AU2002327193A1

AU2002327193A1 - Method of ablating an opening in a hard, non-metallic substrate

Info

Publication number: AU2002327193A1
Application number: AU2002327193A
Authority: AU
Inventors: Cec Archibald; Mike Cummings; Ruiz Glover
Original assignee: Virtek Laser Systems Inc
Current assignee: Virtek Laser Systems Inc
Priority date: 2001-07-02
Filing date: 2002-07-02
Publication date: 2003-05-22
Anticipated expiration: 2022-07-02

Description

METHOD OF ABLATING AN OPENING IN

A HARD. NON-METALLIC SUBSTRATE

BACKGROUND OF THE INVENTION

The present invention relates generally to a method of ablating a hole in a hard,

non-metallic substrate, particularly including glass and ceramics. More specifically, the

subject invention relates to ablating a hole in a hard, non-metallic substrate using at

least one laser.

Drilling or ablating a hole into a hard, non-metallic substrate, such as, for

example, glass, has proven to be difficult and impractical in a production environment.

Prior art efforts to drill holes in a hard, non-metallic substrate have utilized diamond

tipped drill bits. In order to drill a hole entirely through a hard, non-metallic substrate

24 without causing the edge around the hole to chip, the hole must be drilled, generally,

simultaneously from two sides of the substrate. Therefore, two drill bits must be

aligned precisely along the same drilling axis. Absent a precise alignment, the hole will

not be properly formed, and the substrate could be irreparably damaged.

A further difficulty of using opposing drill bits on two sides of the substrate is

the probability of damaging the drill bits should contact be made between the two drill

bits while drilling the hole. Generally, one drill will be withdrawn from the hole prior

to the other drill being engaged with this substrate. However, due to production

variability and the small distance between the opposing drill bits, a high probability

exists that the drill bits will make contact and the article being drilled is generally destroyed. If the drill bits become damaged, new drill bits must be installed, which is

known to take several hours.

A still further drawback of using drill bits to form a hole in a hard, non-metallic

substrate is the inability to form holes having various shapes. It is desirable in many

industrial applications to form a hole in a hard, non-metallic substrate that has a shape

other than circular, such as, for example, oval, square or other polygonal shape. Given

the operational limitations of a diamond tipped drill bit, only circular holes may be

drilled in a substrate.

Many glass products require holes that are presently formed by diamond tipped

drill bits. These include patio furniture, tempered automotive glass, glass, mirrored

electrical and outlet covers. Eye glass lenses are shaped with diamond tipped drill bits.

Even glass shower doors require notches to provide space to attach hinges. Forming

some of these holes is known to take upwards of 45 minutes. Further, patio furniture

does not always present a smooth surface to initiate drilling, which has resulted in

production problems.

Lasers have been introduced to cut and etch glass substrates recently to

overcome the problems associated with diamond tipped drill bits, but with limited

success. United States Patent No. 6,204,472 discloses a method of cutting a hollow

glass article using a CO₂ laser. The laser forms an incision channel in the glass

substrate by vaporizing the glass. However, the depth of the channel is limited and a

secondary operation is necessary to separate the hollow glass article at the channel.

More specifically, the glass is heated with burners and separated with a percussion tool. United States Patent No. 5,902,368 discloses severing thin-walled glass

substrates using a CO₂ laser to heat a particular area of the glass substrate forming a

severance point. The glass substrate is then stretched and separated at the heated

separation point. However, because the focal point of the laser is not adjustable relative

to the glass substrate, the thickness of the glass substrate can be no more than about 0.2

mm.

United States Patent No. 4,441,008 discloses a method of drilling an ultrafine

hole through a glass substrate. A CO₂ laser is used to drill a hole by establishing a stationary focal point of the laser 0.02 to 0.08 inches below one surface of the glass.

The laser is pulsed three to five times to form the hole in the glass substrate. In order to prevent cracking of the glass substrate, the glass substrate is heated to a temperature

of between 500° and 1,040°F prior to activating the laser.

