Laser drawing apparatus and method for adjusting the same

A laser drawing apparatus is provided including a splitting means for splitting laser light emitted from a laser source into at least two groups of drawing beams, the beams of each group being aligned in a common plane; a scanning means for scanning a drawing surface with said at least two groups of drawing beams in a main scanning direction; a first adjusting means for rotating the common plane, in which one of the at least two bundles of drawing beams are aligned, about an axis extending parallel to the drawing beams; a second adjusting means for moving at least one of the at least two groups of drawing beams in said main scanning direction of the scanning means; and, a third adjusting means for moving at least one of the at least two groups of drawing beams in a sub-scanning direction perpendicular to the main scanning direction.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a laser drawing apparatus which is 
adapted, for example, to form a predetermined pattern of circuit on a 
circuit board. 
2. Description of the Related Art 
In a known method of forming a circuit pattern on a circuit board (i.e., 
substrate), a photopolymer or the like is uniformly applied to the 
substrate coated with a thin film layer of electrically conductive metal, 
such as copper. Thereafter, the substrate is illuminated with ultraviolet 
light, for example, while masking the substrate with an exposing and 
printing photomask (photomask film) having a predetermined shape, so that 
a circuit pattern corresponding to the photomask is formed on the 
substrate. The exposed photopolymer on the substrate is dissolved by a 
solvent and is subjected to a predetermined treatment by chemicals in 
liquid state so that the exposed conductive metal is corroded. No 
corrosion occurs at the portion of the substrate on which the non-exposed 
photopolymer layer remains. Hence, the same circuit pattern as the 
photomask pattern is formed on the substrate. 
However, in the known manufacturing method as mentioned above, it requires 
a long time and a number of processes to examine the photomask. 
Furthermore, it is necessary not only to create the environment for the 
photomask in which temperature and humidity are kept constant to thereby 
prevent the photomask from being thermally contracted or expanded, but 
also to protect the photomask from dust or possible damage. Consequently, 
maintenance of the photomask is troublesome. 
It is also known to directly draw the circuit pattern on the substrate, 
using a scanning laser beam with which the substrate is scanned with the 
help of a polygonal mirror or the like, without using an exposing and 
printing photomask. In this method, the above-mentioned drawbacks in the 
manufacturing method in which the photomask is employed can be eliminated, 
but the drawing speed is unacceptably slow. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is to provide a laser drawing 
apparatus that does not use an exposing and printing photomask, in which 
the adjustment thereof can be easily effected and the drawing speed can be 
increased. 
To achieve the object mentioned above, according to the present invention, 
there is provided a laser drawing apparatus comprising a splitting means 
for splitting laser light emitted from a laser source into at least two 
groups of drawing beams, the beams of each group being aligned in a common 
plane, a scanning means for scanning a drawing surface with said at least 
two groups of drawing beams in a main scanning direction, a first 
adjusting means for rotating the common plane, in which one of said at 
least two groups of drawing beams are aligned, about an axis extending 
parallel to the drawing beams, a second adjusting means for moving at 
least one of said at least two groups of drawing beams in said main 
scanning direction of the scanning means, and a third adjusting means for 
moving at least one of said at least two groups of drawing beams in a 
sub-scanning direction perpendicular to the main scanning direction. 
With this arrangement, it is possible not only to considerably increase the 
drawing speed in a laser drawing apparatus in which the substrate is 
scanned with the laser beams to directly draw a predetermined pattern of 
image on the substrate, but also to easily perform the adjustment of a 
plurality of drawing beams. 
Preferably, the second adjusting means comprises a pair of pitch changing 
convergent optical systems which are arranged along an optical path of one 
of the two groups of drawing beams and receive one of the two groups of 
drawing beams, and an adjusting means for moving the pair of pitch 
convergent optical systems in a direction parallel to the common plane, 
respectively. 
