Patent Description:
Apparatuses emitting an energy beam, such as laser apparatuses, are long known and are widely used for processing different objects owing, inter alia, to the precision and energy with which they may process the objects. For example, laser may be used for additive manufacturing, welding, cutting, hardening of objects such as metal sheets, vehicle components like crankshafts, etc..

Recently, improvements to energy beam radiation have been made. These consist in the provision of effective spots of the energy beam by scanning, with high speeds, the energy beam according to patterns. The energy distribution of the effective spot may be adjusted and controlled by varying the scanning patterns, speeds and power with which the source provides the energy beam. Examples of such improvements are disclosed in patent documents <CIT> and <CIT>.

High speed scanning requires the provision of scanners that may be operated such that they scan the energy beam according to scanning patterns and with the required speeds. However, in many cases, current scanner technology is not capable of scanning the energy beam with such demanding conditions, for example when the scanning pattern or trajectory requires small rotations of the mirrors within the scanner and/or when the energy beam is scanned by rotating the mirrors at the maximum supported speed. Therefore, due to the limitations of the scanner, there exists a difference between the predetermined scanning pattern, that is, the desired scanning pattern, and the actual scanning pattern, that is, the pattern that the spot provided by the energy beam emitting apparatus has followed.

There are some developments intended to have some control of this phenomenon, for example: <CIT>, which relates to an apparatus for forming three-dimensional objects from a medium solidifiable when subjected to a beam of pulsed radiation; a computer controls the movement of the mirrors which guide the laser beam across the surface of the solidifiable medium; pulsing of the laser beam is correlated to the position of the mirrors and thus, is not dependent upon time; the pulsing linked to position of beam placement allows controlled and repeatable use of a pulsed beam for the formation of objects. <CIT> (describing all the steps and features of the preamble of claims <NUM> and <NUM>), which relates to a laser scanning system in a rapid-prototyping system that is controlled during vector scanning by providing a commanded-position signal to each of first and second rotary motive devices to rotate respective mirrors of the scanning system, each mirror undergoing acceleration at the beginning of the vector, wherein the commanded-position signals are calculated based on physical mathematical modeling of the acceleration of the mirrors taking into account effects of inertia of the scanning system, and actual positions of the mirrors are measured with fast-response devices and digital feedback control of the mirror positions is employed at a periodic rate sufficiently small to maintain a following error of the laser spot less than about <NUM> microseconds. None of these developments, however, detect if the ongoing scanning is according to the expected behavior of the mirrors and establish anomalous operation thereof.

Further, in some occasions, the scanner cannot cope with the required speeds and stops working for certain time duration, for example few milliseconds, tens or hundreds of milliseconds, or even few seconds. Even when the scanner is not working for few milliseconds, the object processed by the energy beam emitting apparatus may be incorrectly processed, which means that the quality thereof is insufficient for the use of the same.

Generally, the energy beam emitting source, such as a laser source, of such apparatuses provides an energy beam with high power, e.g. over <NUM> kW. If the scanner breaks, for example a mirror thereof gets broken due to the high power of the energy beam, there are serious safety concerns because the energy beam could undesirably be aimed outside from the working area, for instance aimed at a person or a machine within the premises.

There exists a need to know whether a scanner of an apparatus providing an energy beam scans the energy beam according to the expected capacity of the scanner both for reasons of safety and quality of the objects processed by the apparatus.

A first aspect of the invention relates to a method for supervision of a scan of an energy beam as defined in claim <NUM>, comprising: providing an apparatus configured to provide the energy beam; providing a scanner configured to scan the energy beam, the scanner comprising a first mirror and a second mirror; operating the apparatus and the scanner such that the energy beam is provided while it is scanned according to a predetermined scanning pattern; determining, at least one processor of a computer device or system, an actual scanning pattern of the energy beam, when both the apparatus and the scanner are operated, by processing measurements provided by encoders of the first mirror and the second mirror; and comparing, the at least one processor, the actual scanning pattern with a predetermined threshold area.

The apparatus configured to provide the energy beam may be an apparatus for emitting an energy beam. The apparatus may be a laser apparatus for emitting a laser beam.

The scanner is commanded to scan the energy beam according to the predetermined scanning pattern. The predetermined scanning pattern may be any with which it is desired to irradiate the object to be processed by the apparatus. For example, the predetermined scanning pattern may be a pattern intended to provide an energy distribution on the object such that an effective spot of the energy beam is provided. There may be a variety of scanning patterns, for example, scanning patterns comprising a plurality of parallel lines, scanning patterns comprising curvilinear lines, scanning patterns in which the effective spot follows a path involving sudden changes of the direction, corresponding to sharp corners in the pattern, for example, changes in the direction by <NUM> degrees, and scanning patterns comprising discontinuous lines or even a set of discrete points not forming one or more lines. As the energy beam is scanned the energy deposited on the object builds up thereby providing an effective spot of the energy beam. Such pattern is repeated a number of times and, simultaneously, either the pattern is moved over the surface of the object by means of the scanner, that is, there is a superimposed movement for processing different parts of the object, or the pattern is provided yet maintained static (i.e. the scanner does not move it over the surface of the object) but the axes of the energy beam emitting apparatus are moved for processing different parts of the object.

In preferred embodiments, the energy beam is a beam of electromagnetic radiation or a light beam, for example, a laser beam. In preferred embodiments, the power of the energy beam is over e.g. <NUM> kW, for instance <NUM> kW, <NUM> kW, <NUM> kW, etc. and less than e.g. <NUM> kW, for instance less than <NUM> kW or less than <NUM> kW.

