JP5826387B2 - Method and apparatus for optimally laser marking an object - Google Patents

Description

  The present invention relates to laser marking on an object. In particular, the present invention exposes the underlying surface of the object by laser ablating the coating applied to the object, thereby contrasting the appearance between the exposed surface of the object and the adjacent residual coating. It is related with the laser marking to the target object which forms a mark by this. In addition, the first coating or the uppermost coating layer is laser ablated to expose the base of the second coating layer, and a contrast is provided between the exposed second coating and the adjacent first coating. This mark may be formed by forming a mark. The laser parameters are selected so that they have a uniform and commercially desirable appearance, maintain system throughput in an acceptable range, and do not damage the underlying surface.

Background of the Invention

  Products that are sold generally require some kind of marking on the product for commercial, regulatory, decorative, or functional purposes. A mark refers to a continuous region or range on the surface of an object that is visually contrasted with an adjacent surface. Desirable attributes for marking include consistent appearance, durability, and ease of application. Appearance refers to the ability to reliably and repeatably have a selected shape, uniform color, and optical density for a mark. Durability refers to the property of remaining unchanged despite wear on the marked surface. Ease of application refers to the time and resources to generate a mark, including the cost of the material and being programmable. Programmable means that the marking device can be programmed with a new pattern to be marked by changing the software rather than changing the hardware such as the screen or mask.

  Of particular concern is the creation of marks on coated or painted objects. Objects made of metal or various types of plastics are often painted or coated with various industrial coatings to protect or change the appearance of the surface of the object. Laser ablating the coating, particularly the pattern, to remove the coating and expose the underlying surface of the object is a desirable method for marking the object. Covering the object with two or more coatings and laser ablating the first coating to expose the second coating substrate is another desirable method for marking. Marking the product by using a laser to remove the coating and expose the substrate of the object is disclosed in US Patent Application Publication No. 2008/0152859 by inventor Shogo Nagai, published June 26, 2008. It is stated in. This method uses a coating brightness that is brighter than the surface of the object. Japanese Patent Application No. 03-150842 by inventor Noboru Iwasaki, published on October 29, 1992, describes using a laser to remove one or more coating layers and exposing the underlying layer of the coating layer.

  Common to these documents is that in order to remove the coating without removing the material underlying the removed coating layer, the laser ablation threshold of the material to be removed is set to the laser ablation threshold of the underlying material. It must be lower than that. The laser ablation threshold is the minimum energy required for material removal. This removal may be ablation in which sufficient energy is injected into the material by the laser and the material dissociates into a plasma, or a thermal one that the material essentially melts and evaporates. Or a combination of the two. What is related to the ablation threshold is the damage threshold. The damage threshold is the minimum laser energy required to cause an undesirable change in material appearance. Material damage thresholds are generally lower than ablation thresholds and sometimes much lower than ablation thresholds. Damage is defined as an undesirable change in the appearance of the material comprising the underlying coating after laser removal of the object or top layer.

FIG. 1 shows an example of a prior art tool path for marking an object. A tool path refers to a series of positions on an object that are exposed to laser radiation to generate a mark. This laser radiation may be continuous wave (CW) or pulsed. In either case, the laser and the optical system have a laser beam that is an optical path through which either pulsed or CW laser energy propagates when excited to the extent that the laser emits. FIG. 1 shows an object 10 covered with an opaque coating 11. Shape 12 shows the outline of the area where material is removed to form the mark. The tool path 13 is laid out so that the laser begins to remove material at the starting point 14. Then, the laser beam is moved along the tool path 13 with respect to the object 10 to remove the material until the end point 16 is reached. This tool path is optimized to configure the tool path to maximize the time the laser actually spends removing material compared to positioning the laser beam without cutting. The FIG. 2 shows the result of removal of the material shown in FIG. In the object 20 having the coating 21, the coating is removed from the region of the mark 22, and the underlying materials 24 and 26 are exposed. In this case, the laser irradiation density that optimizes the material removal rate of the portion forming the “T” -shaped vertical portion 24 is selected. The irradiation density is a ratio per unit area of the laser energy irradiated on the surface of the object, and is measured in units of watts / cm ² . This irradiation density causes damage or undesirable appearance to other portions 26 of the “T” shape, making the appearance of the mark unacceptable. The prior art solution to this problem is to slow down the laser movement relative to the object or to reduce the illumination density, both of which are undesirable because they reduce throughput.

