WO2012031580A2

WO2012031580A2 - Method for the open-loop and/or closed-loop control of a laser device, and a laser device

Info

Publication number: WO2012031580A2
Application number: PCT/DE2011/001579
Authority: WO
Inventors: Stefan Schur
Original assignee: Mtu Aero Engines Gmbh
Priority date: 2010-09-06
Filing date: 2011-08-11
Publication date: 2012-03-15
Also published as: DE102010052368A1; WO2012031580A3

Abstract

The invention relates to a method for the open-loop and/or closed-loop control of a laser device, wherein the method comprises the following steps: determining a laser characteristic curve by setting a predetermined laser variable and detecting the total laser power or total laser energy of the laser beam of the laser device which is established in the case of the laser variable; and open-loop and/or closed-loop control of the laser device on the basis of the laser characteristic curve.

Description

Method for controlling and / or regulating a laser device and a laser device

The present invention relates to a method for controlling and / or regulating a laser device and such a laser device.

From the prior art, as disclosed in DE 196 15 630 AI, a method and an apparatus for controlling the laser power is known. In this case, a partial beam of the laser is decoupled from a laser beam and the partial beam is measured.

Furthermore, EP 0 419 671 A1 discloses a control system for controlling the output of a laser, here an NC laser. In this case, a numerical control device (CNC) and a gas laser Osziallator are coupled together. In a first output control mode, a shutter is closed before starting a machining. The laser is thereby vibrated in advance to adjust the laser gas temperature, so that the temperature can be kept constant on an inner wall of a discharge tube. In a second output control mode, after a machining command is input, the shutter is opened and an output value is increased to generate a laser beam.

Further, from US 5,080,506 the control of the output of a laser as a light source is known, wherein the laser is connected to an optical conductor. Here, part of an optical signal guided in the optical guide is decoupled to detect and determine that part of the optical signal.

Against this background, the object of the invention is to provide an improved method for controlling a laser device. According to the invention there is now provided a method for controlling and / or regulating a laser device, the method comprising the following steps: Determining a laser characteristic by adjusting a predetermined laser size (Sl) and detecting the laser laser size adjusting total laser power or total laser energy of the laser beam of the laser device (S2); and

Controlling and / or regulating the laser device based on the laser characteristic.

The method has the advantage that by determining a laser characteristic, the total laser power or external laser power or the total laser energy or external laser energy of the laser can be set very accurately, so that a constant quality of the laser can be ensured without a readjustment by a Bedie - ner is necessary. Since the laser beam or the total laser beam of the laser of the device for determining the laser characteristic is detected or measured and no partial beam of the laser is coupled out for this purpose, reductions in performance, which are caused for example by optical elements and impurities, are taken into account. This can also be dispensed with correction factors, as is necessary when decoupling a partial beam to correct the laser beam to the actual available for processing total laser power (external laser power) or total laser energy (external laser energy).

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims and the description with reference to the drawings.

The invention will be explained in more detail with reference to the exemplary embodiments indicated in the schematic figures of the drawings. 1 shows a schematic view of an oscillatable PT2 element;

Fig. 2 is a schematic view of a non-vibratory PT2 member;

3 is a diagram of a characteristic of a laser of a laser device;

4 is a flow chart of a polynomial approximation of a control function; 5 is a diagram of a polynomial approximation for forming a control function;

6 shows a diagram of a linear interpolation for forming a controllable data base for a laser device;

Fig. 7 is a diagram showing a fulcrum measurement for securing the timeliness of a laser characteristic; 8 shows an exemplary embodiment of a flow diagram for a laser device in the context of an industrial application; and

Fig. 9 is a schematic view of a laser device according to the invention. In the figures, like elements or similar elements are designated by like reference numerals unless otherwise indicated.

In the aviation industry, in particular, the important parameters of critical processes and procedures are not changed after a rather elaborate qualification. This is called freezing the process. On the one hand, this is to forestall the personal arbitrariness of the operator, who could possibly change the process in such a way that the original design would no longer be guaranteed. On the other hand, a consistent quality in different locations and situations of production is to be achieved.