None of the prior art discussed above discloses a method of drilling holes in glass substrates that is practical and cost efficient in a production environment. The

underlying drawback of each of these laser devices is the inability to change the focal point of the laser relative to the glass substrate. Therefore, additional steps are

necessarily added to the process in order to prevent the substrate from being damaged

by the laser. Accordingly, it would be desirable to provide a laser device and ablating

method that would enable ablating a hole into a hard, non-metallic substrate by moving

the focal point of the laser relative to the depth of the substrate. SUMMARY OF THE INVENTION AND ADVANTAGES

A method of ablating a hole in a hard, non-metallic substrate, particularly

including, but not limited to glass and metallic substrates, with a laser is disclosed. At

least one laser assembly is provided that is capable of generating a laser beam having a movable focus. The focus is movable relative to the hard, non-metallic substrate

along a length, width and depth of the substrate. The laser is activated generating the

laser beam. The laser is focused to provide a focus of the laser beam adjacent at least

one surface of the hard, non-metallic substrate. A first layer of the substrate is ablated

in a configured pattern from at least one surface of the hard, non-metallic substrate. The

focus is moved relative to an axis corresponding to the depth of the substrate to enable

ablation of successive layers of the substrate. Successive layers of the substrate are

ablated by successively moving the focus deeper into the substrate to generate a hole

into the substrate.

The present method of ablating a hole in a hard, non-metallic substrate solves

the problems associated with the prior art methods by providing the step of moving the

focus of the laser relative to the depth of the substrate. Further prior art methods of ablating glass substrates do not include a focus movable relative to the depth of the

substrate. Therefore, an additional step is required to prevent damaging the substrate.

While the reasons why the method set forth above results in successfully

ablating a hole into a hard, non-metallic substrate is not fully understood, one theory is

based upon adjusting the focus of the laser incrementally deeper into the substrate. By

refocusing the laser to establish a focus incrementally deeper into the substrate,

successive layers of the substrate can be ablated in order to prevent damaging the substrate with the laser beam. Further, configured patterns may be ablated into the

substrate by moving the focus along the length and width of the substrate as well as the

depth. Therefore, predetermined configurations of holes may be ablated into the

substrate, which is not possible unless the focus is movable relative to the depth, width

and length of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated as the

same becomes better understood by reference to the following detailed description when

considered in connection with the accompanying drawings wherein:

Figure 1 is a schematic of the laser apparatus of the subject invention;

Figure 2 is top view of various shaped holes ablated into a hard, non-metallic

substrate;

Figure 2A is sectional view of holes ablated into the hard, non-metallic substrate

though line 2B-2B of Figure 2A;

Figure 3 A is an illustrative view of the inventive laser ablating process; and

Figure 3B is a partial sectional view of a wall defining the hole in the hard non-

metallic substrate; and

Figure 4 is a top view of the preferred embodiment of laser drilling apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figure 1, a schematic view of the laser ablating apparatus used for

the method of the present invention is generally shown at 10. A first CO₂ laser 12 and a second CO₂ laser 14 each generate a laser beam 16a, 16b preferably having a

wavelength of generally lO.όjiim capable of ablating a hard, non-metallic substrate 24,

particularly including glass and ceramics. The laser beam 16a, 16b is directed through

a first set of optics 18 A, 18B and into a galvanometer 20a, 20b. Each galvanometer

20a, 20b refocuses the laser beam 16a, 16b through a z axis lens 22a, 22b and redirects

the laser beam 16a, 16b toward opposing sides of the hard, non-metallic substrate 24.

Therefore, the substrate 24 is ablated on opposite sides. Alternatively, a single laser

may be used for ablating a single side of the substrate 24.

Each laser 12, 14 and each galvanometer 20a, 20b is directed by a controller 25

in order to coordinate ablating of the substrate 24 as will be explained further below.

Preferably, the hard, non-metallic substrate 24 is supported by a gantry 26 or equivalent support device. A cooling apparatus 28A, 28B positioned on each side of the substrate

24 directs a coolant 30 onto the substrate 24 adjacent the area of the substrate 24 being

ablated by the laser beam 16a, 16b. The coolant 30 may be liquid or gaseous and

dissipates the heat generated by the laser to prevent the substrate 24 from cracking.

Water has proven to be the most effective coolant to dissipate heat generated by the

laser. An additional advantage to using water as a coolant is the water's filtering

characteristics. Unlike a gaseous coolant, water absorbs gaseous by-products resulting from the ablating process. The by-products absorbed by the water may be filtered for

waste removal or the water may be disposed of in an environmentally sound manner if

necessary.

