JP2008000774A - Laser beam irradiation device, laser beam irradiation method and pattern drawing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam irradiation device capable of performing machining at high precision. <P>SOLUTION: The laser beam irradiation device comprises: a laser light source for emitting a laser beam; a branching apparatus for branching the laser beam emitted from the laser light source to a plurality of laser beams; and a diffraction optical element arranged at a position on which the plurality of laser beams branched in the branching apparatus are made incident and branching each of the plurality of laser beams branched in the branching apparatus to a plurality of laser beams. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser irradiation apparatus, and more particularly to a laser irradiation apparatus that irradiates an irradiation object with a plurality of laser beams. In particular, the present invention relates to a laser irradiation method for irradiating an irradiation object with a plurality of laser beams. Furthermore, the present invention relates to a method for drawing a pattern using a laser beam.

  A technique is known in which a laser beam is incident on a layer to be transferred that is in close contact with the surface of the base substrate, and the layer to be transferred at the position where the beam is incident is adhered (transferred) to the base substrate. After transferring a part of the transferred layer, the transferred part of the transferred layer that is not transferred is peeled off, so that a convex portion made of the transferred layer can be left on the base substrate.

  FIG. 4 shows an example of a convex pattern formed by transferring the transfer layer. A plurality of linear patterns 100Y parallel to the Y-axis are arranged in the X-axis direction at a pitch Px, and linear patterns 100X parallel to the X-axis direction are arranged in the Y-axis direction at a pitch Py. A lattice pattern 100 is constituted by the linear patterns 100X and 100Y intersecting each other. The grid pattern 100 shown in this figure defines, for example, pixels of a flat-type image display device. For the sake of later explanation, the linear pattern 100X positioned between the adjacent linear patterns 100Y is defined as the branch portion 101.

  Various pattern drawing methods for drawing the pattern shown in FIG. 4 by irradiating a laser beam have been proposed. Here, when the linear pattern 100Y parallel to the Y axis is drawn and then the linear pattern 100X parallel to the X axis is drawn, the laser beam is again irradiated onto the already transferred pattern at the intersection of the two. . Due to this second irradiation, the transferred pattern is damaged.

  A laser irradiation apparatus capable of drawing the pattern shown in FIG. 4 while avoiding this problem and a configuration of a laser light source used in the laser irradiation apparatus are disclosed. (For example, refer to Patent Document 1.) The laser irradiation apparatus described in Patent Document 1 includes “a first laser oscillator and a second laser oscillator that emit a laser beam, and a laser emitted from the first laser oscillator. An optical path synthesizer that emits light by changing the optical paths of the two laser beams so that the traveling directions of the beam and the laser beam emitted from the second laser oscillator are parallel to each other and the cross sections of the two beams are in contact with each other. A laser light source is used.

  FIG. 5 is a schematic diagram of a laser irradiation apparatus including a diffractive optical element (DOE).

  The illustrated laser irradiation apparatus includes two laser oscillators 51 and 52, a cross-sectional shaping imaging optical system 53, and a DOE 54. The laser oscillators 51 and 52 use the same laser medium, and can emit laser beams having the same wavelength, for example, a second harmonic of an Nd: YLF laser. The cross-sectional shaping imaging optical system 53 includes, for example, a mask having a through hole that transmits a laser beam and an imaging optical system that can form an image of the shape of the through hole. The DOE 54 splits the incident laser beam into a plurality of, for example, 100 laser beams. The cross-sectional image forming optical system 53 and the DOE 54 are arranged in a positional relationship such that the shape of the through hole included in the cross-sectional image forming optical system 53 is imaged on the DOE 54.

  Pulse laser beams 10a and 10b (second harmonics of Nd: YLF laser) are emitted from the laser oscillators 51 and 52, respectively, with the same pulse width. The pulsed laser beams 10 a and 10 b are incident on the DOE 54 via the cross-sectional shaping imaging optical system 53. This figure shows beam cross sections 53a and 53b of the laser beams 10a and 10b incident on the DOE 54 by forming an image of the shape of the transmitted through hole. The cross sections of the two pulse laser beams 10a and 10b are in contact with each other. In addition, the figure of the beam cross sections 53a and 53b is the figure seen along the advancing direction of a beam.

