JP2009014793A - Focal length adjusting device, laser machining device, laser displacement meter, and electro-optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-optical element with which a focal length is appropriately adjusted while accelerating the focal length adjustment, and to provide a focal length adjusting device, a laser machining device, and a laser displacement meter. <P>SOLUTION: In an electro-optical member 22 as an electro-optic material (a dielectric material), a slope 22d as a second placing face with a second electrode 24 arranged thereon is sloped so as to make its inner face oriented to the optical axis L side. Thereby, when a potential difference is imparted between first and second electrodes 23, 24, an electric field of which the electric flux line passing through the electro-optical member 22 is shown to be bent so as to protrude to the optical axis L side is generated, and a spread angle of the laser beam is varied by the action of the electric field. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a focal length adjusting device, a laser processing device, a laser displacement meter, and an electro-optical element.

  2. Description of the Related Art Conventionally, for example, there is a laser processing apparatus that uses a focal length adjustment apparatus including a beam expander (see, for example, Patent Document 1). In such a focal length adjusting device, the spread angle of the laser light emitted from the laser light source is adjusted by the beam expander and converged by the converging lens. When the spread angle of the laser beam changes, the focal position moves in the optical axis direction. Therefore, the focal position can be adjusted by controlling the spread angle by the beam expander. Such a beam expander has a concave lens and a convex lens provided along the optical axis of the laser beam, and adjusts the spread angle of the laser beam by mechanically changing the distance between the lenses. Therefore, there is a limit to speeding up the focal length adjustment.

Therefore, for example, in the laser processing apparatus (laser printer) of Patent Document 2, a focal length adjustment apparatus including an electro-optic element having an electro-optic material is used. The electro-optic material has a refractive index that changes according to the applied electric field strength, and the spread angle of the incident laser beam is changed by controlling the applied electric field strength. In other words, since the focal position is adjusted by voltage control, the focal length can be adjusted at high speed. In such a laser processing apparatus, the laser light emitted from the laser light source is linearly polarized by the polarizing plate, and the deflection direction thereof is orthogonal to the direction of the electric field generated by the electro-optic element. The electro-optical element is provided with two electro-optical elements arranged so that the directions of the generated electric fields are orthogonal to each other. Then, after the laser beam is narrowed (or expanded) in one direction orthogonal to the optical axis by the first electro-optical element to make the beam diameter of the laser beam elliptical, the polarization direction of the laser beam is changed to λ / 2. The wave plate is rotated by 90 °, and the second electro-optic element narrows (or expands) the laser beam in the longitudinal direction of the elliptical shape of the beam diameter. In this way, the spread angle of the laser beam is changed in two stages by the two electro-optic elements.
JP 2007-111763 A JP-A-3-210580

  However, in the laser processing apparatus described in Patent Document 2 described above, the laser light incident on the electro-optic material is actually refracted so as to bend along the direction of the electric field applied to the electro-optic material. Further, the magnitude of the bending changes according to the electric field strength. For this reason, when the laser beam passes through the electro-optic material, not only the spread angle is adjusted, but also the optical axis is bent according to the electric field, which may make it difficult to process the workpiece. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electro-optic element and a focal length adjustment capable of accurately performing the focal length adjustment while achieving a high speed focal length adjustment. An apparatus, a laser processing apparatus, and a laser displacement meter are provided.

  In order to solve the above-mentioned problem, the invention according to claim 1 applies an electric voltage between the first and second electrodes, and an electro-optical element having a dielectric material interposed between the first and second electrodes. A voltage applying means for changing the voltage applied by the voltage applying means to change the divergence angle of the incident light incident on the dielectric material with respect to the optical axis, and emitted from the electro-optic element. A focal length adjusting device for adjusting a focal length of converged light, wherein the electro-optic element has a passing portion through which the incident light passes and an electrode portion in which the first and second electrodes are arranged. The electrode portion is provided with a first arrangement surface for providing the first electrode on the end surface on the incident side of the dielectric material and a second arrangement surface for providing the second electrode on the end surface on the emission side, At least one of the first and second arrangement surfaces is the optical axis Across its inner surface in a symmetric position is a gist that formed on the inclined surface facing the optical axis side.

