KR20030064088A - Laser beam alignment system with the rotation axis of cylindrical structures for laser-assisted fabrication - Google Patents

Abstract

PURPOSE: An apparatus for aligning beam with a rotational axis of a cylindrical member is provided to precisely aligning beam with the rotational axis of the cylindrical member or a cylindrical structure by using a measuring system having a laser. CONSTITUTION: An apparatus for aligning beam with a rotational axis of a cylindrical member includes a conveying section having an X-Y axis conveying system(10), a rotational conveying system(11) and a rotational shaft(12). A first two-axis angle adjusting plate(14) is connected to the conveying section. A first reflection plate(31) is mounted on the first two-axis angle adjusting plate(14) in order to horizontally maintain a turntable. The first reflection plate(31) is connected to a second two-axis angle adjusting plate(15). A beam splitter(34) is installed on the second two-axis angle adjusting plate(15). A vertical measuring section includes a second reflection plate(32), an iris(33) and a light receiving device(22).

Description

Laser beam alignment system with the rotation axis of cylindrical structures for laser-assisted fabrication

The present invention relates to an alignment device of a laser beam for producing a microcylindrical structure in microfabrication using a laser, and in particular, vertical alignment and planar alignment of the laser beam is aligned with the bottom surface of the laser beam. The present invention relates to an alignment device with respect to the axis of rotation of the laser beam, which makes it possible to improve the work efficiency by preventing malfunctions and shortening the measurement work time during machining.

One of the notable trends in the recent rapid growth of the telecommunications, electronics, and life industries is the miniaturization and integration of products. In the field of semiconductor, micro machining technology has already achieved the precision of micrometer or less in the case of planar processing, and recently, interest in 3D micro machining technology for use in MEMS and micro systems based on micro sensors and actuators Technological development efforts are greatly increasing.

Laser micromachining technology has attracted a lot of attention due to the advantages that the complex three-dimensional structure can be manufactured relatively easily than the conventional semiconductor processing technology and the equipment is relatively simple. In addition, laser processing technology has the advantage that it is possible to process not only semiconductor materials but also various materials such as ceramics, metals and polymers. As a representative example of a three-dimensional structure manufacturing technology using a laser, the deposition process to induce deposition locally in the position of the laser beam to form a three-dimensional structure, etching only the region irradiated with the laser beam in the liquid or gas (etching), such as etching process to be scraped off little by little, or photopolymer (microstereolithography) to cure only the polymer solution exposed to light by irradiating laser light to the photopolymer (photopolymer).

The shape of the three-dimensional structure that can be manufactured by the above laser micromachining technology is mainly composed of a linear structure and a curved structure, and the shape is defined by the linear and rotational motion of the feed system. In the case of cylindrical rotors, in order to set the radius of micrometer-sized structures, the alignment of the laser beam and the axis of rotation should be preceded, and the exact alignment of the laser beam and the axis of rotation is directly related to the diameter precision of the cylindrical structure. .

Existing rotation center axis alignment techniques show how to accurately connect the center of the power transmission axis using a dial gauge, laser system, etc. to the axis of the rotating machine, and the difficulty of general alignment that requires the removal and repositioning of optical components. Although there is a device called Seward Alignment Module that removes and performs beam position and angle adjustment quickly and precisely, there is no method to align the laser beam to the axis of rotation of the structure when laser processing a rotating structure such as a micro cylinder. . On the other hand, it is possible to align the laser beam and the rotational center axis manually by trial and error, but in this case, it is difficult to rely on the experience of the skilled person every time and it takes much time for the skilled person. In addition, in the case of manual alignment, the laser beam is visually aligned and thus there may be a safety problem, and it is difficult to obtain a precise alignment result repeatedly.

The present invention proposes an optical method for aligning a laser beam with a rotational axis in the manufacture of a rotor structure symmetrical about the central axis, such as a cylinder, as an alternative to the beam alignment method used by those skilled in the laser processing field. . In the manufacture of microscopic cylindrical structures and similar rotor structures using lasers, this measuring system can be used by beginners to easily align laser beams and their central axis of rotation on a micrometer level, as well as to repeat identical alignments. Since the result can be obtained, it is an object of the present invention to ensure dimensional accuracy and dimensional uniformity of the microstructure.

1 is an overall configuration diagram of the measurement system of the present invention

Figure 2 is a configuration view from above of the measuring unit of the measuring system of the present invention

3 is a block diagram for explaining the basic principle of the present invention

4 is a block diagram for explaining the application of the basic principle according to the present invention

5 is a configuration diagram for explaining the laser beam and the rotation center axis alignment error correction amount according to the present invention;

6 is a configuration diagram illustrating a laser beam and rotational axis alignment error correction procedure according to the present invention.

