Abstract:
A method of determining compatibility of user input parameters for use with a laser drilling system includes providing compatibility data characteristic of a plurality of laser drilling operations, receiving input parameters characteristic of a desired laser drilling operation, and comparing the input parameters to the compatibility data, thereby determining whether the input parameters are incompatible.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/398,652, filed on Jul. 25, 2002. The disclosure of the above application is incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention generally relates to laser drilling and laser milling and particularly relates to computer automated control methods for use with a laser drilling system.  
         BACKGROUND OF THE INVENTION  
         [0003]    Material ablation by pulsed light sources has been studied since the invention of the laser. Reports in 1982 of polymers having been etched by ultraviolet (UV) excimer laser radiation stimulated widespread investigations of the process for micromachining. Since then, scientific and industrial research in this field has proliferated—mostly spurred by the remarkably small features that can be drilled, milled, and replicated through the use of lasers.  
           [0004]    Ultrafast lasers generate intense laser pulses with durations from roughly 10 −11  seconds (10 picoseconds) to 10 −14  seconds (10 femtoseconds). Short pulse lasers generate intense laser pulses with durations from roughly 10 −10  seconds (100 picoseconds) to 10 −11  seconds (10 picoseconds). A wide variety of potential applications for ultrafast and short pulse lasers in medicine, chemistry, and communications are being developed and implemented. These lasers are also a useful tool for milling or drilling holes in a wide range of materials. Hole sizes as small as a few microns, even sub-microns, can readily be drilled. High aspect ratio holes can be drilled in hard materials, such as cooling channels in turbine blades, nozzles in ink-jet printers, or via holes in printed circuit boards.  
           [0005]    Advanced laser drilling systems contain elements that maneuver the laser beam(s) and/or the workpiece(s) in a pattern such that the laser beam ablates the workpiece according to pre-determined geometry requirements. Computers can be programmed to rapidly perform the calculations required to guide precision drilling of a variety of shapes. Once these calculations are made for a given geometry, they can be executed in a repeatable manner for many workpieces. The coordinates calculated by laser milling algorithms are subsequently communicated to the elements of the laser drilling system to create the pre-determined geometry in the workpiece. Manually selecting laser drilling system parameters and making changes to those settings can be complex, and laser physicists are usually directly responsible for these activities.  
           [0006]    Among the challenges in computer automation of laser drilling system is the problem of how to provide a more marketable laser drilling system. Current laser drilling systems do not have an intuitive approach to select workpiece geometry, laser type, or workpiece material as required in a manufacturing environment. Having a way to streamline changes to parameter input would increase the appeal, utility, and sales of laser drilling systems. What is needed is a way to provide a more marketable laser drilling system.  
           [0007]    Also among the challenges in computer automation of laser drilling system is the problem of how to decrease the operating costs of a laser drilling system. Laser drilling systems utilize many complex elements and concepts to perform a specific task. Highly skilled laser physicists are often required to operate the laser drilling system because they understand the technical details of operating the laser drilling system, its elements, and the necessary input parameters. Employing high-salaried laser physicists that understand the technical details of the laser drilling system adds considerably to the operating costs of the laser drilling system. What is needed is a way to decrease the operating costs of a laser drilling system.  
           [0008]    Further among the challenges in computer automation of laser drilling system is the problem of how to facilitate the reconfiguration of a laser drilling system to mass manufacture a variety of laser-drilled products. Laser drilling systems can be used to create any number of complex shapes in a workpiece. In a mass-manufacturing environment, changes to the laser type, workpiece geometry, and workpiece materials are necessary to produce varied shapes and such changes must be made quickly. What is needed is a way to facilitate the reconfiguration of a laser drilling system to mass manufacture a variety of laser-drilled products.  
           [0009]    Still further among the challenges in computer automation of laser drilling system is the problem of how to prevent repetition of previously failed laser drilling system parameter combinations in future drilling runs. In laser drilling systems, certain combinations of laser type, workpiece geometry, and workpiece materials cannot be used to meet product specifications. For example, excimer lasers are not conducive to drilling high quality holes in metal foils because the long-duration (nanoseconds) excimer pulses cause significant melting in metal foils that leads to poor hole quality. Each attempt with a new combination of inputs is expensive; therefore, the number of failed attempts must be kept to a minimum to reduce operating costs. What is needed is a way to prevent repetition of previously failed laser drilling system parameter combinations in future drilling runs.  
