JP2000028948A - Laser beam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the gradient as to the intensity generated along a circumferential diction in a diffraction ring which is to appear in the vicinity of the periphery of a laser beam by rotating at least one lens which is included in an optical system around an axis whose direction is different from that of the optical axis of the lens. SOLUTION: A lens 20 whose optical axis coincides with the center axis in a design of an optical system is irradiated with a laser beam. Then, side robes are generated near by both hems of a curve indicating the intensity distribution of a final image. Next, a point at which side robes of both the left and the right become equal or they become the nearest to being equal is searched by changing the angle relation around the axis between a lens holder 21 and a lens holder 23 by rotating the lens holder 21 in a state in which bolts 24 are loosened. When the side robes become equal, peaks of the side robes become the lowest. That is, the gradient as to the intensity generated along the circumferential direction is corrected in the diffraction ring which is to appear in the vicinity of the periphery of the final image and the maximum intensity of the diffraction ring can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam device, and more particularly, to a laser beam device used for, for example, a laser printer or a plate-making output scanner for drawing with a laser beam.

[0002]

2. Description of the Related Art In a laser beam apparatus which is used in a laser printer or an output scanner for plate making and performs drawing by a laser beam, a laser beam is focused at a drawing position until the beam diameter reaches a diffraction limit in order to obtain high resolution. Is required. An ideally focused laser beam has a Gaussian intensity distribution on its cross section (see FIG. 13). Here, the beam diameter is defined as the distance between two points where the beam intensity is 1 / e ² with the maximum intensity being 1 (W in the figure). However, in reality, the intensity distribution of a laser beam focused to the diffraction limit does not become a perfect Gaussian distribution, and a diffraction ring appears near the periphery of the beam (see FIG. 14). In FIG. 14, the peaks (the above-described diffraction rings) formed at both tails of the Gaussian curve indicating the beam intensity are called side lobes, and the magnitude of the peak determines the image quality.

In FIG. 14, the sizes of the left and right side lobes are different from each other. It is considered that such unevenness of the left and right side lobes (that is, the diffraction ring has a gradient regarding the intensity along the circumferential direction) is due to the accuracy of the optical element included in the optical system. This is because the degree of unevenness differs depending on the optical element. When the left and right side lobes are equal and unequal in the same optical system, the peak of the side lobe is known to be lower in the former case (see FIG. 15). Therefore, in order to equalize the left and right side lobes, a high-precision optical element has been used, and the accuracy at the time of assembly has been increased. Alternatively, it has been practiced to replace the optical element many times, and to accidentally find one having an even side lobe.

[0004]

However, in the former case, a high-precision optical element is expensive, and it is costly to increase the accuracy of assembly. On the other hand, in the latter case, the precision of the optical element and the precision of assembly do not have to be very high, but the replacement work has to be performed many times until a suitable element is found, which takes a lot of trouble.

Therefore, an object of the present invention is to equalize the left and right side lobes (ie, appear near the periphery of the focused laser beam) by using a simple operation without using a highly accurate optical element or the like. It is an object of the present invention to provide a laser beam device which can correct the inclination with respect to the intensity generated along the circumferential direction in the diffraction ring to reduce the maximum intensity, and as a result, it is inexpensive and can obtain high image quality.

[0006]

Means for Solving the Problems and Effects of the Invention The first invention is a laser beam apparatus for performing drawing by a laser beam, and an optical system for guiding a laser beam emitted from a light source to focus at a drawing position. By rotating the system and at least one lens included in the optical system around an axis having a direction different from the optical axis of the one lens,
A mechanism is provided for correcting the inclination related to the intensity generated along the circumferential direction in the diffraction ring appearing in the vicinity of the periphery of the focused laser beam to reduce the maximum intensity.

In the first aspect of the present invention, the optical axis of the lens moves so that its trajectory describes a cone as the lens is rotated. Therefore, the shift of the optical axis of the entire optical system including the lens changes, and as a result, the gradient related to the intensity generated along the circumferential direction in the diffraction ring appearing near the periphery of the focused laser beam changes. Therefore, the above-mentioned inclination can be corrected and the maximum intensity can be reduced without using a highly accurate optical element or the like and performing a simple adjustment operation of rotating the lens in one direction.