Even though the scanner is commanded to scan the energy beam according to the predetermined scanning pattern, owing to the limitations of the scanner, the actual scanning pattern of the energy beam scanned differs from the predetermined scanning pattern. This is so due to many factors, for example, the weight and moment of inertia of the mirrors, the rotation speeds of the mirrors, the accuracy in the rotations of the mirrors, etc. Based on a predetermined scanning pattern and a scanner, for instance by making experimental tests it may be determined what is the expected scanning pattern of the energy beam scanned, which is different from the predetermined scanning pattern for the aforementioned reasons. For example, a number of experimental tests may be conducted for statistically determining how much does the spot of the energy beam deviate from where it usually illuminates a surface; that is to say, as the spot of the energy beam does not exactly repeat the pattern in each cycle, the expected scanning pattern may be determined in accordance with the greatest illuminated surface as the energy beam is scanned according to the predetermined scanning pattern a plurality of times.

However, in some cases the scanner cannot even scan the energy beam with the expected scanning pattern, let alone with the predetermined scanning pattern and, thus, any differences between the expected scanning pattern or the predetermined scanning pattern and the actual scanning pattern may be due to either the underperformance of the scanner due to its limitations, or the failure of the scanner itself, for example a mirror not working anymore or a broken mirror. This may lead to incorrect processing of the object, and/or risk of aiming the energy beam outside of the working area.

While the energy beam is scanned during operation of the apparatus for emitting an energy beam, the encoders of the mirrors of the scanner provide measurements of one of: the absolute position of the mirror within the scanner, the angle of the mirror, and the movement of the mirror. These measurements thus provide information about the operation of the scanner while it scans the energy beam, particularly it can be determined what the actual scanning pattern is. Oftentimes commercially available scanners for energy beam radiating apparatuses are already provided with the encoders.

The comparison of the actual scanning pattern with the predetermined threshold area may reveal if there have been problems in the scan. To this end, it may be determined that the scan is anomalous if the result of the comparison is that at least part of the actual scanning pattern falls either within the predetermined threshold area or outside of the predetermined threshold area.

In some embodiments, the predetermined threshold area (or a majority thereof) does not comprise an expected scanning pattern; and it is determined by the at least one processor that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is outside of the predetermined threshold area. In some of these embodiments, the predetermined threshold area comprises the predetermined scanning pattern. In these embodiments, preferably it is determined that the scan is not anomalous otherwise, i.e. if the actual scanning pattern is inside of the predetermined threshold area, that is to say, no part of the actual scanning pattern is outside of the predetermined threshold area.

In some embodiments, the predetermined threshold area comprises an expected scanning pattern; and it is determined by the at least one processor that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is inside of the predetermined threshold area. In these embodiments, preferably it is determined that the scan is not anomalous otherwise, i.e. if the actual scanning pattern is outside of the predetermined threshold area, that is to say, no part of the actual scanning pattern is inside of the predetermined threshold area.

Whether the actual scanning pattern shall be inside or outside of the predetermined threshold area for determining that the scan is anomalous depends on how the predetermined threshold area is defined: either as a threshold area corresponding to the expected scanning pattern (thus, it is desirable that the actual scanning pattern falls within the threshold area), or as a threshold area corresponding to the deviation from the expected scanning pattern (thus, it is not desirable that the actual scanning pattern falls within the threshold area because the threshold area represents deviation from the expected scanning pattern). In other words, the threshold area can also be seen as either a forbidden area when it is defined that it is not desirable that the actual scanning pattern falls within the threshold area, or as an area representing the correct scan when it is defined that it is desirable that the actual scanning pattern falls within the threshold area. Moreover, in the latter case, the predetermined threshold area may comprise the predetermined scanning pattern, that is, the desired scanning pattern that is commanded to the scanner. This is so because the closer the actual scanning pattern is to the predetermined scanning pattern, the more likely it is that the scanner has a problem: for example, upon breaking of a mirror, the weight and moment of inertia of the same changes thereby making it less demanding to follow the predetermined scanning pattern.

The expected scanning pattern is defined by or is based on the predetermined scanning pattern. In this sense, it is possible to provide expected scanning patterns by scanning an energy beam according to a predetermined scanning pattern, preferably in same or similar conditions as when objects are to be processed by the energy beam emitting apparatus, and measure the actual scanning pattern or trajectory followed by the energy.

In some embodiments, the method further comprises indicating, if it is determined that the scan of the energy beam is anomalous, that an object that was processed by the apparatus is incorrectly processed.

When it is determined that the scan is anomalous, it is considered that the object during the processing of which the anomalous scan occurred is incorrectly processed. Accordingly, it is indicated that the object is incorrect because the quality thereof may not meet the quality requirements, thereby making possible to avoid the use or sale of said object.

In some embodiments, the method further comprises stopping the apparatus for emitting an energy beam if it is determined that the scan of the energy beam is anomalous.

When it is determined that the scan is anomalous, there exists a risk that the energy beam is not or will not be aimed at the working area. Therefore, operating the apparatus for radiating an energy beam is not safe, and thus it is stopped so as to avoid any possible damages.

In some embodiments, the encoders of the first mirror and the second mirror provide the measurements with a frequency equal to or greater than <NUM>.

A more accurate determination that a scan is anomalous may require a large number of measurements per second provided by the encoders. Depending on the rotation speeds of the mirrors of the scanners the number of measurements will have to be higher in order to compare the actual scanning pattern with the predetermined threshold area with sufficient resolution. To this end, the number of measurements provided by the encoders of the first and second mirror is preferably <NUM> or more, e.g. <NUM>, <NUM>, <NUM>, <NUM>, etc. and less than <NUM>, and/or less than <NUM>.

In some embodiments, the actual scanning pattern is determined by further processing measurements provided by encoders of axes of the apparatus.

Sometimes the predetermined scanning pattern commanded to the scanner is adjusted based on the movement of the axes of the apparatus. Hence, the provision of measurements of the encoders of the axes to the at least one processor may be used for determining the actual scanning pattern, which will then be compared with the predetermined threshold area.

In some embodiments, the actual scanning pattern is determined by further processing data of a geometry of the object being processed by the apparatus.