         SUMMARY OF THE INVENTION  
         [0010]    In accordance with one aspect of present invention, the method determines compatibility of user input parameters for use with a laser drilling system, based on previously determined compatibility data. The method begins with the input of at least one first parameter associated with laser beam characteristics into a computer system, at least one second parameter associated with workpiece material characteristics into said computer system, and at least one third parameter associated with workpiece geometry characteristics into said computer system. The computer system processes these first, second and third parameters to calculate a tool path. A laser drilling data set that includes said tool path is then generated and exported to the laser drilling system.  
           [0011]    There exist several differences between the present invention and previous technology. A first difference between the present invention and the previous technology is that the present invention allows for changes within the same system, whereas the previous technology does not provide an adjustable laser drilling system. A second difference between the present invention and the previous technology is that the present invention provides a user-friendly interface to configure a laser drilling system, whereas the previous technology does not. A third difference between the present invention and the previous technology is that the present invention includes an implementation of the combination of laser milling correction and milling algorithms with a computer, whereas the previous technology does not. A fourth difference between the present invention and the previous technology is that the present invention provides a way to improve laser drilling system performance by “learning” from failed attempts and incorporating feedback into the system operation, whereas the previous technology does not. A fifth difference between the present invention and the previous technology is that the present invention provides intelligent screening procedures to interactively detect and abort another attempt of using previously known failure factors, whereas the previous technology does not.  
           [0012]    The present invention has several advantages over the previous technology. A first advantage of the present invention is that it provides a more marketable laser drilling system. A second advantage of the present invention is that it provides a way to decrease the operating costs of a laser drilling system. A third advantage of the present invention is that it provides a way to facilitate the reconfiguration of a laser drilling system to mass manufacture a variety of laser-drilled products. A fourth advantage of the present invention is that it provides a way to prevent repetition of previously failed laser drilling system parameter combinations in future drilling runs. A fifth advantage of the present invention is that it allows for expandability of parameters and a nearly infinite number of combinations of workpiece materials, workpiece geometry, and laser characteristics. A sixth advantage of the present invention is that it provides faster re-configuration of a laser drilling system when changes are made.  
           [0013]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0015]    [0015]FIG. 1 is a schematic block diagram of a computer system for controlling a laser drilling system according to the present invention;  
         [0016]    [0016]FIG. 2 is a flow chart diagram depicting a method of using a computer system to control a laser drilling system according to the present invention;  
         [0017]    [0017]FIG. 3A is a flow chart diagram depicting a method of inputting laser beam parameters into a computer system for use in a laser drilling system according to the present invention;  
         [0018]    [0018]FIG. 3B is an example of a laser parameters data table according to the present invention;  
         [0019]    [0019]FIG. 4A is a flow chart diagram depicting a method of inputting workpiece material characteristics for use in a laser drilling system according to the present invention;  
         [0020]    [0020]FIG. 4B is an example of a workpiece material data table according to the present invention;  
         [0021]    [0021]FIG. 5A is a flow chart diagram depicting a method of inputting workpiece geometry into a computer system for use in a laser drilling system according to the present invention;  
         [0022]    [0022]FIG. 5B is an example of a workpiece geometry data table according to the present invention;  
         [0023]    [0023]FIG. 5C is an example of a combination of parameters table according to the present invention;  
         [0024]    [0024]FIG. 5D is an example of a drilling data table according to the present invention;  
         [0025]    [0025]FIG. 6 is a perspective view showing major constituent components of an ink-jet printer; and  
         [0026]    [0026]FIG. 7 is a schematic, cross-sectional view of an ink-jet head.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0028]    [0028]FIG. 1 shows an exemplary computer system  100  to control a laser drilling system. The present invention is not limited to working with the combination of elements as shown in computer system  100 . A computer system with additional or different elements may be used to execute the present invention.  
         [0029]    Computer system  100  includes a means for operator input  120  through a user interface  180 , one or more specification files  110 , or manual inputs  130 ; a computer  140  with a memory  145 , a digital-to-analog (D/A) adaptor  170 , and software  165  that contains one or more algorithms  160  and a database (DB)  167 ; and laser system elements  190 .  