The laser processing is also such a critical manufacturing process and would have to be operated according to the international control value with frozen parameters. But this is not possible without further ado. Especially with lamp-pumped lasers, such as Nd: YAG lasers, the tool is not easy to predict in advance. Although the contour of the tool, in terms of beam diameter, quality and focusing, does not change very much, the laser lamps also suffer from wear in the form of decreasing power. Differences in the obstruction of the laser lamps result in non-constant and machine-specific aging. After a certain period of time, the lamps have to be replaced and the system changes to a completely different power state. Now you can compensate to compensate for this aging at certain intervals increase the lamp power to achieve a consistent laser power. However, this is not constantly decreasing and depends on many factors. For this reason, while all essential parameters for laser processing in the aviation industry are frozen, the performance that decreases over time must be readjusted by the operator. In particular, for laser percussion processing of, for example, blades and guide vanes, such as HDT (high-pressure turbine blades) - blades and vanes, where usually different bore diameters are used, entire parameter blocks must be set manually. This is done by measurements on the produced component in the form of diameter measurements and air flow rate measurements. To compensate for power loss due to lamp aging, a number of options are available for different operating states.

The power control by measuring the laser power applied in the beam path is the most common method (internal power). Here, a small part of the laser light is coupled out of the beam path and the power (internal power) is measured by a photodiode. This variant is used in almost all industrially used lasers for power control. In this case, however, the measurement is carried out in the beam path and not at the processing point (where the external or actually to be provided laser power or total laser power is applied). Reductions in performance, which inevitably occur for example due to optical elements and impurities, are not taken into account. Although correction factors can be used to correct for the actual power available for machining (external laser power or total laser power), this only works at constant power and not at more complex power control since the differences in different power ranges and aging conditions are not equal are. Another method calibrates the external power applied to the component by means of an external calibrated power meter. This can be sufficient for most processes, as the processing parameters change very little in many applications. Most process parameters can be stored in a kind of recipe collection.

To control pulsed lasers, however, it is aggravating that not the power applied in the resonator chamber is relevant to the process, but rather the emitted pulse energy. Although the laser lamps are controlled here, as with lasers in cw-Bertieb by regulating the lamp power, but the pulse energy is measured. This also complicates the laser control, since thus only one control loop must be established. The energy meter continuously picks up the pulse energy applied in the resonator and provides feedback to the lamp controller which regulates the power. Usually this is a parameter value in the form of volts or power percent of the laser to regulate. The system is generally sluggish since both the energy measurement and the controller are not immediately effective. Each incremental control requires a few seconds, so minutes can pass until the right energy is applied. With several jumps in performance or energy jumps during a CNC program run, the control times add up to an enormous amount of time.

There are basically two types of regulations available. Fig. 1 shows a variant 1, which relates to a vibratable PT2 member. 1 shows the transfer function of the oscillatable PT2 element and a diagram with a step response 2 of the PT2 element. FIG. 2 again shows a variant 2, which relates to a non-oscillatory PT2 Ghed. FIG. 2 shows the transfer function of the non-oscillating PT2 element and a diagram with a step response 2 of the PT2 element.

Here, for example, only variant 2 is important. Variant 1 could under certain circumstances strain too much or even damage a laser lamp, especially in an upper power range. There is now provided according to the invention, a system engineering proposal for controlling and / or controlling the laser power and / or laser energy of a laser device.

As shown in FIG. 3, first, a power factor or power curve 3 of a laser device is recorded as a function of a laser size. In the exemplary embodiment in FIG. 3, more precisely, a machine-typical or system-typical lamp characteristic curve is recorded. This includes performance measurements or energy measurements. In the present example, a power measurement of the laser beam or entire laser beam of a laser of a laser device takes place over a predetermined power range, e.g. the entire power range or at least a power section of the laser or more precisely the laser lamp in a lamp-pumped laser. Likewise, an energy measurement may also be carried out on the laser beam or on the entire laser beam of the laser of the laser device, the energy measurement taking place over a predetermined energy range, e.g. the entire energy range or at least an energy portion of the laser or more precisely the laser lamp in a lamp-pumped laser.