The third adjusting means comprises a polarization beam splitter which 
combines the two groups of drawing beams in a plane, one of said groups of 
drawing beams being passed through the polarization beam splitter and the 
other of said groups of drawing beams being reflected by the polarization 
beam splitter, and means for moving the polarization beam splitter in a 
direction normal to one of the groups of drawing beams which pass the 
polarization beam splitter so that the two groups of drawing beams align 
in a plane. 
Preferably, the third adjusting means aligns said two groups of drawing 
beams in such a manner that each of drawing beams in one of the said 
groups of drawing beams is positioned between neighboring two drawing 
beams in the other of the groups of drawing beams. 
According to another aspect of the present invention, there is provided a 
method for adjusting a laser drawing apparatus including a splitting means 
for splitting laser light emitted from a laser source into at least two 
groups of drawing beams, the beams of each group of drawing beams being 
aligned in a common plane, and a scanning means for scanning a drawing 
surface with the at least two groups of drawing beams, comprising the 
steps of installing a detector for detecting an image drawn on the drawing 
surface, adjusting the parallel arrangement of said at least two groups of 
drawing beams by rotating one of the groups relative to the other group, 
while observing the drawn image detected by the detector, and making the 
two groups of drawing beams coincident with each other by translating one 
of the groups relative to the other group, while observing the drawn image 
detected by the detector. 
The translating step can consist of a step of translating one of the groups 
relative to the other groups in the main scanning direction of the 
scanning means, and a step of translating one of the groups relative to 
the other groups in the sub-scanning direction of the scanning means. 
According to the present invention, there is provided a laser drawing 
apparatus comprising a beam splitter which separates the laser light into 
two beams, a beam separator which separates each of two beams into two 
groups of drawing beams, each of the two groups of drawing beams being 
aligned in a respective plane, and a polarization beam splitter which 
combines the two groups of drawing beams in a plane, one of the groups of 
drawing beams being passed through the polarization beam splitter and the 
other of the groups of drawing beams being reflected by the polarization 
beam splitter, wherein the polarization beam splitter aligns the two 
groups of drawing beams in such a manner that each of drawing beams in one 
of the groups of the drawing beams is positioned between each drawing beam 
in the other of the groups of drawing beams. 
The present disclosure relates to subject matter contained in Japanese 
patent application No. 5-181610 (filed on Jul. 22, 1993) which is 
expressly incorporated herein by reference in its entirety.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 and 2 are a perspective view and a schematic plan view of a laser 
drawing apparatus to which the present invention is applied, respectively, 
and FIG. 3 is a schematic plan view of main components of a laser drawing 
apparatus shown in FIGS. 1 and 2. 
The laser drawing apparatus 11 includes an argon laser (Ar laser) unit 12, 
beam benders 13, 23-25, 28-30, 35, 41, 44, 45 and 54, adjusting targets 
15, 17 and 33, a half prism 16, a beam bender (half mirror) 14, and lenses 
52, 53, 65, 71, on a table 10. The laser drawing apparatus 11 further 
includes acoustooptic modulators 19 and 20, beam separators 21 and 22, 
pitch changing convergent optical systems 26, 31, 27 and 32, acoustooptic 
modulators of 8 channels 36 and 37, a beam bender 38, a condenser optical 
system 34, a .lambda./2 plate 39, a polarization beam splitter 40, an 
image rotator 43, a polygonal mirror 46, an f.theta. lens 47, a gathering 
lens 48 for an X-scale, a condenser lens 49, an X-scale 50, a mirror 60, 
monitoring mirrors 51a and 51b, and a photo detector 62 for the X-scale. 
The adjusting targets 15, 17 and 33 are reference marks (FIG. 8) which are 
adapted to confirm optical paths of groups of beams L2 and L3 and 
monitoring beam Lm when the Ar laser device 12 is exchanged. 
There is a substrate setting device (not shown) in the vicinity of the 
laser drawing apparatus 11 to form a substrate S on a drawing table 
surface T (indicated at a two-dotted and dashed line) corresponding to an 
image surface. The substrate setting device is provided with a Y-table 
(not shown) which is movable in the Y-direction (i.e., sub-scanning 
direction of the polygonal mirror 46 corresponding to the transverse 
direction in FIG. 1) and a swing mechanism (not shown) which swings about 
a rotational shaft (not shown) in the vertical direction in FIG. 1. 
