JP2006088216A - Laser marking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser marking device of a simple structure capable of performing micro-marking. <P>SOLUTION: The laser marking device comprises a semiconductor laser unit 2, a semiconductor laser unit housing 3, a lens housing 5 and a condensing lens 11. The semiconductor laser unit includes a semiconductor laser 1, and has a cylindrical shape having the axis of rotational symmetry matched with the optical axis. The semiconductor laser unit housing has a cylindrical hollow part to be fitted to the semiconductor laser unit, and further has a surface of a predetermined angle with respect to the optical axis when the semiconductor laser unit is fitted thereto. The semiconductor laser unit can be position-adjusted in the optical axial direction and the rotational direction around the axis of rotational symmetry in the cylindrical hollow part. The lens housing can be position-adjusted with respect to the semiconductor laser unit housing by sliding. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser marking apparatus using a semiconductor laser. In particular, the present invention relates to a marking device capable of micro marking and traceable marking.

  Marking that records characters, codes, symbols, etc. on products made of resin, etc. is intended to provide information to customers, etc., and to provide information in the manufacturing process and distribution process Some are intended, but not intended to provide information to customers. The former provides information by visually recognizing it with the naked eye, so it is necessary to make it large enough to visually recognize the marking target. For this reason, the former is called macro marking. The latter does not aim to provide information by being visually recognized by the naked eye, and it is preferable not to impair the beauty of the product or the like. Such a marking that is so small that it cannot be seen with the naked eye is called micro-marking.

  An example of micro marking is traceable marking for management of a manufacturing process. The traceable marking records a manufacturing date, a manufacturing line, a model number, a material used, parameters of a processing process, and the like by marking a special symbol such as a fine two-dimensional barcode at a specific position of a product. The recorded information is used in the downstream manufacturing process, or is used to confirm the cause of the defect by going back to the upstream process when a defective product is found.

  Some marking devices used for micro marking use a fiber laser as a light source. The fiber laser is suitable for micro-marking with a laser because the light source is single mode and can be focused to the diffraction limit and has high energy. However, a marking apparatus that uses a fiber laser as a light source becomes large and expensive.

  A marking device using a fiber laser as a light source is disclosed in, for example, Patent Document 1 (FIG. 3 and page 20, first paragraph to page 24, first paragraph). Further, a marking device that can focus laser light from a semiconductor laser into a minute spot light is disclosed in Patent Document 2 (FIGS. 1 and 22 to 28) and Patent Document 3 (FIGS. 1 and 25 to 31). Yes. However, these are not suitable for micro marking.

JP-T-2002-501436 JP 2001-100135 A JP 2000-334585 A

  There has been no laser marking device with a simple structure capable of performing micro marking. Therefore, there is a need for a laser marking apparatus having a simple structure capable of performing micro marking.

  The laser marking device according to the present invention includes a semiconductor laser unit, a semiconductor laser unit housing, a lens housing, and a condenser lens. The semiconductor laser unit includes a semiconductor laser and has a cylindrical shape having an axis of rotational symmetry that coincides with the optical axis. The semiconductor laser unit housing includes a cylindrical hollow portion that is fitted to the semiconductor laser unit, and further includes a surface having a certain angle with respect to the optical axis when the semiconductor laser unit is fitted. The condensing lens condenses the light beam collimated by the collimator lens. The semiconductor laser unit is configured to be position-adjustable in a cylindrical hollow portion of the semiconductor laser unit housing in an optical axis direction and a rotational direction around a rotational symmetry axis that coincides with the optical axis. On the other hand, the position of the semiconductor laser unit housing can be adjusted by sliding the surface having the predetermined angle.