7 is a detailed flowchart showing the alignment order of the laser beam and the rotational axis of the present invention.

8 is a configuration diagram illustrating an alignment error between a laser beam and a rotation center axis due to a horizontal error between a virtual reference plane perpendicular to a rotation axis and a rotating mirror plane;

9 is a configuration diagram for explaining the correction of the alignment error occurring when the focus lens is inserted into the beam path after the laser beam and the rotation center axis alignment is completed in the present invention;

10 is a schematic view of a quadrant photodiode in the present invention

11 is a schematic view of the mirror stop in the present invention

* Explanation of symbols for main parts of the drawings

10: XY feed system 11: rotary feed system

12: center of rotation axis 13: rotary table

14: 2-axis angle adjuster 1 15: 2-axis angle adjuster 2

16: laser 17: incident light

18: Reflected light 19: Focus lens

20: light receiving element capable of position sensing 1

20-1: Light receiving element 1-1 capable of position sensing

21: light receiving element capable of position sensing

22: light receiving element capable of position sensing 3

30: reference plane 31: reflector 1

32: reflector 2 33: aperture

34: Light splitter with plane mirror 35: Mirror with 45 ° slope

36: Flat mirror attached to the splitter

The present invention as a means for achieving the above object as a laser beam alignment device,

In the laser beam aligning device comprising a laser beam generating means and means for aligning the laser beam to the center of rotation axis,

A transfer unit having at least an XY feed system performing a plane motion and a rotation feed system performing a rotational motion;

An optical splitter installed on the table of the rotary feed system and capable of adjusting an angle with a horizontal plane;

A planar measuring unit having a position sensing light receiving element fixedly disposed on an extension line of the table at a predetermined angle;

And a vertical measuring unit having at least a position sensing light receiving element for measuring a beam reflected from an aperture and a predetermined reflecting plate for adjusting a beam path.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

1 shows an overall configuration diagram of the present invention.

The conveying part is composed of an XY feed system 10 having a plane motion, a rotation feed system 11 having a rotational motion, and a rotating shaft 12 transmitting the motion thereof, and a 2-axis angle adjusting plate 1 (14) connected thereto. Reflector plate 1 (31) used to level the rotary table above is attached, and the biaxial angle adjuster plate 2 (15) is connected thereon, and the light splitter 34 having a flat mirror attached thereto is coupled thereon.

Vertical measuring unit includes a reflector 2 (32) for adjusting the beam path, a diaphragm 33 having a hole having the same diameter as the diameter of the laser beam, and a light receiving element 3 (22) capable of position sensing for measuring a beam reflected from the diaphragm. Corresponds to

Planar measuring unit for measuring the plane alignment is composed of light-receiving elements 1,2 (20, 21) capable of position sensing, where the light-receiving elements 1, 2 (20, 21) capable of position sensing are provided with a splitter with a flat mirror. It is arranged at a 90 ° angle as shown in FIG. 2.

And it consists of the laser 16 which is a light source.

The basic principle of sorting and the sorting order according to the present invention will be described.

3 is a block diagram illustrating a basic principle according to the present invention.

Assuming that the laser beam is irradiated perpendicularly to the rotating table, attaching a mirror 35 having a 45 ° inclined surface thereon can measure the deviation from the axis of rotation of the laser beam as follows.

The beam a indicates the position of the reflected beam in the initial state (0 °) of the rotating table 13, and when the table is rotated 180 °, the reflecting surface of the mirror is reversed like the dotted line and the beam is reflected at the position of b. If a height deviation of H is generated between the reflected beams a and b, it can be seen that the incident laser beam is not aligned with the central axis of rotation 12. The height deviation due to the axis alignment error can be measured by the light receiving element capable of position sensing on both left and right sides as shown in FIG. 3.

In this case, the position sensing light receiving element should be located at the same height from the surface, and as shown in FIG. 3, the light receiving elements 1,1-1 (20,20-1) capable of position sensing may have two sensors positioned on the same line. There is a problem that is difficult to install.

To solve this problem, the present invention uses a light splitter 34 with a flat mirror 36 attached thereto. The light splitter may transmit a part of light and reflect the remainder, so that when a mirror is attached, light may be reflected in both directions as shown in FIG. 4.