  The pulse laser beams 10 a and 10 b are branched into a plurality of beams by the DOE 54 and enter the beam incident surface 55. In this figure, the beam incident areas 54a and 54b of the laser beams 10a and 10b incident on the beam incident surface 55 are shown as viewed along the beam traveling direction.

  For example, the beam incident areas 54 a and 54 b are in contact with each other at an incident position close to the DOE 54. However, as the incident position of the beam becomes farther from the DOE 54, the two may gradually move away from each other. In other words, the relative positional relationship between the two may be shifted depending on the incident position of the beam.

  This phenomenon is caused by variations in oscillation wavelength due to individual differences between the laser oscillators 51 and 52. Even if the emitted laser beams 10a and 10b are both the second harmonic of the Nd: YLF laser, the wavelengths of both may be slightly different. The diffraction rate of the DOE 54 is strongly dependent on the wavelength of the incident beam. For this reason, a difference occurs in the branch pitch between the laser beams 10a and 10b by the DOE 54, and as a result, the relative positional relationship between the beam incident areas 54a and 54b may differ depending on the incident position of the beam.

International Publication No. 2005-088873

  An object of the present invention is to provide a laser irradiation apparatus and a laser irradiation method capable of performing processing with high accuracy.

  Another object of the present invention is to provide a pattern drawing method capable of drawing with high accuracy.

  According to one aspect of the present invention, a laser light source that emits a laser beam, a branching device that branches the laser beam emitted from the laser light source into a plurality of laser beams, and a plurality of laser beams branched by the branching device are provided. There is provided a laser irradiation apparatus including a diffractive optical element that is arranged at an incident position and branches each of a plurality of laser beams branched by the branching device into a plurality of laser beams.

  According to another aspect of the present invention, (a) a step of branching an original laser beam emitted from one laser oscillator into a first laser beam and a second laser beam, (b) There is provided a laser irradiation method including the steps of causing the first laser beam and the second laser beam to enter a diffractive optical element, branching each of the first laser beam and the second laser beam into a plurality of laser beams, and causing the laser beam to enter an irradiation object.

  When the laser irradiation apparatus or the laser irradiation method described above is used, the laser beam branched by the diffractive optical element is incident on the irradiation object while keeping the relative positional relationship of the incident region constant regardless of the incident position. Processing can be performed with high accuracy.

  Furthermore, according to another aspect of the present invention, a step of branching an original laser beam emitted from one laser oscillator into a first laser beam and a second laser beam, and via a diffractive optical element When the first and second laser beams are incident on the object to be processed, the incident areas of the first laser beam and the second laser beam are mutually in the first direction on the surface of the object to be processed. Adjusting the optical axis so that they are in contact with each other, and the incident positions of the first laser beam and the second laser beam move from a start point to an end point in a second direction intersecting the first direction As described above, while moving the object to be processed, the first laser beam is continuously incident from the start point to the end point, and the second laser beam is intermittently incident to branch from the linear locus. Draw a pattern with protruding parts Pattern writing method and a that steps are provided.

  According to this pattern drawing method, drawing can be performed with high accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the laser irradiation apparatus and laser irradiation method which can process with high precision can be provided.

  In addition, it is possible to provide a pattern drawing method capable of drawing with high accuracy.

  With reference to FIGS. 1A and 1B, a laser irradiation apparatus according to a first embodiment will be described.

  FIG. 1A is a schematic diagram of a laser irradiation apparatus according to the first embodiment. One laser oscillator 59 emits a laser beam, and the emitted laser beam enters the half mirror 62.

The half mirror 62 branches the incident beam into two laser beams 60a and 60b. The laser beam 60a transmitted through the half mirror 62 enters the shutter mechanism 64a, and the laser beam 60b reflected by the half mirror 62 is reflected by the total reflection mirrors 63a, 63b, and 63c and enters the shutter mechanism 64b.
A beam expander 61 is disposed on each optical path of the laser beams 60a and 60b. The beam expander 61 expands the beam diameter of the incident laser beam and emits it as a parallel beam bundle.