  What is desired but not disclosed in the prior art is that the ablation threshold for the material to be removed is close to or lower than the damage threshold of the underlying material, or even if the damage threshold changes due to previous laser processing. This is a reliable and repeatable material removal method that does not damage the underlying material. And what is needed is to use a laser to remove a layer of the coating on the coated object without undesirably damaging the underlying material while maintaining acceptable system throughput. A method for reliably and repeatably generating marks having a desired appearance.

Aspects of the present invention use a laser marking system on a coated object to produce marks having desired characteristics. The laser marking system has a storage device and a controllable laser fluence. Fluence is defined as the cumulative laser energy irradiated per unit area and is measured in units of joules / cm ² . Aspects of the invention determine a first laser fluence associated with generating a mark having a desired characteristic in a first portion of the mark. An aspect of the invention then determines a second laser fluence associated with generating a mark having a desired characteristic in the second portion of the mark. These fluences are stored in the storage device of the laser marking system. The laser marking system then marks the sample using the stored first laser fluence in the first part of the mark and uses the stored second laser fluence in the second part of the mark. To instruct the sample to be marked, thereby marking the sample with the desired properties.

  To form a mark on a coated object by ablating the top coating layer to expose another coating or surface of the object, the ablation threshold for the material to be ablated is Must be below the ablation threshold for. In many cases this is possible by appropriate selection of materials. For example, the top coating or paint that is darker or less reflective than the underlying layer absorbs more laser energy than the underlying layer and is typically ablated at a lower fluence threshold.

  Aspects of the present invention take into account the damage threshold at the time of marking in order to generate a mark that exhibits the desired appearance. In order to generate marks efficiently, the irradiation density is adjusted to maximize the material removal rate without damaging the underlying material. Irradiation density is a measure of the fraction of energy irradiated on the surface of the object, and the tool path indicates the time that the laser beam is directed to each point on the mark, so combine the irradiation density with the tool path. This determines the fluence. The laser beam illumination density and tool path are greater than the ablation threshold of the material to be removed and smaller than the damage threshold of the underlying material, while maximizing the speed of movement of the laser beam relative to the object to maximize throughput. Is calculated as follows. The difficulty is that these thresholds can be different for different areas of the mark at different times during the marking process. Laser parameters that provide a commercially desirable appearance and an acceptable material removal rate, and thus an acceptable throughput in certain areas of the mark, can damage the underlying material in other areas of the mark. FIG. 2 shows the result of laser marking an object with a single illumination density and moving speed, the result being non-uniform and commercially unacceptable. While it may be possible to select a set of laser parameters that produce a mark with a commercially desirable appearance, the resulting material removal rate is the fastest of the acceptable removal rates for all parts of the mark Do not exceed that, which will unacceptably reduce throughput. Aspects of the invention divide the area to be marked into smaller areas and optimize the material removal rate for each area of the mark depending on the shape of the mark and the characteristics of the laser pulse used. By calculating the laser parameters for the area, the laser parameters used in producing the commercially desired mark are determined.

  The damage threshold for a material at a particular location is not only dependent on the irradiation density of the laser currently directed at that location, but also on the recent history of exposure to laser radiation. Therefore, the appearance of the material after laser processing cannot be appropriately predicted simply by measuring the laser fluence. This is because previous irradiation at or near that location tends to heat the material. This heating can have a cooling time constant that can exceed the time between passes of the laser beam. This allows the material to retain heat from previous passes in subsequent passes of the laser, reducing the damage threshold at a particular location at that particular time. Aspects of the present invention calculate this residual heat based on the mark shape and planned dimensions and the timing of the laser pulses used to ablate the topmost material. Based on the calculated residual heating, aspects of the present invention vary the laser fluence to compensate for the damage threshold that was lowered by previous laser irradiation. This change depends on the specific area of the mark to be processed, previous laser irradiation on or near this area, and the waiting time from previous irradiation.