The beam irradiated in the initial state is partially reflected at position a on the inclined plane of the light splitter, and is transmitted through the rest, reflected at the plane mirror 36, and then goes back to the a 'position through the light splitter. That is, since it is assumed that the beam is irradiated vertically, the reflected beams are perpendicular to each other with respect to the incident beam, and the beams are reflected in the T-shape. When the turntable rotates 180 °, the position of the splitter is changed as shown by the dotted line, and it is divided into the b beam and the b 'beam. Therefore, the height H due to the alignment error is measured by comparing the beams of a and b' with one sensor on the left side. can do. And it measures also in the same way about 90 degrees and 270 degrees like FIG.

Therefore, only two light-receiving elements capable of position sensing need to be provided at intervals of 90 ° with respect to the light splitter.

Since the rotation axis center does not change due to the rotation of the rotary table, it is not necessary to exactly match the center axis of the rotation table with the rotation axis of the rotary table when attaching the optical splitter. There are no possible difficulties in the initial installation of the splitter as there are possible advantages.

The compensation amount of the rotation center axis alignment error thus measured can be obtained from the geometric shape of the optical splitter as shown in FIG. 5. If the alignment error between the laser beam and the rotational central axis is S and the measured height deviation is H, the following relation holds.

That is, the error is corrected by moving the optical splitter 34 to the XY transfer system 10 in the direction of the rotational central axis by half of the value measured by the position sensing light receiving element. As shown in FIG. 6, since the rotational center axis alignment error exists in the X and Y axis directions, the optical splitter is rotated by 90 ° one time and then the X axis direction (A → B) and the Y axis direction (B) using the measured error. → O) and move the light splitter sequentially to compensate for the laser beam to coincide with the point O, which is the central axis of rotation.

In the present invention, a four-segment photodiode is used as a light-receiving element capable of position sensing, and FIG. 10 shows a basic operation principle of the four-segment photodiode. A quadrant photodiode is like four independent photodiodes in a bundle. In FIG. 10, A, B, C, and D are independent photodiodes, respectively, and generate current when light shines on each surface. As shown in FIG. 10, when the laser beam (hatched portion) shines on the A, B, C, and D regions by different amounts, each photodiode generates a current corresponding to the amount of light shined. The quadrant photodiode determines the position of the laser beam center using the following formula using the amount of current generated in each of A, B, C, and D planes.

The overall beam alignment method according to the embodiment of the present invention together with the above-described basic principle will be described with reference to the flowchart of FIG. 7.

In the description of FIG. 3, it is assumed that the laser beam is irradiated perpendicularly to the surface of the turntable 13. However, in the actual system, if there is a shape error in the optical splitter 34 or the rotation table 13 is inclined with respect to the center of rotation, the rotational center of the laser beam is generated because it generates a horizontal error that changes the height of the mirror surface while rotating. In order to minimize the axis alignment error, first, in step 100, alignment is performed so that the beam is incident perpendicularly to the rotation table.

In FIG. 1, the table consists of a biaxial angle adjusting plate 1 (14) and attaches a reflector to the upper surface for reflecting light, where the reflecting plate 1 (31) is used and is positioned with an aperture 33 having a diameter equal to the diameter of the laser beam. Sensing light-receiving elements are used as measuring instruments. Fig. 8 shows the state when the incident beam exiting the aperture hole is irradiated to the reflector plate 1 and rotated by 0 ° and 180 °. If the horizontal error of the reflector 1 with respect to the reference plane is 0, the incident laser beam is irradiated perpendicularly to the reference plane, and the reflected beam will pass through the aperture hole again by the reflection law. However, reflector 1 is If it was inclined as much as the reflected light 18 with respect to the incident light 17 Proceed with angular error. When the reflecting plate 1 rotates 180 °, the reflected light 18 also has the same error and proceeds in a symmetrical direction, and draws the same circular locus as shown in FIG. 8 during one rotation. This circular trajectory forms a beam reflected from the aperture on the light receiving element 3 (22) capable of position sensing of FIG. 1, and the distance from the aperture to the reflector 2 (32). , The distance from reflector 2 to reflector 1 (31) In this case, the radius d of the observed beam trajectory is formed from the geometric symmetric figure indicated by the dotted line.

By adjusting the inclination of the biaxial angle adjusting plate 1 (14) to reduce the radius d of the reflected light trajectory, the reflecting plate 1 is perpendicular to the rotation axis, and when the vertical alignment is completed, the reflected light passes through the aperture hole.