The Ar laser (i.e., laser source) 12 is a water-cooled type having an 
output of 1.8 W which emits laser beam L1 whose wavelength is 488 nm. The 
acoustooptic modulators 19 and 20 adjust the quantity(power) of beams L2 
and L3 which are split by the half prism (i.e., splitting means) 16, so 
that the quantities of the beams L2 and L3 are identical. The acoustooptic 
modulators 19 and 20 also carry out the fine adjustment of the inclination 
of the reflecting surfaces 46a (FIG. 14) of the polygonal mirror (i.e., 
scanning means) 46 in accordance with data on the inclination of each 
reflecting surface 46a, stored in a memory (not shown) of a control means 
8. To prevent the acoustooptic modulators 19 and 20 from being broken due 
to an excess quantity of light received thereby, the slit beams L2 and L3 
which are obtained by splitting the laser beam L1 are made incident upon 
the acoustooptic modulators 19 and 20. 
The beams L2 and L3 emitted from the acoustooptic modulators 19 and 20 are 
made incident upon the beam separators (i.e., splitting means/first 
adjusting means) 21 and 22 in which the beams L2 and L3 are respectively 
split into 8 first drawing beams L5 and 8 second drawing beams L6. As can 
be seen in FIG. 4, the beam separators 21 and 22 are respectively provided 
with 8 emission holes "h" aligned in the longitudinal direction (i.e., 
vertical direction in FIG. 4). The beam separators 21 and 22 are swingably 
supported by the swing adjusting mechanism 79 (FIG. 7) to rotate in the 
direction indicated at an arrow A (i.e., direction perpendicular to the 
optical path of the first and second beams L5 and L6) about respective 
pivot shafts coaxial to the respective uppermost emission holes "h". 
The beam separators 21 and 22 are respectively made of a plurality of 
optical elements 100(FIG. 5) in the form of a plate, which are adhered to 
each other by an adhesive separating surfaces 101; then cut at an angle of 
45.degree. with respect to the separating surfaces; and thereafter 
enclosed by and in frames 102. The separating surfaces 101 partly reflect 
and partly transmit therethrough the beams L2 and L3 incident upon 
uppermost incident holes "ha" formed on the rear surfaces of the beam 
separators 21 and 22 to obtain groups of beams (first and second drawing 
beams L5 and L6) spaced at a predetermined distance. 
The swing adjusting mechanism 79 includes a base portion 80 secured on the 
table 10 of the laser drawing apparatus 11, an upright supporting wall 81 
projecting upward from the base portion 80, and a bracket 82 which extends 
at the upper end of the supporting wall 81 in parallel with the base 
portion 80, as shown in FIG. 9. The supporting wall 81 is provided with a 
micrometer head 84 which extends in the lateral direction in FIG. 9 (i.e., 
Y-direction in FIG. 1). The bracket 82 is provided with a pivot shaft 83 
coaxial to the uppermost emission hole "h" of the beam separator 21 (22). 
The beam separator 21 (22) is rotatably biased in the clockwise direction 
in FIG. 9 about the pivot shaft 83 by a biasing means (not shown). A 
spindle 85 of the micrometer head 84 abuts at the front end thereof 
against the lower end of the beam separator 21 (22), so that when the 
spindle 85 is reciprocally moved in the longitudinal axial direction 
thereof by the micrometer head 84, the swing movement of the beam 
separator 21 (22) about the pivot shaft 83 in the direction "A" takes 
place to rotate the aligned drawing beams L5 (L6) about the axis of the 
pivot shaft 83 (FIG. 15) to thereby make the drawing beams L5 and L6 
parallel to each other. 