  Here, any one of the total reflection mirrors 63a, 63b, and 63c, for example, the total reflection mirror 63a, is arranged so that a part of the incident laser beam 60b travels straight and the remaining part is reflected. Accordingly, the sectional diameter of the laser beam 60b incident on the shutter mechanism 64b is smaller than the sectional diameter of the laser beam 60a incident on the shutter mechanism 64a. A part of the straight laser beam 60b is absorbed by the damper. The total reflection mirrors 63a, 63b, and 63c are arranged such that the cross sections of the laser beams 60a and 60b are in contact with each other and enter the shutter mechanisms 64a and 64b in parallel.

  The shutter mechanisms 64a and 64b transmit, for example, a polarizing plate that makes a laser beam linearly polarized light, an electro-optic modulator (EOM) that exhibits a Pockels effect, and an incident laser beam, and transmits a P component. A polariser that reflects the component is included.

The laser beam that has been linearly polarized by the polarizing plate is incident on the EOM. The EOM is manufactured from, for example, a uniaxial anisotropic crystal such as LiTaO _3, and can change the phase of polarized light at high speed using an electro-optic effect in which the refractive index changes when an electric field is applied. The laser beam that has passed through the EOM enters the polarizer.

  The P component of the laser beam incident on the polarizer passes through the laser beam and travels straight. On the other hand, the S component is reflected and absorbed by the beam damper. By controlling the polarization direction of the laser beam with the EOM, a state of being reflected by the polarizer (light shielding state) and a state of being transmitted through the polarizer (light transmitting state) are switched. As a result, the shutter mechanisms 64a and 64b can selectively transmit / shield the laser beams 60a and 60b, respectively.

  The laser beams 60 a and 60 b that have passed through the shutter mechanisms 64 a and 64 b have their beam cross-sections shaped by the mask 65 and are incident on the zoom lens system 66. The mask 65 will be described in detail later.

  The zoom lens system 66 forms an image of the beam section shaped by the mask 65 on the DOE 54. The DOE 54 splits the incident laser beam into a plurality of, for example, 100 laser beams. The beam lens system 66 and the DOE 54 are arranged in a positional relationship such that the beam cross section shaped by the mask 65 is imaged on the DOE 54.

  In this figure, beam cross sections 66a and 66b of laser beams 60a and 60b incident on the DOE 54 after forming an image of the shape of the beam cross section shaped by the mask 65 are shown. The cross sections of the two pulsed laser beams 60a and 60b are in contact with each other. In addition, the figure of the beam cross sections 66a and 66b is the figure seen along the advancing direction of a beam.

  The pulsed laser beams 60a and 60b are branched into a plurality of beams by the DOE 54, and each branched beam is incident on an irradiation target 68 placed on the XY stage 69. On the irradiation object 68, a shaped beam section by the mask 65 imaged on the DOE 54 is imaged for each beam section. In this figure, the beam incident areas 67a and 67b of the laser beams 60a and 60b incident on the irradiation object 68 are shown as a view seen along the beam traveling direction.

  The arrangement of the beam incident areas 67 a and 67 b on the irradiation object 68 is determined by the DOE 54. For example, a plurality of (for example, 100) sets of beam incident areas 67a and 67b are arranged along one straight line. An XYZ orthogonal coordinate system that is a right-handed system is defined with the arrangement direction as the X-axis direction and the laser beam propagation direction as the Z-axis direction. The XY stage 69 described above can move the irradiation object 68 in the X axis direction and the Y direction.

  A control device 70 is connected between the XY stage 69 and the shutter mechanisms 64a and 64b. The control device 70 can synchronize the operation of the XY stage 69 with the transmission / shielding of the laser beams 60a and 60b by the shutter mechanisms 64a and 64b.

  FIG. 1B shows a schematic plan view of the mask 65. The mask 65 includes, for example, a rectangular through hole 65a in a plate-like member that shields the laser beam, and shapes the beam cross section of the incident laser beam.

  In this figure, the incident laser beams 60a and 60b are indicated by dotted lines. The laser beams 60a and 60b are each cut out in a rectangular shape by a rectangular through hole 65a. As described above, since the cross-sectional diameter of the laser beam 60a is larger than that of the laser beam 60b, the length of the rectangular cross-section of the laser beam to be cut out is that of the laser beam 60a. Longer than.