  A method of manufacturing a laser marking device according to the present invention manufactures a marking device including a semiconductor laser unit, a semiconductor laser unit housing, and a lens housing. The semiconductor laser unit includes a semiconductor laser and has a cylindrical shape having an axis of rotational symmetry that coincides with the optical axis. The semiconductor laser unit housing includes a cylindrical hollow portion that is fitted to the semiconductor laser unit, and further includes a surface having a certain angle with respect to the optical axis when the semiconductor laser unit is fitted. The semiconductor laser unit is configured to be position-adjustable in a cylindrical hollow portion of the semiconductor laser unit housing in an optical axis direction and a rotational direction around a rotational symmetry axis that coincides with the optical axis. On the other hand, the position of the semiconductor laser unit housing can be adjusted by sliding the surface having the predetermined angle.

  A method of manufacturing a laser marking device according to the present invention includes a step of fitting a semiconductor laser unit into a cylindrical hollow portion of a semiconductor laser unit housing, and a semiconductor laser while observing a point image of a wavefront using the optical axis as a Z axis. Adjusting the position of the semiconductor laser unit housing in the X-axis direction and the Y-axis direction so that the center of the light is aligned with the center of the image. Furthermore, the lens housing is mounted on a surface at a certain angle with the optical axis of the semiconductor laser unit housing, and the position of the point image of the wavefront image is symmetrical in the left and right and up and down directions in the X and Y axis directions. Adjusting the position. Further, measuring the wavefront aberration, adjusting the position of the lens housing and the height of the semiconductor laser unit based on the measurement result, and fixing the semiconductor laser unit, the semiconductor laser unit housing and the lens housing as a unit Including.

  According to the present invention, the positional relationship between the semiconductor laser unit and the lens housing is determined via the semiconductor laser unit housing so as to minimize the wavefront aberration while measuring the wavefront of the laser beam collimated by the collimator lens. Can be adjusted. Therefore, the laser beam collimated by the collimator lens can be condensed into the minute spot light by the laser marking device having a simple structure, and the micro marking can be realized.

  According to one embodiment of the invention, the constant angle is 90 degrees.

  Therefore, it is easy to adjust the position of the lens housing with respect to the optical axis.

  According to another embodiment of the present invention, a mechanism for adjusting the tilt of the lens is provided between the semiconductor laser unit housing and the lens housing.

  Therefore, astigmatism can be corrected.

  According to another embodiment of the present invention, the lens housing further comprises a wavefront correction plate.

  Therefore, the aberration can be further reduced by processing the shape of the wavefront correction plate by the laser ablation processing method.

  According to another embodiment of the present invention, the collimator lens has a beam shaping function that aligns the beam divergence angle in the direction parallel to the direction perpendicular to the active layer of the semiconductor laser.

  Therefore, astigmatism can be reduced.

  According to another embodiment of the marking device of the present invention, the position of the condenser lens in the optical axis direction is set so that the intensity of the return light from the marking object is maximized or the beam diameter of the return light is minimized. An autofocus mechanism for adjusting is further provided.

  Therefore, it is possible to prevent the marking from being blurred by the autofocus mechanism.

  With reference to FIG. 1 and FIG. 2, the structure of the laser light source part of the laser marking apparatus of this invention is demonstrated. The laser light source portion includes a semiconductor laser unit 2, a semiconductor laser unit housing 3, and a lens housing 5. The semiconductor laser unit 2 includes the semiconductor laser 1 and has a cylindrical shape having an axis of rotational symmetry that coincides with the optical axis. The semiconductor laser unit housing 3 includes a cylindrical hollow portion that is fitted to the semiconductor laser unit, and further includes a surface having a certain angle with respect to the optical axis when the semiconductor laser unit is fitted. The lens housing 5 includes a collimator lens 4 and includes a surface having a constant angle with respect to the optical axis corresponding to a surface having a constant angle with respect to the optical axis of the semiconductor laser unit housing 3. In the present embodiment, the constant angle is 90 degrees.

  The semiconductor laser 1 to be used may be any wavelength as long as it is a single mode semiconductor laser. The wavelength is mainly 406 nanometers or 940 nanometers. The output of the semiconductor laser 1 is in the range up to 2 W, and in this embodiment is 200 mW.

