted, and the first-order diffracted light 14b emitted from the objective lens 51 can be arbitrarily scanned by moving the laser scanning unit 30 to an arbitrary plane position. Here, as shown in FIG. 4, the laser scanning unit 30 includes stage bodies 31X and 31Y movable in directions orthogonal to each other using a ball screw as a feed mechanism and a rolling guide as a guide mechanism. It is configured as a stage (XY stage) that can move in two Y-axis directions. The stage main bodies 31X and 31Y include DC servo motors 32X and 32Y for driving the stage main bodies 31X and 31Y, respectively, and the stage main bodies 31X and 31Y.
Position detectors 33X and 33Y such as, for example, linear encoders for detecting the position are provided.

The stage bodies 31X and 31Y using such ball screws and rolling guides can be manufactured, for example, with a straightness of about 1 μm for a stroke of about 100 mm at present, and have extremely high precision. Has excellent athletic performance. Therefore, it is possible to easily obtain one that can scan the primary diffraction light 14b emitted from the objective lens 51 with high accuracy.

Further, the DC servo motors 32X and 32Y for driving the stage bodies 31X and 31Y are actuators excellent in constant speed controllability that can be rotated at a rotational speed proportional to the applied voltage. The scanning speed of the primary diffracted light 14b emitted from the objective lens 51 can be controlled with high accuracy by moving the object under constant velocity motion.

The laser scanning unit 30 further includes a stage control device (light beam scanning speed control means) 63X, 63
Y and motor amplifiers 64X and 64Y are provided. Here, the position signals P from the position detectors 33X and 33Y are supplied to the stage controllers 63X and 63Y, respectively.
x and Py are input and the host computer 6
7, position command signals Rx and Ry are input.

The stage controller 63X receives the position signal Px
And the position command signal Rx, and these signals Px,
The position error signal δPx indicating the difference between Rx is
X. Similarly, the stage control device 63Y outputs a position error signal δPy indicating the difference between the position signal Py and the position command signal Ry to the motor amplifier 64Y.

The motor amplifiers 64X and 64Y amplify the position error signals δPx and δPy and
X, 32Y to apply DC servo motors 32X, 32Y
Rotates at a rotational speed corresponding to the position error signals δPx and δPy to drive the stage bodies 31X and 31Y. Therefore, the stage bodies 31X, 3
The position of 1Y is feedback-controlled with high accuracy.
Thereby, the moving speed of the stage main bodies 31X and 31Y,
That is, the laser beam scanning speed v is controlled with high accuracy.

Next, the autofocus section 50 will be described with reference to FIGS. The auto focus unit 50
As shown in FIGS. 5 and 6, an objective lens 51 having an objective lens driving device 60 is mounted, and a fold mirror 1 is provided.
6 (see FIG. 1), the first-order diffracted light 14b
A fold mirror 52 that reflects light to the wave plate 53, a λ / 2 wave plate 53 that rotates the polarization plane of the first-order diffracted light 14 b so as to match the reflection polarization plane of the subsequent polarization beam splitter 54, and a polarization beam splitter 54. λ / 4 wavelength plate 5
5, a fold mirror 56, a condenser lens 57, a cylindrical lens 58, and a four-divided photodetector (reflected light shape detecting means) 59. Although not shown, the photodetector 43 of the laser intensity stabilizing unit 40
Similarly to (see FIG. 3), the four-divided photodetector 59 is used by grounding.

Here, as shown in FIG. 5, the first-order diffracted light 14b incident on the polarization beam splitter 54 is
The λ / 4 wavelength plate 55 changes the polarization plane of the incident first-order diffracted light 14b from linearly polarized light to circularly polarized light. Then, as shown in FIG. 6, the first-order diffracted light 14b converted into circularly polarized light by the polarization beam splitter 54 is reflected by the fold mirror 56, and enters the objective lens 51 located above the fold mirror 56, and The liquid photocurable resin 2 in the resin storage tank 21 is
3 is focused.