As described with reference to FIG. 1A, the laser irradiation apparatus according to the first embodiment further uses a DOE to further divide a set of two laser beams into which a laser beam emitted from one laser oscillator is branched. Branches into a large number and enters the object to be irradiated. Since the wavelengths of the two laser beams branched by the DOE are the same, the relative positional relationship between the beam incident areas on both irradiation objects is always constant regardless of the beam incident position. For this reason, processing can be performed with high processing accuracy.
FIG. 2 shows an example of a pattern drawn by irradiating a laser beam.

  A pattern drawing method for drawing the pattern shown in FIG. 2 will be described as an example of laser processing performed using the laser irradiation apparatus according to the first embodiment.

  On the XY stage 69 shown in FIG. 1A, an irradiation object 68 having a transfer layer in close contact with the surface of the base substrate is placed.

  1A and 1B, the incident region 67a of the laser beam 60a and the incident region 67b of the laser beam 60b are formed on the surface of the irradiation target 68. However, the optical axis of the apparatus is adjusted so that they are arranged in contact with each other in the X-axis direction.

  While emitting a continuous wave laser beam from the laser oscillator 59, the irradiation object 68 is moved at a constant speed in the Y-axis direction by the XY stage 69.

  The shutter mechanism 64b is always in a translucent state. Thereby, a plurality of (for example, 100) laser beams 60b branched by the DOE 54 are incident on the transfer target layer of the irradiation target 68, and, for example, 100 continuous portions 90 are drawn. That is, the continuous portion 90 is drawn as a locus of the incident region 67b.

  The shutter mechanism 64a normally blocks light and intermittently (periodically) transmits light with respect to the movement of the irradiation target 68 by the XY stage 69. When the shutter mechanism 64a is in a translucent state, for example, 100 laser beams 60a branched by the DOE 54 are incident on the transfer layer of the irradiation target 68, and the intermittent portion 91 branched from the continuous portion 90 is drawn. .

  When the laser irradiation apparatus according to the first embodiment is used, the relative positional relationship between the beam incident areas 67a and 67b on the irradiation target 68 is always constant regardless of the beam incident position. Therefore, the continuous portion 90 and the intermittent portion 91 are not separated, and the laser beam is not irradiated to a certain portion. Therefore, high quality drawing can be performed with high accuracy.

  With reference to FIGS. 3A and 3B, a laser irradiation apparatus according to the second embodiment will be described.

  FIG. 3A is a schematic view of a laser irradiation apparatus according to the second embodiment. The laser irradiation apparatus according to the first embodiment is an object to be irradiated with an image at the position of the zoom lens 73, the second mask 71, and the second mask 71 on which a large number of laser beams 60a and 60b branched by the DOE 54 are incident. 68 in that an imaging lens 72 that forms an image on 68 is provided. Further, the laser oscillator 59 of the laser irradiation apparatus according to the second embodiment emits a continuous wave laser beam, for example.

  The laser irradiation apparatus according to the second embodiment branches an image of the mask 65 formed on the DOE 54 surface, and forms an image of the second mask 71 on which the branched laser beam is incident on the irradiation surface. That is, the laser irradiation apparatus according to the second embodiment is a laser irradiation apparatus that relays a mask image to form an image on an irradiation surface.

  FIG. 3B shows a schematic plan view of the second mask 71. The second mask 71 includes, for example, a plate-like member that shields the laser beam, and has an elongated rectangular through hole 71a extending in the X-axis direction, and shapes the beam cross sections 66a and 66b of the incident laser beams 60a and 60b.

  The second mask 71 is disposed at a position where the laser beams 60a and 60b branched by the DOE 54 shown in FIG. 3A pass through the through hole 71a.

  In the drawing, the beam cross sections 66a and 66b of the laser beams 60a and 60b incident on the second mask 71 are indicated by dotted lines. All the sets of the laser beams 60a and 60b branched by the DOE 54 are incident on the second mask 71 so that the adjacent sections and the beam cross sections 66a and 66b are in contact with each other. That is, the laser beams 60 a and 60 b branched by the DOE 54 form a slender incident region extending in the X-axis direction and enter the second mask 71. Then, the light is shielded from the portion other than the through hole 71 a, so that the cross-sectional shape is further elongated and the second mask 71 is emitted.