  Here, the semiconductor laser unit 2 is configured such that the position of the semiconductor laser unit 2 can be adjusted in the direction of the optical axis and the rotational direction around the rotationally symmetric axis that coincides with the optical axis in the cylindrical hollow portion of the semiconductor laser unit housing 3. Further, the lens housing 5 is configured such that the position of the lens housing 5 can be adjusted with respect to the semiconductor laser unit housing 3 by sliding a surface having a certain angle with respect to the optical axis.

  FIG. 3 shows an adjusting device 51 for adjusting the laser light source portion of the laser marking device of the present invention. The lens unit 5 is disposed at a position P in the drawing, and the semiconductor laser unit housing 3 is disposed below the lens unit 5 for adjustment. A in the drawing indicates a position adjustment mechanism in the X-axis direction of the lens housing 5 with respect to the semiconductor laser unit housing 3. B in the drawing indicates a position adjustment mechanism in the Y-axis direction of the lens housing 5 with respect to the semiconductor laser unit housing 3. In these adjustments, the semiconductor laser unit housing 3 is fixed, and the lens housing 5 is screwed in the X-axis direction or the Y-axis direction while applying a reaction force by a spring on a surface at a certain angle with respect to the optical axis. This is done by pushing and sliding. C in the drawing indicates a position adjustment mechanism in the Z-axis (optical axis) direction of the semiconductor laser unit 2 with respect to the semiconductor laser unit housing 3. In this adjustment, the semiconductor laser unit 2 is fitted into the cylindrical hollow portion of the fixed semiconductor laser unit housing 3, and the position of the bottom surface of the semiconductor laser unit 2 in the Z-axis (optical axis) direction is changed by a screw mechanism. By doing. D in the drawing indicates a rotational position adjusting mechanism around the Z axis (optical axis) of the semiconductor laser unit 2 with respect to the semiconductor laser unit housing 3. The rotational position around the Z axis (optical axis) is adjusted by rotating a circular table on which the semiconductor laser unit 2 is mounted. E in the drawing indicates a fixing mechanism for fixing the semiconductor laser unit housing 3 and a tilt adjusting mechanism for the entire stage on which a circular table on which the semiconductor laser unit 2 is mounted is mounted. F in the figure indicates a fixing mechanism for fixing the semiconductor laser unit housing 3 and a tilt adjusting mechanism for the entire stage on which a circular table on which the semiconductor laser unit 2 is mounted is mounted.

  The positional relationship between the semiconductor laser unit housing 3 and the lens housing 5 can be adjusted via the semiconductor laser unit housing 3 by the adjusting device 51 described above for adjusting the laser light source portion. How to adjust using the adjusting device 51 will be described below.

  FIG. 4 shows a configuration of an adjustment system including the adjustment device 51 and a measurement optical system that measures the wavefront of the laser light. As will be described in detail below, the laser light source portion is adjusted by the adjusting device 51 while measuring the wavefront of the laser light by the measuring optical system. The laser beam emitted by the semiconductor laser 1 is collimated by the collimator lens 4. The diameter of the parallel laser beam is changed by allowing the parallel laser beam to pass through the lens 101 having the focal length F1 and the lens 103 having the focal length F2 which are arranged with an interval of the sum of the focal points. Specifically, the diameter of the parallel laser beam is F2 / F1 times. The diameter of the parallel laser beam is adjusted so as to match the area of the microlens array 105 disposed behind.