Here, a part of the first-order diffracted light 14b focused on the liquid photocurable resin 23 is reflected at the interface between the transmission window 22 and the liquid photocurable resin 23, and the reflected light 14e
Is λ / through the objective lens 51 and the fold mirror 56.
The light passes through the four-wavelength plate 55 again, and is converted from circularly polarized light into linearly polarized light. Since the plane of polarization of the linearly polarized light coincides with the plane of polarization of the transmission direction of the polarization beam splitter 54, the polarization beam splitter 54
Is transmitted through the polarizing beam splitter 54, passes through the condenser lens 57 and the cylindrical lens 58, and enters the four-divided photodetector 59. At this time, the reflected light 14e is condensed on the photoelectric surface of the four-divided photodetector 59 by the condenser lens 57. The cylindrical lens 58 has a light collecting characteristic that is asymmetrical with respect to the optical axis.
Light 14 incident on the four-divided photodetector 59 from
The beam cross-sectional shape (shape of the reflected light) of the resin storage tank 2
1 and the focal position of the first-order diffracted light 14b and the transmission window 22
For example, as shown in FIG. 7, the relative positional relationship with the upper surface changes.

That is, the beam sectional shape of the reflected light 14e is such that the objective lens 51 is located relatively close to the transmission window 22, and the focal position of the first-order diffracted light 14b is positioned above the upper surface of the transmission window 22. Figure 7
FIG. 4A shows a case where the objective lens 51 is located at a predetermined position from the transmission window 22 and the focal position of the first-order diffracted light 14b is focused on the upper surface of the transmission window 22 as shown in FIG. 7 (b), the objective lens 51 is located at a position relatively separated from the transmission window 22, and the focal position of the first-order diffracted light 14b is located below the upper surface of the transmission window 22. In such a case, the shape becomes a horizontally long elliptical shape as shown in FIG.

Here, the four-split photodetector 59
The center C1 of the quadrant photodetector 59 is reflected light 14e.
Are arranged so as to substantially coincide with the center C2 of the beam cross-section, and at the center C1, the photocathodes 59A, 59
B, 59C and 59D. With such a configuration of the four-segment photodetector 59, when the beam cross-sectional shape of the reflected light 14e becomes vertically long, the area irradiated with the reflected light 14e of the photoelectric surfaces 59A and 59B arranged in the vertical direction becomes larger than the photoelectric surface 59C arranged in the lateral direction. , 59D reflected light 14
e is larger than the area irradiated with the reflected light 1
When the beam cross-sectional shape of 4e becomes horizontal, the areas of the photocathodes 59C and 59D irradiated with the reflected light 14e become larger than the reflected light 14e.
Is larger than the area of the photocathodes 59A and 59B.

Each of the photoelectric surfaces 59A, 59B, 59C,
From 59D, an intensity signal S indicating the intensity of light (laser power) according to the size of the area irradiated with the reflected light 14e.
_A , S _B , S _C , and S _D are detected.
As shown in FIG. 6, the autofocus unit 50 further includes a calculator (focus position detecting means) 65 and a comparator 66. The control of the autofocus unit 50 is performed based on the signals S _A , S _B , S _C , and S _D.

The control by the arithmetic unit 65 and the comparator 66 will be described.
First, the intensity signal S_A , S _B , S_C , S_D Is
As shown in FIG.
Calculates the intensity signal S by the following equation (3),
The intensity signal S is output to the comparator 66.
You. S = (S_A + S_B )-(S_C + S_D(3) Then, the objective lens 51 is relatively close to the transmission window 22.
And the focal position of the first-order diffracted light 14b is
7 (a) is located above the upper surface of
As shown, the beam cross-sectional shape of the reflected light 14e is a vertically long ellipse.
The photocathode 59 is shaped and irradiated with the reflected light 14e.
A, the photocathode 5 on which the area of 59B is irradiated with the reflected light 14e
9C and 59D. Therefore,
No. S_A , S _BIs the intensity signal S_C , S_DLarger than
The intensity signal S is a positive number.

When the objective lens 51 is located at a predetermined position from the transmission window 22 and the focal position of the first-order diffracted light 14b is focused on the upper surface of the transmission window 22, the light is reflected as shown in FIG. Since the beam cross-sectional shape of the light 14e is substantially a perfect circle, and the intensity signals S _A and S _B and the intensity signals S _C and S _D are approximately equal, the intensity signal S is substantially zero. When the objective lens 51 is located at a relatively distant position from the transmission window 22 and the focal position of the first-order diffracted light 14b is located below the upper surface of the transmission window 22, FIG.
As shown in (c), the beam cross section of the reflected light 14e becomes a horizontally long elliptical shape, the intensity signals S _C and S _D become larger than the intensity signals S _A and S _B , and the intensity signal S becomes negative. It is supposed to be a number.