  Aspects of the present invention provide laser pulse parameters such as pulse duration and pulse replenishment speed or spot size or laser beam position, or to increase laser marking system throughput while avoiding damage to the underlying material, or Control various laser parameters including tool path parameters such as laser beam velocity. The laser is selected to achieve the desired material removal rate, and the power, repetition rate, pulse time shape and pulse duration are selected. Then, the tool path, that is, the position where the laser irradiates the object to form the mark and the number of times are calculated so as to obtain a desired material removal speed while avoiding damage to the underlying material. An example of a tool path calculation is the spacing between subsequent pulses on the object that is controlled by changing the speed of relative motion between the laser pulse and the object. Another example of a tool path calculation is a spot size that controls the illumination density by moving the focal spot in the Z axis to a point above or below the surface of the object. A further example of calculating the tool path calculates the spacing between adjacent columns of pulse positions. A tool path is selected that covers the area to be marked in the line moved by the raster technique. The set of lines to be moved is divided into subsets, and the laser marking thermal load is determined for each region. The heat load can be calculated, estimated or measured empirically. The laser irradiation density is adjusted by changing the laser parameters based on the thermal load determined for each subset.

  Aspects of the present invention control the laser output. In order for the tool path to be easily selected by the present invention, the laser pulses need to be turned on and off very accurately under the control of the laser marking system. Aspects of the present invention control the laser illumination density accurately enough to obtain a tool path that produces marks having commercially desirable uniformity, color, texture, and shape. An optical switch is used to switch the laser beam on and off at high speed without turning the laser on and off. Aspects of the present invention use an acousto-optic modulator (AOM) to accurately and rapidly modulate a beam so that the beam is directed to an object or propagates to a beam dump without adverse effects. Orient.

  Embodiments of the present invention are realized by modifying an existing laser micromachining system, the ESI model ML5900 laser micromachining system manufactured by Electro Scientific Industries, Portland, Oregon, 97229, USA. This system is described in detail in “ESI Service Guide ML5900” No. 178472A, published in October 2009, by Electro Scientific Industries, Portland, Oregon, 97229, which is hereby incorporated by reference in its entirety. Included in the description. Improvements include adding electro-optic devices to control fluence changes and to allow more precise control of laser fluence in real time.

  Another aspect of the present invention uses an infrared (IR) camera focused on the object to measure the temperature of the marked object. The infrared camera detects the heat released from the surface of the object in the area to be marked and communicates this information to the controller, which adjusts the laser fluence to compensate for the heat remaining on the object. . For a particular object with a particular coating applied, a given reading from the IR camera will determine the amount of fluence that should be used to remove the topmost coating without undesirably damaging the underlying material. The IR camera is calibrated as shown to produce a mark with the desired appearance.

  Objects that are coated with visible marks having a desired commercial quality to accomplish the above-described matters in accordance with these and other aspects specifically and broadly described herein for purposes of the present invention. Disclosed herein is a method of generating above and an apparatus adapted to perform the method. Included is a laser processing system having a laser operatively connected to a controller having stored predetermined laser pulse parameters, a laser optical system, and a motion stage. The stored laser pulse parameters are associated with a desired fluence that is selected depending on the area of the mark being processed to produce a mark having commercially desirable characteristics.

FIG. 1 shows a prior art marking. FIG. 2 shows a prior art mark. FIG. 3 shows marks indicating the calculated fluence area. FIG. 4 shows an improved laser marking system. FIG. 5 shows an improved laser marking system. FIG. 6 shows an improved laser marking system. FIG. 7 shows an improved laser marking system. FIG. 8 shows an improved laser marking system with feedback.

Detailed Description of the Preferred Embodiment

  Embodiments of the present invention use a laser marking system on a coated object to generate a mark having the desired characteristics. The laser marking system has a storage device and a controllable laser fluence or dose. Embodiments of the present invention determine a first laser fluence associated with generating a mark having a desired characteristic in a first portion of the mark. An aspect of the invention then determines a second laser fluence associated with generating a mark having a desired characteristic in the second portion of the mark. These fluences are stored in the storage device of the laser marking system. The laser marking system then marks the sample using the stored first laser fluence in the first part of the mark and uses the stored second laser fluence in the second part of the mark. To instruct the sample to be marked, thereby marking the sample with the desired properties. Embodiments of the present invention provide laser pulse parameters such as pulse duration and pulse replenishment rate and spot size and laser beam position to increase the throughput of the laser marking system while avoiding damage to the underlying material, Alternatively, the laser fluence is controlled by controlling various laser parameters including tool path parameters such as laser beam velocity. Typically, the laser is selected to achieve the desired material removal rate, and the power, repetition rate, pulse time shape, and pulse duration are selected. Then, the tool path is calculated so as to obtain a desired material removal rate while avoiding damage to the base material.