Each laser 12, 14 preferably generates a wavelength of about 10.6μm and is

operated at between 75 and 150 watts. More preferably, each laser 12, 14 generates an output of about 100 watts. However, the desired energy level is optimized according

to the substrate 24 being ablated. 100 kw has proven to be most effective to ablate

several types of glass. It is believed that that tempered glass may require slightly more

energy (and density) than regular glass. An energy level should be chosen that is known

to be absorbed by the glass (or other clear substrate) in order to transfer the energy from

the laser beam to the glass. Otherwise, the laser beam will travel through the glass. A

suitable water-cooled CO₂ laser for the method of this invention is a Model No.

LC100NV of DEOS, Maria ElectroOptics Systems, Inc. of Bloomfield, Connecticut, now a division of Coherent. An air-cooled or equivalent laser is also suitable to practice

the method of this invention. The CO₂ laser 12, 14 is preferred to practice the method

of this invention because a laser beam is generated that includes the energy level and

wavelength that is absorbed by hard, non-metallic substrates 24, such as, for example

glass and ceramics, and tempered glass. Other types of lasers generate laser beams having different wavelengths and power outputs are known to transmit through glass

thereby preventing the ablation of a glass substrate 24.

In order to ablate the hard, non-metallic substrate 24, a galvanometer capable

of generating a laser focus moveable in the x, y and z axes is preferable where x and y correspond to the length and width of the substrate 24 and z corresponds to the depth.

A suitable galvanometer capable of moving the focus in this manner is available from

SCAN Lab AG of Puchhein, Germany, Model "Hurry SCAN" with a "Vario SCAN" built in as part of the galvanometer system to provide movement along the z axis. The

thickness of the substrate 24 that may be ablated is determined by the extent of

movement along the z axes of the focus of the laser. Presently, galvanometers capable of moving the focus along the z axes are able to move the focus a distance of about 1.6

cm. Therefore, the thickness of the hard, non-metallic substrate 24, which is sufficient

for many applications, being ablated can presently be no more than about 3.2 cm, absent

moving the glass relative to the lasers 12, 14. Until galvanometer technology capable

of moving the focus along the z axis becomes more adaptable, it is necessary to move

the hard, non-metallic substrate 24 in the z axis in order to ablate a depth of more than

about 3.2 cm.

As shown in Figures 2A and 2B, a galvanometer capable of moving a focus of the laser along the x, y and z axes can ablate an opening into the hard, non-metallic

substrate 24 having various configurations. As stated above, the x and y axes are

correlated to the length and width of the substrate 24, and the z axis is correlated to the

depth of a substrate 24. In order to prevent damaging the substrate 24, the depth of the focus in the z direction is continuously increased as layers of the substrate 24 are

ablated. Figure 2B shows a typical scenario where up to 10 passes of the laser are made

to ablate successive layers of the substrate 24 in order to form a hole into one side of

the substrate 24. A circular hole 32 is shown having a width of about 4.0 cm. It is

believed that holes having a diameter of up to 8 cm can be ablated into the substrate 24

with presently available galvanometer 20a, 20b technology. In order to ablate holes

having a greater diameter, the substrate 24 may be moved relative to the galvanometers.

A square hole 34 is formed in the same manner as the circular hole 32. Preferably, the

corners of any square or polygonal hole formed in the substrate 24 will have radiused corners in order to prevent stress points being formed in the substrate 24. Also shown in Figure 2 is an oval hole 36 having tight radiuses in order to prevent forming stress

points in the substrate 24.

As shown in Figure 2, each successive pass of the laser is preferably moved at

a greater depth into the substrate than the prior pass. A slightly concave surface 38 is

formed along a wall of the various holes 32, 34, 36 into the substrate 24. For the

purpose of this application, a hole may be defined as any aperture either partially or

entirely through the substrate 24, a generally three-sided notch on the edge of the

substrate 24, an etching partially into the substrate 24, and any groove ablated into the

substrate 24. In order to ablate large diameter openings in the substrate 26, the laser is moved about the circumference of the hole 32, 34, 36 along each pass. Because the

laser beam 16a, 16b is generated at the z axis, which is central to the hole 32, 34, 36,

the larger the diameter of the hole, yields a greater radius of a convex wall 38. As

should be understood by those of skill in the art, by ablating the circumference of a

desired hole a "plug" of substrate 24 remains inside the hole. When the laser beam 16a,

16b passes completely through the substrate 26, the coolant 30, through impingement,

forces the "plug" from the hole 32, 34, 36.