         [0030]    Operator input  120  consists of specific instructions from the laser drilling system operator regarding the geometry of the workpiece, the characteristics of the laser, and the physical characteristics of the workpiece. Input regarding the workpiece geometry, the laser, and the physical characteristics of the workpiece is achieved by importing specification files  110  (e.g. database table or CAD file) or, alternatively, with manual inputs  130 .  
         [0031]    Within computer  140 , memory  145  is random access memory. In one example, computer  140  has sufficient cache (not shown) and memory  145  to hold and send laser drilling data sets to laser system elements  190  without creating a separate file. In an alternate example, laser drilling data sets are stored in a file (not shown) within computer  140  and sent to laser system elements  190  when ready for transmission. Computer  140  has at least 200 MHz Pentium II processor with 64 MB RAM.  
         [0032]    Software  165  manages the operation of computer  140  for use in a laser drilling system. Software  165  controls: gathering inputs and running algorithms  160  prior to milling, accessing data from DB  167 , sending data to D/A adaptor  170 , and populating user interface  180 . Software  165  may be written with any of a variety of programming languages, such as C/C++, Java, FORTRAN, or COBOL.  
         [0033]    Algorithms  160  consist of milling (material ablation) and correction algorithms to be used in controlling and defining the movements of laser system elements  190  required to achieve desired workpiece geometry, including the laser beam parameters, workpiece material characteristics, and variable inputs of workpiece geometry. Parameter inputs are fed into algorithms  160 , which are run by software  165 . Algorithms  160  define the milling points on the X- and Y-axes, as well as the amount of time (T) to drill each milling point. In a specific example, the workpiece (not shown) is milled using a constant tool path algorithm that can be used to direct the movement of a piezo electric transducer (PZT) scan mirror in a laser drilling system to produce tapered holes in a consistent, repeatable process. In another example, correction algorithms are also used to compensate for hysteresis and reflection geometry issues in using a PZT scan mirror to direct a laser upon a workpiece.  
         [0034]    DB  167  is a database management system containing ordered and structured data to be used by software  165  to control a laser drilling system. Inputs from user interface  180  and data sets generated by algorithms  160  are stored in DB  167  for future use. DB  167  stores profiles of pre-defined workpiece geometries, laser beam parameters, and workpiece material parameters in the form of data tables as illustrated below. DB  167  also contains a buffer (not shown) for the storage of data that drives laser system elements. Data storage and recall within DB  167  is completed with conventional database management system processes and rules, such as those available from Oracle Corporation.  
         [0035]    D/A adaptor  170  is a digital-to-analog adaptor that converts digital information resulting from algorithms  160  into voltages that are sent to laser system elements  190 . If laser system elements  190  have their own digital-to-analog adaptor function, D/A adaptor  170  is removed from computer  140 . In this case, laser system elements  190  accept the digital information directly from computer  140 .  
         [0036]    User interface  180  provides a way for a system operator to efficiently use computer  140 . User interface  180  is displayed on a monitor (not shown) attached to computer  140 , and displays prompts to direct the operator to select a workpiece geometry. In one example, user interface  180  is a graphical user interface (GUI) that includes menu-driven screens providing a way to select the workpiece geometry parameters, laser beam parameters, and workpiece material parameters, or, alternatively, define new parameters, and begin the laser drilling process.  
         [0037]    Laser system elements  190  are elements within a laser drilling system (not shown) that control the drilling process. Examples of elements included in laser system elements  190  include galvanometers, PZT scan mirrors, and moveable workpiece stages.  
         [0038]    In operation, computer system  100 &#39;s task is to control a laser drilling system. When a laser system operator provides operator input  120 , software  165  starts user interface  180 , and user interface  180  prompts the operator to select and/or enter new input parameters to be stored in DB  167 . Milling information and algorithms  160  that are specific to the combination of input parameters are sent to memory  145  from DB  167 . Software  165  calls on and executes algorithms  160 . Algorithms  160  then generate a drilling data set that defines every milling point upon workpiece, the corresponding voltages required to direct laser system elements  190 , and the sequence in which the points are to be drilled. Data specific to each point to be milled by the laser drilling system, the voltages, and the sequence are sent by software  165  to D/A adaptor  170 . D/A adaptor  170  converts data to analog voltages required to maneuver laser system elements  190 . Laser system elements  190  drill the specified geometry in specified workpiece.  