For this, e.g. The same laser variables (laser control variable in FIG. 3) are set as the input variable and the resulting output variable, in this case external power (total load power) or external energy (total laser power), is recorded. In other words, in at least a predetermined range for a laser size, the resulting power (total laser power) and / or energy (total laser energy) of the laser beam of the laser is detected or measured. In this case, different values of the laser size are set, which are within the predetermined range and which are detected and stored for the respectively set value of the laser large resulting external energy (total laser energy) and / or external power (total laser energy) of the laser.

This results in an individual and temporally only temporarily constant curve, which exactly describes with which presetting or input variable, ie laser size, a certain output variable, in this case an output power and / or output energy, can be achieved. An example of a characteristic of a laser system is shown in FIG. In this case, a laser variable (referred to here as laser control variable) in a predetermined range is set as an input variable. The range shown in FIG. 3 extends between the values 260 and 760 for a predetermined laser size. This results in a corresponding power or energy of the laser beam of the laser. The illustrated range of laser size and the resulting energy or power of the laser is purely fictitious and serves only to illustrate the principle of the invention. As a laser quantity for which the resulting power (W) and / or energy (J) is measured and recorded as output in at least one predetermined range, the laser voltage (V), the laser current (A), the laser control power (%) , the pump power in a lamp-pumped laser, the laser focus (eg diameter of the laser focus), the distance of the resonator, etc. are selected. However, the invention is not limited to the aforementioned examples of a laser size.

In principle, any laser size can be selected that influences the power and / or energy of the laser.

Since with each measurement a certain error both by the measurement, z. B. by means of a thermo-active measuring device, as well as by the slightly fluctuating output power or output energy, for example, a certain or predetermined number of measuring points 4 is recorded, thus statistically to keep the error as low as possible. The measuring points 4 of the characteristic curve 3 recorded in FIG. 3 are now converted in a further step into a control and / or regulating function for the laser device. Based on this control function, the laser device can determine for which external laser power or laser energy of the laser beam or the entire laser beam in Fig. 3, which value must be set for the laser size. In the embodiment shown in FIG. 3, for example, in order to achieve a power or an energy of the laser with a value of 10, the laser size with the value 560 must be set. The conversion of such a recorded characteristic curve, as shown in the example in FIG. 3, into a shape that can be used for machine control can now be done in various ways:

In Fig. 4, a scheme for approximation, e.g. for polynomial approximation, a control and / or control function shown to express the characteristic curve 3 as a function or to approximate the measurement points 4 of the characteristic curve 3 as accurately as possible by a curve.

To control a program of a laser device, such as a CNC program, the characteristic curve 3, as shown by way of example in FIG. 3, must be converted into a function. More specifically, the characteristic curve 3 must be converted into a characteristic function, which has as an input the external laser power (W) or laser energy (J) and as an output the laser size. As described above, as the laser size, for example, the laser control power may be e.g. in percent of power (%), in volts (V) or in ampere (A), pump power in a lamp pumped laser, laser focus (e.g., laser focus diameter), resonator spacing, etc. For the desired power (total laser power) or energy (total laser energy) of the laser then the laser size can be controlled to the value required for this purpose.

Expressing the characteristic curve 3 as a characteristic function can be easily realized by standard software. In this case, for example, a polynomial of the nth degree is produced, which maps the characteristic curve 3 or its curve, in particular as accurately as possible. The resulting function of the characteristic curve can in turn be used easily in any machine control of a machine installation, in particular a laser apparatus. 4 schematically illustrates the process. In the flowchart, steps are listed for creating a characteristic curve as a function for a laser system.