Data about the geometry of the object may also assist in determining the actual scanning pattern. For instance, if the at least one processor has information about the existence of an irregular surface of the object, the existence of cavities, recesses, protrusions and the like on the surface of the object, etc. it may combine that information with the measurements received to determine the actual scanning pattern, which may be influenced by said geometry. The data may be provided in many forms, for example as a digital 3D model representing a 3D geometry of the object, a digital image representing in 2D a surface or a perimeter of the object, etc..

In some embodiments, the energy beam is provided and scanned such that it produces an effective spot of the energy beam on a surface of an object processed by the apparatus, the effective energy spot of the energy beam featuring a two-dimensional energy distribution.

In some embodiments, the scanner is operated such that each of a maximum angular coverage in a first direction and a maximum angular coverage in a second direction is greater than <NUM>° and equal to or less than <NUM>°, the first direction being perpendicular to the second direction. In some of these embodiments, the maximum angular coverage is equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°.

The problem of anomalous scans is exacerbated as the maximum angular coverage is reduced. When predetermined scanning patterns involve a reduced maximum angular coverage, the precision required for scanning the laser beam increases due to the small angular rotations the mirrors have to perform during the scan.

Predetermined scanning patterns in reduced maximum angular coverages make possible to control the energy distribution over a small portion of the surface of the processed object, therefore the processing may be more accurate.

In some embodiments, the method further comprises: obtaining data indicative of the actual scanning pattern being different from the predetermined scanning pattern, and modifying the predetermined scanning pattern based on said data indicative of the actual scanning pattern being different from the predetermined scanning pattern.

In some embodiments, the method further comprises identifying and/or tracking anomalous scans. For example, the one or more points in which an actual scanning pattern falls either within a predetermined threshold area or outside of a predetermined threshold area, as the case may be, may be marked. The marked points can be checked later in order to determine quality errors or process error. A quality error may be an incorrectly processed object.

In some embodiments, the method further comprises triggering an alarm when a certain amount of anomalous scans are tracked. The certain amount of anomalous scans may be one or a plurality of anomalous scans.

A second aspect of the invention relates to a system for supervision of a scan of an energy beam as defined in claim <NUM>, comprising: an apparatus configured to provide the energy beam; a scanner configured to scan the energy beam, the scanner comprising a first mirror and a second mirror, each mirror at least comprising an encoder, the scanner and the apparatus being configured to provide the energy beam while it is scanned according to a predetermined scanning pattern; and a computing device or system comprising at least one processor; the at least one processor is configured to: determine an actual scanning pattern of the energy beam, when both the apparatus and the scanner are operated, by processing measurements provided by the encoders of the first mirror and the second mirror; and compare the actual scanning pattern with a predetermined threshold area.

The scanner is commanded to scan the energy beam provided by the apparatus according to the predetermined scanning pattern, for example a pattern intended to provide an energy distribution on the object such that an effective spot of the energy beam is provided. The object is thus processed in a controlled manner with the effective spot.

The scanner scans the energy beam following an actual scanning pattern rather than following the commanded predetermined scanning pattern due to the limitations thereof. Therefore, an expected scanning pattern may be defined in accordance with the predetermined scanning pattern and the scanner (thus considering the general operation of the mirrors). However, the energy beam scanned with the scanner generally deviates from the expected scanning pattern, which may result in the incorrect processing of the object, and/or the possibility of aiming the energy beam outside of the working area.

The encoders of the mirrors provide measurements of one of: the absolute position of the mirror within the scanner, the angle of the mirror, and the movement of the mirror. These measurements provide information about the operation of the scanner while it scans the energy beam, and they make possible to determine what the actual scanning pattern is.

By comparing the actual scanning pattern with the predetermined threshold area, it may be determined if the scan is anomalous.

In some embodiments, the predetermined threshold area (or a majority thereof) does not comprise the predetermined scanning pattern; and the at least one processor is further configured to determine that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is outside of the predetermined threshold area. In these embodiments, preferably the at least one processor determines that the scan is not anomalous otherwise, i.e. if the actual scanning pattern is inside of the predetermined threshold area, that is to say, no part of the actual scanning pattern is outside of the predetermined threshold area.

The predetermined threshold area is defined as a threshold area corresponding to the deviation from the expected scanning pattern (thus, it is not desirable that the actual scanning pattern falls within the threshold area because the threshold area represents deviation from the expected scanning pattern).

In some of these embodiments, the predetermined threshold area comprises the predetermined scanning pattern.

In some embodiments, the predetermined threshold area comprises the predetermined scanning pattern; and the at least one processor is further configured to determine that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is inside of the predetermined threshold area. In these embodiments, preferably the at least one processor determines that the scan is not anomalous otherwise, i.e. if the actual scanning pattern is outside of the predetermined threshold area, that is to say, no part of the actual scanning pattern is inside of the predetermined threshold area.

The predetermined threshold area is defined as a threshold area corresponding to the expected scanning pattern (thus, it is desirable that the actual scanning pattern falls within the threshold area).

The expected scanning pattern is defined by or is based on the predetermined scanning pattern, for example by measuring the actual scanning pattern or trajectory followed by the energy beam when the scanner is commanded to scan according to a predetermined scanning pattern.

In some embodiments, the at least one processor is further configured to indicate, if it determines that the scan of the energy beam is anomalous, that an object that was processed by the apparatus is incorrectly processed.

In some embodiments, the at least one processor is further configured to stop the apparatus for emitting an energy beam if it determines that the scan of the energy beam is anomalous.

In some embodiments, the encoders of the first mirror and the second mirror are configured to provide the measurements with a frequency equal to or greater than <NUM>.

In some embodiments, the at least one processor determines the actual scanning pattern by further processing measurements provided by encoders of axes of the laser apparatus.