         [0039]    Use of computer system  100  greatly streamlines and simplifies the operation of a laser drilling system.  
         [0040]    In accordance with the present invention a method of using a computer system (e.g. computer system  100 ) to control a laser drilling system provides a way to reduce the costs of operating and configuring a laser drilling system in a mass-manufacturing environment by allowing a layperson to operate and change drilling system parameters. The disclosed method further allows for capture and storage of performance feedback, preventing repetition of previously failed laser drilling system parameter combinations.  
         [0041]    [0041]FIG. 2 shows a method  200  of using computer system to control a laser drilling system. Throughout method  200  and all submethods, computer system  100  is used as an example, although the present invention is not limited to the specific elements and arrangement of computer system  100 . Method  200  includes several steps.  
         [0042]    Step  210 : Inputting laser beam parameters. In this step, the system operator inputs the specific laser beam parameters (e.g. laser pulse energy, pulse width, and spot size) of the laser drilling system. The laser beam parameters must be specified because laser beam parameters such as laser wavelength, laser pulse energy, pulse width, repetition rate and spot size in a specific laser drilling system impact the ability to drill certain materials and achieve the desired workpiece geometry specifications. A laser beam with given characteristics will interact with different workpiece materials in different ways that impact the quality of drilling results. The system operator selects a predefined laser beam parameters profile that has been stored in a database, or alternatively creates a new laser beam profile and stores the profile within a computer for future use. A “profile” is defined as a grouping of parameters related to a required input for laser drilling, and is referred to throughout this disclosure as such (e.g. workpiece geometry profile, laser beam profile, workpiece material profile). The process of inputting laser beam parameters is detailed in Method  300  in FIG. 3A, wherein a method  300  of inputting laser beam parameters into a computer system includes several steps.  
         [0043]    Step  310 : Are laser beam parameters established? In this decision step, the system operator determines if the laser beam parameters have already been defined as a profile and saved. In one example, the laser beam parameter profiles are displayed to the system operator via user interface  180 , which retrieves profile data stored in DB  167  within computer  140 . If the laser beam parameters have been defined, method  300  proceeds to step  330 , if the laser beam parameters have not been defined, method  300  proceeds to step  320 .  
         [0044]    Table 1 of FIG. 3B shows an example of a table structure and exemplary data contained in DB  167  to define laser parameter profiles. Each row in Table 1 represents a specific laser parameter profile and contains the critical laser measurements within a laser drilling system.  
         [0045]    In one example, software  165  selects the stored laser parameter profiles from DB  167 , and user interface  180  displays the stored laser parameter profiles to the system operator. Once the system operator reviews the stored laser parameter profiles, if the desired laser parameter profile is displayed in user interface  180 , method  300  proceeds to step  330 , if the laser parameter profile is not displayed (and therefore has not been defined) and method  300  proceeds to step  320 .  
         [0046]    Step  320 : Inputting required laser parameters. In this step, the system operator inputs laser beam parameters. In one example, the system operator inputs laser beam parameters via user interface  180  by importing specification file  110  (e.g. a database table) containing the required parameters, or alternatively via manual input  130  (e.g. keyboard input, parameter by parameter). A set of laser beam parameters is stored as a profile in DB  167 , within computer  140 . Examples of laser beam parameters include but are not limited to laser wavelength, laser pulse energy, pulse width, repetition rate and spot size. In one example, values of trivial parameters such as laser pulse energy and repetition rate are not saved in DB  167 . Profiles that differ only in “trivial fields” are considered identical. “Trivial parameters” are used in speed scaling in the tool path calculation and do not impact the drilling capability of the system. Discarding “trivial parameters” as described in this example enhances the manageability of DB  167  and offers ease of use.  
         [0047]    Step  330 : Selecting laser beam parameter profile. In this step, the system operator selects a laser beam profile from the list of established profiles stored in a database. In one example, user interface  180  displays the profiles stored in DB  167 , within computer  140 . Then the system operator selects the desired laser beam profile via user interface  180 . Trivial parameters such as laser pulse energy and repetition rate also can be modified at this step. The data from the selected profile is held in memory for use in the algorithms used in step  240 . Method  300  ends by returning to step  220  in method  200 .  