The group of first drawing beams L5 emitted from the beam separator 21 is 
made incident upon a pair of pitch changing convergent optical systems 26 
and 31. The group of second drawing beams L6 emitted from the beam 
separator 22 is made incident upon a pair of pitch changing convergent 
optical systems 27 and 32. The pitch changing convergent optical systems 
26, 31 and 27, 32 change the pitches of the 8 first drawing beams L5 and 
the 8 second drawing beams L6, split by the beam separators 21 and 22, so 
that the respective pitches correspond to the pitches of the 8 channel 
acoustooptic modulators 36 and 37. 
The pitch changing convergent optical systems 26 and 31 are moved and 
adjusted in the X-direction (FIG. 1, 12,13) by the X-direction adjusting 
mechanism 91 (FIG. 12) to move the first group L5 of aligned drawing beams 
toward the second bundle L6 of aligned drawing beams (FIG. 14). Thus, the 
pitch changing convergent optical systems 26 and 31 constitute a second 
adjusting means to adjust the deviation of the group of beams in the 
direction X. 
The X-direction adjusting mechanism 91 includes a stationary supporting 
wall 93 which projects upward from the base portion 92, and a movable 
supporting wall 94 which is movable in the vertical direction (i.e., 
direction X) in FIG. 12. The micrometer head 95 is mounted to the upper 
portion of the movable supporting wall 94 extending in the vertical 
direction. The movable supporting wall 94 is provided with a supporting 
hole 94a extending therethrough, in which the pitch changing convergent 
optical system 26 (31) is secured. The stationary supporting wall 93 is 
provided with a hole 93a in which an annular portion 26a (31a) of the 
pitch changing convergent optical system 26 (31) is movably inserted. 
The hole 93a has a diameter larger than the diameter of the annular portion 
26a (31a) so as to permit the latter to move therein through the movable 
supporting wall 94. The movable supporting wall 94 is biased by a biasing 
means (not shown) in the vertical direction to bias the pitch changing 
convergent optical system 26 (31) and the micrometer head 95 in the same 
direction. Consequently, the spindle 96 of the micrometer head 95 is 
pressed at the front end thereof against the upper portion of the 
stationary supporting wall 93. With the arrangement of the X-direction 
adjusting mechanism 91 as constructed above, the pitch changing convergent 
optical system 26 (31) can be slid and adjusted in the vertical direction 
(X-direction) through the movable supporting wall 94 when the spindle 96 
is reciprocally moved by the micrometer head 95. 
The beam bender 38 and the polarization beam splitter 40 which constitute a 
Y-direction adjusting means (third adjusting means) are moved to move the 
first drawing beams L5 in the direction Y, i.e., toward the second drawing 
beams L6 (FIG. 7), to thereby adjust the positional relationship 
therebetween. The beam bender 38 is rotated about the pivot shaft 38a 
(FIG. 2) extending in the direction X to move and adjust the first drawing 
beams L5 in the direction Y. The polarization beam splitter 40 is 
supported by the Y-axis adjusting mechanism 85 (FIG. 10) so as to move in 
the direction Y. 
The Y-direction adjusting mechanism 85 includes a base portion 86 secured 
to the table 10 of the laser drawing apparatus 11, a movable portion 87 
capable of moving in the direction Y with respect to the base portion 86, 
and a micrometer head 89 which is supported by the base portion 86 to 
extend in the direction Y. The polarization beam splitter 40 is secured to 
the movable portion 87, so that the half mirror surface 40a of the 
polarization beam splitter 40 is inclined at an angle of 45.degree. with 
respect to the direction Y. The movable portion 87 is biased by a biasing 
means (not shown) toward the micrometer head 89 (i.e., the left direction 
in FIG. 10), so that one side surface thereof is pressed against the front 
end of the spindle 90 of the micrometer head 89. Consequently, when the 
spindle 90 is moved in the longitudinal direction thereof by the operation 
of the micrometer head 89, the polarization beam splitter 40 is moved in 
the direction Y to move and adjust the first drawing beams L5 in the 
direction Y (FIG. 11). 