The first-order diffracted light 1 with respect to the transmission window 22
The relationship between the relative position of the focal point of 4b and the intensity signal S is
For example, the host computer 67 reads an intensity signal corresponding to the focal position of the predetermined first-order diffracted light 14b from the S-shaped curve, and predicts the intensity signal as a reference focal position as shown in FIG. The signal is output to the comparator 66 as a signal S0. The reference focus position signal S0 is compared with the intensity signal S so that the focal point of the first-order diffracted light 14b is controlled to be always at a fixed position with respect to the transmission window 22.

That is, the comparator 66 receives the reference focus position signal S0 from the host computer 67 as described above.
The intensity signal S is input from the arithmetic unit 65, and the intensity signal S and the reference focus position signal S
A deviation signal δS indicating a difference from 0 is calculated. The deviation signal δS is applied to an objective lens driving device 60 equipped with the objective lens 51, and the objective lens driving device 60 adjusts the deviation signal δS by an amount corresponding to the deviation signal δS.
The first-order diffracted light 14 is driven by driving the objective lens 51 in the vertical direction.
The focal position of b is controlled to a fixed position.

Therefore, if the reference focus position signal S0 is set to zero, the first-order diffracted light 14b is controlled to a fixed position so as to always focus on the upper surface of the transmission window 22, and the reference focus position signal S0 is set to a predetermined positive value. If set to a number, the first-order diffracted light 14b
Is set at a predetermined position on the upper surface of the transmission window 22, and if the reference focus position signal S0 is set to a predetermined negative number, the position of the focal point of the first-order diffracted light 14b becomes a predetermined position on the lower surface of the transmission window 22. Each is controlled to a fixed position.

As described above, from the shape of the reflected light 14e incident on the four-divided photodetector 59, the first-order diffracted light 1
A method of detecting the position of the focal point of 4b is called an astigmatism method. Stereolithography apparatus 1 according to a first embodiment of the present invention
Is configured as described above, a desired three-dimensional solid is formed by the following procedure (the stereolithography method according to the present embodiment).

First, referring to FIG. 1, laser light 12 is emitted from a laser light source 11, and this laser light 12
The light is bent at a right angle by the fold mirror 13 and enters the laser intensity stabilizing unit 40. Then, as shown in FIG. 3, when the laser light 12 passes through the AOM 41 in the laser intensity stabilizing unit 40, a high-order diffracted light 14 is generated. The first-order diffracted light 14 a having power is extracted by the spatial filter 44, and enters the subsequent beam expander 15 via the half mirror 42. At this time, a part of the first-order diffracted light 14a incident on the half mirror 42 is incident on the photodetector 43 as the power reference light 14c.
Then, the photodetector 43 detects the power signal Sp from the power reference light beam 14c and sends it to the laser power control device 61. The laser power control device 61 has a host computer 67 along with the power signal Sp.
From the reference power signal Sp based on the cross-sectional slice data.
0 is input, and the laser power control device 61 outputs to the AOM drive amplifier 62 a power fluctuation signal δSp indicating the difference between these power signals Sp and the reference power signal Sp0. Then, the power fluctuation signal δSp is AOM
After being amplified by the driving amplifier 62, the amplified power fluctuation signal δ is input to the AOM 41.
Based on Sp, the first-order diffracted light 14a output from the laser intensity stabilizing unit 40 is controlled (light beam power control) so as to have a predetermined laser power.

Then, the first-order diffracted light 14a output from the laser intensity stabilizing section 40 enters the beam expander 15 as shown in FIG. 1, and is expanded to a predetermined beam diameter.
The first-order diffracted light 14b having a predetermined beam diameter is reflected by the fold mirror 16 and enters the autofocus unit 50. Next, the first-order diffracted light 14b incident on the autofocus unit 50 is reflected by the fold mirror 52 to the λ / 2 wavelength plate 53, as shown in FIGS.
The deflecting surface of the first-order diffracted light 14b is a λ / 2 wavelength plate 5
3 and coincides with the reflected polarization plane of the polarization beam splitter 54. Then, the rotated first-order diffracted light 14 b on the deflecting surface is reflected by the polarization beam splitter 54 and enters the λ / 4 wavelength plate 55. Then, the polarization plane of the first-order diffracted light 14b changes from a state of linear polarization to a state of circular polarization by the action of the λ / 4 wavelength plate 55.
Thereafter, the first-order diffracted light 14b is transmitted to the fold mirror 5
The light is reflected upward at a right angle by 6 and is focused on the liquid photocurable resin 23 in the resin storage tank 21 through the transmission window 22 by the objective lens 51 positioned above the fold mirror 56.