         [0048]    Step  220 : Inputting workpiece material parameters. In this step, the system operator inputs the workpiece material characteristics. It is important to consider the physical characteristics of the workpiece with regard to ablation and laser drilling system performance. For example, it may be important to consider that a stainless steel foil workpiece reflects much of a specific type of laser&#39;s energy. User interface  180  displays all the stored material profiles from DB  167  and highlights those that are known to be compatible to the laser parameter profile selected in step  210 . The system operator selects an existing workpiece material, profile that has already been defined and stored in a computer or other file storage media, or alternatively creates a new workpiece material profile and stores the profile for future use. The process of inputting workpiece material characteristics is detailed in method  400  in FIG. 4A, wherein a method  400  of inputting workpiece material characteristics for use in a laser drilling system includes several steps.  
         [0049]    Step  405 : Displaying known workpiece materials. In this step, a database operation searches the database to determine the list of material parameter profiles stored in DB  167 . In one example, workpiece materials compatible with the laser parameter profiles selected in step  210  are highlighted by software  165  in user interface  180  to ease selection by the system operator. In this example, the pre-defined workpiece material profiles, including known incompatible profiles, are displayed to the system operator via user interface  180 , which retrieves profile data stored in DB  167  within computer  140 . This step eases the process of selecting a proper material profile because the highlighted profiles are only a subset of all the material profiles stored in DB  167 . This step also helps to avoid the system operator accidentally inputting a known incompatible material. In another example, the system operator selects an incompatible material profile for testing purposes.  
         [0050]    Step  410 : Is a known workpiece material selected? In this decision step, the system operator determines if the workpiece material characteristics have already been defined as a profile and saved. In one example, the system operator selects a workpiece material profile known to be compatible with the laser parameter profiles defined in step  210 . In another example, the system operator selects a new workpiece material profile that does not have a workpiece material profile stored in DB  167 . If a known workpiece material characteristics is selected, method  400  proceeds to step  430 , if the workpiece material characteristics have not been defined, method  400  proceeds to step  420 . Table 2 of FIG. 4B shows an example of a table structure and exemplary data stored to define laser parameter profiles. Each row in Table 2 represents a specific workpiece material profile to be drilled with a laser drilling system, and contains the critical measurements of the workpiece for each of the workpiece geometries in the table. In this example, software  165  selects a stored workpiece material profile from DB  167 , and user interface  180  displays the stored workpiece material profiles to the system operator. Once the system operator reviews the stored workpiece material profiles, if the stored workpiece material profile is displayed in user interface  180 , method  400  proceeds to step  430 , if the workpiece material profile is not displayed (and therefore has not been defined), the system operator can enter a new material profile and method  400  proceeds to step  420 .  
         [0051]    Step  420 : Inputting required material characteristics. In this step, the system operator inputs workpiece material characteristics. In one example, the system operator inputs workpiece material characteristics via user interface  180  by importing specification file  110 , or alternatively via manual input  130 . A set of material characteristics is stored as a profile in DB  167  within computer  140 .  
         [0052]    Step  430 : Selecting workpiece material characteristics from list. In this step, the system operator selects workpiece material characteristics from a list of established workpiece materials from a database. In one example, user interface  180  displays the profiles stored in DB  167 , within computer  140 . Then the system operator selects the desired workpiece material profile via user interface  180 . In another example, the system operator chooses an un-highlighted, incompatible material profile via user interface  180  for further experimentation and user interface  180  displays a warning message before accepting the incompatible material profile. The data from the selected profile is held in memory for use in the algorithms used in step  240 . Method  400  ends by returning to step  230  in method  200 .  
         [0053]    Step  230 : Inputting workpiece geometry parameters. In this step, the system operator inputs the workpiece geometry parameters. The required workpiece geometry represents the desired shape of the finished product, and provides the information needed to define the tool path in step  240 . The system operator selects either an existing workpiece geometry profile that has been defined and stored in a computer or other file storage media, or creates a new workpiece geometry profile and stores the profile for future use. Predefined workpiece geometry profiles are associated with a specific milling (and if necessary, correction) algorithm, and this information is stored within a computer or other file storage media. The process of inputting workpiece geometry parameters is detailed in method  500  in FIG. 5A, wherein a method  500  of inputting workpiece geometry into a computer system includes several steps.  
