JPH08248338A - Beam split image forming device - Google Patents

Abstract

PURPOSE: To provide an economically advantageous beam split image forming device capable of reducing the deterioration in picture quality due to a manufacturing error of a beam separator by arranging a luminous flux division element and an image forming surface of an image forming optical system at a mutually almost conjugative position. CONSTITUTION: The beam separators 21, 22 and a substrate ST being the image forming surface of the image forming optical system I are arranged on the mutually almost conjugative position. The optical system I is constituted of lenses 65-70, 26, 27, 31, 32, 40, 52, 53, a polygon mirror 46 and an fθ lens 47, etc. Since the beam separators 21, 22 are placed on a convergent point of beams L2, L3, and are placed on the position nearly conjugative with respective image forming surfaces of the beams splitting the beams L2, L3, even when there is the tilting of the reflection surface formed by optical parts and a luminous flux split film, all beams are projected on the position where the beams L2, L3 are reached intrinsically, and they are arranged in a line on the image forming surface (ST).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to beam splitting in which one beam is split into a plurality of beams arranged in a row through a beam splitting element, and the split beams are imaged on an image forming surface through an image forming optical system. The present invention relates to an imaging device.

[0002]

2. Description of the Related Art A laser beam from a laser light source is divided into a plurality of beams by a beam separator,
The applicant of the present invention has proposed a laser drawing apparatus that scans a substrate with a plurality of beams in a line (see Japanese Patent Application No. 5-181610). This laser drawing device
By turning on and off the single row of beams individually based on the setting data and scanning with a rotating polygon mirror slightly tilted with respect to the main scanning direction, the required circuit pattern can be rapidly drawn on the substrate. it can.

When scanning a divided beam with this laser drawing apparatus, the spot position of each divided beam in the main scanning direction orthogonal to the rotation axis of the polygon mirror can be easily adjusted by shifting the ON / OFF time. The spot position in the sub-scanning direction largely depends on the light dividing performance of the beam separator. Therefore, extremely high processing accuracy is required for manufacturing the beam separator, which causes a cost increase.

[0004]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above-mentioned awareness, and provides a beam splitting image forming apparatus which can reduce the deterioration of the image quality due to the manufacturing error of the beam separator and which is economically advantageous. The purpose is to

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides:
In the beam splitting image forming device, the beam splitting device splits the beam into a plurality of beams arranged in a row through a light beam splitting device, and forms the split beam on an image forming surface through an image forming optical system. And the image forming plane of the image forming optical system are arranged at positions substantially conjugate with each other.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. 3 is an external perspective view showing the whole of the laser drawing apparatus (beam division scanning device) 11 according to the present invention, and FIG. 4 is a schematic plan view showing the whole of the laser drawing apparatus 11.

The laser drawing apparatus 11 has an argon laser apparatus 12 on a table 10 and a beam bender 1
3, 23-25, 28-30, 35, 38, 41, 4
4, 45, 54, half prism 16, half mirror 1
4 and lenses 52, 53, 65 to 71.
The laser drawing device 11 further includes acousto-optic modulators 19, 2
It has beam separators (beam splitting elements) 21 and 22 for splitting 0 and 1 beams into a plurality of beam lines (drawing light beam lines) arranged in the same plane.

The laser drawing apparatus 11 also includes focusing optical systems 26, 31, 27, 32 for pitch conversion, multi-channel (8-channel) acousto-optic modulators 36, 37, focusing optical system 34, and polarization beam splitter 60. , Λ / 2 plate 39,
Polarization beam splitter 40, image rotator 43,
Polygon mirror 46, fθ lens 47, X scale condenser lens 48, condenser lens 49, X scale 5
0, monitor light mirrors 51a and 51b, an X-scale photodetector 62, and long mirrors 63 and 64.

Each of the acousto-optic modulators 36 and 37 has an acoustic property that when an ultrasonic wave is generated in a crystal such as tellurium dioxide, the refractive index of the crystal is periodically changed by elastic strain due to the ultrasonic wave and the light is diffracted. It is configured based on the optical effect, when high frequency is applied to the transducer provided on the end face of the crystal, ultrasonic traveling wave is generated inside the crystal to diffract the laser light, and when high frequency is not applied, the crystal It is possible to transmit the laser light incident on. Therefore, by switching the high frequency application to the acousto-optic modulator 36 (37), the incident light, that is, the beam trains L5 and L6 can be switched on and off freely.