The polarization beam splitter 40 constitutes a beam combining means to 
alternately align the first group L5 of the aligned drawing beams 
deflected by the beam bender 38 and the second group L6 of the aligned 
drawing beams transmitted through the .lambda./2 plate 39 at a 
predetermined pitch in the direction X. The direction of polarization of 
the first drawing beams L5 is not changed in order to be deflected by 
90.degree. by the half mirror surface 40a. Then the direction of 
polarization of the second drawing beams L6 is changed by 90.degree. with 
respect to the direction of polarization of the first drawing beams L5 
through the .lambda./2 plate 39 in order to passe through the half mirror 
surface 40a. Hence, the drawing beams L5 and L6 having a difference of 
90.degree. in the direction of polarization are combined by the 
polarization beam splitter 40 to be alternately aligned along one line in 
the direction X. 
The 8-channel acoustooptic modulators 36 and 37 function to eliminate the 
difference in the quantity of light between 8 first drawing beams L5 and 8 
second drawing beams L6. The acoustooptic modulators 36 and 37 also 
function to independently control the drawing beams L5 and L6 split by the 
beam separators 21 and 22 through the control means 8 in accordance with 
predetermined data to thereby provide independent ON/OFF drawing data to 
the first and second drawing beams L5 and L6. The acoustooptic modulators 
36 and 37 are each made of a crystal of tellurium dioxide, for example, 
which exhibits an acoustooptic effect that the refractive index of the 
crystal is slightly changed in proportion to the frequency of an 
ultrasonic wave to be applied to the crystal. 
The acoustooptic modulators 36 and 37 generate a traveling-wave shape of 
ultrasonic wave within the crystal to thereby diffract the laser beam, 
when a high frequency electric field is applied to transducers provided at 
the opposed ends of the crystal. When a high frequency electric field is 
not applied to the transducers, the laser beam incident upon the crystal 
at a Bragg angle is transmitted through the acoustooptic modulators. 
Consequently, the ON/OFF control of the incident beams, i.e., the drawing 
beams L5 and L6 can be optionally and easily carried out by switching the 
application of the high frequency electric field to the acoustooptic 
modulators 36 and 37. Each of the acoustooptic modulators 36 and 37 has 8 
channels aligned so as to receive the aligned drawing beams L5 (L6) and 
modulate the incident beams in the transverse direction (direction Y in 
FIG. 1). Moreover, the acoustooptic modulators 36 and 37 are each provided 
with a slit 78 (FIG. 7) elongated in the vertical direction (direction X 
in FIG. 1) so as to correspond to the 8 channels. 
The monitoring beam Lm is independent from the beams L2 (L5) and L3 (L6) 
and has an optical path spaced from the optical paths of the drawing beams 
L5 and L6 at a predetermined distance. The monitoring beam Lm is deflected 
by the mirrors 54 and 25 and travels along an optical path spaced from the 
drawing beams L5 and L6 at a predetermined distance. Thereafter, the 
monitoring beam Lm is deflected by the mirrors 35 and 60 to come close to 
the drawing beams L5 and L6. Thereafter, the monitoring beam Lm passes 
along an optical path close to the optical paths of the drawing beams L5 
and L6 through the lens 71, the beam bender 41 and the lens 52, etc. 
The image rotator 43 is comprised of a mirror system which converges the 16 
aligned beams of the drawing beams L5 and L6 onto the substrate S located 
at the drawing table surface T with a predetermined oblique angle, upon 
scanning by the polygonal mirror 46. Therefore, although the 16 beams of 
the first and second drawing beams L5 and L6 are aligned along one line in 
the main scanning direction (i.e., direction X) of the polygonal mirror 46 
before they are made incident upon the image rotator 43, the 16 beams are 
rotated with respect to the direction X in the clockwise direction by a 
predetermined angle when emitted from the image rotator 43, as can be 
seen, for example, in FIG. 15. 