  In this invention, an electro-optic element formed by interposing a dielectric material between the first and second electrodes has a passage portion through which incident light passes, and an electrode portion in which the first and second electrodes are arranged, At least one of the first and second arrangement surfaces provided with the first and second electrodes in the dielectric material of the electrode portion is inclined so that the inner surface thereof faces toward the optical axis side at a symmetrical position across the optical axis of the incident light. Formed on the surface. With this configuration, when a potential difference is applied between the first and second electrodes, the electric force lines passing through the dielectric material are curved between the first and second electrodes so as to protrude toward the optical axis. An electric field is generated, and the spread angle of incident light is varied by the action of the electric field. Therefore, the spread angle can be adjusted by changing the electric field strength applied to the dielectric material by controlling the voltage applied to the first and second electrodes, thereby speeding up the focal length adjustment. The focal length can be adjusted accurately.

  According to a second aspect of the present invention, in the focal length adjusting apparatus according to the first aspect, the first and second electrodes each have a pair of electrodes arranged in one direction orthogonal to the optical axis. The electro-optic elements are arranged in parallel on the optical axis so that the directions in which the pair of electrodes are arranged are orthogonal to each other.

  In this invention, the first and second electrodes each include two electro-optic elements each having a pair of electrodes arranged in one direction orthogonal to the optical axis, and each of the electro-optic elements is a pair of electrodes. Are arranged side by side on the optical axis so that the directions of For this reason, the spread angle of incident light can be adjusted by voltage control with respect to each electro-optical element.

  According to a third aspect of the present invention, in the focal length adjustment apparatus according to the first aspect, the electro-optic element is formed so that the first and second arrangement surfaces extend over 360 ° about the optical axis. In addition, the gist is that the first and second electrodes are formed over 360 ° with the optical axis as the center.

  In the present invention, the first and second arrangement surfaces of the electro-optic element are formed over 360 ° centered on the optical axis, and the first and second electrodes are formed over 360 ° centered on the optical axis. It is formed. For this reason, the spread angle of incident light can be adjusted by voltage control even for incident light that is not linearly polarized.

  The invention according to claim 4 is the focal length adjusting device according to any one of claims 1 to 3, wherein one of the first and second arrangement surfaces of the dielectric material is the optical axis. The gist is to form an orthogonal plane.

  In this invention, since one of the first and second arrangement surfaces of the dielectric material forms a plane perpendicular to the optical axis of the incident light, a suitable electric field for changing the spread angle of the incident light is generated. Can do.

  A fifth aspect of the present invention is the focal length adjusting device according to any one of the first to fourth aspects, wherein the inclined surface is formed in a curved shape protruding toward the optical axis. And

  In this invention, since the inclined surface provided with the first or second electrode is formed in a curved shape protruding toward the optical axis, a suitable electric field for varying the spread angle of incident light can be generated. .

  The invention according to claim 6 is the focal length adjustment device according to any one of claims 1 to 5, wherein the first and second electrodes are transparent electrodes, and the electrode portion also serves as the passage portion. This is the gist.

In the present invention, the first and second electrodes are transparent electrodes, and the electrode portion also serves as a passage portion, so that the electro-optic element can be configured in a small size.
A seventh aspect of the present invention is the focal length adjusting device according to any one of the first to sixth aspects, wherein the dielectric material is an electro-optic material whose refractive index changes according to the applied electric field strength. It becomes the gist.

  In this invention, since the dielectric material is made of an electro-optic material whose refractive index changes according to the applied electric field strength, the spread angle of incident light can be adjusted by controlling the voltage on the electro-optic element.

  The invention described in claim 8 is provided with a processing laser light source, and laser light emitted from the laser light source is applied to the object to be processed via the focal length adjusting device according to any one of claims 1 to 7. The gist is to irradiate.

  The invention according to claim 9 includes a laser light source, and irradiates the measurement object with the laser light emitted from the laser light source via the focal length adjustment device according to any one of claims 1 to 7. This is the gist.