         [0054]    Step  510 : Is workpiece geometry established? In this decision step, the system operator determines if the workpiece geometry has already been defined as a profile and saved. In one example, the pre-defined workpiece geometry profiles are presented to the system operator through user interface  180 , which presents profile data stored in DB  167  within computer  140 . If the workpiece geometry profile has been pre-defined, method  500  proceeds to step  525 ; if not, method  500  proceeds to step  520 .  
         [0055]    In one example, Table 3 of FIG. 5B provides an example of workpiece geometry data stored in DB  167 . The tables shown throughout this disclosure are simplified examples, to increase understanding of how method  200  is implemented, using a database such as DB  167 . Table 3 shows an example of a table structure and exemplary data stored to define workpiece geometry profiles. Each row in Table 3 represents a specific workpiece geometry profile to be drilled with a laser drilling system and contains the critical measurements for each of the workpiece geometries in the table.  
         [0056]    In this example, software  165  selects the stored workpiece geometry profiles from DB  167 , and user interface  180  displays the stored workpiece geometry profiles to the system operator. The system operator reviews the stored workpiece geometry profiles. If the stored workpiece geometry profile is displayed in user interface  180 , method  500  proceeds to step  525 ; if the workpiece geometry profile is not displayed (and therefore has not been defined), method  500  proceeds to step  520 .  
         [0057]    Step  520 : Inputting workpiece geometry profile. In this step, the system operator inputs the workpiece geometry. In one example, the system operator inputs the workpiece geometry through user interface  180  by importing a specification file  110 , (e.g., CAD file or database table) or, alternatively, the operator inputs workpiece geometry via manual input  130 . The input, whether it is a specification file  110  or a manual input  130 , must contain the minimally required data fields (e.g., Table 3).  
         [0058]    Step  525 : Does selected workpiece geometry have associated algorithm? In this step, the software determines whether an algorithm exists to execute the milling of the selected workpiece geometry. In one example, software  165  validates that an existing algorithm exists within DB  167  in computer  140 . If a matching algorithm exists for the selected workpiece geometry, method  500  proceeds to step  530 . If no algorithm exists within DB  167  that can execute the desired geometry, method  500  (and method  200 ) ends. Without an algorithm and the proper association between geometry and algorithm, milling cannot be conducted. In one example, user interface  180  queries the system operator to select from a list of existing algorithms (e.g., for a conical, cylindrical, or other shape).  
         [0059]    Step  530 : Selecting workpiece geometry. In this step, the system operator selects a workpiece geometry from the list of established geometries stored in a database. In one example, user interface  180  displays the profiles stored in DB  167  within computer  140 . Then the system operator selects the desired workpiece geometry profile through user interface  180 . The data from the selected profile is held in memory for use in algorithms in step  240 .  
         [0060]    Step  535 : Is selected workpiece geometry compatible with the selected material parameters? In this step, the software determines whether the required geometry is compatible with the material parameters provided in step  220 . In one example, software  165  compares the workpiece geometry with the material profile. If there is no compatibility issue, method  500  proceeds to step  536 . If the geometry is incompatible, method  500  (and method  200 ) ends. In this example, if the drilling depth is deeper that the material thickness, milling cannot be conducted to achieve the desired geometry and method  500  (and method  200 ) ends.  
         [0061]    Step  536 : Is selected workpiece geometry compatible with the laser beam size? In this step, the software determines whether the required geometry is compatible with the laser beam size specified in step  210 . In one example, software  165  compares the smallest hole diameter with the laser beam size. If the laser beam size is larger than the smallest hole diameter, method  500  (and method  200 ) ends. Milling cannot be conducted to achieve smaller diameter than the laser beam size. Otherwise, method  500  ends by returning to step  240  in method  200 .  
         [0062]    Steps  210 ,  220 , and  230  facilitate the reconfiguration of a laser drilling system and allow the addition of new laser drilling profiles to enable mass manufacturing a variety of laser-drilled products.  