  An example of a tool path calculation is the spacing between subsequent pulses on the object that is controlled by changing the speed of relative motion between the laser beam and the object. Another example of a tool path calculation is a spot size that controls the illumination density by moving the focal spot in the Z axis to a point above or below the surface of the object. A further example of calculating the tool path calculates the spacing between adjacent columns of pulse positions. A tool path is selected that covers the area to be marked in the line moved by the raster technique. The set of lines to be moved is divided into subsets, and the laser marking thermal load is determined for each region. The heat load can be calculated, estimated or measured empirically. The laser irradiation density is adjusted by changing the laser parameters based on the thermal load determined for each subset.

  Embodiments of the present invention control the output of the laser. In order for the tool path to be easily selected by the present invention, the laser pulses need to be turned on and off very accurately under the control of the laser marking system. Aspects of the present invention control the laser illumination density accurately enough to obtain a tool path that produces marks having commercially desirable uniformity, color, texture, and shape. Aspects of the present invention use an acousto-optic modulator (AOM) to accurately and rapidly modulate a beam so that the beam is directed to an object or propagates to a beam dump without adverse effects. Orient.

  FIG. 3 is an improvement used by embodiments of the invention. The object 30 is covered with a coating 31, and the coating 31 in the shaping region 32 is removed. The laser begins to remove material from the starting point 34 along the tool path 33 and removes material as it travels to point 36 as represented by the solid line. At point 36, the laser is turned off and the laser marking system repositions the object relative to the laser beam as represented by the dotted line to begin removing material at point 38 when the laser is turned on. To do. The laser continues cutting and repositioning until reaching the end point 40. Removing material by a raster scan technique means that for adjacent tool path lines of similar length, the delay between adjacent points being laser processed is constant, so the temperature of the material being laser processed is Means constant. This assumes that the moving speed of the laser beam relative to the object is constant.

  With this tool path method, the temperature rise will be constant along the line, but the temperature rise will vary with different lengths of retrace time and line breakage, thus potentially reducing the appearance of the underlying material. Come different. For example, after the laser moves from the start point 34 and removes material to the end point 36 of the stroke, the time between repositioning and starting the next stroke 38 starts the material removal at the upper end 41 of the longer stroke. However, after the material is removed to the end point 42 of the stroke, it differs from the time until it is repositioned at the upper end 44 of the next stroke. Because this time is different, the temperature at point 38 when the laser begins to remove material will be different from the temperature of the material at point 44, and the underlying material potentially has an undesirable appearance in these respects. It will be.

  Embodiments of the present invention solve this problem by dividing the tool path into regions based on the length of the stroke being machined. FIG. 4 shows an object 50 covered with a coating 51 having marks 52 to be laser machined. The stroke is intended to be a vertical raster as shown in FIG. The mark is divided into regions 54, 56, 58, 60, 62, 64, 66 having similar adjacent strokes of approximately the same length. For each stroke length group, a laser fluence is selected that can remove material at a desired rate while compensating for the temperature rise expected to be caused by adjacent strokes. In this way, for example, the region 66 has a shorter stroke than the region 64, and the time between the strokes is shortened, so that the temperature becomes higher and the fluence is lowered. Lines can be grouped due to tolerances in laser-material interaction. Similar laser fluences have a similar effect on the material, even if the temperature may vary slightly between the processing steps in the group. In this example, the first region 54 is processed with a laser fluence, and when the processing moves to the next region 56, the fluence is set so that the appearance of the base material is the same while maintaining the throughput within an allowable range. Is lowered. The laser fluence is continuously adjusted for each of the remaining regions 58, 60, 62, 64, and 66. FIG. 5 shows the result of applying an embodiment of the present invention to generating a mark 72 on a coating object 70 coated with a coating 71. The underlying material 74 visible in the mark 72 does not exhibit damage or a non-uniform appearance, which is a desirable result.