4, in a first step S1, a value for a laser size Y "(laser control variable) is initially set, for example a specific laser voltage V. In the subsequent step S2, the value for the laser variable Y "resulting power X" and / or energy X "of the laser determined or measured. In this case, the external or actual laser power of the laser is determined, and the external or actual laser energy of the laser is determined as well For example, the steps S1 and S2 are repeated for n values of a predetermined range of the laser quantity Yn, and the power X1 and / or energy resulting for the n values are respectively measured and correction factors are used to calculate the actual or external laser power The n-values can be chosen such that they cover a predetermined range for the laser size Y "as far as possible, for example covering as uniformly as possible over the entire width of the region.

The characteristic curve or the points X), Y to X ", Y" of the characteristic curve are converted into a function F in a step S3. In other words, in step S3 the characteristic curve or its points are approximated, for example polynomially approximated. In this case, the characteristic curve or its measuring points is converted into a characteristic function or expressed as a function in which, for example, a polynomial is approximated to the characteristic curve or its points. In this case, for example, a polynomial of the nth degree is produced, which maps the characteristic curve and preferably maps it as accurately as possible. In step S4, the approximated characteristic or the approximated points of the characteristic is converted into a function F (x = y, such as a control function for a laser precursor). Direction implemented by means of which the laser device, the power and or the energy of the laser can control and / or regulate.

For example, when converting the characteristic into a function or control function in step S4 for controlling and / or regulating the laser device, the characteristic may be expressed as a function such that from the function F (x = i based on the laser energy X, or laser power X _} corresponding corresponding laser size Y _, or the corresponding value or magnitude for the laser variable Y _} can be calculated In this way, it can be ensured by means of the characteristic curve or the function of the characteristic that always a required total laser energy or total laser power can be automatically provided without that, for example, a manual readjustment by an operator is necessary to compensate for aging phenomena of the laser of the laser device.

Instead of polynomially approximating the laser characteristic in step S3, any other method suitable for converting the characteristic into a function or approximating the characteristic by a function can also be used. Further examples for converting the characteristic into a function are explained below with reference to FIGS. 6 and 7, which relate to a linear interpolation and a so-called spline interpolation. The invention is not limited to the examples described in FIGS. 5, 6 and 7 for representing a characteristic as a function. It will be apparent to those skilled in the art that there are a variety of ways to transform a characteristic into a function or express it as a function.

FIG. 5 shows the laser characteristic curve 3 according to FIG. 3. In addition, a polynomial is shown which approximates the laser characteristic 3 in order to convert the laser characteristic 3 into a function or to express it as a function. FIG. 5 illustrates the approximation of a polynomial to the laser characteristic curve 3 and its measuring points 4. Variations can be statistically compensated by a large number of individual measurements. In addition to a polynomial approximation of a characteristic curve for forming a control and regulation function, as was explained above with reference to FIGS. 4 and 5, so-called linear interpolation can also be used, as shown in FIG. 6 below. FIG. 6 likewise shows the characteristic curve 3 or the laser characteristic curve according to FIG. 3, as well as a curve which is approximated to the laser characteristic curve 3 and its measuring points 4 by means of linear interpolation.

The laser characteristic can also be brought into a form (function) by interpolation, for example a linear interpolation, which can be used by the machine controller of a laser device for regulation and / or control. For this purpose, a moving average can be formed at the same time compensating the measurement error.

FIG. 6 shows a linearly interpolated curve as an example of an interpolation. One advantage in particular is that curves which have higher order polynomials (e.g.,> 5.

Grades) require approximation, can be represented safely. In this way, a controllable database can be formed by means of, for example, linear interpolation. For the approximation of characteristic curves 3, which can no longer be reliably represented by polynomial approximation, e.g. a spline interpolation can be used.

Based on the described polynomial function, as previously described with reference to FIG. 5, or the interpolated values, such as by means of linear interpolation or spline interpolation, a power and / or energy of the laser of the laser device required for processing can always be set the same. This is done via a kind of processing recipe, which in particular component is created specifically. In other words, the characteristic curve can be stored as a function in an internal or external memory device of a laser device and retrieved by a control and / or regulating device of the laser device. Based on the function of the characteristic curve, the laser device can be used, for example, for a required output power or output energy an associated laser size, such as the laser voltage, the laser power in percent, the laser current, etc. determine and adjust or regulate. The same parameters can be used for always identical states. Since no control element in the true sense is now absolutely necessary for the control, the laser can be operated directly via the determined function with its desired laser control power or laser control energy due to an associated laser size [%, V, A, ...]. The desired level of performance or energy level is set faster.