A part of the first-order diffracted light 14b incident on the liquid photocurable resin 23 is reflected at the interface between the transmission window 22 and the liquid photocurable resin 23, and the reflected light 14e is
The objective lens 51, the fold mirror 56, and the λ / 4 wavelength plate 55 proceed in this order, and when passing through the λ / 4 wavelength plate 55,
The deflecting surface changes from circularly polarized light to linearly polarized light.
Next, the reflected light 14e is transmitted to the polarization beam splitter 54.
However, since the deflecting surface of the reflected light 14e is in the same direction as the polarizing surface in the transmission direction of the polarizing beam splitter 54, the reflected light 14e is transmitted through the polarizing beam splitter 54 and condensed by the condenser lens 57 and the cylindrical surface. The light enters the four-divided photodetector 59 via the lens 58.

Then, the four-division photodetector 59
As described above, the four photoelectric surfaces 59A, 59B, 59C, 5
9D, each of these photoelectric surfaces 59A,
From 59B, 59C, 59D, intensity signals S _A , S _B , S _C , S _D indicating laser power are detected according to the size of the irradiation area of the reflected light 14e. Then, these intensity signals S _A , S _B , S _C , and S _D are output to the arithmetic unit 65, and the arithmetic unit 65 calculates the intensity signal S by the above equation (3). Is output to the comparator 66. Further, the reference focus position signal S0 indicating the focus position of the predetermined first-order diffracted light 14b is input from the host computer 67 to the comparator 66 together with the intensity signal S. Then, the comparator 66 calculates the intensity signal S and the reference focus position signal S
The deviation signal δS indicating the difference from 0 to the objective lens driving device 60
Then, the objective lens driving device 60 drives the objective lens 51 to a predetermined position based on the deviation signal δS, and controls the focal position of the first-order diffracted light beam 14b to a predetermined position (focal position control). ).

Now, as shown in FIG.
Control unit 63 of the laser scanning unit 30 equipped with
X and 63Y receive laser position command signals Rx and Ry from the host computer 67, and position detectors 33X and 33 attached to the stage bodies 31X and 31Y, respectively.
From Y, position signals Px and Py indicating the positions of the stage bodies 31X and 31Y are input. Then, the stage controllers 63X and 63Y determine the difference between the signals Px and Rx and the signal Px.
The position error signals δPx and δPy indicating the difference between y and Ry are output to the motor amplifiers 64X and 64Y.
X and 64Y amplify the position error signals δPx and δPy and output them to the DC servo motors 32X and 32Y. The DC servo motors 32X and 32Y drive the stage bodies 31X and 31Y based on the amplified position error signals δPx and δPy to control the scanning speed v of the first-order diffracted light 14b (light flux scanning speed control). You do it.

The first-order diffracted light 14b controlled to the predetermined laser power P, the scanning speed v, and the focal position (laser spot diameter w) as described above is converted into a liquid in the resin storage tank 21 as shown in FIG. The photocurable resin 23 is irradiated.
At this time, for example, when the first cured resin layer is formed, the target plate 24 in the resin storage tank 21 is driven by the elevator 26 so that the target plate 24 is lower than the upper surface of the transmission window 22 at the bottom of the resin storage tank 21 by a predetermined distance. The liquid photocurable resin 23 is disposed above the thickness of the resin layer and is present in a region between the lower surface of the target plate 24 and the upper surface of the transmission window 22.
Then, the first-order diffracted light 14b is irradiated to form a first cured resin layer having a predetermined planar pattern. Thereafter, based on a control signal from the host computer 67, the elevator 26 moves the target plate 24 upward by a predetermined resin layer thickness. At this time, the first resin cured layer is bonded to the target plate 24 and Since it moves upward together with the target plate 24, the uncured liquid photocurable resin 23 flows between the first resin cured layer and the transmission window 22. Then, by irradiating the first-order diffracted light 14b, a second resin cured layer having a predetermined planar pattern and a predetermined resin layer thickness is formed between the lower surface of the first resin cured layer and the transmission window 22. is there. At this time, the second
Is bonded to the first cured resin layer.