  Next, wavefront measurement will be described. For the wavefront measurement, the Shack-Hartmann measurement method is used. In measurement, for example, reference light from a helium-neon light source 111 is incident on the microlens array 105. The microlens focal length of the microlens array 105 is 10,000 micrometers, and the arrangement pitch is 0.3 millimeters. Each microlens collects the incident reference light. A focus image is formed on a detector array (CCD) 109 using the imaging lens 107, and the position of each focus is recorded. Next, measurement light is made incident on the microlens array 105, and similarly a focus image is recorded. A deviation amount between the focus position of the reference light and the focus position of the measurement light is obtained. Since the amount of deviation from the reference light represents the inclination of the wavefront, the wavefront of the beam light can be obtained by integrating the entire beam diameter.

  The aberration can be individually evaluated by expanding the measured wavefront displacement, that is, the wavefront aberration, with the Chernike coefficient. Specifically, the first term of the Chernike coefficient is the tilt of the X axis, the second term of the Chernike coefficient is the tilt of the Y axis, the third term of the Chernike coefficient is the defercus of the collimating lens 4, the fourth and fifth terms of the Chernike coefficient are astigmatism, Chernike coefficients 6 and 7 indicate coma aberration (positions of the front and back surfaces of the lens, axial misalignment between the semiconductor laser light source and the collimator lens, etc.), and Chernike coefficient 8 indicates spherical aberration. The above-described processing for expanding the wavefront aberration to the Chernike coefficient is performed by a processor (not shown) connected to the detector array 109. The processor may be a personal computer, for example.

  Based on the result of the wavefront measurement described above, the adjustment device 51 adjusts the positional relationship between the semiconductor laser unit 2 and the lens housing 5 via the semiconductor laser unit housing 3.

  Even if the positional relationship between the semiconductor laser unit housing 3 and the lens housing 5 is adjusted, if the aberration still does not become a target value, for example, λ / 4 or less, the processing laser light source 113 and the processing condensing lens 115 are changed. The aberration is further reduced by processing the shape of the wavefront correction plate 6 by laser ablation processing. Specifically, the wavefront of the semiconductor laser light that has passed through the collimator lens 4 and the wavefront correction plate 6 is measured, and a contour map indicating the degree of phase advance is created. The portion of the wavefront correction plate corresponding to the place where the phase of this map is delayed is removed by laser ablation to adjust the phase. By using a resin wavefront correction plate, correction can be performed even if the collimator lens 4 is made of glass. Details of the laser ablation processing method are described in Japanese Patent No. 3085875 (method for forming an optical surface).

  The above adjustment procedure will be described with reference to the flowchart of FIG. In step S 010, the semiconductor laser unit 2 and the semiconductor laser unit housing 3 are attached to the adjustment device 51. In step S020, the following adjustment is performed while observing the point image of the wavefront. The direction of the semiconductor laser is adjusted by rotating the semiconductor laser unit 2 according to D in FIG. The entire adjustment device is moved in the X-axis direction and the Y-axis direction by an adjustment mechanism not shown in FIG. 3 so that the center of the semiconductor laser beam is aligned with the center of the image. Adjust the position in the Y-axis direction. Further, the optical axis shift of the semiconductor laser light due to the mounting error of the semiconductor laser chip is adjusted by the tilt adjustment stages E and F in FIG. In step S030, the lens housing 5 is placed on a surface having a certain angle with the optical axis of the semiconductor laser unit housing 3, and is aligned with the center of the semiconductor laser light. The positions of the lens housing 5 in the X-axis direction and the Y-axis direction are adjusted by A and B in FIG. 3 so that the position of the point image of the wavefront image is symmetrical left and right and up and down. In step S040, the wavefront aberration is measured by the detector array 109. The position of the lens housing 5 and the height of the semiconductor laser unit 2 are adjusted by C in FIG. 3 so that the Cernike coefficients 1, 2 and 3 terms approach 0. In step S050, it is determined whether astigmatism adjustment is necessary. If necessary, the process proceeds to step S060, and if not necessary, the process proceeds to step S070. In step S060, the lens is tilted in the X-axis direction or the Y-axis direction between the semiconductor laser unit housing 3 and the lens housing 5 shown in FIG. 3G so that the Chernike coefficients 4 and 5 are close to zero. In order to tilt the lens, for example, a shim may be inserted. Or you may incline by providing a mechanism which consists of a screw and a spring, or a bias screw mechanism, and adjusting a screw. Thereafter, the process returns to step S030, and the position of the lens housing 5 and the height of the semiconductor laser unit 2 are adjusted again. In step S070, the semiconductor laser unit 2 and the semiconductor laser unit housing 3 are fixed with an adhesive such as a UV curable resin. Further, the lens housing 5, the shim, and the semiconductor laser unit housing 3 are fixed with an adhesive such as UV curable resin. In step S080, the wavefront is measured to determine whether correction by the wavefront correction plate is necessary. If necessary, go to step S090. Exit if not needed. In step S090, the aberration is further reduced by processing the shape of the wavefront correction plate 6 by the laser ablation processing method using the processing laser light source 113 and the processing condensing lens 115.