In the inventions according to the eighth and ninth aspects, the focal length adjustment can be accurately performed in the laser processing apparatus or the laser displacement meter while increasing the focal length adjustment speed.
In a tenth aspect of the present invention, a dielectric material is interposed between the first and second electrodes, and the incident light is incident upon changing the voltage applied between the first and second electrodes. An electro-optic element capable of varying a spread angle with respect to an axis, wherein the dielectric material has a passing part through which the incident light passes and an electrode part in which the first and second electrodes are arranged, and the electrode The portion is provided with a first arrangement surface for providing the first electrode on the end surface on the incident side of the dielectric material and a second arrangement surface for providing the second electrode on the end surface on the emission side. At least one of the second arrangement surfaces has a gist that an inner surface thereof is formed as an inclined surface facing the optical axis side at a symmetrical position across the optical axis.

  In the present invention, at least one of the first and second arrangement surfaces provided with the first and second electrodes in the dielectric material has its inner surface facing the optical axis side at a symmetrical position with the optical axis of the incident light in between. It is formed on an inclined surface. With this configuration, when a potential difference is applied between the first and second electrodes, the electric force lines passing through the dielectric material are curved between the first and second electrodes so as to protrude toward the optical axis. An electric field is generated, and the spread angle of incident light is varied by the action of the electric field. Therefore, the spread angle can be adjusted by changing the electric field strength applied to the dielectric material by controlling the voltage applied to the first and second electrodes, thereby speeding up the focal length adjustment. The focal length can be adjusted accurately.

  According to an eleventh aspect of the present invention, in the electro-optic element according to the tenth aspect, each of the first and second electrodes has a pair of electrodes arranged in one direction orthogonal to the optical axis. The gist of this is

  In the present invention, each of the first and second electrodes has a pair of electrodes arranged in one direction orthogonal to the optical axis, so the voltage applied to the first and second electrodes is controlled. The spread angle can be adjusted by changing the electric field strength applied to the dielectric material.

  According to a twelfth aspect of the present invention, in the electro-optic element according to the tenth aspect, the first and second arrangement surfaces of the dielectric material are formed over 360 ° centering on the optical axis. The gist of the invention is that the first and second electrodes are formed over 360 ° centered on the optical axis.

  In the present invention, the first and second arrangement surfaces are formed over 360 ° centered on the optical axis, and the first and second electrodes are formed over 360 ° centered on the optical axis. For this reason, the spread angle of incident light can be adjusted by voltage control even for incident light that is not linearly polarized.

  According to a thirteenth aspect of the present invention, in the electro-optic element according to any one of the tenth to twelfth aspects, one of the first and second arrangement surfaces of the dielectric material is orthogonal to the optical axis. The gist is to form a flat surface.

  In this invention, since one of the first and second arrangement surfaces of the dielectric material forms a plane perpendicular to the optical axis of the incident light, a suitable electric field for changing the spread angle of the incident light is generated. Can do.

  According to a fourteenth aspect of the present invention, in the electro-optical element according to any one of the tenth to thirteenth aspects, the inclined surface is formed in a curved shape protruding toward the optical axis side. To do.

  In this invention, since the inclined surface provided with the first or second electrode is formed in a curved shape protruding toward the optical axis, a suitable electric field for varying the spread angle of incident light can be generated. .

  Therefore, according to the above-described invention, in the electro-optic element, the focal length adjustment device, the laser processing device, and the laser displacement meter, the focal length adjustment can be accurately performed while the focal length adjustment is speeded up.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
A laser processing apparatus 10 of the present embodiment schematically shown in FIG. 1 is configured to display characters, symbols, graphics, etc. on the surface of a workpiece (processing object) W transported by a transport line based on control of a control circuit 11. Marking is to be processed.

The laser processing apparatus 10 includes a processing laser light source 12 that emits a processing laser beam. The laser light source 12 is composed of a laser oscillator, and its oscillation is controlled by the control circuit 11.
The beam expander 13 disposed at the subsequent stage of the laser light source 12 temporarily expands the beam diameter of the laser light emitted from the laser light source 12 at a constant magnification. In the present embodiment, the beam expander 13 emits laser light that spreads at a constant spread angle with respect to the optical axis L.

  An electro-optic unit 14 is disposed at the subsequent stage of the beam expander 13. The electro-optic unit 14 varies the divergence angle of the laser light once enlarged by the beam expander 13 based on control by the control circuit 11.