Referring to Figure 3A, a schematic of a hole 37 ablated entirely through the

hard, non-metallic substrate 26 is shown. The hole 37 is ablated from opposing sides

of the substrate 26. The laser beam 16a, 16b travels around the circumference of the

hole as directed by the controller 25 (Figure 1). The controller 25 also adjusts the galvanometers 20a, 20b to align the laser beams 16a, 16b along a common z axis.

Therefore, the laser beam 16a generated by the first laser 12 points through the z axis

optics 22a directly opposite the laser beam 16b generated by the second laser 14 through the z axis optics 22b. Therefore, if each laser were to continuously operate until a hole

37 is ablated completely through the substrate 24, the z axis optics 22a, 22b would be

damaged by the opposing laser beam 16b, 16a. Therefore, it is preferable that one laser

beam 16a, 16b ablates a depth greater than the other laser beam 16b, 16a by making

additional passes. A shutter 40a, 40b (Figure 1) closes over the z axis optics 22a, 22b

on the laser that terminates emission first in order to prevent the opposing laser from

damaging its z axis optics 22a, 22b.

As represented in Figure 3A, the first laser beam 16a completes the four passes

along the circumference of the hole 37 after which, the shutter 40 closes. Either

concurrently or subsequently to the four passes made by the first laser beam 16a, the

second laser beam 16b makes six passes along the circumference of the hole 37 until the hole 37 is ablated completely through the substrate 24. Any number of passes may

be completed by each of the laser beams 16a, 16b in order to ablate the hole 37

completely through the substrate 24 as long as one laser beam 16a, 16b terminates

emission prior to the other laser beams 16b, 16a in order to prevent damage to the z axis optics 22a, 22b. In other words, one laser beam preferably ablates up to about 51% of

the depth of the substrate 24 while the other laser beam ablates only about 49% of the

depth of the substrate 24.

By ablating a hole into a hard, non-metallic substrate 24 from opposing sides of

the substrate 24, a variety of benefits are derived that are not realized by ablating only

one side of the substrate 24. For example, it should be understood by those of skill in

the art, sharp edges formed in a hard, non-metallic substrate 24, such as, for example glass, causes stress points in the glass which could result in cracking. Therefore, it is preferable to ablate the substrate 24 from opposing sides of the substrate 24. During the

first pass made by each laser beam 16a, 16b a groove is formed in the surface of the

substrate 24 initiating a smooth and rounded edge circumscribing the hole 37 being

formed in the substrate 24. Therefore, the final pass required to ablate completely

through the substrate 24 is made generally mid way through the substrate 24. The final

pass of the laser beam that ablates through the substrate 24 leaves a rough inconsistent

surface as shown in Figure 3B. It is believed that this rough inconsistent surface will

not adversely affect the stability of the hard, non-metallic substrate 24 because it is not

located at an edge of the substrate 24. In order to ablate a smooth hole into the substrate 24, the parameters of the lasers 12, 14 are predetermined by the controller 23. The parameters of each laser 12,

14 are preprogrammed into the controller 23 according to the type of hole being ablated

into the substrate 24 and the type of hard, non-metallic substrate 24 being ablated.

Different types of substrates 24 require different laser 12, 14 settings in order to prevent

cracking or otherwise damaging the substrate 24. The most important laser parameters

pre-programmed into the controller 23 are the laser power, the galvanometer speed, the

laser frequency (pulse rate), and the pulse with modulation of the laser. Each of these

parameters are tuned in to generate a power density adjacent the surface of the substrate 24 of generally between 40 and 50 kw/cm . More preferably, a power density of

generally 45 kw/cm² is generated. Power densities in this range are believed to be

significantly higher than power densities generated in the prior art references cited in

the Background section of this application. Although not fully understood, it is believed that the high power density of the laser beam in combination with a focus moveable along the z axis of the substrate 24 may play a role in the successful ablation of the

substrate 24 absent additional steps such as, for example heating the substrate 24 to a

high temperature.