In some embodiments, the at least one processor determines the actual scanning pattern by further processing data of a geometry of the object to be processed by the apparatus.

In some embodiments, the energy beam is provided and scanned so as to produce an effective spot of the energy beam on a surface of an object to be processed by the apparatus, the effective spot featuring a two-dimensional energy distribution.

In some embodiments, the scanner is configured to scan the energy beam such that each of a maximum angular coverage in a first direction and a maximum angular coverage in a second direction is greater than <NUM>° and equal to or less than <NUM>°, the first direction being perpendicular to the second direction. In some of these embodiments, the maximum angular coverage is equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°.

In some embodiments, the at least one processor obtains data indicative of the actual scanning pattern being different from the predetermined scanning pattern, and modifies from said data the predetermined scanning pattern.

Similar advantages as those described with reference to the first aspect of the invention also apply to this aspect of the invention.

A third aspect of the invention relates to a computer program product as defined in claim <NUM>, having instructions which, when executed by the at least one processor of the computing device or system of the system according to the second aspect of the present invention, cause the processor to perform the steps of: operating an apparatus and a scanner such that an energy beam thereof is provided while it is scanned with the scanner according to a predetermined scanning pattern; determining an actual scanning pattern of the energy beam, when both the apparatus and the scanner are operated, by processing measurements provided by encoders of a first mirror and a second mirror of the scanner; and comparing the actual scanning pattern with a predetermined threshold area.

In some embodiments, the predetermined threshold area (or a majority thereof) does not comprise an expected scanning pattern; and the instructions cause the computing device or system to determine that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is outside of the predetermined threshold area. In some of these embodiments, the predetermined threshold area comprises the predetermined scanning pattern. In these embodiments, preferably the computing device determines that the scan is not anomalous otherwise, i.e. if the actual scanning pattern is inside of the predetermined threshold area, that is to say, no part of the actual scanning pattern is outside of the predetermined threshold area.

In some embodiments, the predetermined threshold area comprises an expected scanning pattern; and the instructions cause the computing device or system to determine that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is inside of the predetermined threshold area. In these embodiments, preferably the computing device determines that the scan is not anomalous otherwise, i.e. if the actual scanning pattern is outside of the predetermined threshold area, that is to say, no part of the actual scanning pattern is inside of the predetermined threshold area.

In some embodiments, the instructions further cause the computing device or system to indicate, if it is determined that the scan of the energy beam is anomalous, that an object that was processed by the apparatus is incorrectly processed.

In some embodiments, the instructions further cause the computing device or system to stop the apparatus for emitting an energy beam if it is determined that the scan of the energy beam is anomalous.

In some embodiments, the instructions further cause the computing device or system to receive the measurements of the encoders of the first mirror and the second mirror with a frequency equal to or greater than <NUM>.

The instructions may cause the computing device or system to receive measurements provided by the encoders of the first and second mirror at <NUM> or more, e.g. <NUM>, <NUM>, <NUM>, <NUM>, etc., and less than <NUM>, and/or less than <NUM>.

In some embodiments, the instructions cause the computing device or system to determine an actual scanning pattern of the energy beam by further processing measurements provided by encoders of axes of the apparatus.

In some embodiments, the instructions cause the computing device or system to determine an actual scanning pattern of the energy beam by further processing data of a geometry of the object being processed by the apparatus.

In some embodiments, the instructions cause the scanner to scan the energy beam so as to produce an effective spot of the energy beam on a surface of an object to be processed by the apparatus, the effective energy spot featuring a two-dimensional energy distribution.

In some embodiments, the instructions cause the scanner to scan the energy beam such that each of a maximum angular coverage in a first direction and a maximum angular coverage in a second direction is greater than <NUM>° and equal to or less than <NUM>°, the first direction being perpendicular to the second direction. In some of these embodiments, the maximum angular coverage is equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°, and/or equal to or less than <NUM>°.

A fourth aspect of the invention relates to a data stream which is representative of a computer program product according to the third aspect of the invention.

Similar advantages as those described with reference to the first and second aspects of the invention also apply to the third and fourth aspects of the invention.

<FIG> illustratively shows a system with an apparatus <NUM> intended to have the energy beam 3a, 3b thereof scanned according to a predetermined scanning pattern <NUM>.

The system comprises: the apparatus for radiating a laser beam <NUM>, the apparatus including a laser source (not illustrated) for providing the laser beam 3a; a scanner <NUM> with mirrors (not illustrated) for scanning the laser beam 3b on a surface <NUM> of an object <NUM>, such as a cylindrical journal of a crankshaft having an oil lubrication hole <NUM>; a computing device <NUM>; and a housing <NUM> within which the apparatus <NUM> and the computing device <NUM> may be both included.

The computing device <NUM> operates the apparatus <NUM> so that it provides the laser beam 3a, and also operates the scanner <NUM> so that the mirrors thereof scan the laser beam 3b in the working area, and more particularly, on the surface <NUM> of the object <NUM> such that a laser spot <NUM> is thereon. The computing device <NUM> commands the scanner <NUM> to scan the laser beam 3b according to the predetermined scanning pattern <NUM> (shown with dashed lines for illustrative purposes only) that is or may be changed while the object <NUM> is processed. To this end, the computing device <NUM> is connected to apparatus <NUM>, so as to be communicatively coupled therewith, and to the scanner <NUM>, for instance with cables <NUM> and <NUM>. In operation of the system, the laser apparatus <NUM> and the scanner <NUM> may move with respect to the object <NUM> to be processed, or the object <NUM> to be processed moves with respect to the laser apparatus <NUM> and the scanner <NUM>.