  Embodiments of the present invention control the rate of material removal and the continuous appearance of the underlying material by controlling the laser fluence. Laser fluence can be controlled by controlling laser output energy, beam size, shape or pulse duration. However, it is typically more desirable to control tool path parameters such as speed and pitch between lines to maintain maximum material removal rate. A simple way to maintain a uniform appearance of the underlying material is to stop between strokes so that the material is completely cooled before processing of the next stroke. Tests on sample objects have shown that a delay of about 10 milliseconds is required between strokes to ensure that the material is sufficiently cooled to avoid damage. Inserting this delay provides a uniform appearance, but slows the process to an unacceptable extent. Embodiments of the present invention control the laser fluence precisely and accurately using changes in tool path parameters such as speed, spot size, pitch, etc., in addition to laser pulse parameters, to achieve commercially desirable colors, light densities, A mark having uniformity, texture, and shape is produced on the coated material. Embodiments of the present invention use an acousto-optic modulator (AOM) to switch the laser pulses on and off to help ensure that the tool path dimensions are accurate. Optionally, embodiments of the present invention measure the temperature of the object being marked using an infrared (IR) camera to determine the tool path.

  Embodiments of the present invention use an optical switch that turns the laser beam on and off without turning the laser on or off. Embodiments of the present invention use AOM to direct the laser beam from the normal path by diffraction into a beam dump that is emitted without adversely affecting the laser beam energy to the surface of the object. Modulating the fluence of the laser beam by reattaching. AOM is used because it can modulate the laser beam very quickly. High speed modulation is advantageous for embodiments of the present invention because the laser marking system allows the laser beam to be turned on and off quickly and accurately without disturbing the laser itself. .

  FIG. 6 shows a diagram of an improved ESI model ML5900 laser micromachining system 80 adapted to mark objects as an embodiment of the present invention. This example application includes a laser 82 and an AOM fluence attenuator 84. A laser pulse is emitted by the laser 82 and directed to the beam shaper 86 and AOM 84 by a series of mirrors and other optical elements (not shown) and then optical by another series of mirrors and optical elements (not shown). Directed to the head 88. The optical head includes X, Y, and Z motion control elements 90 and a galvanometer block 92. These elements are combined to position a laser beam (not shown) with respect to the object 98 to be marked to generate a two-dimensional display of the mark on the surface of the object 98. The object 98 is attached to a rotary stage element 94 that aligns the object 98 from the load / unload position to below the optical head 88 (not shown). In optical head 88, object 98 is marked and then to optical inspection station 96, which inspects object 98 before alignment to return to load / unload station 96 for unloading. The alignment of the object 98 is performed. All of these operations are performed under the control of the controller 100. The controller 100 adjusts the operation of the laser 82, AOM 84, motion control element 90, galvanometer block 92, and rotary stage 94 to irradiate the appropriate location on the object 136 with the appropriate laser fluence and provide a commercially desirable appearance. A mark having

Improved laser 82 is a diode-pumped Nd: YVO ₄ solid state laser operating at a triple frequency of 355 nm wavelength, model Vanguard manufactured by Spectra-Physics, Santa Clara, Calif., USA. Laser 82 is configured to generate up to 2.5 W, but typically operates at an 80 MHz mode-locked pulse repetition rate that produces approximately 1 W of power. In embodiments of the present invention, lasers having a power of 0.5 watts to 100 watts, more preferably 0.5 watts to 12 watts, can be advantageously used. A laser repetition rate of 10 KHz to 500 MHz, more preferably 1 MHz to 100 MHz can be used. Laser 82 cooperates with controller 100 to generate a laser pulse having a duration of about 1 picosecond to 1,000 nanoseconds, more preferably 100 picoseconds to 100 nanoseconds. The temporal and spatial distribution of pulses is typically Gaussian. Combining the motion control element 90 and the galvanometer block 92 enables beam positioning relative to the object. In an embodiment of the present invention, a laser spot is used whose size measured on the object is in the range of 5 microns to 500 microns, more preferably in the range of 10 microns to 100 microns. The beam velocity used in this system, i.e. the relative movement between the laser beam and the object, is in the range of 10 mm / s to 1 m / s, more preferably in the range of 50 mm / s to 500 mm / s. The pitch, ie the spacing between adjacent lines of laser pulses, can be in the range of 1 micron to 250 microns, more preferably in the range of 10 microns to 50 microns.