A second aspect of the present invention is a laser beam apparatus for performing drawing by using a laser beam, wherein the optical system guides a laser beam emitted from a light source to focus at a drawing position, and at least one of the optical systems included in the optical system. By translating the lenses along an axis that is different from the optical axis of the one lens, the intensity associated with the intensity generated along the circumferential direction in the diffraction ring appearing near the periphery of the focused laser beam A mechanism for correcting the inclination and reducing the maximum strength.

In the second aspect of the present invention, the optical axis of the lens moves so that its trajectory describes a plane in accordance with the parallel movement of the lens. Therefore, the shift of the optical axis of the entire optical system including the lens changes, and as a result, the gradient related to the intensity generated along the circumferential direction in the diffraction ring appearing near the periphery of the focused laser beam changes. Therefore, the above-mentioned inclination can be corrected and the maximum strength can be reduced without using a highly accurate optical element or the like and by performing a simple adjustment operation of moving the lens in one direction.

A third aspect of the present invention is a laser beam apparatus for performing drawing by a laser beam, wherein the optical system guides a laser beam emitted from a light source to focus at a drawing position, and at least one of the optical systems included in the optical system. By changing the direction of the lenses, a mechanism is provided to correct the inclination related to the intensity generated along the circumferential direction in the diffraction ring appearing near the periphery of the focused laser beam and reduce the maximum intensity. .

In the third aspect, the optical axis of the lens moves as the direction of the lens changes. Therefore, the shift of the optical axis of the entire optical system including the lens changes, and as a result,
In the diffraction ring appearing near the periphery of the focused laser beam, the gradient of the intensity generated along the circumferential direction changes. Therefore, the above-described inclination can be corrected and the maximum intensity can be reduced without using a highly accurate optical element or the like and only by performing an adjustment operation for changing the direction of the lens.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a perspective view showing a laser beam device according to a first embodiment of the present invention. The laser beam apparatus shown in FIG. 1 is used in, for example, a laser printer or a plate-making output scanner, and a laser beam is applied on a photosensitive surface by a laser beam.
Form a two-dimensional image. In FIG. 1, a light source 11 (for example, an LD), a collimating lens 12, a deflector 13, and a scanning lens 14 are provided near one end of a support base 10. The light source 11, the collimating lens 12, and the deflector 13 are arranged along the Y direction.
The scanning lens 14 is placed on a straight line passing in the Z direction.

The collimating lens 12, the deflector 13 and the scanning lens 14 cooperate to guide the laser beam emitted from the light source 11 and draw the laser beam at a drawing position (a straight line 15 parallel to the Y direction).
(The above one point) has a function of focusing, and these are collectively called an optical system. A straight line 16 indicates a designed optical axis of the optical system.

In the above laser beam device, the light source 1
The light emitted from 1 passes through the collimating lens 12 and becomes parallel light. The traveling direction of the parallel light is deflected by the deflector 13 and travels toward the scanning lens 14. Then, the light is condensed by the scanning lens 14 and
An image is formed near the other end of 0. At this time, the deflector 13 is rotated about a straight line extending in the X direction as an axis, and the image forming position moves accordingly along the straight line 15 (the direction in which the image forming position moves is called the main scanning direction). ). On the other hand, a straight line 15
And the photosensitive surface is placed on a plane perpendicular to the Z direction, and is moved along the X direction (the direction in which the photosensitive surface moves is referred to as a sub-scanning direction). Thus, on the photosensitive surface, 2
A two-dimensional image is formed.