When the laser beam 3b is scanned at a high speed, such as, for example at a speed that repeats the predetermined scanning pattern <NUM> or more times per second, preferably <NUM> or more times, and even more preferably between <NUM> and <NUM> (both endpoints being included in the range) times per second, an effective laser spot is provided that makes possible to process the object <NUM> more accurately as the energy deposited on the object may be better controlled. Accordingly, even though the predetermined scanning pattern <NUM> is shown static, the entire surface <NUM> of the object <NUM> may be e.g. hardened with the apparatus <NUM> and, thus, the laser beam 3b is to be scanned according to the predetermined scanning pattern <NUM> at different parts of the surface <NUM>, for instance by superimposing a movement to the predetermined scanning pattern <NUM> so as to have a predetermined scanning trajectory or by generating a relative movement between the object <NUM> and the apparatus <NUM> or the scanner <NUM>. Further, the predetermined scanning pattern <NUM> may be changed while irradiating the different parts of the surface <NUM> so that the energy is deposited thereon as desired, as exemplarily illustrated in <FIG>.

<FIG> illustratively show, in two dimensions, how the predetermined scanning pattern <NUM> of <FIG> changes as the laser beam is to be scanned. The arrows superimposed on the predetermined scanning pattern 8a-8c represent a direction in which the laser beam is to be scanned so as to follow the pattern; it is readily apparent that different directions for scanning the laser beam are possible within the scope of the present disclosure.

<FIG> shows the first predetermined scanning pattern 8a commanded to the scanner <NUM> for scanning the laser beam 3b. The first scanning pattern 8a resembles the number eight in digital form (i.e. straight lines and sharp change of directions).

<FIG> shows the second predetermined scanning pattern 8b commanded to the scanner <NUM> as the laser beam 3b could reach the oil lubrication hole <NUM> to the predetermined scanning trajectory. In order not to irradiate the oil lubrication hole <NUM>, the second predetermined scanning pattern 8b has two endpoints 9a, 9b at which the laser beam is scanned so as to go backwards, as seen in <FIG> in which when the laser beam reaches the second endpoint 9b, the laser beam is scanned in reverse direction until it reaches the first endpoint 9a, where it is reversed again, and so on and so forth.

As the laser beam advances owing to the predetermined scanning trajectory, the oil lubrication hole <NUM> falls within the third predetermined scanning pattern 8c, which is equal to the first predetermined scanning pattern 8a. The laser beam may be scanned without reversing the direction as occurred with the second predetermined scanning pattern 8b.

<FIG> illustratively shows the system of <FIG> with the laser beam 3a, 3b being scanned according to an expected scanning pattern <NUM>.

Albeit the scanner <NUM> is commanded to scan the laser beam 3b according to the predetermined scanning pattern <NUM>, which in this example changes as described with reference to <FIG>, the scanner <NUM> is unable to scan it accurately and, thus, the laser spot <NUM> may follow a pattern similar to the expected scanning pattern <NUM>.

There are many factors that influence the capability of the scanner <NUM> to actually scan the laser beam 3b according to the desired scanning pattern (the predetermined scanning pattern <NUM> of <FIG> and <FIG>), such as the weight of the mirrors, the moment of inertia of the mirrors, the rotating speeds of the mirrors, and the maximum angular coverage (in both directions, only the maximum angular coverage <NUM> in one direction being represented with dotted lines for the sake of clarity) or maximum angular area coverage that the scanner <NUM> is configured to cover. Hence, the expected scanning pattern <NUM> features curvilinear lines and smooth corners.

<FIG> illustratively show, in two dimensions, how the expected scanning pattern of <FIG> changes as the predetermined scanning pattern 8a-8c of <FIG> changes.

The scanner <NUM> is commanded to scan according to the predetermined scanning patterns 8a-8c of <FIG>, however the laser spot <NUM> is expected to follow the pattern illustrated in <FIG>.

The first expected scanning pattern 18a, shown in <FIG>, is a continuous pattern meanwhile the oil lubrication hole <NUM> is outside of it. The second expected scanning pattern 18b, shown in both <FIG>, makes the laser beam to stop at first and second endpoints 19a, 19b (so that oil lubrication hole <NUM> is not irradiated) and go in the reverse direction every time one of these endpoints 19a, 19b is reached. The third expected scanning pattern 18c is equal to the first expected scanning pattern 18a as illustrated in <FIG>.

<FIG> illustratively shows, in two dimensions, differences between a predetermined scanning pattern <NUM> and an expected scanning pattern <NUM>.

As it can be appreciated, the expected scanning pattern <NUM> has curvilinear lines and rounded corners whereas the predetermined scanning pattern <NUM>, according to which the scanner is operated, has straight lines and sharp corners forming <NUM>° angles.

The arrows superimposed on the predetermined scanning pattern <NUM> and the expected scanning pattern <NUM> represent a direction in which the laser beam is to be scanned so as to follow the pattern. It is readily apparent that different directions for scanning the laser beam are possible within the scope of the present disclosure.

<FIG> illustratively shows, in two dimensions, a predetermined threshold area <NUM>-<NUM> according to the present disclosure.

The predetermined threshold area <NUM>-<NUM> is illustrated superimposed on the predetermined scanning pattern <NUM> and the expected scanning pattern <NUM> for the sake of clarity only. The predetermined threshold area <NUM>-<NUM> comprises a plurality of areas that are not connected one to each other. The predetermined threshold area may be defined in a number of ways. For example, each area of the plurality of areas may be defined based on the predetermined scanning pattern <NUM>, or more preferably based on the expected scanning pattern <NUM> since the pattern that the laser beam is expected to follow is generally regarded as the normal operation of the scanner; in the latter case, if the expected scanning pattern <NUM> is defined by statistically determining the likeliness with which the laser beam deviates when scanned according to the predetermined scanning pattern <NUM>, the predetermined threshold area <NUM>-<NUM> may be defined for scanning deviations that amount to less than a certain value, for example less than <NUM>%, or less than <NUM>%, or less than <NUM>% of a Gaussian distribution of the scanned laser beam. The predetermined threshold area <NUM>-<NUM> may be made larger or smaller depending on the allowed or tolerated margin of error of the scan, accordingly the determination that the scan of the laser beam is anomalous will allow more or less error.