In the above, the reflector has a material capable of reflecting light, such as a flat mirror, a metal surface such as polished stainless steel, copper, bronze, nickel, etc., and a material having a surface that is not metallic but excellent in light reflection, such as a silicon wafer. And the like.

The aperture stops the position of the reflected light, but it is difficult to determine whether the light is vertically aligned by adjusting the reflector 1 due to the fine trajectory of the laser beam appearing on the aperture during the actual experiment. When used, the laser beam reflected on the mirror surface can be seen through the light receiving element, so the alignment of the laser beam is easy.

In FIG. 11, the beam emitted from the laser travels through the small hole in the mirror diaphragm to the reflector 1 and is reflected by the reflector 1 and returns. If the laser beam is incident perpendicularly to the reflector 1, the returned beam must pass through the hole in the diaphragm mirrored exactly along the original path, according to the law of reflection. However, if the laser beam is not incident vertically, it will be deviated from its original path and directed in a different direction and will not pass through the hole as shown below. If the laser beam incident on the reflector 1 is slightly away from the vertical, the returned beam returns to a position far away from the hole of the mirror aperture. When using a normal aperture, this distance is so small that the eye can identify the correct position. It is very hard to do and the error is big.

The mirror surface diaphragm of FIG. 11 is for overcoming the difficulty caused by measuring how far the reflected and returned beam is from the hole when using the general aperture. In the case of using the mirror aperture, the beam reflected by the reflector 1 is reflected back from the mirror aperture surface to measure the amount of reflected light. If the beam reflected from Reflector 1 travels exactly along its original path, it will all enter the hole, so the amount of light reflected from the mirror aperture surface will be nearly zero. Through this, it is known whether the intended laser beam is incident perpendicularly to the reflector 1.

When the light splitter is placed on this rotating surface in step 101, it is reflected toward the light source by a plane mirror attached to the bottom of the light splitter. If there is a shape error in the part, the reflected beam does not pass through the aperture hole and is not vertically aligned. In this case, the 2-axis angle adjusting plate 2 (15) is installed on the reflecting plate 1 (31), which is a rotating surface, and the light splitter 34 having a flat mirror is installed thereon, and then the only adjustment is made to the 2-axis angle adjusting plate 2 (15). By passing through the hole, the measuring instrument and the reference plane coincide.

In step 102, the position difference-sensing light receiving elements 1 and 2 are used to measure the height deviation of the beam reflected perpendicularly to the light splitter to correct the rotational central axis alignment error. At this time, since the laser beam is fixed, the rotation axis is corrected by moving in the XY direction on the plane by using the XY feed system.

In step 103, the alignment error caused by the insertion of the focus lens when laser processing is corrected. In FIG. 9, r denotes a reference beam as an aligned beam path, and t denotes a beam path changed after lens insertion. Position-sensing light-receiving element, the difference between the t-beam and r-beam , Measure and adjust and angle the lens in the XY direction so that the distorted t beam comes to the position of the r beam.

The effect of the present invention is to precisely align the central axis of the laser beam and the cylindrical structure when manufacturing a microcylindrical structure and similar rotating body structure using a laser to improve the dimensional accuracy of the structure, even beginners can easily achieve precise and repeatable alignment results It is possible to provide micro beam processing by providing an optical beam alignment method that can be obtained.

Claims (7)

In the laser beam aligning device comprising a laser beam generating means and means for aligning the laser beam to the center of rotation axis, A transfer unit having at least an XY feed system performing a plane motion and a rotation feed system performing a rotational motion; An optical splitter installed on the table of the rotary feed system and capable of adjusting an angle with a horizontal plane; A planar measuring unit having a position sensing light receiving element fixedly disposed on an extension line of the table at a predetermined angle; And a vertical measuring unit having at least a position sensing light receiving element for measuring a beam reflected from an aperture and a predetermined reflecting plate for adjusting a beam path. The rotating table of claim 1, wherein And at least a biaxial angle adjusting plate 1, a reflecting plate 1 attached to an upper surface of the adjusting plate 1, and a biaxial angle adjusting plate 2 attached to an upper surface of the reflecting plate. The method of claim 1, Light splitter is a laser beam alignment device with a flat mirror. The method of claim 1, The planar measuring unit is a laser beam alignment device in which the light receiving elements are disposed at 90 ° intervals. The method according to claim 1 or 2, Reflector is a laser beam alignment device that is a flat mirror. The method of claim 1, The light-receiving element is a laser beam aligning device which is a quadrant photodiode. The method of claim 1, Aperture is mirror mirror individual alignment device.