FIG. 2 is an exploded perspective view showing an example of the collimator lens 12 shown in FIG. 1, FIG. 3 is a sectional view of the collimator lens of FIG. 2, and FIG. 4 is a front view of the collimator lens of FIG. . 2 to 4, the collimating lens includes a lens 20, a lens holder 21, a lens holding ring 22, and a lens holder 23. The lens holder 21 and the holding ring 22 are threaded, and the lens 20 is fixed in the lens holder 21 by storing the lens 20 in the lens holder 21 and screwing the holding ring 22. The lens holder 21 further includes
Three arc-shaped (center angle θ) bolt holes 21b to 21d are provided at equal intervals along the periphery of the lens hole 21a.
On the other hand, the lens holder 23 is provided with three bolt holes 23b to 23d at equal intervals along the periphery of the lens hole 23a. These bolt holes 21b to 21d and bolt hole 2
3b to 23d, and bolt 2
By inserting 4, the lens holder 21 and the lens holder 23 are fixed to each other.

What is important is that the bolt holes 21b to 21d have an arc shape. Here, the center angle θ is approximately 60 degrees. Since the hole is formed in a 60-degree arc shape, when the lens holder 21 is fixed to the lens holder 23, the angular relationship between the lens holder 21 and the lens holder 23 around the axis can be variously changed (FIG. 5). reference). That is, the lens 20 can be rotated around the central axis (indicated by a dashed line in FIG. 3). Note that the angular relationship between the lens holder 21 and the lens holder 23 around the axis can be changed without necessarily selecting the number of the bolt holes (21b to 21d, 23b to 23d) and the central angle θ as described above. . However, it is preferable to select as described above in consideration of the processing labor and strength. Further, for example, if another bolt hole is provided between the bolt holes in the lens holder 23 (that is, six bolt holes are provided at equal intervals along the periphery),
Lens 20 can be rotated 360 degrees about a central axis.

The lens 20 is decentered. An eccentric lens is a lens whose central axis and optical axis are shifted from each other (see FIG. 6). Here the lens center axis of refers to the central axis of the cylinder such that the outer peripheral surface of the lens with the side surface, the optical axis, the curvature center R ₁ of the first surface and the center of curvature R ₂ of the second surface Points through a straight line. Most lenses are decentered as a result of processing errors, and there is no need to intentionally manufacture decentered lenses.

In the following description, the center axis of the lens 20 is light
Coincides with the optical axis (straight line 16 in FIG. 1) in the academic system design
It will be described as an example. Now the worker is using a laser beam device
Is turned on to start beam irradiation. this
Sometimes the final image (focused) using a measuring device (not shown)
The intensity distribution of the laser beam was measured, for example, as shown in FIG.
It is assumed that the measurement result as shown is obtained. Figure 14
Near the tails of the curve showing the intensity distribution of the final image.
Each side lobe (see prior art) has occurred. This
These left and right side lobes have different sizes,
The peak (peak of the side lobe as a whole) is the allowable value 1 /
e ^Two Is over.

Then, the operator turns the lens holder 21 with the bolt 24 loosened, and variously changes the angular relationship between the lens holder 21 and the lens holder 23 around the axis, so that the left and right side lobes become uniform. (See FIG. 15)
Or find the closest point. To supplement here, since the lens 20 is decentered, when the lens 20 is rotated around the central axis as described above,
The optical axis moves so that its trajectory describes a cone (see FIG. 7). Therefore, when the lens 20 is rotated as described above, the shift of the optical axis of the entire optical system including the lens 20 changes (the image is shown in FIG. 8), and as a result, the balance between the left and right side lobes changes. Note that, in FIG.
Indicates the shift of the optical axis of the lens 20, the arrow b indicates the shift of the optical axis of the entire optical system excluding the lens 20, and the arrow c indicates the shift of the optical axis of the entire optical system including the lens 20.

When the left and right side lobes are equal, the peak of the side lobe becomes the lowest and falls below the allowable value 1 / e ² . That is, in the diffraction ring appearing near the periphery of the final image, the inclination related to the intensity generated along the circumferential direction is corrected, and the maximum intensity of the diffraction ring falls within the allowable value 1 / e ² .
Then, if the bolt 24 is tightened at the found point and the lens holder 21 is fixed, the adjustment operation is completed. As described above, in the laser beam device of FIG. 1, the maximum intensity of the diffraction ring can be reduced by a simple adjustment operation of rotating the lens 20 in one direction. That is, it is not necessary to use a very high-precision optical element or the like, and it is not necessary to replace the lens, so that high image quality can be obtained at a correspondingly low cost.