  The galvanometer mirror 15 arranged at the rear stage of the electro-optic unit 14 reflects the laser light whose spread angle is changed by the electro-optic unit 14 and changes the irradiation direction thereof. It consists of a mirror and a Y-axis mirror. The galvanometer mirror 15 is angle-controlled by driving of the driving device 16 based on the control of the control circuit 11, and scans the laser beam two-dimensionally based on the characters, symbols, figures, etc. to be marked.

  A converging lens (fθ lens) 17 disposed at the subsequent stage of the galvanometer mirror 15 converges the laser light whose divergence angle is adjusted by the electro-optical unit 14 until a predetermined spot diameter is obtained on the surface of the workpiece W, and performs marking processing. To an energy density suitable for

[Focal distance adjustment device]
In the laser processing apparatus 10 having such a configuration, the electro-optic unit 14 and the converging lens 17 constitute a focal length adjustment apparatus. In such a focal length adjusting device, since the refractive index of the converging lens 17 that focuses the laser beam on the surface of the workpiece W is constant, the focal length changes according to the change of the divergence angle by the electro-optic unit 14 ( (See FIG. 3). That is, the focal length of the laser light is determined by the size of the spread angle of the laser light emitted from the electro-optic unit 14, and the control circuit 11 measures the measurement result from the distance sensor 18 that measures the distance to the surface of the workpiece W. In response, the electro-optic unit 14 is controlled so that the focal length of the laser beam is adjusted to the distance. Hereinafter, the electro-optical unit 14 will be described in detail.

  As shown in FIG. 2, the electro-optic unit 14 has two electro-optic elements 21. The electro-optic element 21 includes an electro-optic member 22 made of an electro-optic material (dielectric material) whose refractive index changes according to the strength of the applied electric field, and first and first electrodes for applying an electric field to the electro-optic member 22. Two electrodes 23 and 24 are provided. In this embodiment, the electro-optical member 22 is made of KTN (potassium niobate tantalate) crystal.

  The electro-optic member 22 has a substantially trapezoidal columnar shape, and as shown in FIG. 3, the optical axis L is set from the center of the upper bottom surface toward the center of the lower bottom surface, and the cross section along the optical axis L is left and right. It is formed in a symmetrical chevron. In FIG. 3, for convenience of explanation, only one electro-optic element 21 is shown in the electro-optic unit 14 and the galvanometer mirror 15 is omitted. The electro-optic member 22 is arranged so that the center line in the left-right direction overlaps the optical axis L of the laser beam, and the incident surface 22a facing the incident side (the beam expander 13 side) is orthogonal to the optical axis L of the laser beam. It has a flat shape. The incident surface 22a is a first arrangement surface for arranging the first electrode 23, and the first electrode 23 having a planar shape substantially the same as the incident surface 22a is fixed to the incident surface 22a. The first electrode 23 is formed in the shape of a flat plate, and a through hole 23a constituting a passage part for entering laser light is formed at the center thereof (see FIG. 2). In the electro-optic element 21, a passage portion through which laser light passes is formed at the center in the left-right direction in FIG. 3, and electrode portions for arranging electrodes on both sides in the left-right direction of the passage portion are formed.

  The bottom surface (top surface) of the convex portion 22b that protrudes toward the emission side along the optical axis L direction of the electro-optic member 22 is an emission surface that emits laser light incident on the incident surface 22a from the through hole 23a of the first electrode 23. The exit surface 22c is formed in a flat shape parallel to the entrance surface 22a. The side surface of the convex portion 22b is an inclined surface 22d that is formed in a curved shape that approaches the incident surface 22a and protrudes toward the optical axis L as the distance from the optical axis L increases. That is, the inclined surface 22d is inclined so that the inner surface thereof faces the optical axis L side at a symmetrical position across the optical axis L of the laser beam. The inclined surface 22d is a second arrangement surface for arranging the second electrode 24, and the second electrodes 24 each having a shape along the curvature of the inclined surface 22d are fixed to the inclined surfaces 22d on both the left and right sides. That is, the pair of second electrodes 24 are arranged side by side in one direction orthogonal to the optical axis L (the left-right direction in FIG. 3). In addition, the emission surface 22c located between the second electrodes 24 is a passing portion on the second electrode 24 side. The first and second electrodes 23 and 24 are both made of a metal member.