The actual scanning pattern, that is, the pattern that the laser beam actually follows is compared with the predetermined threshold area <NUM>-<NUM>. In this case, it is desirable that the actual scanning pattern or at least part thereof (preferably, a majority of the actual scanning pattern) is outside of the predetermined threshold area <NUM>-<NUM> because the predetermined threshold area represents excessive deviation of the actual scanning pattern.

If the actual scanning pattern coincides with the expected scanning pattern <NUM>, which hardly ever happens, no part of the actual scanning pattern falls within the predetermined threshold area <NUM>-<NUM>. This means that in order to determine that a scan of a laser beam is anomalous, instantaneous determinations (i.e. it is enough that, according to at least one processed measurement, the actual scanning pattern is within the predetermined threshold area <NUM>-<NUM> at one time instant to determine that the scan is anomalous) or ranged determinations (i.e. the actual scanning pattern is within the predetermined threshold area <NUM>-<NUM> at a plurality of time instants, according to a plurality of measurements, to determine that the scan is anomalous) may be carried out.

Ranged determinations are generally preferred since occasional errors in the scan may occur without existing a problem in the scanner that would result in further errors, or that would result in frequent or continuous anomalous scans. Depending on the number of occasional errors over a period of time or over a range of comparisons, or depending on the percent of occasional errors with respect to a range of comparisons (e.g. at least <NUM>% of the comparisons of a range of comparisons being inside or outside of the predetermined threshold area, in this case inside of the predetermined threshold area; other exemplary values may be, e.g. at least <NUM>%, at least <NUM>%, at least <NUM>%, etc.), it may be indicated that the object is not correctly processed yet the laser apparatus and the scanner are not stopped so that further objects may be processed.

In these and in other embodiments, the range of comparisons may include: a number of comparisons within a scanning trajectory (which may include a single scanning pattern, a number of repetitions of a scanning pattern, a plurality of scanning patterns, etc.), a number of comparisons in one single scanning pattern, a number of comparisons in a number of scanning pattern repetitions, etc. Preferably, the number of comparisons comprises a number of consecutive comparisons, that is, comparisons of consecutive points of the actual scanning trajectory with the predetermined threshold area.

<FIG> illustratively shows, in two dimensions, a predetermined threshold area <NUM> according to the present disclosure.

The predetermined threshold area <NUM> is illustrated superimposed on the predetermined scanning pattern <NUM> and the expected scanning pattern <NUM> for the sake of clarity only. The predetermined threshold area <NUM> may be defined in a number of ways. For example, it may be defined based on the predetermined scanning pattern <NUM>, or more preferably based on the expected scanning pattern <NUM>. The predetermined threshold area <NUM> may be made larger or smaller depending on the allowed or tolerated margin of error of the scan.

The actual scanning pattern is compared with the predetermined threshold area <NUM>. In this case, it is desirable that at least part of the actual scanning pattern (preferably, a majority of the actual scanning pattern) is outside of the predetermined threshold area <NUM> because the predetermined threshold area represents excessive deviation of the actual scanning pattern.

In this case, however, the predetermined threshold area <NUM> comprises area in the center overlapping both the predetermined scanning pattern <NUM> and the expected scanning pattern <NUM> (in other examples it could overlap only one of these, for example the predetermined scanning pattern <NUM>). It is expected and desired (according to the predetermined scanning pattern <NUM>) that the laser spot of the laser beam irradiates a surface of an object in this center-most area.

In order to determine that a scan of a laser beam is anomalous, it is carried out a ranged determination because at some time instants the laser spot is expected to be within the predetermined threshold area <NUM>. Accordingly, it is determined that the scan is anomalous if a number of comparisons or a percent of comparisons (with respect to a range of comparisons) of the actual scanning pattern and the predetermined threshold area <NUM> exceeds a predetermined threshold value.

The predetermined threshold value may be established based upon a frequency with which encoders of the mirrors of the scanner provide measurements to the computing device or system carrying out the comparisons and determinations of whether the scan is anomalous, and also based upon the number of commanded repetitions of the predetermined scanning pattern <NUM> per second (something which influences the rotating speeds of the mirrors of the scanner). From the frequency and the number of commanded repetitions it can be determined how many comparisons may be carried out per repetition, and how many times the actual scanning pattern will be expected to be within the predetermined threshold area <NUM> due to the overlap between said area <NUM> and the expected scanning pattern <NUM>. Therefore, the predetermined threshold value should be greater than the number of times the actual scanning pattern will be expected to be within the predetermined threshold area <NUM> so as to determine a possibly anomalous scan.

In comparison with the predetermined threshold area <NUM>-<NUM> of <FIG>, the predetermined threshold area <NUM> of <FIG> may be less preferable because it lacks an area at the outer-most part of the expected scanning pattern <NUM> (such as the area <NUM> of <FIG>). Such area at the outer-most part is convenient for determining that a scan entailing a greater risk for the safety of people is anomalous, mainly because a laser beam being aimed at said outer-most part may be aimed further away from the expected scanning pattern <NUM> and, therefore, out from the working area.

In some other embodiments, the predetermined threshold area only comprises area at the outer-most part of the expected scanning pattern <NUM> (such as the area <NUM> of <FIG>). Also, in some other embodiments, the predetermined threshold area may be provided as the areas <NUM>, <NUM> of <FIG> that do not overlap the expected scanning pattern <NUM> and/or the predetermined scanning pattern <NUM>. In such embodiments, the determination that a scan of a laser beam is anomalous may be carried out either as instantaneous determinations (because the expected scanning pattern <NUM> does not overlap the area <NUM>, or the areas <NUM>, <NUM> forming the predetermined threshold area) or as ranged determinations.