In the above description, as a typical example, the decentered lens is rotated around the central axis. However, in general, if the lens is rotated around an axis different from the optical axis, Since the optical axis moves so that the trajectory draws a cone, the same effect as described above can be obtained. However, just like most lenses are eccentric, in many cases the optical axis and the rotation axis do not match due to processing errors or assembly errors in the lens holder, so it is necessary to intentionally shift the optical axis and the rotation axis. There is no.

The collimating lens 12 shown in FIG. 1 is not limited to those shown in FIGS. Therefore, another example of the collimating lens 12 is shown in FIG. In FIG. 9, the lens 90 is housed in a lens holder 91. The lens holder 92 has a lens hole 92a into which an end 91a of the lens holder 91 is inserted. A gap 92b is provided at the upper end of the lens holder 92 so that the lens holder 91 can be rotated with the lens holder 92 inserted into the lens hole 92a. When the angular relationship between the lens holder 91 and the lens holder 92 around the axis is determined, the gap 9
The bolt 93 that penetrates the lens holder 9b is tightened.
1 is fixed.

The lens included in the collimating lens 12 shown in FIG. 1 has a single lens configuration (the lens 2 shown in FIGS. 2 to 4).
0 corresponds to this) and those having a plurality of sheets. When the lens has, for example, two lenses, one of the lenses may be rotated, the two lenses may be individually rotated, or the two lenses may be rotated collectively. That is, when the collimating lens 12 includes a plurality of lenses, at least one or a group of the lenses may be rotated.

As described above, the present embodiment focuses on the fact that when the lens is rotated around an axis different from the optical axis, the optical axis moves so that the trajectory draws a cone. Is provided. At this time, since the optical axis and the rotation axis do not often coincide with each other due to eccentricity of the lens, deformation of the lens holder, and assembly error, it is not necessary to intentionally shift the optical axis and the rotation axis. . This makes it possible to use a highly precise optical element, etc., and to perform a simple adjustment operation of rotating the lens in one direction. The maximum strength can be reduced by correcting the slope of the resulting strength.

(Second Embodiment) FIG. 10 is a perspective view showing a laser beam device according to a second embodiment of the present invention. The laser beam device shown in FIG. 10 is used for, for example, a laser printer or a plate making output scanner, and forms a two-dimensional image on a photosensitive surface by a laser beam. In FIG. 10, a light source 101 is provided near one end of a support base 100.
(Eg, LD), collimating lens 102, mirror 10
3. Cylindrical lens 104, polygon mirror 10
5 and a scanning lens 106 are provided, and a cylindrical lens 107 is provided near the other end.
Light source 101, collimating lens 102, and mirror 10
Numeral 3 is arranged along the Z direction, a cylindrical lens 104 and a polygon mirror 105 are arranged on a straight line passing through the mirror 103 in the Y direction, and a scanning lens 1 is arranged on a straight line passing through the polygon mirror 105 in the Z direction.
06 and the cylindrical lens 107 are placed.

The collimating lens 102, the mirror 103,
A cylindrical lens 104, a polygon mirror 105,
The scanning lens 106 and the cylindrical lens 107 cooperate to guide the laser beam emitted from the light source 101 to converge it at a drawing position (one point on a straight line 108 parallel to the Y direction). Called an optical system. A straight line 109 indicates a designed optical axis of the optical system.