In addition, for example, random intermediate measurements may be carried out to confirm the current condition. As long as the intermediate measurements are not too far from the characteristic curve or within a specified tolerance range, the characteristic can be maintained.

If the specified limit values or the tolerance range are exceeded, a new characteristic can be recorded, for example, and stored as a new function or control and / or regulating function.

In the case of intermediate measurements, it makes sense to carry out not only one measurement, but several measurements one after another with, for example, the same energy and / or power, since this again results in a small statistic which compensates for measurement errors and fluctuating output powers and / or output energies. In terms of time, the effort is not too great, since no new power state and / or energy state has to be set. FIG. 7 shows interpolation measurements for a power or energy characteristic with an upper limit 5 and a lower limit 6 or an upper and a lower tolerance limit. Scattering of the output power or the output energy are also shown here, as well as the determined average value of the respective intermediate measurement. As can be seen from FIG. 7, first of all a characteristic curve is created, as previously described eg with reference to FIG. 3. In addition, for example, an upper limit or upper tolerance limit 5 and a lower limit or lower tolerance limit limit 6 for the characteristic or laser characteristic, as shown in Fig. 7.

For example, if the power or energy at each laser size value is within these limits or at one of these limits, the laser size will be within a predetermined tolerance range and the characteristic may be maintained. If, on the other hand, a laser variable with its resulting power or energy exceeds the upper limit 5 or if a laser variable with its resulting power or energy exceeds the lower limit 6, the laser size is outside the tolerance range and, for example, a new characteristic curve, here laser characteristic, can be created become.

As further shown in FIG. 7, one or more intermediate measurements may be performed. In the example shown in FIG. 7, a first intermediate measurement has been performed at a first laser size, here 350, a second intermediate measurement at a second laser size, here 450, and a third intermediate measurement at a third laser size, here 600.

In this case, an intermediate measurement comprises at least one or, in particular, several measurements of the power or the energy of the laser beam or of the entire laser beam of the laser, given the respectively assigned laser size. In other words, for example, for a laser size of 350 in the example in FIG. 7, the power or energy may be determined one or more times. In the case that the measurement is carried out several times for the same value of the laser variable, for example 350, an average value is formed from the acquired measured values, which is determined as the result of the respective intermediate measurement, here for example the first intermediate measurement. Accordingly, it is possible to proceed for the second and third intermediate measurements. Thus, in the first, second and third intermediate measurement, the corresponding scattering can be taken into account as well. By means of such interpolation point measurements, the actuality of the characteristic curve or laser characteristic curve can be ensured. As shown in the example in FIG. 7, the intermediate measurements lie, for example, within the tolerance range, ie within the predetermined upper and lower limits lower tolerance limit. Thus, the laser characteristic shown can continue to be used and no new laser characteristic has to be determined and converted into a function. If, on the other hand, one of the intermediate measurements were outside the upper or lower tolerance limit, it can be determined that a new characteristic or laser characteristic is determined.

Fig. 8 illustrates an embodiment of a process, as it may appear useful in an industrial environment. Since the control of the laser hides interference sources only by its external active power or active energy, such as optical elements and soiling after a resonator, it makes sense to regularly observe the beam quality of the laser of a laser device.

A collapse of the power, for example, as a result of lamp failure of a laser of a laser device, can be detected early on.

As shown in the example in FIG. 8, in a first step S1 * a control of the beam quality of the laser takes place. In this case, as described above with reference to FIGS. 3 to 6, first a characteristic or laser characteristic is determined and expressed as a function F, for example by means of polynomial approximation or interpolation (eg linear interpolation or spline interpolation) etc. The function F of the characteristic curve can be stored so as to be retrievable, for example, in a memory device of a device for controlling and / or regulating the laser device.