The actual scanning pattern is compared with the predetermined threshold area <NUM>. In this case, it is desirable that the actual scanning pattern or at least part thereof (preferably, a majority of the actual scanning pattern) is inside of the predetermined threshold area <NUM> because the predetermined threshold area represents lack of deviation of the actual scanning pattern.

The determination that a scan of a laser beam is anomalous is carried out either as instantaneous determinations or as ranged determinations, depending on which one or more than one comparison should be outside of the predetermined threshold area <NUM> to determine that the actual scanning pattern has deviated and, therefore, the scan may be anomalous.

When the predetermined scanning pattern and the expected scanning pattern changes during the processing of objects, for instance as described with reference to <FIG> and <FIG>, the predetermined threshold areas also change so that the comparison between the actual scanning pattern and the predetermined threshold area corresponds. By way of example, if the second predetermined scanning pattern 8b and the second expected scanning pattern 18b are considered, the predetermined threshold area will be influenced by the endpoints 9a, 9b, 19a, 19b and, thus, the actual scanning pattern during that part of the processing will have to be outside of the predetermined threshold area (if the area is defined as in <FIG>) or inside of the predetermined threshold area (if the area is defined as in <FIG>) with regards to the position of the oil lubrication hole <NUM>.

Even though the expected scanning pattern <NUM> has been represented as a line, the same may be in some cases represented as a line having a thickness (thus, having an area) which illustrates where the spot of the energy beam is expected to be when the expected scanning pattern <NUM> is defined by means of a statistical determination. The thickness may be selected based, for example, on the standard deviation of a normal distribution.

<FIG> illustratively shows, in two dimensions, a comparison between an actual scanning pattern <NUM> and the predetermined threshold area <NUM> of <FIG>.

The encoders of the mirrors of the scanner sense the absolute position of the mirrors within the scanner, the angle of the mirrors, or the movement of the mirrors. The values sensed are then processed by a computing device or system for determining the actual scanning pattern <NUM> of a laser beam. The actual scanning pattern <NUM> is then compared with the predetermined threshold area <NUM> to determine whether the scan is anomalous.

As it may be observed in <FIG>, there are two portions 26a, 26b of the actual scanning pattern <NUM> that fall outside from the predetermined threshold area <NUM>. Depending on the criteria for determining that the scan is anomalous (e.g. number of points or percent of points outside from the predetermined threshold area <NUM>), the existence of such two portions 26a, 26b may result in the determination that the scan is in fact anomalous, or that it is not anomalous (i.e. a greater percent or number of points must be out from the predetermined threshold area <NUM>). Accordingly, if it is established that one or two points are enough to determine that the scan is anomalous, in the example of <FIG> it would be determined that the scan is in fact anomalous; if it is more than two points, depending on the number of points in the portions 26a, 26b the same determination could be made.

Even though the actual scanning pattern <NUM> illustrated is shown as a continuous line, it is readily apparent that the measurements provided by the encoders are discrete, thus the actual scanning pattern <NUM> determined by the computing device or system is a cloud of discrete points rather than a continuous line. Each point of the cloud of points may be compared with the predetermined threshold area <NUM>. The computing device or system may, in some embodiments, connect consecutive discrete points to provide a continuous actual scanning pattern <NUM> in order to make the comparison, however this is normally not necessary.

<FIG> diagrammatically shows a system <NUM> in accordance with an embodiment.

The system <NUM> comprises a computing device or system <NUM>, a laser apparatus <NUM> with a laser source (not illustrated) for providing a laser beam with a power over e.g. <NUM> kW, for instance <NUM> kW, <NUM> kW, <NUM> kW, etc. and less than e.g. <NUM> kW, such as <NUM> kW or <NUM> kW, and a scanner <NUM>. The computing device or system <NUM> is connected to the laser apparatus <NUM> and the scanner <NUM>, for example with means such as cables <NUM>, <NUM>, or through a programmable logic controller in turn connected to the laser apparatus <NUM> and/or the scanner <NUM>, or with Ethernet connections through a switch or router, etc..

According to the present invention, the scanner <NUM> comprises a first mirror <NUM>, a second mirror <NUM>, at least a first encoder <NUM> that senses and provides measures of the first mirror <NUM>, and at least a second encoder <NUM> that senses and provides measures of the second mirror <NUM>. The first and second mirrors <NUM>, <NUM> scan the laser beam provided by the laser apparatus according to scanning patterns or trajectories.

The computing device or system <NUM> comprises at least one processor <NUM>, at least one memory <NUM>, and means <NUM> for transmitting and receiving data. The computing device or system <NUM> may comprise input means and user interfaces that enable an operator to adjust and control the operation of the computing device or system <NUM>, something which may also be carried out remotely by transmitting data to and receiving data from the computing device or system <NUM> through the means <NUM>.

The at least one processor <NUM>, together with the at least one memory <NUM> and the means <NUM>, processes measurements provided by the at least first and second encoders <NUM>, <NUM> so as to determine the actual scanning pattern of the laser beam as scanned, compares the actual scanning pattern with a predetermined threshold area (that may include a plurality of areas not connected one to each other), and determines whether the scan is anomalous. Further, the at least one processor <NUM> may operate the laser apparatus <NUM> and/or the scanner <NUM> so as to change the laser beam provided, e.g. the power thereof, the diameter of the laser spot, etc. and/or the scan of the laser beam, e.g. the predetermined scanning pattern, the rotating speeds of the mirrors, etc..

In the present disclosure, the computing device or system <NUM> may be a single device, i.e. a computing device; or it may be a plurality of computing devices that are communicatively coupled, i.e. a computing system, each of which carries out one or more computing operations, or all computing devices carry out one or more computing operations in a distributed manner.

<FIG> diagrammatically shows a method <NUM> in accordance with an embodiment.