Figure 4 shows a possible production configuration of the inventive method.

A first robot arm 42 grasps the substrate 24 and positions the substrate 24 between the

lasers 12, 14 into a gantry 44 or equivalent fixture. Alternatively, robot arm 42 may

include a gripper (not shown) for supporting the substrate 24 during processing. The

controller 23 is signaled that the substrate 24 is in position to be ablated by a sensor (not

shown). The controller 23 then signals the lasers 12, 14 to begin the ablating operation.

Additionally, the controller 23 signals the lasers 12, 14 with the substrate 24 type,

power settings, galvanometer speed, hole size, hole shape, hole location, depth of

penetration, focus adjustments, and glass thickness each correlating to the type of substrate 24 and a type of hole being drilled in the substrate 24.

The controller signals the galvanometers 20a, 20b to control the focus of the

laser along the x, y and z axes. As stated above, the x and y axes correlating to the

length and width of the substrate 24, and the z axis correlates to the depth of the

substrate 24. Further, several holes can be ablated into the substrate 24 at different

locations of the substrate 24 relative to the galvanometers 20a, 20b by moving the

substrate 24 relative to the lasers 12, 14. The substrate 24 may also be moved along the

z axis if the thickness of the substrate 24 is greater than about 3.2 cm. All the

movements of the substrate 24 are also directed by the controller 23 according to the pre-programming sequence. It may be desirable to ablate a hole only partially through the substrate 24 in

order to etch the substrate 24 with a figure. Therefore, the controller is also

programmable with graphics information enabling the lasers 12, 14 to ablate figures,

such as designs, digits, letters, and bar codes into the substrate 24. Figures may be

etched into the substrate 24 by activating either both 12, 14 or one 12 of the lasers. By

activating both of the lasers 12, 14, a three-dimensional figure may be etched into the

substrate 24.

The invention has been described in an illustrative manner, and it is to be

understood that the terminology which has been used is intended to be in the nature of

words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are

possible in light of the above teachings. It is, therefore, to be understood that within the

scope of the appended claims, wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as

specifically described.

Claims

CLAIMSWhat is claimed is:

1. A method of ablating a hole into a hard, non-metallic substrate including the steps of:

providing at least one laser assembly capable of generating a laser beam in an

axis having a focus wherein said focus is moveable relative to said axis;

activating said at least one laser thereby generating said laser beam;

focusing said focus of said laser beam adjacent at least one surface of the hard,

non-metallic substrate;

ablating a first layer of the hard, non-metallic substrate from at least one surface

of the hard, non-metallic substrate; moving said focus relative to an axis corresponding to the depth of the hard,

non-metallic substrate thereby enabling ablation of successive layers of the substrate; and

ablating successive layers of the hard, non-metallic substrate thereby generating

a hole into said substrate.

2. A method as set forth in claim 1 further including the step of cooling the

hard, non-metallic substrate adjacent the hole being ablated by said laser beam thereby

preventing said substrate from cracking.

3. A method as set forth in claim 2 wherein said step of cooling the hard,

non-metallic substrate adjacent the hole being ablated is further defined by flushing

said the at least one surface with liquid.

4. A method as set forth in claim 2 wherein said step of cooling the hard, non-metallic substrate adjacent the hole being ablated is further defined by flushing said

the at least one surface with water.

5. A method as set forth in claim 1 further including the step of moving

said focus relative the axes generally corresponding to the length and width of said hard,

non-metallic substrate thereby ablating the hole through the substrate having a

predetermined configuration.

6. A method as set forth in claim 5 wherein said laser beam is moveable

relative to said length and width of said hard non-metallic substrate thereby generating

a hole having a polygonal shape.

7. A method as set forth in claim 5 wherein said laser beam is moveable

a hole having a circular shape.

8. A method as set forth in claim 5 wherein said laser beam is moveable

a hole having an oval shape.

9. A method as set forth in claim 1, wherein said step of providing at least

one laser assembly is further defined by providing a second laser assembly being

capable of generating a second laser beam coincident with said first laser beam.