Thereafter, the same steps are repeated to form a desired three-dimensional shape by stacking the resin cured layers having a predetermined planar pattern. Therefore, according to the optical shaping apparatus of the present embodiment, the following effects can be obtained. That is, the laser power P to be controlled, the scanning speed v, and the focal position corresponding to the laser spot diameter w are directly detected, and based on these detection results,
By individually performing feedback control of the laser power P by the laser intensity stabilizing section 40, the scanning speed v by the stage controllers 63X and 63Y, and the focus position by the autofocus section 50, high-speed control is possible. Therefore, there is an advantage that the irradiation state of the laser beam is prevented from deviating from the target value due to the control delay, and it is possible to form a three-dimensional solid with high accuracy.

Further, since feedback control is performed based on the detection results of the laser power P, the scanning speed v, and the focal position, even when a sudden disturbance such as vibration or temperature change occurs during the formation of a three-dimensional solid, There is also an advantage that a control corresponding to such a disturbance is performed to enable a high-precision three-dimensional solid modeling. Further, the laser intensity stabilizing section 40 is provided with an AOM 41, and has an advantage that the power of the light beam can be easily controlled by changing the amplitude of the electric signal applied to the AOM 41.

Next, a second embodiment will be described. FIG. 9 is a schematic view showing the entire configuration of an optical shaping apparatus according to the second embodiment of the present invention. In FIG. 9, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The optical shaping apparatus 1a according to the present embodiment has a structure shown in FIG.
As shown in (1), a part of the optical shaping apparatus 1 of the first embodiment is modified, and a laser beam
0 (see FIG. 1) is replaced by galvanometer mirrors 71 and 72, and the objective lens (see FIG. 1) is replaced by f-
It is replaced with a θ lens 73.

That is, the optical shaping apparatus 1 of this embodiment
a is a resin storage tank 21 in which a liquid photocurable resin 23 is stored.
And a laser light source (light source) 11 for emitting a laser beam (light flux) 12
Then, a fold mirror 13 that reflects the laser light 12 and makes it incident on a laser intensity stabilizing unit (light flux power control unit) 40, and extracts a first-order diffracted light 14a of a predetermined laser power (laser intensity) from the laser light 12 ( That is, a laser intensity stabilizing section 40 for stabilizing the laser power, a beam expander 15 for enlarging the beam diameter of the primary diffracted light 14a, and a liquid photocurable resin in the resin storage tank 21 for the primary diffracted light 14b. An autofocus section (focus position control means) 50 for focusing on the laser beam 23 (that is, adjusting the focal position of the laser beam);
, And an f-θ lens (lens) 73 provided with a lens driving device 60.

Here, a driving device (not shown) is provided for the galvanometer mirrors 71 and 72, and the driving device is controlled by a host computer (not shown) to drive the galvanometer mirrors 71 and 72 to a predetermined deflection angle. It has become. The galvanomirror 71 scans the first-order diffracted light 14b in the XY plane by changing its deflection angle, while the galvanomirror 72 changes the first-order diffracted light 14b into Y by changing its deflection angle. It scans in the -Z plane. Thereby, the galvanometer mirror 7
The first and second rays make the first-order diffracted light 14b incident on the f-θ lens 73 and the first-order diffracted light 1b on the f-θ lens 73.
4b can be changed.

Here, the f-θ lens 73 changes the optical axis of the first-order diffracted light 14 b, which is a parallel light beam incident at an angle to the optical axis of the f-θ lens 73, of the f-θ lens 73. At the same time as being refracted so as to be parallel to the optical axis, the first-order diffracted light 14b is converged on a certain plane called a focal plane. Therefore, instead of moving the objective lens 51 on a plane by the laser scanning unit 30 as in the first embodiment (see FIG. 1), f-θ is used as described above.
Incident angle θ of first-order diffracted light 14b incident on lens 73
Is changed by the galvanometer mirrors 71 and 72, so that the focal point of the first-order diffracted light 14b can be moved (scanned) to an arbitrary position on the focal plane.