  As shown in FIG. 2, a polarizing plate 25 for changing laser light into linearly polarized light is provided on the incident side (beam expander 13 side) of the two electro-optic elements 21 in the electro-optic unit 14. The polarizing plate 25 is provided such that its plate surface is orthogonal to the optical axis L and the polarization direction of the linearly polarized laser light coincides with the left-right direction of the electro-optic element 21 immediately after the polarizing plate 25. That is, the polarization direction of the laser light that passes through the polarizing plate 25 and enters the electro-optical element 21 immediately after the polarizing plate 25 and the direction of the electric field generated between the first and second electrodes 23 and 24 of the electro-optical element 21 are as follows. It is supposed to match. The electro-optic elements 21 are arranged in parallel on the optical axis L so that the direction in which the pair of second electrodes 24 are arranged (one direction perpendicular to the optical axis L described above) is perpendicular to each other. A λ / 2 wavelength plate 26 for rotating the polarization direction of the laser light linearly polarized by the polarizing plate 25 by 90 ° is interposed between the electro-optic elements 21.

  In such an electro-optical unit 14, the laser light emitted from the beam expander 13 is linearly polarized by the polarizing plate 25 and enters the first electro-optical element 21. In each electro-optic element 21, the first electrode 23 is grounded, and a voltage of the same magnitude is applied to each second electrode 24 by the control circuit 11 including a voltage applying unit. The control circuit 11 converts the voltage from the power source 19 into a DC voltage, and applies a voltage having a magnitude based on the measurement result of the distance sensor 18 to the second electrode 24.

  In the electro-optic element 21, when a voltage is applied to the second electrode 24, a potential difference is generated between the first electrode 23 and the second electrode 24, and the optical axis L of the electro-optic element 21 is shown in FIG. With respect to the optical axis L, an electric field symmetric with respect to the optical axis L is generated. The electric field lines of the electric field between the first and second electrodes 23 and 24 are curved so as to protrude toward the optical axis L, as indicated by broken lines in FIG. When an electric field is generated between the first and second electrodes 23 and 24, the refractive index of the electro-optic member 22 changes according to the strength of the electric field. The laser light incident from the incident surface 22a of the electro-optic member 22 travels while being refracted toward the center line (optical axis L) side of the electro-optic member 22, and the beam diameter is uniformly contracted from each second electrode 24 side. It is like that. That is, the beam diameter of the laser light emitted from the first electro-optic element 21 has an elliptical shape that is uniformly contracted from each second electrode 24 side.

  Next, the polarization direction of the laser light emitted from the first electro-optic element 21 is rotated by 90 ° by the λ / 2 wavelength plate 26. At this time, although the polarization direction of the laser light changes, the elliptical shape of the beam diameter is maintained as it is without rotating. The laser beam that has passed through the λ / 2 wavelength plate 26 is incident on the second electro-optic element 21. A voltage equal to that of each second electrode 24 of the first electro-optical element 21 is applied to each second electrode 24 of the second electro-optical element 21 by the control circuit 11. Then, the laser light is contracted in the longitudinal direction of the ellipse by the second electro-optical element 21, and the beam diameter becomes substantially circular. As described above, the electro-optical unit 14 varies the spread angle of the laser light emitted from the beam expander 13.

  The spread angle of the laser beam is the magnitude of the electric field strength generated between the first and second electrodes 23 and 24 of each electro-optic element 21, that is, the voltage applied to the second electrode 24 by the control circuit 11. The amount of expansion is varied according to the size of. When the voltage applied to the second electrode 24 is increased to increase the electric field strength, the focal position moves along the optical axis L toward the converging lens 17 side. That is, the focal length is shortened. On the other hand, when the voltage applied to the second electrode 24 is reduced to reduce the electric field strength, the focal position moves along the optical axis L to a position away from the converging lens 17. That is, the focal length becomes long. That is, by the voltage control by the control circuit 11, the spread angle of the laser light is varied, and the focal position converged by the converging lens 17 is adjusted.