  Reference is again made to FIG. The laser beams 60 a and 60 b are imaged by the imaging lens 72 in the shape of the beam cross-section shaped by the second mask 71 (the beam cross-section formed by continuation of the individual beam cross-sections 66 a and 66 b in the X-axis direction). , And enters the irradiation object 68.

  In the laser irradiation apparatus according to the second embodiment, as in the case of the first embodiment, the number of sets of two laser beams branched from the laser beam emitted from one laser oscillator 59 is further increased by the DOE 54. Since the beam is branched and incident on the irradiation object, the relative positional relationship between the beam incident areas on both irradiation objects is always constant regardless of the beam incident position. Accordingly, the multiple laser beams 60a and 60b branched by the DOE 54 are irradiated in such a manner that the beam incident regions 67a and 67b of the individual laser beams 60a and 60b are in contact with each other and are continuous in the X-axis direction. 68 is incident. In this figure, the beam incident areas 67a and 67b of the laser beams 60a and 60b incident on the irradiation object 68 are shown as a view seen along the beam traveling direction.

  As an example of laser processing performed using the laser irradiation apparatus according to the second embodiment, a pattern drawing method for drawing the pattern shown in FIG. 4 will be described.

  On the XY stage 69 shown in FIG. 3A, an irradiation object 68 having a transfer layer in close contact with the surface of the base substrate is placed.

  3A and 3B, the incident region 67a of the laser beam 60a and the incident region 67b of the laser beam 60b are formed on the surface of the irradiation target 68. However, the optical axis of the apparatus is adjusted so that they are arranged in contact with each other in the X-axis direction.

  While emitting a continuous wave laser beam from the laser oscillator 59, the irradiation object 68 is moved at a constant speed in the Y-axis direction by the XY stage 69.

  The shutter mechanism 64b is always in a translucent state. Thereby, a plurality of (for example, 100) laser beams 60b branched by the DOE 54 are incident on the transfer target layer of the irradiation target 68, and, for example, 100 linear patterns 100Y are drawn. That is, the linear pattern 100Y is drawn as the locus of the incident region 67b.

  The shutter mechanism 64a normally blocks light and intermittently (periodically) transmits light with respect to the movement of the irradiation target 68 by the XY stage 69. When the shutter mechanism 64a is in a translucent state, for example, 100 laser beams 60a branched by the DOE 54 enter the transfer target layer of the irradiation target 68, and the branch portion 101 branched from the linear pattern 100Y is drawn. The That is, the length in the X-axis direction of the incident region 67a of the laser beam 60a is the length of the branch portion 101. The branch part 101 branched from a certain linear pattern 100Y reaches the adjacent linear pattern 100Y and forms a linear pattern 100X parallel to the X axis. Thus, by moving the irradiation object 68 in one direction, a lattice pattern can be drawn.

  When the laser irradiation apparatus according to the second embodiment is used, the relative positional relationship between the beam incident areas 67a and 67b on the irradiation target 68 is always constant regardless of the beam incident position. Therefore, the linear pattern 100Y and the branch portion 101 are not separated, and a laser beam is not irradiated on a certain portion. Therefore, high quality drawing can be performed with high accuracy.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these. It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like are possible.

  The laser irradiation apparatus and the laser irradiation method can be used for laser processing performed by irradiating an irradiation object with a plurality of laser beams.

  The pattern drawing method can be used for printing a wiring board and defining pixels of an image display device.

(A) is a schematic view of the laser irradiation apparatus according to the first embodiment, and (B) is a schematic plan view of the mask 65. It is a figure which shows an example of the pattern drawn by irradiating a laser beam. (A) is a schematic view of the laser irradiation apparatus according to the second embodiment, and (B) is a schematic plan view of the second mask 71. It is a figure which shows an example of the convex pattern formed by transcribe | transferring a to-be-transferred layer. It is the schematic of the laser irradiation apparatus comprised including a diffractive optical element (Diffractive Optical Element; DOE).