On the other hand, the laser drawing device 11 has a substrate setting device (not shown) for setting the substrate ST so as to be positioned on the drawing table surface (only the position of the surface is shown by the chain double-dashed line) which is the image surface. are doing. This substrate setting device is a Y table (not shown) movable in the Y direction (the sub-scanning direction of the polygon mirror 46, which is the left-right direction in FIG. 1), and a vertical direction in FIG. It has a swing mechanism (not shown) that swings to the front.

By the way, the beam separators 21 and 2 are
2 is manufactured by the following steps. First, as shown in FIG. 7, a light beam splitting optical component 74 made of a plane-parallel plate.
The required light beam splitting film 75 is attached to one surface of the optical component 7
4 between the adjacent optical components 74 without fail
Are laminated so as to intervene with each other, and are joined by an epoxy resin adhesive, an ultraviolet curable adhesive, or the like. Then, the light beam splitting element block 55 in which a large number of optical components 74 are joined
Is cut at a required angle to cut out a plurality of cutting blocks 61. In the example shown in the figure, the angle at the time of cutting is a direction forming 45 ° with respect to the light beam splitting film 75, and the cutting surface 76 serves as a light incident surface and a light emitting surface. The cutting surface 76 of the cutting block 61 is polished to a smooth surface, if necessary.

Separately from the above steps, a transparent plane-parallel plate 77 (see FIG. 6) is prepared, and an antireflection film 78 is formed on one surface of the plane-parallel plate 77 by, for example, vapor deposition or sputtering. . The plane-parallel plate 77 having the antireflection film 78 attached thereto is joined to both surfaces of the cutting block 61. That is, the plane parallel plates 77 are joined to the cut surfaces 76 on both sides of the cutting block 61 by using, for example, an epoxy resin adhesive or an ultraviolet curable adhesive so that the antireflection film 78 is located outside. This joining block is the beam separators 21 and 22. 6 and 7, for the sake of convenience, the light beam splitting film 75 and the antireflection film 7 are shown.
8 and the plane parallel plate 77 are exaggeratedly drawn, but in reality, the light beam splitting film 75 and the antireflection film 78 have a thickness of about 100 nanometers (nm) to 1000 nanometers.
The plane parallel plate 77 has a thickness of about several millimeters.

The completed beam separator 2 shown in FIG.
The beams L2 and L3 applied to the beam Nos. 1 and 22 are divided into beam rows L5 and L6, respectively. That is, in the beams L2 and L3, a part of the light components is the uppermost light beam splitting film 7.
5 is directly transmitted to become beams L5a and L6a, and the remaining light components are reflected by the light beam splitting film 75 and are deflected by 90 ° to become beams L5a 'and L6a'. Further, a part of the light components of the beams L5a 'and L6a' is reflected by the next light beam splitting film 75 and is deflected by 90 °, so that the beams L5b and L6 are deflected.
6b, and the remaining light components pass through the light beam splitting film 75 as they are to become beams L5b 'and L6b'. And
A part of the light components of the beams L5b 'and L6b' is reflected by the next light beam splitting film 75 and is deflected by 90 °, so that the beam L5 'is deflected.
c and L6c, and the remaining light components pass through the light beam splitting film 75 as they are to become beams L5c 'and L6c'. Thereafter, by repeating the same light division, eight beams L5a to L5h and L6a to L6h are emitted respectively.

Beam separator 2 which is a beam splitting element
Since Nos. 1 and 22 have the above structure, when there is a tilt or the like on the reflecting surface formed by each optical component 74 and the light beam splitting film 75, the split beams are arranged in a direction (sub-scanning direction) substantially orthogonal to the row of split beams. The pitch b (see FIG. 5) becomes non-uniform and the image quality deteriorates. The positional deviation of the spot in the main scanning direction can be adjusted by shifting on / off temporally, but the positional deviation of the spot in the sub-scanning direction can be adjusted by the beam separators 21 and 2.
It largely depends on the division performance of 2. Therefore, the beam separators 21 and 22 are required to have very high processing accuracy, which is not economical.

According to the present invention, such split beams L5a ...
The positional deviations of the spots L5h and L6a to L6h, especially the pitch deviations in the sub-scanning direction, are detected by the beam separators 21 and 22.
It is intended to solve the problem without particularly improving the light splitting performance of. The characteristic part of the present invention in the laser drawing apparatus 11 will be described below.