Next, characteristic effects of the present embodiment will be described.
(1) In the electro-optic member 22 as the electro-optic material (dielectric material), the inclined surface 22d as the second arrangement surface on which the second electrode 24 is provided has an inner surface facing the optical axis L side. Inclined. As a result, when a potential difference is applied between the first and second electrodes 23 and 24, an electric field that is curved so that the electric lines of force that pass through the electro-optical member 22 protrude toward the optical axis L is generated. The spread angle of the laser beam is varied by the action of the electric field. Therefore, it is possible to adjust the spread angle by controlling the voltage applied to the electro-optic element 21 and changing the electric field strength applied to the electro-optic member 22, thereby speeding up the focal length adjustment. The focal length can be adjusted accurately.

  (2) Two electro-optic elements 21 in which a pair of second electrodes 24 are arranged in one direction orthogonal to the optical axis L are provided, and the electro-optic elements 21 are arranged in a direction in which the pair of second electrodes 24 are arranged. Are arranged on the optical axis L so as to be orthogonal to each other. For this reason, the spread angle of incident light can be adjusted by voltage control with respect to each electro-optical element. At the same time, the dispersion of the laser light due to the fact that the polarization direction of the laser light does not coincide with the direction of the electric field generated by the electro-optic member 22 can be suppressed.

(3) Since the incident surface 22a forms a plane orthogonal to the optical axis L, it is possible to generate a suitable electric field for changing the spread angle of the laser light.
(4) Since the inclined surface 22d provided with the second electrode 24 is formed in a curved shape protruding toward the optical axis L, it is possible to generate a suitable electric field for changing the spread angle of the laser light.

  (6) Since the electro-optic member 22 as a dielectric material is made of an electro-optic material whose refractive index changes according to the applied electric field strength, the spread angle of the laser beam is adjusted by voltage control on the electro-optic element 21. Can do.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the electro-optical unit 14 is provided at the subsequent stage of the beam expander 13, but is not particularly limited to this, and is not limited to this, the rear stage of the laser light source 12, the subsequent stage of the galvano mirror 15, or the converging lens 17. You may provide in a back | latter stage. In the above embodiment, the converging lens 17 is provided at the rear stage of the galvanometer mirror 15, but may be provided at the rear stage of the laser light source 12, the rear stage of the beam expander 13, or the rear stage of the electro-optic unit 14.

  In the above embodiment, the entrance surface 22a and the exit surface 22c of the electro-optic member 22 are formed in parallel planes. However, for example, at least one of the entrance surface 22a and the exit surface 22c is spherical. It may be formed.

In the above embodiment, the electro-optic element 21 is disposed so that the top surface of the convex portion 22b is the exit surface 22c, but may be disposed so as to be the entrance surface 22a.
In the above embodiment, the first electrode 23 on the incident surface 22a side is grounded, and the voltage is applied to the second electrode 24 on the outgoing surface 22c side. However, the present invention is not particularly limited to this. For example, the first electrode A voltage may be applied to 23 and the second electrode 24 may be grounded, or a voltage may be applied to both the first and second electrodes 23 and 24. At this time, in the above embodiment, the first electrode 23 is set to a low potential and the second electrode 24 is set to a high potential to reduce (shrink) the spread angle of the laser beam. The second electrode 24 and a low potential may be made to act so as to increase (diverge) the spread angle of the laser beam.

  In the above embodiment, one first electrode 23 and two second electrodes 24 are provided. However, the present invention is not limited to this. For example, the first electrode 23 is divided and orthogonal to the optical axis L. A pair of first electrodes arranged side by side (in the left-right direction in FIG. 3) may be provided. Moreover, you may comprise each 2nd electrode 24 with one member so that it may connect in positions other than a laser beam pass.

In the above embodiment, the inclined surface 22d is formed in a curved shape that protrudes toward the optical axis L, but may be formed to have, for example, a linear cross section.
In the above embodiment, the inclined surfaces 22d of the convex portions 22b of the electro-optic member 22 are formed up to both ends in the left-right direction in FIG. 3, but as shown in FIG. 5, both end portions in the left-right direction are parallel to the incident surface 22a. You may form so that it may become.