10. A method as set forth in claim 9 further including the step of focusing

said laser beam generated from each of said lasers on opposing sides of said hard non-

metallic substrate generally along the axis corresponding to the depth of the hard non-

metallic substrate thereby ablating a hole through said hard, non-metallic substrate from

opposing sides of said substrate.

11. A method as set forth in claim 10 further including the step of cooling

the opposing sides of said hard, non-metallic substrate adjacent the hole being ablated

by said laser beam thereby preventing said substrate from cracking.

12. A method as set forth in claim 11 wherein said step of cooling the hard,

non-metallic substrate adjacent the hole being ablated is further defined by flushing said

the at least one surface with liquid.

13. A method as set forth in claim 11 wherein said step of cooling the hard,

the at least one surface with water.

14. A method as set forth in claim 9 wherein said step of abating a hole

through said hard, non-metallic substrate from opposing sides of said hard non-metallic

substrate is further defined by one of said laser beams ablating more successive layers of said hard non-metallic substrate than the other of said laser beams.

15. A method of ablating a hole into a hard, non-metallic workpiece

including the steps of:

generating a laser beam onto the hard, non-metallic workpiece having

^' a focus adjacent a surface of the workpiece;

changing said focus of said laser beam generally along an axis of said

laser beam to a first predetermined depth;

changing said focus of said laser beam generally along said axis to a

second predetermined depth to ablate said hard, non-metallic workpiece to a second predetermined depth; and

continuing to change said focus of said laser beam to successive depths

to ablate a hole into the hard, non-metallic workpiece.

16. A method as set forth in claim 15 further including the step of moving

said laser beam along a length and width of the hard, non- metallic workpiece in a

predetermined pattern between each change of said focus relative to the depth of the

workpiece thereby ablating a hole in the workpiece having the shape of said predetermined pattern.

17. A method as set forth in claim 15 wherein said step of generating a laser

beam onto a hard non-metallic workpiece is further defined by generating a laser beam

onto opposing sides of said hard, non-metallic workpiece.

18. A method as set forth in claim 17 wherein said step of generating a laser

beam onto opposing sides of the hard, non-metallic workpiece is further defined by generating a laser beam onto opposing sides of the workpiece along a same axis

correlating to the depth of the workpiece.

19. A method as set forth in claim 15 further including the step of cooling

the hard, non-metallic workpiece with a coolant adjacent the hole being ablated into the

workpiece by said laser.

20. A method as set forth in claim 19 wherein said step of cooling the hard,

non-metallic workpiece with a coolant is further defined by cooling the workpiece with a liquid.

21. A method as set forth in claim 19 wherein said step of cooling the hard,

non-metallic workpiece with a coolant is further defined by cooling the workpiece with

water.

22. A method as set forth in claim 15 further including the step of adjusting

said laser to emit said laser beam having a power density, wavelength, diameter, and ablation rate correlated to a type of hard, non-metallic workpiece being ablated.

23. A method as set forth in claim 15 wherein said step of continuing to

change said focus of said laser beam to successive depths to ablate a hole into the hard, non-metallic workpiece is further defined by ablating a hole entirely through the

workpiece.

24. A method as set forth in claim 15 wherein said step of continuing to

change said focus of said laser beam to successive depths to ablate a hole into the hard, non-metallic workpiece is further defined by ablating a hole partially through the

workpiece.

25. A method as set forth in claim 24 wherein said step of ablating a hole

partially through the hard, non-metallic workpiece is further defined by ablating a figure

into said workpiece.

26. A method as set forth in claim 23 wherein said step of ablating a hole

into the workpiece.

27. A method as set forth in claim 23 wherein said step of ablating a hole

into opposing sides of the workpiece.

28. A method of ablating a hole into a hard, non-metallic substrate including

the steps of:

providing at least one laser assembly having focusing apparatus capable

of moving a focus of a laser beam generated by said laser assembly along three

directional axes corresponding to a length, width, and depth of the hard, non-metallic

substrate;

activating said at least one laser thereby generating said laser beam;

focusing said focus of said laser beam adjacent at least one surface of the

hard, non-metallic substrate;

ablating a first layer of the hard, non-metallic substrate in a configured

pattern;

moving said focus along an axis corresponding to the depth of the hard,

non-metallic substrate thereby enabling ablation of successive layers of the substrate;

and ablating successive layers of the hard, non-metallic substrate thereby generating a hole into said substrate.