  Embodiments of the present invention use a diffractive beam shaper optical system to change the typical Gaussian spatial profile of the laser beam into a “top hat” shape so that the distributed laser power is uniform across the laser spot area. This improves the performance over a typical Gaussian beam profile because the laser fluence of the top hat is equal in the region of the focal spot, so that the material removal and damage thresholds are equal across the spot. In a Gaussian profile, assuming that the ablation threshold is exceeded at some point in the profile, the focal spot area within the ablation threshold area exceeds the ablation threshold, and the area of the focal spot outside the ablation threshold does not remove material while damaging it. May occur. The use of diffractive optical elements in microfabrication is due to inventors Corey M. Dunsky, Xinbing Liu, Nicholas J. Croglio, Ho W. Lo, Bryan C. Gundrum, and Hisashi Matsumoto, published on August 13, 2002. U.S. Pat. No. 6,433,301. This patent is assigned to the assignee of the present invention and is hereby incorporated by reference in its entirety.

  The embodiment of the present invention shown in FIG. 7 adds the application of real-time feedback to the laser marking system so that prior to laser fluence can be obtained by obtaining IR information from the object in real time while marking. Complementing the calculation produces a mark with a commercially desirable appearance. In the embodiment shown in FIG. 7, the laser 120 directs the laser beam 122 through the diffractive optics 125 to the optical switch 124 (in this case AOM) and then the beam steering optics 126 (in this case). Galvanometer block with a galvanometer set at a right angle and arranged to guide the laser beam 122 in a programmable X, Y pattern on the surface of the object 130. The object 130 to be marked is fixed on a motion control stage 132 that cooperates with the beam steering optics 126 to direct the laser beam 122 into a programmable pattern on the surface of the object 130. An infrared (IR) sensor 128 is adapted to detect the temperature of the surface of the object 130 when marking with the laser beam 122. In this way, the temperature of the next portion of the surface of the object 130 to be marked can be measured by the IR sensor 128 and sent to the controller 134. Based on the measured temperature of the object 130, the controller 134 calculates the optimal fluence to use and directs the laser beam 122 to the appropriate position of the object 130 at the appropriate fluence to produce a commercially desirable appearance. Instructing the laser 120, the optical switch 124, the diffractive optical system 125, the beam steering optical system 126, and the motion control stage 132 to cooperate in generating the mark having. An example of an IR sensor that can be used according to embodiments of the present invention is the model IR-TCM 640 manufactured by Jenoptik of Jena, Germany.

  It will be appreciated by those skilled in the art that many changes can be made to the details of the above-described embodiments without departing from the underlying principles of the invention. Accordingly, the scope of the invention should be defined only by the claims.

Claims (18)