  In the above embodiment, the electro-optical unit 14 includes the two electro-optical elements 21. However, for example, a configuration including one electro-optical element 31 as illustrated in FIG. 4 may be used. As shown in FIG. 4, the electro-optic member 32, the first electrode 33, and the second electrode 34 that constitute the electro-optic element 31 are all formed in a planar circular shape centered on the optical axis L. That is, the first and second arrangement surfaces for arranging the first and second electrodes 33 and 34 in the electro-optical member 32 are formed over 360 ° centering on the optical axis L, and the first and second Two electrodes 33 and 34 are formed over 360 ° centered on the optical axis L. The cross section along the optical axis L of the laser light in the electro-optical element 31 is the same as the cross section (see FIG. 3) of the electro-optical element 21 of the above embodiment. The electro-optical member 32 has a convex portion 32a protruding in the optical axis L direction, and the second electrode 34 is provided over the entire circumferential direction of the side surface. Further, the convex portion 32a side of the electro-optic element 31 may be arranged so as to face either the incident side or the emission side. According to this configuration, since the electro-optic element 31 has a planar circular shape, when a potential difference is applied between the first and second electrodes 33 and 34, the lines of electric force project toward the optical axis L in the entire circumferential direction. Thus, the electric field shown curved is generated, so that the spread angle can be adjusted even for laser light that is not linearly polarized. Accordingly, not only can the number of electro-optic elements 31 be reduced, but the polarizing plate 25 and the λ / 2 wavelength plate 26 as in the above embodiment are not necessary, and the number of components can be reduced. Further, the electro-optic element 31 may be configured as shown in FIGS. In the electro-optic element 31 shown in FIG. 6, the peripheral edge of the second electrode 34 is parallel to the first electrode 33. In the electro-optic element 31 shown in FIG. 7, the side surface of the convex portion 32a is inclined so as to have a linear cross section, and the second electrode 34 is provided on a part of the side surface. Further, in the electro-optic element 31 as shown in FIG. 4, as shown in FIG. 8, a pair arranged side by side in one direction (left-right direction in FIG. 8) orthogonal to the optical axis L on the side surface 32b of the convex portion 32a. The second electrode 34 may be provided. Note that two electro-optical elements 31 as shown in FIG. 8 are provided in the same manner as in the above embodiment, and each electro-optical element 31 is on the optical axis L so that the direction in which the pair of second electrodes 24 are arranged is orthogonal to each other. It is installed side by side.

  In the above embodiment, the KTN crystal is used for the electro-optic member 22, but other than this, for example, a PLZT (lead rattan zirconate titanate) crystal may be used. The electro-optic material may be a material other than KTN, and mainly uses the Pockels effect or the Kerr effect. That is, the electro-optic element is based on changing the voltage applied between the first and second electrodes. What is necessary is that the electric field strength applied to 21 and 31 changes and the refractive index changes according to the applied electric field strength.

  In the above embodiment, metal members are used for the first and second electrodes 23 and 24. However, for example, a transparent electrode made of indium oxide (ITO) to which tin is added may be used. In this case, since it is a transparent electrode, as shown in FIG. 9, you may form the 1st electrode 23 which has not formed the through-hole 23a, and the 2nd electrode 24 which covers the inclined surface 22d as an output surface. In other words, the electro-optical member 22 may be configured so that the electrode portion where the electrode is disposed also serves as a passing portion through which the laser light passes. According to this configuration, the electro-optic element 21 can be configured in a small size. This configuration is applied to an electro-optic element 31 in which both the first electrode 33 and the second electrode 34 are formed in a planar circular shape with the optical axis L as the center, as shown in FIGS. May be.

In the above embodiment, the laser processing apparatus has been described as an example, but other than this, for example, it may be used for a laser displacement meter.
Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below.

  (A) The spread angle of the incident light is variable by the action of the electric field between the first and second electrodes, which is shown curved so that electric lines of force passing through the dielectric material protrude toward the optical axis. Is done.

  Thereby, the spread angle of the incident light can be suitably varied without bending the incident light passing through the dielectric material following the direction of the electric field applied to the electro-optic material.

The schematic block diagram which shows the laser processing apparatus in this embodiment. FIG. 3 is an exploded perspective view showing an electro-optical unit. Schematic for demonstrating the effect | action of an electro-optical unit. The perspective view which shows the electro-optical element in another example. The perspective view which shows the electro-optical element in another example. The perspective view which shows the electro-optical element in another example. The perspective view which shows the electro-optical element in another example. The perspective view which shows the electro-optical element in another example. Schematic which shows the electro-optical element in another example.