Based on a predetermined or desired power or energy of the laser of the laser device can be determined and adjusted on the basis of the function F of the characteristic required laser size, for example, a required laser voltage.

In a next step S2 *, an intermediate check of the power or energy takes place externally to the characteristic curve. At least one intermediate measurement is carried out for at least one laser variable. More specifically, in an intermediate measurement for one or more values of laser size, the resulting power or energy of the laser is determined stored as intermediate value or intermediate measuring point. In the case that the power or energy of the laser is determined several times for the same value of the laser size, an average value can be formed from the measurement results and stored as an intermediate value or intermediate measuring point.

In a further step S3 *, it is determined whether the respectively determined intermediate value or intermediate measuring point lies within a predetermined tolerance range, which is e.g. is set by an upper tolerance limit and a lower tolerance limit, as previously shown in FIG. If the intermediate value is within the tolerance range, i. If "OK = YES" in step S3 *, a corresponding program is started in the subsequent step S5 *, here e.g. a CNC program for operating the laser of the laser device on the basis of the existing characteristic or existing function F of this characteristic. If, however, it is determined in step S3 * that the at least one determined intermediate value is not within the tolerance range, but has either exceeded the upper tolerance limit in the example in FIG. 7 or has fallen below the lower tolerance limit, in step S3 * "OK = NO "and, in a step S4 *, the determination of a new characteristic curve or laser characteristic curve and the conversion of this characteristic curve into a function F, as described above by way of example with reference to FIGS. 3-6.

In the subsequent step S5 *, a corresponding program for actuating the laser is started on the basis of the new characteristic curve or the function F of the new characteristic curve, as previously determined in step S5 *,

Subsequent to step S5 *, in the subsequent step S2 *, an intermediate check of the power and / or energy takes place externally to the characteristic curve.

FIG. 9 shows a schematic view of an exemplary embodiment of a laser device 7 according to the invention. The laser device 7 in this case has a characteristic device 8 for determining a laser characteristic and a function of the characteristic. The characteristic device 8 in this case has an adjusting device 9 for setting a predetermined laser size and a detection device 10 for detecting and storing the adjusting the laser size laser power (total laser power or external laser power) or laser energy (total laser energy or external laser energy) of the laser beam on.

More specifically, the adjusting means 9 sets a plurality of values of the laser size, and the detecting means 10 detects or measures the laser power or the laser energy of the laser beam of the laser device 7 for each predetermined value of the laser size. The result is stored as a respective measuring point in the characteristic device 8 and the measuring points are converted into a function, in particular by approximation of the measuring points.

For controlling and / or regulating, the function or characteristic can then be called up by a device for controlling and / or regulating the laser device 11, for example for a desired laser power or laser energy of the laser beam of the laser of the laser device 7, a laser variable, such as eg Adjust the laser voltage, etc., based on the characteristic expressed as a function.

Furthermore, the laser device 7 has an intermediate measuring point device 12, which detects or measures the laser power or the laser energy of the laser beam of the laser device 7 for at least one predetermined value of the laser variable and evaluates the obtained intermediate measuring point and compares it with a predetermined tolerance range. The characteristic device 8 can determine a new characteristic curve if the intermediate measuring point of the intermediate measuring point device 12 lies outside the predetermined tolerance range.

The laser device 7 in FIG. 9 represents only an exemplary embodiment. The characteristic device 8, the adjustment device 9, the detection device 10, the device for controlling and / or regulating the laser device 11 and the intermediate measuring point device as well as parts of these devices can be found both in FIG the laser device integrated or coupled with this. The invention described above with reference to embodiments has the advantage that the control of different laser powers or laser energies is much faster than in a control via the internal energy measurement. A direct lamp parameter is specified and not controlled by a controller.

By measuring the external power or external energy actually applied to the component, it is ensured that the production result is always processed in the same way as well. This results in a lower inspection cost of the manufacturing characteristics.

The self-regulating cycle makes possible automation easier to implement. There is no reason to fear that the production result will change over time due to the aging of the flashbulb. Intervention by the staff is no longer necessary. Elaborate set-up scenarios, whereby default values are given based on empirical values, are no longer required.