The method <NUM> comprises a step of providing <NUM> an apparatus (for example, the apparatus <NUM> of <FIG>, <FIG>, <FIG>) configured to provide an energy beam, e.g. a laser beam, that is to be scanned with a scanner. The method <NUM> further comprises a step of providing <NUM> a scanner (for example, the scanner <NUM> of <FIG>, <FIG>, <FIG>) configured to scan the energy beam provided by the apparatus.

The method <NUM> further comprises a step of operating <NUM> the apparatus and the scanner such that the energy beam is provided while it is scanned according to a predetermined scanning pattern. In some embodiments, this step is carried out by at least one processor of a computing device or system (for example, the computing device <NUM> of <FIG>, <FIG> or the computing device or system <NUM> of <FIG>).

The method <NUM> further comprises a step of determining <NUM> an actual scanning pattern (for example, the actual scanning pattern <NUM> of <FIG>) of the energy beam, when both the apparatus and the scanner are operated, by processing measurements provided by encoders of a first mirror and a second mirror of the scanner. This step is carried out by the at least one processor of the computing device or system.

The method <NUM> further comprises a step of comparing <NUM> the actual scanning pattern with a predetermined threshold area (for example, any of the predetermined threshold areas <NUM>-<NUM>, <NUM> of <FIG>). This step is carried out by the at least one processor of the computing device or system.

The method <NUM> may further comprise a step of determining <NUM> that the scan of the energy beam is anomalous if at least part of the actual scanning pattern is inside or outside of the predetermined threshold area. This step is carried out by the at least one processor of the computing device or system.

The method <NUM> comprises the same steps of method <NUM> of <FIG>, and further comprises one or both of the following steps: indicating <NUM>, if it is determined <NUM> that the scan of the energy beam is anomalous, that an object that was processed by the apparatus is incorrectly processed; and stopping <NUM> the apparatus for emitting an energy beam if it is determined <NUM> that the scan of the energy beam is anomalous. In some embodiments, these steps may be carried out by the at least one processor of the computing device or system.

In some embodiments, the method comprises: obtaining data indicative of the actual scanning pattern being different from the predetermined scanning pattern, and modifying the predetermined scanning pattern based on said data. This may involve reprogramming, thus optimizing, the system based on the data indicative of the actual scanning pattern, for example by instructing the scanner to operate more in accordance with the actual scanning pattern, that is to say, by providing to the scanner new instructions that better correspond to the actual operation of the scanner than original instructions.

The data indicative of the actual scanning pattern can, for example, comprise data originating from encoders of the scanner <NUM>, for example, encoders indicative of the real movements of the mirrors or similar of the scanner. Thus, once the real movement followed by the mirrors is detected, the corresponding data can be used to optimize the operation of the scanner <NUM> so as to operate not according to the predetermined scanning pattern <NUM>, but according to the actual scanning pattern, or according to a more or less similar scanning pattern. Thus, the system including the scanner <NUM> can end up being programmed in a manner that better reflects the actual operation of the scanner <NUM>. Thereby, the scanner can be subjected to less operational stress when operated. This serves to minimize the risk of damage to the scanner <NUM> or to operational failures of the type that tend to appear when a scanner <NUM> is operated at its operational limits, for example, forced to follow a scanning pattern including abrupt changes at a high speed. The steps of obtaining data indicative of the actual scanning pattern being different from the predetermined scanning pattern, and modifying the predetermined scanning pattern based on the data indicative of the actual scanning pattern, can be repeated several times, such as as often as deemed possible, until a desired conformity between the programmed (predetermined) scanning pattern and the actual scanning pattern followed by the energy beam has been reached, so as to ensure that the system with scanner ends up being programmed in a manner that substantially coincides with its actual operation, thereby minimizing the operational stresses. Albeit embodiments have been described in which laser beams are scanned according to an exemplary predetermined scanning pattern, it is readily apparent that laser beams may be scanned according to other different scanning patterns and which also fall within the scope of the present disclosure. By way of example, upon determining an expected scanning pattern as herein disclosed when the scanner scans an energy beam according to a predetermined scanning pattern, the scanner may be commanded to scan an energy beam with a predetermined scanning pattern defined on the basis of the determined expected scanning pattern; accordingly, the scanner can be subjected to less operational stress when operated yet an expected scanning pattern and one or more predetermined threshold areas are then determined for the operation of the machine as herein disclosed.

In this text, the terms "actual scanning pattern" and "actual scanning trajectory" refer to the scanning pattern and the scanning trajectory, respectively, as determined based on the processed measurements. Therefore, errors in the processing made result in the determination of a scanning pattern and a scanning trajectory different from the actually followed by the laser beam and the laser spot thereof, as it will be readily apparent to the person skilled in the art. Accordingly, these terms could as well be referred to as, for example but without limitation, "determined scanning pattern" and "determined scanning trajectory", respectively.

Claim 1:
A method for supervision of a scan of an energy beam, comprising:
providing (<NUM>) an apparatus (<NUM>) configured to provide the energy beam;
providing (<NUM>) a scanner (<NUM>) configured to scan the energy beam, the scanner (<NUM>) comprising a first mirror (<NUM>) and a second mirror (<NUM>), and each mirror comprising at least one encoder (<NUM>, <NUM>), and
operating (<NUM>) the apparatus (<NUM>) and the scanner (<NUM>) such that the energy beam is provided while it is scanned according to a predetermined scanning pattern (<NUM>);
characterized in that the method further comprises:
determining (<NUM>), by at least one processor of a computer device or system (<NUM>), an actual scanning pattern of the energy beam, while both the apparatus (<NUM>) and the scanner (<NUM>) are operated, by processing measurements provided by encoders of the first mirror and the second mirror;
comparing (<NUM>), by the at least one processor, the actual scanning pattern with a predetermined threshold area (<NUM>-<NUM>, <NUM>); and
determining (<NUM>), by the at least one processor, whether the scan of the energy beam is anomalous based on the comparison (<NUM>).