Explanation of symbols

  L ... Optical axis, W ... Workpiece, 11 ... Control circuit as voltage application means, 12 ... Laser light source, 14 ... Electro-optic unit, 17 ... Converging lens, 21, 31 ... Electro-optic element, 22, 32 ... Dielectric material And an electro-optical member as an electro-optical material, 22a: an incident surface as a first arrangement surface, 22d: an inclined surface as a second arrangement surface, 23, 33: a first electrode, 24, 34: a second electrode.

Claims (14)

An electro-optic element having a dielectric material interposed between the first and second electrodes, and voltage applying means for applying a voltage between the first and second electrodes, wherein the voltage applied by the voltage applying means is A focal length adjustment device that adjusts a focal length of light emitted from the electro-optic element and converged by changing a divergence angle of the incident light incident on the dielectric material with respect to an optical axis by changing the angle. ,
The electro-optic element has a passage part through which the incident light passes, and an electrode part in which the first and second electrodes are arranged,
The electrode portion is provided with a first arrangement surface for providing the first electrode on an end surface on the incident side of the dielectric material and a second arrangement surface for providing the second electrode on an end surface on the emission side, At least one of the first and second arrangement surfaces is a focal length adjustment device characterized in that an inner surface thereof is formed on an inclined surface facing the optical axis side at a symmetrical position across the optical axis. The focal length adjusting device according to claim 1,
The first and second electrodes each include two electro-optical elements each having a pair of electrodes arranged in one direction orthogonal to the optical axis, and each of the electro-optical elements includes the pair of electrodes. The focal length adjustment device, wherein the alignment directions are arranged on the optical axis so as to be orthogonal to each other. The focal length adjusting device according to claim 1,
In the electro-optic element, the first and second arrangement surfaces are formed over 360 ° centered on the optical axis, and the first and second electrodes are formed 360 ° centered on the optical axis. A focal length adjusting device characterized by being formed over the entire length. The focal length adjustment apparatus according to any one of claims 1 to 3,
One of the 1st and 2nd arrangement | positioning surfaces of the said dielectric material makes a plane orthogonal to the said optical axis, The focal distance adjustment apparatus characterized by the above-mentioned. In the focal length adjusting device according to any one of claims 1 to 4,
The focal length adjusting device, wherein the inclined surface is formed in a curved shape protruding toward the optical axis. In the focal length adjusting device according to any one of claims 1 to 5,
The first and second electrodes are transparent electrodes, and the electrode portion also serves as the passage portion. The focal length adjustment apparatus according to any one of claims 1 to 6,
The focal length adjusting device according to claim 1, wherein the dielectric material is made of an electro-optic material whose refractive index changes according to the applied electric field strength.   A laser processing system comprising: a processing laser light source, and irradiating a processing object with the laser light emitted from the laser light source via the focal length adjusting device according to claim 1. apparatus.   A laser displacement meter comprising a laser light source and irradiating a measurement object with the laser light emitted from the laser light source via the focal length adjusting device according to any one of claims 1 to 7. An electric material in which a dielectric material is interposed between the first and second electrodes, and the spread angle of the incident light with respect to the optical axis can be varied by changing the voltage applied between the first and second electrodes. An optical element,
The dielectric material has a passing part through which the incident light passes, and an electrode part in which the first and second electrodes are arranged,
The electrode portion is provided with a first arrangement surface for providing the first electrode on an end surface on the incident side of the dielectric material and a second arrangement surface for providing the second electrode on an end surface on the emission side, At least one of the first and second arrangement surfaces is formed as an inclined surface whose inner surface is directed toward the optical axis at a symmetrical position across the optical axis. The electro-optic element according to claim 10,
Each of the first and second electrodes has a pair of electrodes arranged in one direction orthogonal to the optical axis. The electro-optic element according to claim 10,
The first and second arrangement surfaces of the dielectric material are formed over 360 ° centered on the optical axis, and the first and second electrodes extend over 360 ° centered on the optical axis. An electro-optic element characterized by being formed. The electro-optic element according to any one of claims 10 to 12,
Either one of the first and second arrangement surfaces of the dielectric material forms a plane orthogonal to the optical axis. The electro-optic element according to any one of claims 10 to 13,
The electro-optic element, wherein the inclined surface is formed in a curved shape protruding toward the optical axis side.

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