The first and second drawing beams L5 and L6 and the monitoring beam Lm are 
deflected by the beam benders 44 and 45 and are thereafter made incident 
upon the reflecting surfaces 46a of the polygonal mirror 46. When the 
polygonal mirror 46 rotates about the rotating shaft 73 in the 
counterclockwise direction in FIG. 14, the deflection angle .theta. is 
continuously changed to move (i.e., scan) the first and second drawing 
beams L5 and L6 and the monitoring beam Lm through the reflecting surfaces 
46a which rotate in the same direction. Consequently, the first and second 
drawing beams L5 and L6 are transmitted through the f.theta. lens 47 and 
the condenser lens 49, and converged onto the substrate S located at the 
table surface T. The rotating shaft 73 of the polygonal mirror 46 is 
supported by a supporting means (not shown) so that the inclination 
thereof in the sub-scanning direction Y can be displaced by an angle 
.beta.. Hence, the perpendicularity of the main scanning line with respect 
to the sub-scanning line in the polygonal mirror 46 can be easily and 
optionally adjusted. 
The f.theta. lens 47 contributes to an elimination of the problem that the 
position of the point image of the drawing beams on the scanning surface 
of the table surface T (FIG. 1) is not proportional to the deflection 
angle .theta. but is scanned at a higher scanning speed determined by 
tan.theta. at the upper portion of the scanning surface. The f.theta. lens 
47 is comprised of a plurality of convex and concave lenses, wherein the 
image height of the point image on the scanning surface is proportional to 
the deflection angle .theta. defined by the reflected beam and the optical 
axis of the f.theta. lens, so that the drawing beams can be moved (i.e., 
scanned) at an equal scanning speed. 
The monitoring beam Lm transmitted through the f.theta. lens 47 and the 
condenser lens 49 together with the first and second drawing beams L5 and 
L6 is successively reflected by the mirrors 51a and 51b to change the 
direction thereof by 180.degree. and is made incident upon the X-scale 50 
located at a position equivalent to the image forming surface of the table 
surface T. The X-scale 50 is made of a glass plate provided with a slit(s) 
to function as a linear encoder. The monitoring beam Lm transmitted 
through the X-scale 50 is reflected and converged by elongated mirrors 63 
and 64, and is then converged by the condenser lens 48 for the X-scale to 
be made incident upon the photo-detector 62 for the X-scale. When the 
positions of the 16 beams of the first and second drawing beams L5 and L6 
are detected in accordance with the position of the monitoring beam Lm 
detected by the photo-detector 62, the control signal is sent from the 
control means 8 (e.g.,micro computer) in accordance with the detection 
data thus obtained. Consequently, the 16 beams of the first and second 
drawing beams L5 and L6 are independently controlled (i.e., turned ON and 
OFF) in accordance with the control signal. 
The beam spots of the first and second drawing beams L5 and L6 which are 
made incident upon the drawing table surface T at a slightly oblique angle 
are adjusted through the acoustooptic modulators 36 and 37 each having 8 
channels so that the each spot diameter is for example 30 .mu.m. 
Consequently, the irregularity in quantity(power) of the beam among the 
beam spots, as shown in FIG. 20 can be eliminated, as can be seen in FIG. 
21. In the illustrated embodiment, the pitch of the beam spots, i.e., the 
distance "a" (FIG. 18) between the adjacent spots is adjusted to be for 
example 5 .mu.m through the acoustooptic modulators 36 and 37. 
The line L (FIGS. 18 through 21) drawn with the beam spots aligned along 
the sub-scanning direction is formed by appropriately turning ON and OFF 
the acoustooptic modulators 36 and 37. Upon drawing the line L, it is 
necessary to provide a space "c" (FIG. 21) between the adjacent beam spots 
of the drawing beams L5 and L6 in order to prevent an interference 
therebetween. For example, if the exposure by the drawing beam L6 adjacent 
to the lowermost drawing beam L5 takes place immediately after the 
completion of the exposure by the lowermost drawing beam L5 in FIG. 21, a 
straight drawing line L is not obtained. To this end, in the laser drawing 
apparatus 11 according to the present invention, the control means 8 
retards the exposure of the subsequent drawing beam L5 by a predetermined 
delay time. Consequently, the subsequent beam spot of the second drawing 
beam L6 can be properly superimposed on the preceding beam spot of the 
first drawing beam L5 that has been exposed. The straight line L, as shown 
in FIG. 21, can be formed by repeating the control process as mentioned 
above. In the control operation, if the line L is not straight due to the 
irregularity in the position of the beam spots, as shown in FIG. 18, the 
modulation timing of the acoustooptic modulators 36 and 37 is varied in 
accordance with the control signal issued from the control means 8 to 
correct the drawing line L, as shown in FIG. 19. 