The optical shaping apparatus 1a according to this embodiment
Is provided with a host computer (not shown) as described above, and the host computer stores arbitrarily set three-dimensional three-dimensional slice data (plane pattern). The host computer controls the galvanometer mirrors 71 and 72, the laser scanning unit 30, the laser intensity stabilizing unit 40, and the autofocus unit 50 based on the slice data.

Here, the galvanomirrors 71 and 72 include:
Angle detection means (not shown) for detecting the deflection angle and light beam scanning speed control means (not shown) are provided, respectively.
The angle detecting means sends angle information of each of the galvanometer mirrors 71 and 72 to the light beam scanning speed control means. A position command signal is input to the light beam scanning speed control means from the host computer based on the slice data. The light beam scanning speed control means calculates the scanning position of the primary diffracted light 14b from the angle information of each of the galvanometer mirrors 71 and 72, and compares the calculated scanning position with a position command signal from the host computer. Thus, the driving device is controlled such that the deflection angles of the galvanometer mirrors 71 and 72 become a predetermined angle. That is, the light beam scanning speed control means controls the scanning speed v of the first-order diffracted light 14b.

The f-θ lens 73 is made of a confocal lens, and the first-order diffracted light 14b incident on the f-θ lens 73 always passes through the transmission window 22 installed at the bottom of the resin storage tank 21. It is always incident vertically. A part of the first-order diffracted light 14b is transmitted to the transmission window 2
2 and the liquid photocurable resin 23, the first-order diffracted light 14b is perpendicularly incident on the transmission window 22,
The reflected light 14e travels in the reverse direction on the same path as the incident path and enters the autofocus unit 50. Then, the auto focus unit 50
The f-θ lens 73 is moved to a predetermined height by the lens driving device 60 based on the beam cross-sectional shape of the reflected light 14e so that the focal position (focal plane) of the first-order diffracted light 14b becomes a predetermined position. Is controlled.

Since the optical shaping apparatus 1a according to the second embodiment of the present invention is configured as described above, a desired three-dimensional solid is formed by the following procedure (an optical shaping method according to the present embodiment). Modeling is performed. First, laser light 12 is emitted from a laser light source 11, and this laser light 12 is bent at a right angle by a fold mirror 13 and enters a laser intensity stabilizing unit 40. Then, the laser beam 12 is controlled (light beam power control) by the laser intensity stabilizing unit 40, and is output as a first-order diffracted beam 14a of a predetermined laser power. Then, the first-order diffracted light 14a is made incident on the beam expander 15 to expand the beam diameter, and then the first-order diffracted light 14b having the expanded beam diameter is transmitted to the autofocus unit 50, the galvanometer mirrors 71, 72, and f. The liquid photocurable resin 23 in the resin storage tank 21 is irradiated from the transmission window 22 of the resin storage tank 21 through the −θ lens 73. At this time, the deflection angles of the galvanometer mirrors 71 and 72 are controlled based on the predetermined slice data, thereby controlling the scanning speed v of the first-order diffracted light 14b (light beam scanning speed control).
I do. Further, the lens driving device 60 drives the f-θ lens 73 to a predetermined height based on a control signal from the autofocus unit 50, thereby controlling the focal position (focal plane) of the first-order diffracted light 14b. Position control).

The transmission window 2 at the bottom of the resin storage tank 21
The liquid photocurable resin 23 between the upper surface of the substrate 2 and the target plate 24 is irradiated with the first-order diffracted light 14b controlled at a predetermined laser power P, a scanning speed v, and a focal position. At this time, the target plate 24 is positioned above the upper surface of the transmission window 22 by a predetermined resin layer thickness, thereby forming a resin cured layer having a predetermined planar pattern and a predetermined resin layer thickness. Then, thereafter, each time a resin cured layer having a predetermined planar pattern and a predetermined resin layer thickness is formed, the target plate 24 is moved upward by a predetermined resin layer thickness, whereby a predetermined planar pattern is formed. The desired three-dimensional shape is formed by stacking the resin cured layers having the same.

Therefore, according to the optical shaping apparatus of the present embodiment, the following effects can be obtained in substantially the same manner as the optical shaping apparatus of the first embodiment. In other words, the laser power P to be controlled and the focal position corresponding to the laser spot diameter w are directly detected, and the laser power
By individually performing feedback control of the scanning speed v by the galvanometer mirrors 71 and 72 and the focal position (focal plane) by the autofocus unit 50, high-speed control becomes possible. There is an advantage that the irradiation state is prevented from deviating from the target value, and high-precision three-dimensional solid modeling becomes possible.