When changing components, you can work without corrections in the same condition as during the last production run. The machine sets the necessary conditions and the components are manufactured on the basis of a component-specific "cooking recipe".

An overload of the laser lamps due to excessive vibration deflection in the power control or energy regulation is not given. The same pattern is always recorded. The measuring device for determining the characteristic or laser characteristic or at least the

Characteristic device, can be integrated into the machine or the laser device and so create a self-regulating system. For example, CNC cycles can easily retrofit such a controller in existing machines.

Although the present invention has been described above with reference to the preferred embodiments, it is not limited thereto, but is in many ways and Modifiable way. In particular, the exemplary embodiments described above can be combined with one another, in particular individual features thereof.

Claims

P a n t a n s p r e c h e

A method of controlling and / or controlling a laser device (7), the method comprising the steps of:

Determining a laser characteristic by adjusting a predetermined laser size; Detecting the total laser power or total laser power of the laser beam adjusting the laser size of the laser device (7); and

Controlling and / or regulating the laser device (7) based on the laser characteristic.

A method according to claim 1, characterized in that the laser size is a laser voltage, a laser current, a laser control power, a pump power in a lamp-pumped laser device, a laser focus or a distance of a resonator of the laser device (7). The method of claim 1 or 2, characterized in that the step of determining the laser characteristic further comprises the steps of: determining a plurality of measurement points of the laser characteristic by adjusting a plurality of values of the laser magnitude;

Detecting the total laser power or the total laser energy of the laser beam of the laser device (7) for the respective predetermined value of the laser size; and storing the respectively obtained measuring point from laser size and resulting total laser power or total laser energy.

A method according to claim 3, characterized in that the step of Bestim¬

the laser characteristic curve further comprises the steps:

Converting the measuring points into a function of the laser characteristic curve by means of a polynomial approximation or interpolation, in particular by means of a linear interpolation or a spline interpolation.

Method according to at least one of the preceding claims, characterized in that the step of controlling and / or controlling the laser device (7) based on the laser characteristic further comprises the following steps: Specifying an upper tolerance limit and / or a lower tolerance limit for the laser characteristic curve;

Determining at least one intermediate measuring point by determining the total laser power or the total laser energy of the laser beam of the laser device (7) for at least one predetermined value of the laser size; and

Determining whether the measuring point is outside a tolerance limit (5, 6), and determining a new laser characteristic when the measuring point is outside the tolerance limit (5, 6).

Method according to at least one of the preceding claims, characterized in that the laser of the laser device (7) is a pulsed laser or lamp-pumped laser and in particular an ND YAG laser.

Laser device with:

a laser;

a characteristic device (8) for determining a laser characteristic, wherein the characteristic device (8) comprises an adjusting device (9) for setting a predetermined laser size and a detection device (10) for detecting and storing the total laser power or total laser energy of the laser variable Laser beam has; and

a device for controlling and / or regulating the laser device (11) based on the laser characteristic of the characteristic device (8).

Laser device according to Claim 7, characterized in that the setting device (9) sets a plurality of values for the laser size and the detection device (10) detects the laser power or the laser energy of the laser beam of the laser device (7) for the respectively predetermined value of the laser variable and The measuring device (8) converts the stored measuring points into a function of the laser characteristic, in particular by approximation of the measuring points, and wherein the function of the laser characteristic of the device for controlling and / or regulating the laser device (11) is retrievable.

9. Laservomchtung according to claim 7 or 8, characterized in that the laser device comprises an intermediate measuring point means (12) which detects the total laser power or the total laser energy of the laser beam of the laser device (7) for at least a predetermined value of the laser size and evaluates the obtained intermediate measuring point and with a predetermined tolerance range (5, 6) compares.

10. Laser device according to claim 9, characterized in that the characteristic device (8) determines a new characteristic or its function when the intermediate measuring point of the intermediate measuring point device (12) lies outside the predetermined tolerance range (5, 6).