The beam benders 13, 14, 23 through 25, 28 through 30, 35, 38, 41, 44, 45 
and 54 are respectively provided with annular mirror supporting members 
74. Each mirror supporting member 74 is provided on the front surface 
(right side in FIG. 6) thereof with an inner peripheral flange 74a which 
constitutes an abutting surface, as shown in FIG. 6. The mirror 75 which 
is fitted in the mirror supporting member 74 abuts against the rear 
surface of the inner peripheral flange 74a. A keep ring 77 is screwed in 
the mirror supporting member 74 through an annular shock absorbing member 
76. Consequently, not only can the mirror 75 be easily exchanged, but also 
the mirror 75 can be always positioned at a reference position. 
The laser drawing apparatus 11 according to the present invention operates 
as follows. 
First of all, the substrate S on which the circuit pattern is to be formed 
is set at an appropriate position in which the positioning hole (not 
shown) of the substrate is registered with the corresponding portion of 
the substrate setting apparatus (not shown). When the substrate S is set 
in the reference position, the substrate S is movable in the direction Y 
and swingable about the pivot shaft (not shown) by the Y-table and the 
swing mechanism (not shown) of the substrate setting apparatus. 
In this state, the Ar laser 12 is activated to emit the laser beam L1. 
Consequently, the laser beam L1 is deflected by the beam bender 13; 
transmitted through the adjusting target 15; and made incident upon the 
half prism 16 in which the laser beam is split into the beam L2 which runs 
straight and the drawing beam deflected by 90.degree. toward the half 
mirror 14. The deflected beam is then split by the half mirror 14 into the 
beam L3 which is deflected by 90.degree. to run parallel to the second 
beam L2 and the monitoring beam Lm which is made incident upon the mirror 
54 wherein the monitoring beam Lm is deflected by 90.degree.. 
The beam L2 is made incident upon the acoustooptic modulator 19 through the 
lens 65, the adjusting target 17 and the lens 67; and the beam L3 is 
transmitted through the lenses 66 and 68 and made incident upon the 
acoustooptic modulator 20. The difference in the quantity of light between 
the beams L2 and L3 is eliminated by the acoustooptic modulators 19 and 
20. The beam L2 and L3 are split into the 8 first drawing beams L5 and the 
8 second drawing beams L6 that are in parallel with the first drawing 
beams L5 in the direction X by the beam separators 21 and 22, 
respectively. The first and second drawing beams L5 and L6 are transmitted 
through the pitch changing convergent optical systems 26 and 27; deflected 
by 90.degree. through the beam benders 28 and 29; and, made incident upon 
the acoustooptic modulators 36 and 37 through the pitch changing 
convergent optical systems 31 and 32, respectively. 
The difference in the quantity of light among the 8 beams of the respective 
first and second drawing beams L5 and L6 is eliminated in accordance with 
the acoustooptic effect of the acoustooptic modulators 36 and 37 each 
having 8 channels. The drawing beams L5 and L6 are controlled (turned ON 
and OFF) by the control means 8 in accordance with the selective 
application of the high frequency electric field to the acoustooptic 
modulators 36 and 37. 