In the above laser beam device, the light source 1
The light emitted from 01 becomes parallel light when passing through the collimating lens 102. The parallel light is reflected by the mirror 10
By 3, the traveling direction is bent, and heads toward the cylindrical lens 104. And the cylindrical lens 1
After being condensed in the ZX plane by 04, it is reflected by the polygon mirror 105 and enters the scanning lens 106. The light condensed on the ZX plane and once formed on the polygon mirror 105 is condensed again by the scanning lens 106 and the cylindrical lens 107 on the ZX plane, and condensed by the scanning lens 106 on the YZ plane. 100 near the other end. At this time, the polygon mirror 105 is rotated around a straight line extending in the X direction as an axis, and the image forming position moves accordingly along the straight line 108 (the direction in which the image forming position moves is called the main scanning direction). ). On the other hand, the photosensitive surface is placed on a plane including the straight line 108 and perpendicular to the Z direction, and is moved along the X direction (the direction in which the photosensitive surface moves is referred to as a sub-scanning direction). Thus, a two-dimensional image is formed on the photosensitive surface.

The collimating lens 102 shown in FIG.
Has a structure as shown in FIGS. The apparatus of FIG. 10 configured as described above is different from the apparatus of FIG. 1 in that a polygon mirror 105 is used as a deflector.
The collimating lens 102 is provided with a mechanism for rotating the lens, and the maximum intensity of the diffraction ring can be reduced by a simple adjustment operation similar to that described in the first embodiment. In other words, there is no need to use very high-precision optical elements or the like, and since there is no need to replace lenses,
High image quality can be obtained inexpensively.

As described above, in the present embodiment, as in the first embodiment, when the lens is rotated around an axis different from the optical axis, the optical axis moves so that the trajectory draws a cone. The collimating lens 102 is provided with a mechanism for rotating the lens. As a result, without using a highly accurate optical element or the like, and simply performing a simple adjustment operation of rotating the lens in one direction, the diffraction ring appears near the periphery of the focused laser beam along the circumferential direction. The maximum strength can be reduced by correcting the inclination of the generated strength.

(Third Embodiment) FIG. 11 is a perspective view showing a laser beam device according to a third embodiment of the present invention. The laser beam device shown in FIG. 11 is used in, for example, a laser printer or a plate making output scanner, and forms a two-dimensional image on a photosensitive surface by a laser beam. In FIG. 11, a light source 111 (for example, L
D) and a cylindrical lens 112 are provided. Near one end, a collimator lens 113 and a mirror 1 are provided.
14, a polygon mirror 115 and a scanning lens 116, and a cylindrical lens 117 near the other end. Light source 111, cylindrical lens 112, collimating lens 113, and mirror 1
14 are arranged along the Z direction,
A polygon mirror 115 is arranged on a straight line going in the direction, and a scanning lens 116 and a cylindrical lens 117 are placed on a straight line going in the Z direction through the polygon mirror 115.

A cylindrical lens 112, a collimating lens 113, a mirror 114, a polygon mirror 115,
The scanning lens 116 and the cylindrical lens 117 cooperate to guide the laser beam emitted from the light source 111 and converge it at a drawing position (one point on a straight line 118 parallel to the Y direction). Called an optical system. A straight line 119 indicates a designed optical axis of the optical system.

In the above laser beam device, the light source 1
The light emitted from 11 is a cylindrical lens 112
(The light source 111 is provided with a relay lens 111a, and the light emitted from the light source 111 is transmitted through the relay lens 1).
11a to pass through the cylindrical lens 1
An intermediate image is once formed just before 12). The light that has become parallel light in the ZX plane is condensed in the ZX plane by the collimator lens 113, turned into parallel light in the YZ plane, and then its traveling direction is changed by the mirror 114. Then, the light is reflected by the polygon mirror 115 and travels to the scanning lens 116. The light condensed in the ZX plane and forms an image once on the polygon mirror 115, and the parallel light in the YZ plane is condensed again by the scanning lens 116 and the cylindrical lens 117 in the ZX plane, and is converged in the YZ plane. The light is condensed by the scanning lens 116 and forms an image near the other end of the support 110.
At this time, the polygon mirror 115 is rotated about a straight line extending in the X direction as an axis, and the image forming position moves accordingly along the straight line 118 (the direction in which the image forming position moves is referred to as the main scanning direction). Call). On the other hand, the photosensitive surface is placed on a plane including the straight line 118 and perpendicular to the Z direction, and is moved along the X direction (the direction in which the photosensitive surface moves is referred to as a sub-scanning direction). Thus, a two-dimensional image is formed on the photosensitive surface.