  FIG. 6 shows the overall configuration of a laser marking device according to an embodiment of the present invention. The laser marking device includes a laser light source portion, that is, a semiconductor laser unit 2, a semiconductor laser unit housing 3, a lens housing 5, a wavefront correction plate 6, and a condenser lens 11, in which wavefront aberration is minimized by the above-described method. Micro marking on the workpiece 21 on the XY stage 22 is possible by minimizing the wavefront aberration by the laser light source part and collecting the collimated laser beam by the condenser lens 11 to obtain a high brightness spot. It becomes. The laser marking apparatus may include a processor 15 for controlling the semiconductor laser driver 16 and the XY stage 22.

  Here, when the light is condensed by the short focus lens, since the depth at the light condensing point is shallow, the marking tends to be unclear due to the unevenness of the marking object. Therefore, the reflected light from the marking object that has been condensed and irradiated is separated by the beam splitter 12, condensed by the condenser lens 13, converted into an electrical signal by the light-electric conversion element 14, and taken into the processor 15. The processor 15 drives the condenser lens 11 with the actuator 17 so as to maximize the signal, and maintains the best focus on the marking surface. As another method, the condenser lens 11 may be driven by the actuator 17 so that the beam diameter is measured by an image and is minimized.

  As the actuator 17, piezo element driving, motor driving, electrostatic driving, magnetic driving, and the like can be used. Such an autofocus mechanism can prevent the marking from becoming blurred.

FIG. 7 shows the optical arrangement of the collimator lens. As the collimator lens, a toroidal lens in which the R1 surface is a Y-toroidal surface and the R2 surface is an X-toroidal surface was used. The shape data of the toroidal lens is shown below. r is a radius of curvature, K is a shape factor, and A, B, C, and D are coefficients of fourth-order, sixth-order, eighth-order, and tenth-order correction terms, respectively.

As the collimator lens, an anamorphic lens or the like is used, and the diameters of the light beams in the X direction (direction parallel to the active layer of the semiconductor laser) and the Y direction (direction perpendicular to the active layer of the semiconductor laser) are made equal. May be.

  A condenser lens having a focal length of 10 mm was used.

  The results of micro marking by the laser marking device according to one embodiment of the present invention are shown in FIGS. FIG. 8 is micromarked on polycarbonate (PC). The dot size is approximately 70 micrometers. FIG. 9 is micromarked on an acrylonitrile butadiene styrene copolymer (ABS). The size of the dot is about 10 micrometers. FIG. 10 is micromarked on epoxy. The size of the dot is about 30 micrometers.