That is, as schematically shown in FIG. 2, in the present laser drawing apparatus 11, the beam separator 2 is used.
1, 22 and the substrate ST, which is the image forming surface of the image forming optical system I, are arranged at positions conjugate with each other. This imaging optical system I
Are the lenses 65 to 70, 26, 27, 31, 32,
40, 52, 53, polygon mirror 46, fθ lens 4
It consists of 7 mag. The beam separators 21 and 22 are
Is located at the focal point of the beams L2 and L3, and the beams L
2, beams L5a to L5h and L6a to L divided from L3
Since the positions are substantially conjugate with the respective image forming planes 6h, even if the reflecting surface formed by the optical component 74 and the light beam splitting film 75 is tilted, the beams L5a to L5h and L6a to L6h are included.
Can be projected onto the positions where the beams L2 and L3 should originally reach, and can be aligned in a line on the image forming surface (ST).

This will be described with reference to FIG. 1. The laser light flux L1 emitted from the argon laser device 12 is split via the half mirrors 16 and 14, and the beams L2 and L3 are split.
Lens 65, 67, 69, or lens 6 after
It is converged to each via 6, 68 and 70. Then, the beams L2 and L3 are eight beams L5a to L5 respectively by the beam separators 21 and 22 in the converging position.
h, L6a to L6h, and then lenses 26, 3
1, 52, 53, etc., or the lenses 27, 32,
The light is guided to the fθ lens 47 via 52, 53 and the like, and is further focused on the substrate ST via the fθ lens 47 and the condenser lens 49. As described above, there are many lenses and the like that form the imaging optical system I between the beam separators 21 and 22 and the substrate ST that is the imaging surface, and the reflecting surfaces of the beam separators 21 and 22 do not fall. Even if
The beams L5a to L5h and L6a to L6h are all on the substrate S.
The image is formed in a line on T.

By the way, the beam separator 21 (22)
And the substrate ST (image plane) have a conjugate positional relationship and the focus is aligned with the image plane, the beam L2 (L
The focus of 3) must be on the light beam splitting film 75 at the uppermost portion of the beam separator 21 (22) in FIG.
In this case, even if the focus of the beam L2 (L3) is made to coincide with the uppermost light beam splitting film 75, strictly speaking, in the other light beam splitting films 75 located below, the uppermost light beam splitting film 75 is located. Due to the distance from 75, L5a ′ to L5
When each of d '(L6a' to L6d ') arrives, the focal point is slightly shifted. However, the imaging optical system I interposed between the beam separator 21 (22) and the substrate ST squeezes each of the beams L5a to L5h (L6a to L6h) divided by the beam separator 21 (22). The beam separator 21 (22) and the substrate ST have a reducing relationship because they are reduction optical systems that irradiate the image forming surface).
The focus shift in (22) is reduced by the vertical magnification,
It becomes extremely small on the substrate ST. As a result, such a focal shift does not cause any problem as long as it is within the depth of focus. Therefore, the relationship between the beam separator 21 (22) and the substrate ST (imaging plane) may be substantially conjugate.

The laser drawing apparatus 11 having the above structure is
It works as follows. First, the positioning holes (not shown) of the substrate ST on which the circuit pattern is to be formed are aligned with the corresponding portions of the substrate setting device, and the substrate ST is properly set in the device. As a result, the substrate ST becomes the Y table and swing mechanism (not shown) of this substrate setting device.
Thus, it is set so as to be slidable in the Y direction in FIG. 1 and capable of swinging about that position about a rotary shaft (not shown). In this state, when the argon laser device 12 is oscillated to start the irradiation of the laser light L1, the laser light L1 is first deflected by the beam bender 13 and enters the half prism 16, and the half prism 16 causes It is split into a beam L2 which goes straight as it is and a beam which is deflected by 90 ° and goes to the half mirror 14.
This beam is split through the half mirror 14 into a beam L3 which is deflected by 90 ° and travels in parallel with the beam L2, and a monitor light Lm which is deflected by 90 ° by the mirror 54 toward the mirror 54.