29. A method as set forth in claim 28 further including the step of cooling

the hard, non-metallic substrate adjacent the hole being ablated by said laser beam

thereby preventing said substrate from cracking.

30. A method as set forth in claim 29 wherein said step of cooling the hard,

the at least one surface with liquid.

31. A method as set forth in claim 30 wherein said step of cooling the hard,

the at least one surface with water.

32. A method as set forth in claim 28 further including the step of moving

said focus relative the axes generally corresponding to the length and width of said hard, non-metallic substrate thereby ablating the hole through the substrate having a

predetermined configuration.

33. A method as set forth in claim 32 wherein said step of moving said focus

is further defined by moving said focus in a polygonal pattern thereby generating a hole

having a polygonal shape.

34. A method as set forth in claim 32 wherein said step of moving said focus

is further defined by moving said focus in a circular pattern thereby generating a hole

having a circular shape.

35. A method as set forth in claim 32, wherein said step of moving said

focus is further defined by moving said focus in a oval pattern thereby generating a hole

having a oval shape.

36. A method as set forth in claim 28, wherein said step of providing at least

one laser assembly is further defined by providing two laser assemblies each being

capable of generating a laser beam having a focus moveable relative to the hard, non-

metallic substrate along the length, width, and depth of the hard, non-metallic substrate.

37. A method as set forth in claim 36 further including the step of focusing

metallic substrate thereby ablating a hole through said hard, non-metallic substrate

from opposing sides of said substrate.

38. A method as set forth in claim 37 further including the step of cooling the opposing sides of said hard, non-metallic substrate adjacent the hole being ablated

by said laser beam thereby preventing said substrate from cracking.

39. A method as set forth in claim 38 wherein said step of cooling the hard,

the at least one surface with liquid.

40. A method as set forth in claim 38 wherein said step of cooling the hard,

the at least one surface with water.

41. A method as set forth in claim 38 wherein said step of abating a hole

through said hard, non-metallic substrate from opposing sides of said hard non-metallic substrate is further defined by one of said laser beams ablating more successive layers

of said hard non-metallic substrate than the other of said laser beams.

42. An apparatus for ablating a hole into opposing sides of a workpiece

comprising: a first laser assembly having a first galvanometer and a second laser assembly

having a second galvanometer;

said first laser assembly having a first optical lens for focusing a first laser beam

emitted from said first laser assembly and said second laser assembly having a second optical lens for focusing a second laser beam emitted from said second laser assembly;

and wherein said first optical lens is positioned on an opposite side of the workpiece

being ablated from said second optical lens thereby focusing said first and second laser beams on opposing sides of the workpiece.

43. An apparatus as set forth in claim 42 wherein said first and second

galvanometer focus said first and second laser beam along axes correlating to the length,

width, and depth of said workpiece.

44. An apparatus as set forth in claim 42 wherein said first optical lens and

said second optical lens are positioned to focus said first and said second laser beams

along a generally same axes.

45. An apparatus as set forth in claim 42 further including a controller

electronically connected to said first and second laser assemblies and being

programmable for directing the ablating rate of said laser beams.

46. An apparatus as set forth in claim 42 further including a cooling

apparatus capable of providing a coolant to the workpiece thereby dissipating heat

generated by said laser beams on said workpiece.

47. An apparatus as set forth in claim 42 wherein said first and said second

laser assembly each include a CO₂ laser.

48. An¹ assembly as set forth in claim 42 wherein said first and second laser

generate a poser density of between generally 40 and 50 Kw/cm .

49. An assembly as set forth in claim 42 wherein said first and second laser

generate a poser density of generally 45 Kw/cm .

50. A hard, non-metallic workpiece comprising:

at least one hole extending through generally opposing outer surfaces of said

hard, non-metallic workpiece, wherein said hole is defined by an inner surface of

said workpiece ablated by opposing laser beams forming a smooth inlet edge and an

irregular pattern on said inner surface positioned inwardly of said outer surfaces of

said workpiece.

51. A workpiece as set forth in claim 40 wherein said hole includes a

circular shape.

52. A workpiece as set forth in claim 40 wherein said hole includes a

polygonal shape.

53. A workpiece as set forth in claim 40 wherein said hole includes an

oval shape.