The collimating lens 113 shown in FIG.
The collimating lens 12 (or the collimating lens 102 in FIG. 10) has a structure as shown in FIGS. The device of FIG. 11 configured as described above differs from the device of FIG. 1 in that a polygon mirror 115 is used as a deflector.
2 is provided not between the mirror 114 and the polygon mirror 115 but between the light source 111 and the mirror 114, but like the device of FIG. 1 or FIG. Is provided, and the maximum intensity of the diffraction ring can be reduced by a simple adjustment operation similar to that described in the first embodiment. That is, it is not necessary to use a very high-precision optical element or the like, and it is not necessary to replace the lens, so that high image quality can be obtained at a correspondingly low cost.

As described above, in this embodiment, as in the first embodiment, when the lens is rotated around an axis different from the optical axis, the optical axis moves so that the locus draws a cone. The collimating lens 113 is provided with a mechanism for rotating the lens. This makes it possible to use a highly precise optical element, etc., and to perform a simple adjustment operation of rotating the lens in one direction. The maximum strength can be reduced by correcting the inclination of the generated strength.

In the first to third embodiments, the collimating lenses (12, 102, 113) are provided with a rotating mechanism to rotate the lenses, but instead / further, the scanning lenses (14, 106, 116) are used. ) May be provided with a rotation mechanism to rotate the lens.

In the first to third embodiments, the collimating lenses (12, 102, 113) are provided with a rotating mechanism to rotate the lenses. Instead, the collimating lenses (12, 102, 113) are rotated. A mechanism for moving the lens in parallel may be provided to move the lens in a direction different from the optical axis, typically in a direction perpendicular to the optical axis. Because
This is because even if the lens is moved in a direction different from the optical axis, the optical axis moves. As a mechanism for moving the lens in parallel, for example, a rail may be provided on the bottom surface of the collimating lens 12 in FIG. 1, and the support base 10 may be carved with a parallel movement groove 10 a to be fitted with the rail along the Z direction. As a result, without using a highly accurate optical element or the like, and by simply performing a simple adjustment operation to translate the lens in one direction, the diffraction ring appears near the periphery of the focused laser beam in the circumferential direction. The maximum intensity can be reduced by correcting the intensity gradient along which occurs. However, in this case, since the optical axis moves so that the trajectory describes a plane, the effect of reducing the maximum intensity of the diffraction ring is weaker than rotating the lens.

Further, the collimating lenses (12, 10)
2, 113) may be provided with a mechanism for rotating and moving the lens in parallel. For example, in the collimating lens shown in FIG. 2, a rail 23e is provided on the bottom surface of the lens holder 23, and a parallel movement groove 10a to be fitted with the rail may be formed in the support table 10 shown in FIG. In this case, the effect of reducing the maximum intensity of the diffraction ring is only rotation,
Or, it is expected to be more remarkable than the case of only translation.

Alternatively, a collimating lens (12, 10
2, 113) may be provided with a mechanism for changing the direction of the lens. FIG. 12 shows an example. In FIG.
The lens 121 is housed in a frame 122. Frame 122
, Three screws 123 are provided at equal intervals. In this mechanism, by pushing and pulling each screw 123 individually, the positional relationship between the frame and the support frame 124 behind it changes, and the (optical axis) direction of the lens 121 changes. Now, it is assumed that the focused laser beam has an intensity distribution as shown in FIG. 14, and it is desired to suppress the side lobe peak value to a predetermined allowable value (1 / e ² ) or less by adjusting the optical axis. At this time, the worker uses a measuring device (not shown).
Push and pull the screws individually while looking at the strength curve displayed in to find a point where the left and right side lobes are equal.
As a result of the left and right side lobes being equalized by this optical axis adjustment operation, the peak value of the side lobe falls below 1 / e ² as shown in FIG. As described above, by providing a mechanism for changing the direction of the lens (optical axis) at (12, 102, 113) in the collimating lens, the direction of the lens can be changed without using a highly accurate optical element or the like. Only by performing the adjustment operation, the inclination related to the intensity generated along the circumferential direction in the diffraction ring appearing near the peripheral edge of the focused laser beam can be corrected and the maximum intensity can be reduced. However, in the adjustment using the mechanism of FIG. 12, the three screws 123 must be individually pushed and pulled to find a point where the left and right side lobes are equal, so that the description has been given in the first to third embodiments. Compared with such an adjustment using a mechanism for rotating the lens in one direction or a mechanism for moving the lens in parallel in one direction, it is not easy to equalize the left and right side lobes, and it takes time and effort.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a laser beam device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing an example of the collimator lens 12 shown in FIG.