Further, since feedback control is performed based on the detection results of the laser power P and the focal position, even when sudden disturbance such as vibration or temperature change occurs during the formation of a three-dimensional solid, such a disturbance can be obtained. There is an advantage that high-precision three-dimensional modeling can be performed by performing control corresponding to disturbance. Incidentally, the stereolithography apparatus and the stereolithography method of the present invention,
The present invention is not limited to the above embodiment, and can be implemented with various modifications.

For example, the photodetector 43 and the four-divided photodetector 59 are used while grounded, but the photodetector 43 and the four-divided photodetector 59 may not be grounded depending on the configuration of the electric circuit. Further, in the present embodiment, the regulated liquid level method of irradiating laser light from below to form a hardened layer is used, but the free liquid level method of irradiating laser light from above to form a hardened layer is used. You may.

[0084]

As described above in detail, according to the optical shaping apparatus of the present invention according to the first aspect and the optical shaping method of the fourth aspect, the power of the light beam, the scanning speed, and the focal position are individually set. By controlling, high-speed control becomes possible,
There is an advantage that the irradiation state of the light beam is prevented from deviating from the target value due to the control delay, and a three-dimensional solid can be formed with high accuracy.

Further, since the control is performed based on the detection results of the power of the light beam, the scanning speed, and the focal position, even when a sudden disturbance such as a vibration or a temperature change occurs during the formation of the three-dimensional solid, this control is performed. By performing control corresponding to such disturbance,
There is an advantage that a three-dimensional solid can be formed with high precision. According to the stereolithography apparatus of the present invention described in claim 2,
Since the light beam power control means is constituted by the acousto-optic device, there is an advantage that the power of the light beam can be easily controlled by changing the amplitude of the electric signal applied to the acousto-optic device.

According to the third aspect of the present invention, the focal position of the light beam can be directly detected by the astigmatism method based on the detection result from the reflected light shape detecting means. There is an advantage that the time required to calculate is unnecessary, and the focus position can be quickly controlled by the focus position control means.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an optical shaping apparatus as a first embodiment of the present invention.

FIG. 2 is a diagram illustrating control signals output from a host computer of the optical shaping apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a configuration and a control block of a light flux power control unit of the optical shaping apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a configuration and a control block of a light beam scanning unit of the optical shaping apparatus according to the first embodiment of the present invention.

FIG. 5 is a schematic plan view showing a configuration of a focus position control unit and a molding unit of the optical molding apparatus according to the first embodiment of the present invention.

FIG. 6 is a schematic side view showing a partial configuration of a focal position control unit, a focal position detection unit, and a molding unit of the optical molding apparatus according to the first embodiment of the present invention;

FIGS. 7A and 7B are diagrams illustrating a beam cross-sectional shape (shape of reflected light) detected by a reflected light shape detecting unit of the optical shaping apparatus according to the first embodiment of the present invention, and FIG. FIG. 4B is a diagram illustrating a beam cross-sectional shape when positioned above the transmission window, FIG. 4B is a diagram illustrating a beam cross-sectional shape when the focal position of the light beam is focused on the upper surface of the transmission window, and FIG. FIG. 4 is a diagram illustrating a beam cross-sectional shape when a focal position is located below an upper surface of a transmission window.

FIG. 8 is a diagram illustrating a relationship between an intensity signal detected by a reflected light shape detection unit of the optical shaping apparatus according to the first embodiment of the present invention and a relative position of a focal point with respect to a transmission window.

FIG. 9 is a schematic diagram illustrating an overall configuration of an optical shaping apparatus according to a second embodiment of the invention.

FIG. 10 is a schematic diagram showing the overall configuration of a conventional free liquid surface type optical shaping apparatus.