Explanation of symbols

10a, 10b Laser beam 51, 52 Laser oscillator 53 Cross-section shaping imaging optical system 53a, 53b Beam cross-section
54 DOE
54a, 54b Beam incident area 55 Beam incident surface 59 Laser oscillator 60a, 60b Laser beam 61 Beam expander 62 Half mirror 63a, 63b, 63c Total reflection mirror 64a, 64b Shutter mechanism 65 Mask 65a Through hole 66 Zoom lens system 66a, 66b Beam cross section 67a, 67b Beam incident area 68 Irradiation target 69 XY stage 70 Controller 71 Second mask 71a Through-hole 72 Imaging lens 73 Zoom lens 90 Continuous part 91 Intermittent part 100 Grid pattern 100X, 100Y Linear pattern 101 Branch Part

Claims (12)

A laser light source for emitting a laser beam;
A branching device for branching a laser beam emitted from the laser light source into a plurality of laser beams;
A laser irradiation apparatus having a diffractive optical element that is arranged at a position where a plurality of laser beams branched by the branching device are incident and branches each of the plurality of laser beams branched by the branching device into a plurality of laser beams. .   The branching device branches the laser beam emitted from the laser light source into a plurality of laser beams so that the traveling directions of the plurality of branched laser beams are parallel to each other and their beam cross sections are in contact with each other. 2. The laser irradiation apparatus according to 1. A first mask disposed on a path of the laser beam between the branching device and the diffractive optical element, and shaping a cross section of the laser beam;
The laser irradiation apparatus according to claim 1, further comprising: a zoom lens system that forms an image of the shaped beam cross section at the position where the first mask is disposed on the diffractive optical element.   The shutter mechanism according to claim 3, further comprising a shutter mechanism that is disposed in an optical path of a laser beam between the branching device and the first mask, and prevents the laser beam from entering the first mask for a certain period. Laser irradiation device. Furthermore, a stage for holding the irradiation object,
A second mask arranged on the path of the laser beam branched by the diffractive optical element and shaping the cross section of the laser beam;
5. The transfer optical system according to claim 1, further comprising: a transfer optical system that transfers the shaped beam cross section at the position where the second mask is arranged onto the surface of the irradiation object held on the stage. The laser irradiation apparatus as described.   The branching device splits an incident laser beam into a first laser beam and a second laser beam, and the first laser beam is diffracted by the diffractive optical element and held on the stage. A plurality of first diffraction images congruent to each other are formed on the object, the second laser beam is diffracted by the diffractive optical element, and a plurality of congruence to each other on the irradiation object held on the stage The second diffraction image is formed, and the first diffraction image and the second diffraction image have a one-to-one correspondence, and the first diffraction image and the second diffraction image corresponding thereto correspond to each other. The laser irradiation apparatus of Claim 5 which is in contact with. The stage can move the irradiation object at a constant speed while holding the irradiation object,
The laser irradiation apparatus according to claim 5, further comprising a control device capable of causing the shutter mechanism to cause the laser beam to be incident on the first mask at certain time intervals. (A) branching an original laser beam emitted from one laser oscillator into a first laser beam and a second laser beam;
(B) A laser irradiation method including a step of causing the first laser beam and the second laser beam to enter a diffractive optical element, branching each of the first laser beam and the second laser beam into a plurality of laser beams, and causing the laser beam to enter an irradiation object.   In the step (b), the traveling directions of the first laser beam and the second laser beam are parallel to each other so that their beam cross sections are in contact with each other. The laser irradiation method according to claim 8, wherein two laser beams are incident on the diffractive optical element. Further, the step (b) includes the step of (c) shaping the cross section of the first laser beam and the second laser beam,
The laser irradiation method according to claim 8 or 9, wherein the beam cross section shaped in the step (c) is imaged on the diffractive optical element. Further, the step (b) includes the step of (d) shaping the cross section of the laser beam branched by the diffractive optical element,
The laser irradiation method according to claim 8, wherein the beam cross section shaped in the step (d) is transferred onto the irradiation object. Branching an original laser beam emitted from one laser oscillator into a first laser beam and a second laser beam;
When the first and second laser beams are incident on the object to be processed via the diffractive optical element, the first laser beam and the second laser beam are incident on the surface of the object to be processed. A step of adjusting the optical axis so as to be in contact with each other in one direction;
While moving the workpiece so that the incident positions of the first laser beam and the second laser beam move from a start point to an end point in a second direction intersecting the first direction, The first laser beam is continuously incident from the start point to the end point, the second laser beam is intermittently incident, and a pattern having a branch projecting from a linear trajectory is drawn. Drawing method.

Images