FIG. 3 is a sectional view of the collimator lens of FIG. 2;

FIG. 4 is a front view of the collimating lens of FIG. 2;

FIG. 5 is a view for explaining that the angular relationship between the lens holder 21 and the lens holder 23 around the axis can be arbitrarily changed in the collimating lens of FIG. 2;

FIG. 6 is a diagram illustrating eccentricity of a lens.

FIG. 7 is a diagram illustrating a state where an optical axis moves when an eccentric lens is rotated around a central axis.

FIG. 8 is a diagram conceptually showing a state in which the shift of the optical axis of the entire optical system including the lens changes when the decentered lens is rotated around the central axis.

FIG. 9 is an exploded perspective view showing another example of the collimating lens 12 of FIG.

FIG. 10 is a perspective view showing a laser beam device according to a second embodiment of the present invention.

FIG. 11 is a perspective view showing a laser beam device according to a third embodiment of the present invention.

FIG. 12 shows the apparatus of FIG. 1, FIG. 10 and FIG.
It is a front view showing an example of an optical axis adjustment mechanism provided with each collimator lens (12, 102, 113).

FIG. 13 is a diagram showing an intensity distribution (Gaussian distribution) of an ideally focused laser beam.

FIG. 14 is a diagram illustrating an example of an intensity distribution of a laser beam focused to a diffraction limit and showing a diffraction ring (when left and right side lobes are not uniform).

FIG. 15 is a diagram showing another example of the intensity distribution of the laser beam that has been focused to the diffraction limit and a diffraction ring has appeared (when the left and right side lobes are equal).

[Explanation of symbols]

10, 100, 110 Support base 10a Parallel movement groove 11, 101, 111 Light source 12, 102, 113 Collimating lens 13 Deflector 14, 106, 116 Scanning lens 104, 107, 112, 117 Cylindrical lens 105, 115 Polygon mirror 20 Lens 21, 23 Lens holder 21b-21d, 23b-23d Bolt hole 23e Rail 103, 114 Mirror

Claims (3)

[Claims] 1. A laser beam apparatus for performing drawing by a laser beam, comprising: an optical system for guiding a laser beam emitted from a light source to focus at a drawing position; and at least one lens included in the optical system. The 1
By rotating the lens around an axis that is different from the optical axis of the lens, the maximum intensity can be corrected by correcting the tilt related to the intensity generated along the circumferential direction in the diffraction ring that appears near the periphery of the focused laser beam. And a mechanism for reducing the size of the laser beam. 2. A laser beam apparatus for performing drawing by a laser beam, comprising: an optical system for guiding a laser beam emitted from a light source to focus at a drawing position; and at least one lens included in the optical system. The 1
By translating along the axis that is different from the optical axis of the lenses, the inclination of the intensity generated along the circumferential direction in the diffraction ring appearing near the periphery of the focused laser beam can be corrected to the maximum. A laser beam device comprising: a mechanism for reducing intensity. 3. A laser beam device for performing drawing by a laser beam, comprising: an optical system for guiding a laser beam emitted from a light source to focus at a drawing position; and at least one lens included in the optical system. A mechanism for correcting the inclination of the intensity generated along the circumferential direction in the diffraction ring appearing near the periphery of the focused laser beam by changing the direction of the focused laser beam, thereby reducing the maximum intensity. .