         [0063]    Step  240 : Is exact combination of input parameters known? In this decision step, a software program, written in any of a variety of programming languages, such as C/C++, Java, FORTRAN, or COBOL, is used to determines whether the combination of workpiece geometry, laser parameters and workpiece characteristics, as input in steps  210 ,  220  and  230  above has already been stored as an existing profile. In one example, software  165  in computer  140  compares the combination of inputs from steps  210 ,  220 , and  230 , against existing combinations in DB  167 . If the specific combination of inputs (workpiece geometry, laser parameters, and workpiece characteristics) exists, method  200  proceeds to step  245 . Otherwise, method  200  proceeds to step  260 .  
         [0064]    Step  245 : Is input combination known to be incompatible? In this decision step, software  165  compares the known combination of workpiece geometry, laser parameters and workpiece characteristics input in steps  210 ,  220  and  230  above against known combinations that are not compatible in a laser drilling system (e.g. a laser energy that is incompatible with a specific workpiece material). This is a safeguard step to complement the incompatibility checking procedures in steps  210 ,  220  and  230 . Previously used parameter combinations are stored in DB  167  as part of operation log. If the specific profile is known to be incompatible based on information from previous laser drilling attempts, method  200  ends. Otherwise, method  200  proceeds to step  250 . An example of how laser system parameter combination information is stored in a. DB  167  is shown in Table 4 of FIG. 5C.  
         [0065]    Table 4 shows an example of a table structure and exemplary data stored to define known combinations of input parameters and feedback in a laser drilling system. In a first example illustrated using the data in Table 4, the system operator selects a combination (shown as “combination_id”=3) of workpiece geometry (shown as “wp_geometry_id”=1), laser beam (shown as “laser_beam_id”=2) and workpiece material (shown as “wp_material_id”=1). Because this combination has been previously determined to be incompatible with laser drilling system  100  (e.g., “compatible”=NO), method  200  ends. In another example, where the operator selects a combination (shown as “combination_id”=1) of workpiece geometry (shown as “wp_geometry_id”=1), laser beam (shown as “laser_beam_id”=1) and workpiece material (shown as “wp_material_id”=1) that has previously been determined to be compatible with laser drilling system  100  (e.g., “compatible”=YES or NULL), method  200  proceeds to step  250 .  
         [0066]    Step  245  prevents repetition of previously failed laser drilling system parameter combinations in future drilling runs. Before the cause of the incompatibility is understood and the understanding is incorporated into steps  210 ,  220  and  230  to stop the drilling procedure, this is the last screening step for possible failure.  
         [0067]    Step  250 : Extracting input parameters from database. In this step, a computer system extracts the selected input parameters from the database where they are stored. In one example, software  165  extracts the selected input parameters from database  167  associated with the profile as identified in step  240 . Method  200  proceeds to step  270 .  
         [0068]    Step  260 : Creating and storing new parameter profile in database. In this step, software  165  stores the new parameter profile in a database for future use. In one example, software  165  stores the new parameter profile using the workpiece geometry, laser parameters and workpiece characteristics that were input in steps  210 ,  220 , and  230  above in DB  167 .  
         [0069]    Step  270 : Executing tool path algorithm using new parameters. In this step, software combines the laser drilling parameters input by the system operator and calculates the tool path required to create the workpiece geometry. In one example, software  165  directs algorithms  160  to calculate laser drilling data set using the workpiece geometry, laser parameters and workpiece characteristics values input in steps  210 ,  220 , and  230  above. In another example, this step is done after each combination of profiles is created (e.g., between steps  240  and  260  and the drilling data set is stored in DB  167 , the profile and complete drilling data set is used again without recalculation in future laser drilling sessions.  
         [0070]    Step  280 : Exporting laser drilling data set to laser system elements. In this step, the laser drilling data set is exported to direct laser system elements to execute the desired pattern in a workpiece (not shown). In one example, a digital data set is converted to analog signal within computer  140  by D/A adaptor  170  and appropriate voltages are sent to laser system elements  190 . In another example, a digital data set is sent directly to laser system elements  190  containing their own D/A adaptor. The laser drilling data set may be sent to more than one element of laser system elements  190 , and the laser drilling data set is used to drill the desired workpiece geometry in the workpiece as specified in step  210 . An example of an exported laser drilling data set is shown in Table 5 of FIG. 5D.  