FIG. 11 is a schematic view showing the overall configuration of a conventional regulated liquid level type optical shaping apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 1a Stereolithography device 11 Laser light source (light source) 12 Laser beam (light flux) 13, 16, 52, 56 Fold mirror 14 Diffracted beam 14a, 14b Primary diffracted beam 14c Power reference beam 14e Reflected beam 15 Beam expander 20 Modeling unit DESCRIPTION OF SYMBOLS 21 Resin storage tank 22 Transmissive window 23 Liquid photocurable resin 24 Target plate 25 Lifting rod 26 Elevator 30 Laser scanning part (light beam scanning means) 31X, 31Y Stage main body 32X, 32Y DC servomotor 33X, 33Y Position detector 40 Laser intensity Stabilizing unit (beam power control unit) 41 AOM (acousto-optic modulation element) 42 Half mirror 43 Photodetector 44 Spatial filter 50 Autofocus unit (focal position control unit) 51 Objective lens (lens) 53 λ / 2 wavelength plate 54 Polarized beam Pretitter 55 λ / 4 wavelength plate 57 Condenser lens 58 Cylindrical lens 59 Quadrant photodetector (reflected light shape detecting means) 59A, 59B, 59C, 59D Photocathode 60 Objective lens drive device, lens drive device 61 Laser power control device 62 AOM drive amplifier 63X, 63Y Stage control device (light beam scanning speed control means) 64X, 64Y Motor amplifier 65 Computing unit (focal position detecting means) 66 Comparator 67 Host computer 71, 72 Galvano mirror (light beam scanning means) 73 f-θ Lens (lens) P Laser power (power of light beam) Px, Py Position signal Rx, Ry Position command signal S, S _A , S _B , S _C , S _D intensity signal S 0 Reference focal position signal Sp power signal Sp 0 Reference power signal δPx, δPy Position error signal δSp Power fluctuation signal v The light scanning speed w laser spot diameter (scanning speed of the light beam)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryosuke Hoshina 1-8-1, Koura, Kanazawa-ku, Yokohama-shi Inside Mitsubishi Heavy Industries, Ltd. Basic Research Laboratory (72) Inventor Takayuki Goto 1-8-1, Koura, Kanazawa-ku, Yokohama-shi Mitsubishi Heavy Industries, Ltd. Basic Technology Research Laboratory F-term (reference) 4F203 AA44 DA12 DB01 DC07 DF01 DF46 DK07 4F213 AA44 WA25 WA53 WA86 WA87 WA97 WB01 WL02 WL12 WL15 WL85 WL92

Claims (4)

[Claims] 1. A resin storage tank for storing a liquid photocurable resin, a light source for emitting a light beam, a light beam scanning means for scanning the light beam, and the liquid light curable resin in the resin storage tank for transmitting the light beam. A step of forming a resin cured layer having a predetermined planar pattern by scanning the light beam focused by the lens and irradiated to the liquid photocurable resin by the light beam scanning means. By repeatedly stacking the resin cured layer, in an optical shaping apparatus for shaping a desired three-dimensional shape, a light beam power control means for suppressing fluctuation of the power based on detection information of the power of the light beam; A focus position detecting means for detecting a focal position of the light beam focused by the lens; and a focal position for moving the focal point of the light beam to a predetermined position based on information on the focal position detected by the focus position detecting means. Position control means, and light beam scanning speed control means for suppressing fluctuations in the scanning speed based on detection information of the light beam scanning speed, the light beam power control means, the focal position control means, and the light beam scanning speed An optical shaping apparatus, wherein the control means and the control means are configured to perform control individually. 2. An optical shaping apparatus according to claim 1, wherein said light beam power control means comprises an acousto-optic element. 3. The apparatus according to claim 2, wherein said focus position detecting means includes reflected light shape detecting means for detecting a shape of reflected light of said light beam reflected from a liquid surface of said liquid photocurable resin. The stereolithography apparatus according to claim 1, wherein the focal position is detected by an astigmatism method based on the detection result. 4. A process of forming a resin cured layer having a predetermined planar pattern by irradiating a liquid light curable resin in a resin storage tank with a light beam focused and irradiated by a lens and scanning the light beam. In the optical shaping method for forming a desired three-dimensional shape by laminating the resin cured layer, a light beam power control for suppressing a fluctuation of the power of the light beam based on detection information of the power of the light beam when the light beam is irradiated. A focus position control for moving the focal point of the light beam focused by the lens to a predetermined position based on the detection information of the focus position of the light beam; and a scanning speed of the light beam based on the detection information of the scanning speed of the light beam. An optical shaping method, wherein light flux scanning speed control for suppressing fluctuation is individually performed.