The first drawing beams L5 emitted from the acoustooptic modulator 36 is 
deflected by 90.degree. through the beam bender 38. The first drawing beam 
L5 is then made incident upon the polarization beam splitter 40 and 
deflected by 90.degree. by the half mirror surface 40a. The second drawing 
beams L6 emitted from the acoustooptic modulator 37 is transmitted through 
the .lambda./2 plate 39 wherein the direction of polarization thereof is 
changed. The second drawing beam L6 is then made incident upon the 
polarization beam splitter 40 and passes through the half mirror surface 
40a. The drawing beams L5 and L6, each having 8 beams are successively 
combined by the polarization beam splitter 40, so that the 16 beams are 
aligned along one line in the direction X. 
The control means 8 actuates the substrate setting apparatus (not shown) in 
synchronization with the scanning operation of the drawing beams L5 and L6 
by the polygonal mirror 46 to slide the substrate S on the drawing table 
surface T in the direction Y. Consequently, a two-dimensional 
predetermined circuit pattern is formed (i.e., drawn or exposed) on the 
substrate S by the 16 beams of the drawing beams L5 and L6 that are 
selectively emitted in a slightly oblique angle with respect to the 
direction X. The drawing speed is theoretically 16 times the drawing speed 
at which a circuit pattern is drawn by one drawing beam. 
The following adjustment of the drawing beams can be effected prior to the 
commencement of the drawing operation by the laser drawing apparatus 11. 
For instance, a detector 9 such as a CCD is set on the drawing table 
surface T. Similar to the drawing operation of a circuit pattern on the 
substrate S, the laser beam L1 is emitted from the Ar laser 12, so that 
the split beams L5 and L6 are made incident upon the detector 9. The 
micrometer head 84 of the swing adjusting mechanism 79 is actuated while 
observing the drawn image detected by the detector 9. Consequently, the 
beam separator 22 is swung about the rotating shaft 83 in the direction A 
in FIG. 9 to rotate the aligned drawing beams L5, for example, in the 
direction a in FIG. 15 to thereby adjust the aligned drawing beams L5 to 
be in parallel with the aligned drawing beams L6. Alternatively, it is 
possible to swing the beam separator 21 about the rotating shaft 83 to 
rotate the aligned drawing beams L6 in the direction opposite to the 
direction .alpha. in FIG. 15 to thereby adjust the aligned drawing beams 
L6 to be parallel with the aligned drawing beams L5. 
Thereafter, the X-direction adjusting mechanism 91 is actuated while 
observing the drawn image detected by the detector 9. Consequently, the 
pitch changing convergent optical systems 26 and 31 are appropriately 
moved in the direction X (i.e., main scanning direction of the polygonal 
mirror 46) to move only the drawing beams L5 in the direction X incident 
upon the drawing table surface at an oblique incident angle (FIG. 16). 
Furthermore, the micrometer head 89 of the Y-direction adjusting mechanism 
85 is actuated to move the polarization beam splitter 40 in the direction 
Y to thereby move the drawing beams L5 in the direction Y (i.e., 
sub-scanning direction of the polygonal mirror 46), whereby the beam spots 
of the drawing beams L5 and L6 are aligned at a predetermined pitch (FIG. 
17). Note that the adjustment by the swing adjusting mechanism 79, the 
X-direction adjusting mechanism 91 and the Y-direction adjusting mechanism 
85 can be carried out in a sequential order different from that mentioned 
above. 
As can be understood from the foregoing, according to the present 
invention, since an exposing and printing photomask is not necessary, it 
is not necessary to examine or inspect the photomask, thus resulting in a 
decreased number of manufacturing steps and a curtailed manufacturing time 
of the laser drawing apparatus. Moreover, it is not necessary to create an 
environment for the photomask in which the temperature and humidity are 
kept constant to thereby prevent the photomask from being thermally 
contracted or expanded. In addition to the foregoing, it is possible not 
only to considerably increase the drawing speed in a laser drawing 
apparatus in which the substrate is scanned with the laser beams to 
directly draw a predetermined pattern of image on the substrate, but also 
to easily perform the adjustment of a plurality of drawing beams. 
Although the invention has been described with reference to particular 
means, materials and embodiments, it is to be understood that the 
invention is not limited to the particulars disclosed and extends to all 
equivalents within the scope of the claims.