The beam L2 is incident on the acousto-optic modulator 19 via the lenses 65 and 67, and the beam L3 is incident on the acousto-optic modulator 20 via the lenses 66 and 68.
Then, the difference in the amount of light between the beams L2 and L3 is removed by the acousto-optic modulators 19 and 20. The beam L2,
L3 is further separated by the beam separators 21 and 22 from the X
It is divided into eight beams which are parallel to each other in the direction (coplanar direction). The beam trains L5 and L6 respectively divided into the eight beams are further transmitted to the pitch converting condensing optical systems 26 and 27, respectively, and the beam bender 2
After being deflected by 90 ° by 8 and 29 respectively, the acousto-optic modulators 36 and 3 are transmitted through the pitch converting condensing optical systems 31 and 32.
It is made incident on 7 respectively.

In the beam arrays L5 and L6, variations in the light amount of each of the eight beams L5a to L5h and L6a to L6h are individually removed by the acousto-optic effect of the acousto-optic modulators 36 and 37 of 8 channels. The acousto-optic modulators 36 and 37 are turned on and off at appropriate times by switching the application of high frequency based on a control unit (not shown).

The beam train L5 emitted from the acousto-optic modulator 36 is deflected by the beam bender 38 by 90 ° and then enters the polarization beam splitter 40. The beam train L6 emitted from the acousto-optic modulator 37 is transmitted through the λ / 2 plate 39 and changed in the polarization direction, and then enters the polarization beam splitter 40. Each of these beam rows L5 and L6 has eight beams L5a to L5h and L6a to L6.
The 6h are alternately combined by the polarization beam splitter 40 and are combined so as to be arranged in a line in the X direction. Further, a control unit (not shown) operates the substrate setting device in synchronization with the scanning of the beam rows L5 and L6 from the polygon mirror 46, and slides the substrate ST in the Y direction on the drawing table surface (T). . Therefore, it is 1 diagonally to the X direction.
A circuit pattern is two-dimensionally drawn (exposed) on the substrate ST by each of the beams of the beam lines L5 and L6 that are turned on and off at appropriate times in parallel with each other.

At the time of drawing, the beam separators 21 and 22
The beam separator 2 and the image forming surface (substrate ST) of the image forming optical system I are arranged at positions substantially conjugate with each other.
Even if there is a fall on each of the reflecting surfaces 1 and 22, the beam L
5a to L5h and L6a to L6h are all beam L2, L3
Can be projected to a position which should be reached, and can be aligned in a line on the substrate ST. Therefore, according to the laser drawing apparatus 11, the drawing line E having a substantially constant pitch b can be drawn as shown in FIG.
It is possible to form a precise circuit pattern on T without unevenness.

Even if the pitch b is substantially constant, if the drawing line at the time of exposure does not form a straight line as shown by the symbol E'in FIG. 5, the on / off timings of the acousto-optic modulators 36 and 37 are appropriately set. If the irradiation position in the main scanning direction is adjusted by shifting, it is possible to draw a straight drawing line as indicated by reference numeral E in the figure.

[0025]

As described above, according to the present invention, it is possible to reduce the deterioration of the image quality due to the manufacturing error of the beam separator, and it is possible to provide the economical beam-splitting device.

[Brief description of drawings]

FIG. 1 is a schematic plan view for explaining a laser drawing apparatus according to the present invention.

FIG. 2 is a schematic side view illustrating a conjugate relationship of the laser drawing apparatus.

FIG. 3 is a perspective view showing an embodiment of the laser drawing apparatus.

FIG. 4 is a schematic plan view showing the entire laser drawing apparatus.

FIG. 5 is a diagram for explaining a state of a plurality of beam spots scanned on a substrate by a polygon mirror.

FIG. 6 is a side view detailing a beam separator.

FIG. 7 is a drawing for explaining the manufacturing process of the beam separator.

[Explanation of symbols]

 11 Laser Drawing Device (Beam Division Imaging Device) 21 22 Beam Separator (Light Beam Splitting Element) I Imaging Optical System ST Substrate (Imaging Surface)

Claims (3)

[Claims] 1. A beam splitting / imaging device that splits one beam into a plurality of beams arranged in a row through a light beam splitting element, and forms an image of the split beam on an imaging surface through an imaging optical system. 2. The beam splitting / imaging device, wherein the light beam splitting element and the imaging plane of the imaging optical system are arranged at positions substantially conjugate with each other. 2. The beam splitting / imaging device according to claim 1, further comprising a substrate setting device for setting a substrate to be the imaging surface. 3. The image forming optical system according to claim 2,
A beam splitting / imaging device comprising a plurality of lens systems, a beam bender, and a polygon mirror arranged between a light beam splitting element and a substrate.