A method of generating a laser mark having desired characteristics on a sample,
Providing a laser marking system configured to irradiate a sample with a laser beam according to at least one controllable parameter including laser fluence ;
During a first period , the first portion of the sample is irradiated with the laser beam at a first laser fluence associated with generating the mark having the desired characteristic . Controlling the laser marking system to generate a first portion of a laser mark in a portion of the sample and to generate heat within a second portion of the sample adjacent to the first portion ;
Adjusting the at least one controllable parameter during the second period in which the heat generated during the first period is at least partially retained in the second part, Irradiating the second portion of the sample with the laser beam at a second laser fluence different from the first laser fluence associated with generating the mark having characteristics . Generating a second portion of the laser mark in two portions to control the laser marking system to produce a laser mark of the desired characteristic on the sample;
Method. The sample is coated with an application coating of a first layer and a second layer;
Furthermore , the laser mark is generated by removing the first layer without damaging the second layer.
The method of claim 1. The method of claim 1, wherein the laser fluence is in the range of 1.0 × 10 ⁻⁶ Joules / cm ^{2 to} 1.0 Joules / cm ² . The method of claim 1, wherein the first portion and the second portion of the laser mark have a consistent appearance including uniform color and optical density . The method of claim 1 , wherein the at least one controllable parameter includes pulse duration, pulse repetition rate, spot size, and / or laser beam velocity . Prior to the first period and the second period,
Determining the first laser fluence associated with generating the mark having the desired characteristics in the first portion of the sample comprising the laser mark;
Determining the second laser fluence associated with generating the mark having the desired characteristics in the second portion of the sample comprising the laser mark;
Storing the first laser fluence and the second laser fluence in the laser marking system;
The stored first fluence is used to generate the first portion of the laser mark in the first portion of the sample, and the stored second laser fluence is used to generate the first portion of the sample. Generating the second part of the laser mark in two parts ;
The method of claim 1.   The sample includes a material that is removed from the first portion and the second portion to produce the laser mark;
  Irradiating the laser beam with a predetermined irradiation density at a predetermined moving speed along a predetermined tool path,
  The irradiation density of the laser beam and the tool path are calculated so as to be larger than the ablation threshold of the material and smaller than the damage threshold of the underlying material of the sample while maximizing the moving speed of the laser beam with respect to the sample. To
The method of claim 1.   Dividing the area to be marked of the sample into smaller areas,
  Calculating the at least one controllable parameter to optimize the material removal rate for each of the smaller regions;
The method of claim 1.   Irradiating the laser beam along a predetermined tool path;
  Selecting the laser power, pulse repetition rate, pulse temporal shape, and pulse duration in the laser of the laser marking system to obtain the desired material removal rate;
  Calculating the position and number of times the laser beam is irradiated to generate the tool path or the laser mark so as to obtain a desired material removal rate while avoiding damage to the underlying material of the sample;
  Dividing the tool path of the area to be marked of the sample into smaller areas;
  Determining a thermal load on the laser marking for each of the smaller areas;
  Adjusting the at least one controllable parameter based on the thermal load determined for each of the smaller regions to optimize the material removal rate for each of the smaller regions;
The method of claim 1.   The calculation of the tool path is
i) The pulse interval between subsequent pulses on the sample, controlled by changing the speed of relative motion between the laser beam and the sample.
ii) Spot size controlled by moving the focal spot in the Z axis relative to the surface of the sample
iii) Column spacing between adjacent columns of pulse positions
Based on one or more of
The method of claim 9.   The laser marking system has an infrared sensor,
  further,
  Measure the temperature of a part of the sample with the infrared sensor,
  Determining a laser fluence associated with generating the laser mark having the desired characteristic in a portion of the sample based on the measured temperature of the portion of the sample;
  Instructing the laser marking system to mark a portion of the sample using the determined laser fluence, thereby marking the sample with the desired properties;
The method of claim 1. A laser marking device improved to mark a sample,
A laser marking system capable of irradiating a sample with a laser beam with a controllable laser fluence;
A controller configured to control operation of the laser marking system,
Irradiating the first portion of the sample with the first laser fluence during a first period to generate a first portion of a laser mark in the first portion of the sample; and Generating heat within a second portion of the sample adjacent to the first portion of the sample;
During the second period, the laser beam is directed to a second laser fluence different from the first laser fluence while the second portion of the sample retains at least a portion of the generated heat. To irradiate the second portion of the sample to generate a second portion of the laser mark on the second portion of the sample to generate a laser mark having a desired characteristic on the sample.
A controller configured to:
A laser marking device comprising: The sample is coated with an application coating of a first layer and a second layer;
Furthermore , the laser mark is generated by removing the first layer without damaging the second layer.
The laser marking device according to claim 12 . The laser fluence is in the range of 1.0 × 10 ^-6 Joules / cm ² to 1.0 Joules / cm ^2, the laser marking apparatus according to claim 12. The laser marking system uses an optical switch, laser marking apparatus according to claim 12. The laser marking device of claim 15 , wherein the optical switch is an acousto-optic modulator. The laser marking apparatus of claim 12 , wherein the laser marking system includes a diffractive beam shaper. Laser,
An optical switch,
A diffractive optical system;
Beam steering optics,
A motion control stage;
An infrared sensor that measures the temperature of a portion of the sample;
Based on the temperature of the portion of the sample measured by the infrared sensor, a laser fluence associated with generating the laser mark on the portion of the sample is determined, and the determined laser fluence is used. A controller for instructing the laser marking system to mark a portion of the sample ;
The laser marking device according to claim 12, further comprising:

Images