         [0071]    Table 5 shows an example of a table structure and exemplary laser drilling data set sent to laser system elements  190  as a result of the input of workpiece geometry, laser parameters, and workpiece material. Table 5 contains the following fields: drilling_point_id, X_coordinate, Y_coordinate, and Z_coordinate. Each row in Table 5 represents one point to be drilled with a laser drilling system. To drill the entire workpiece geometry, many points (rows from Table 5) are drilled in a workpiece. The result of executing the laser drilling data set containing the drilled points is the finished workpiece geometry.  
         [0072]    Step  290 : Milling defined shape in workpiece. In this step, laser system elements  190  implement the laser drilling data set exported in step  280  to mill the pre-defined shape in the workpiece using the laser drilling system. In one example, to create a cone-shaped hole in the workpiece, the laser drilling data set directs the tool path to remove material layer by layer, where one layer of material in the workpiece is ablated, then the shape is updated to the shape for the next layer to meet the aspect ratio of the desired workpiece geometry. In another more specific example, drilling a tapered, conical ink jet nozzle hole in a stainless steel foil using a picosecond laser, the first layer drilled is a 1 micron deep disk with 80 micron diameter, the next layer drilled is another 1 micron deep disk with the same center point but with a 78.5 micron diameter.  
         [0073]    Step  295 : Data logging and inputting feedback. In this step, the system operator assesses the final product with respect to the desired workpiece specifications, and enters feedback into a computer along with date, time and laser drilling parameters specified in step  210 ,  220  and  230 , to be stored in a database. In one example, a system operator enters feedback via user interface  180  and feedback is stored in DB  167 , within computer  140 . If the combination of inputs is deemed incompatible (e.g. the specific combination of workpiece geometry X with laser parameters Y, and workpiece materials Z does not result in a product that meets specifications), this incompatibility information is stored as part of the operation log. In one example, the incompatibility is saved and referenced in step  245  during future laser drilling, preventing a laser system operator from using this combination of parameters and repeating this mistake in future laser drilling sessions. The incompatibility is investigated in depth later and the source of incompatibility is identified and incorporated into DB  167  for future use and reference in step  210 ,  220  and  230  to stop repetition of the failing attempt.  
         [0074]    A nozzle plate of an ink-jet head may be constructed with the laser drilling system of the present invention as further detailed below.  
         [0075]    As shown in FIG. 6, an ink-jet printer  600  has an ink-jet head  602  capable of recording on a recording medium  604  via a pressure generator. Ink droplets emitted from the ink-jet head  602  are deposited on the recording medium  604 , such as a sheet of copy paper, so that recording can be performed on the recording medium  604 .  
         [0076]    The ink-jet head  602  is mounted on a carriage  606  capable of reciprocating movement along a carriage shaft  608 . More specifically, the ink-jet head  602  is structured such that it can reciprocate in a primary scanning direction X in parallel with the carriage shaft  608 .  
         [0077]    The recording medium  604  is timely conveyed by rollers  610  in a secondary scanning direction Y.  
         [0078]    The ink-jet head  602  and the recording medium  604  are relatively moved by the rollers  610 .  
         [0079]    Referring to FIG. 7, a pressure generator  700  is preferably a piezoelectric system, a thermal system, and/or equivalent system. In this embodiment, the pressure generator  700  corresponds to a piezoelectric system which comprises an upper electrode  702 , a piezoelectric element  704 , and an under electrode  706 .  
         [0080]    A nozzle plate  708  comprises a nozzle substrate  710  and a water repellent layer  712 . The nozzle substrate  710  is made of metal, resin, and/or equivalent material. The water repellant layer  712  is made, for example, of fluororesin or silicone resin. In this embodiment, the nozzle substrate  710  is made of stainless steel and has a thickness of  50  um, and the water repellent layer  712  is made of a fluororesin and has a thickness of 0.1 um.  
         [0081]    The ink-jet ink is filled in an ink supplying passage  714 , a pressure chamber  716 , an ink passage  718 , and a nozzle  720 .  
         [0082]    Ink droplets are ejected from the nozzle  720  as the pressure generator  700  pushes the pressure chamber element  720 .  
         [0083]    As a result of the present invention, very good nozzles are formed without flash and foreign matter (carbon etc) in the nozzle plate. Further, the accuracy of the nozzle outlet diameter is 20 um±1.5 um.  
         [0084]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.