1 shows a laser light source portion of a laser marking device according to an embodiment of the present invention. 1 shows a laser light source portion of a laser marking device according to an embodiment of the present invention. The adjustment apparatus for adjusting the laser light source part of the laser marking apparatus of this invention is shown. The structure of the optical system for adjusting a laser light source part including an adjustment apparatus is shown. It is a flowchart which shows the adjustment procedure of the laser marking apparatus by one Embodiment of this invention. 1 shows an overall configuration of a laser marking device according to an embodiment of the present invention. The optical arrangement of the collimator lens is shown. 6 shows the result of micro marking by a laser marking device according to an embodiment of the present invention. 6 shows the result of micro marking by a laser marking device according to an embodiment of the present invention. 6 shows the result of micro marking by a laser marking device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Semiconductor laser unit 3 Semiconductor laser unit housing 4 Collimator lens 5 Lens housing 6 Wavefront correction plate 7 Condensing lens

Claims (10)

A laser marking device using a semiconductor laser,
A cylindrical semiconductor laser unit including a semiconductor laser and having a rotational symmetry axis coinciding with the optical axis;
A semiconductor laser unit housing having a cylindrical hollow portion to be fitted with the semiconductor laser unit, and further having a surface at a constant angle with respect to the optical axis when the semiconductor laser unit is fitted;
A lens housing including a collimator lens and having a surface at the fixed angle with respect to the optical axis;
A condensing lens that condenses the light beam collimated by the collimator lens,
The semiconductor laser unit is configured such that the position of the semiconductor laser unit can be adjusted in the direction of the optical axis in the cylindrical hollow portion of the semiconductor laser unit housing and in the rotational direction around the rotational symmetry axis that coincides with the optical axis,
A laser marking device configured such that a lens housing can be adjusted in position with respect to a semiconductor laser unit housing by sliding a surface having the predetermined angle with respect to an optical axis.   The laser marking device according to claim 1, wherein the certain angle is 90 degrees.   3. The laser marking device according to claim 1, further comprising a mechanism for adjusting the tilt of the lens between the semiconductor laser unit housing and the lens housing.   The laser marking device according to claim 1, wherein the lens housing further includes a wavefront correction plate.   5. The laser marking device according to claim 1, wherein the collimator lens has a beam shaping function to align a beam divergence angle in a direction parallel to a direction perpendicular to an active layer of the semiconductor laser. .   6. An autofocus mechanism for adjusting the position of the condenser lens in the optical axis direction so that the intensity of the return light from the marking object is maximized or the beam diameter of the return light is minimized. The laser marking device according to any one of the above. When the semiconductor laser unit includes a semiconductor laser unit and includes a cylindrical semiconductor laser unit having a rotationally symmetric axis that coincides with the optical axis, and a cylindrical hollow portion that is fitted to the semiconductor laser unit. A method of manufacturing a laser marking device comprising: a semiconductor laser unit housing having a surface with a constant angle with respect to the optical axis; and a lens housing including a collimator lens and having the surface with the constant angle with respect to the optical axis. There,
Mating the semiconductor laser unit with the cylindrical hollow portion of the semiconductor laser unit housing; and
Adjusting the position of the semiconductor laser unit housing in the X-axis direction and the Y-axis direction so that the center of the semiconductor laser light is aligned with the center of the image while observing the point image of the wavefront with the optical axis as the Z-axis;
Place the lens housing on a surface at a certain angle with the optical axis of the semiconductor laser unit housing, and position the lens housing in the X-axis direction and Y-axis direction so that the position of the point image of the wavefront image is symmetrical left and right and up and down Adjusting steps,
Measuring wavefront aberration and adjusting the position of the lens housing and the height of the semiconductor laser unit based on the measurement results;
Fixing the semiconductor laser unit, the semiconductor laser unit housing and the lens housing together.   The method of claim 7, wherein the constant angle is 90 degrees.   9. The method according to claim 7, further comprising: adjusting an inclination of the lens in the X-axis direction or the Y-axis direction between the semiconductor laser unit housing and the lens housing by an inclination adjusting mechanism when astigmatism adjustment is necessary. The method described in 1.   The step of attaching a wavefront correction plate to the front surface of the lens housing; and the aberration is further reduced by processing the shape of the wavefront correction plate by a laser ablation processing method while measuring the wavefront. The method described.

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