DE102009031233A1 - Device to structure thin-film solar cell module, where structural lines are introduced in module parallel to its transverse edges in rectangular form by laser, includes loading- and unloading station, processing station, and optical device - Google Patents

Abstract

The device for structuring thin-film solar cell modules, where the structural lines are introduced in the module parallel to its transverse edges in a rectangular form by a laser, comprises a loading station (1), an unloading station (3), a processing station (2) arranged between the loading station and the unloading station, which has a working table in a processing plane (8), an optical device having a laser arranged below the working table, a scanner arranged downstream to the laser in a beam direction, a beam expansion and focusing optics, and a transport device. The device for structuring thin-film solar cell modules, where the structural lines are introduced in the module parallel to its transverse edges in a rectangular form by a laser, comprises a loading station (1), an unloading station (3), a processing station (2) arranged between the loading station and the unloading station, which has a working table in a processing plane (8), an optical device having a laser arranged below the working table, a scanner arranged downstream to the laser in a beam direction, a beam expansion and focusing optics, which is present in a beam path between the laser and the processing plane and focuses a laser beam emerging from the laser in dependent of a deflection angle of the scanner in the processing plane, and a transport device (4) that is designed to transport the module into the processing plane over the assigned working table in a transport direction in the direction of its longitudinal edges. The scanner is a single-axis scanner with a scanning mirror, which is tiltable around the axis, to guide the emerging laser beam vertical to the axis in a scanning direction over the module scanned with alternating sense of direction. The axis with the transport direction has a scanning angle of 90-180[deg] . The scanning mirror and the transport direction are controllable, so that the scanning speed and the transport speed are coordinated to each other in dependent of the scanning angle, so that the laser beam generates a structure line parallel to the transverse edge of the module. The loading station and the unloading station have supporting surfaces in a supporting plane, which deeply lies in a ratio to the processing plane, and a lifter with supporting elements, on which the resting module is highly lifted or lowered between the supporting plane and the processing plane. The supporting elements of the lifter are formed as conveyor belt to transport the lifted module into the processing station up to in a starting position for processing. The working table is formed from table elements, which are arranged and placed to each other, so that a gap is formed between the two adjacent table elements and runs in the direction of the scanning direction and the laser beam is impinged onto the module in an unhindered manner. The table elements are adjustable to each other, where the course of the gap is adapted to optionally changing scanning direction. The optical device is a first optical device, which includes laser, beam expansion and focusing optics and single-axis scanner and is arranged onto a pivoting table that is pivotable around a vertical pivot axis to set the scanning direction. The first optical device, whose axes are aligned in same direction, is provided to produce structural lines parallel to each other. The optical device is a second optical device, which includes laser, beam expansion and focusing optics and second single-axis scanner. A deflection mirror is arranged downstream to the beam expansion and focusing optics to couple the laser beam alternatively in first- or second single-axis scanner and is pivotable in two end positions.

Description

The invention relates to a device for structuring thin-film solar cell modules, as generically from the US 6,559,411 B2 is known.

Thin film solar cell modules (Modules) are made by placing on a substrate that has the function a carrier layer has, several, usually three, functional layers be applied. Each after applying a functional layer is at least these at regular intervals parallel lines (structure lines), each of which together is a structure line group form, again removed, what is called structuring.

The Coating and structuring processes serve for formation individual solar cells and their electrical interconnection. It is known for structuring a laser to use its laser beam either directly or indirectly through the substrate is directed through in the layer to be removed.

Of the Laser is with its wavelength and its power in Dependence on the material and the layer thickness of each selected functional layer to be removed and relative to coated substrate along the desired structure lines moves, usually focusing in the ablated layer becomes.

The Requirements for the structuring process are complex.

A The first requirement is that the structure line groups do not overlap to safely rule out that they do not come into contact with each other. The optionally Resulting risk of short circuit or incorrect connection questions the entire functionality of the module. Around To secure this requirement, the structure line groups with made a safety distance offset from each other.

The necessary width of this safety distance depends on the parallelism, the straightness and the width of the Structure lines down, as with the respective structuring method is reachable.

There the area between two adjacent structure lines by the given width of the module and a selected one Safety margin, the active energy conversion intended Area of solar cells is lost, decreases with increasing Size of the safety distance the efficiency of the module. It is therefore desirable to have a high accuracy Parallelism, best straightness and a constant width the structural lines to achieve the safety distance low to be able to shape.

A Another requirement is that the cycle time, here as the time between feeding and removing the module in or out of the device is to be understood as possible should be short. The cycle time for the introduction of structuring a module with the dimensions of z. B. 1.1 m × 1.3 m should not exceed 60 s. The tact time includes the Process auxiliary times in which a module from a loading position into a position for process execution and after process execution is brought into a removal position, and the process time itself, in which the process of structuring takes place.

From the US 6,559,411 B2 a device for structuring coated glass substrates by means of laser is known with a loading station, an unloading station and a processing station arranged therebetween. The glass substrate to be processed is transported vertically aligned between the stations in the horizontal direction, being rearranged along a transport and processing plane from a loader wagon to an accurately controlled conveyor and subsequently to a discharge wagon.

The Device further comprises a laser and a galvanometer controlled XYZ scanner, which uses a laser beam emitted by the laser deflects a double mirror assembly in the x-y direction, whereby the Laser beam can describe a freely programmable scan line, and by means of focusing optics, the focus of the laser beam in dependence shifts from the deflection angle in the z direction, so this always is moved in a plane.

With Such a device becomes due to the use of an XYZ scanner although a high process speed (structuring speed) achieved, however, the use of this scanner verifiably to deviations from the straightness of the structure lines. They are lost in a non-reproducible waveform passing through the superimposed Movements of the double mirror arrangement in the x and y direction due unavoidable thermal and electrical effects are not ideal Just surrendered. For example, was for a scan field of 600 mm Width is a deviation from a straight line of more than 20 μm and for a scan field of 1250 mm width, a deviation measured from a straight line of over 40 microns.

In order to safely avoid the superposition of structure-line groups, the possible deviations of the structure lines from a straight line into the layout of the solar cells must be included. The means that the safety distance must be increased with increasing width of the module and thus the width of the scan field. The result is a reduction in the efficiency of the individual solar cells and thus of the module.

From the US 6,300,593 a generic device is known in which a scanning movement of a pulsed laser beam is generated by a polygon mirror. In this case, a laser beam is scanned in a direction perpendicular to the direction of the structure lines, wherein it impinges in the distances of the structure lines on Fokussierlinsen that focus the laser beam respectively to the substrate to be structured. At the same time, the substrate is moved in the direction of the structure lines, so that quasi-simultaneous a number of structure lines are generated, equal to the number of the focusing lenses acted upon by the laser beam.

The Speed will be very high in accordance with the pulse rate Highly selected, what with today commercially available Lasers to a distortion of the incident laser spot and thus to a broadening of the structure lines outside the Tolerance leads.

In the WO 2007/144565 a device is described with a two-axis scanner, which is similar to that in the US 6,559,411 B2 described scanner structure lines generated whose course is determined by the superimposed movement of two mirrors.

In order to remedy the drawbacks already presented, which arise with such a scanner for the quality of the structure lines, it is proposed here that the length of the scan line, as determined according to FIG US 6,559,411 is equal to the length of a structure line corresponding to the width of the coated substrate to be processed, by scanning the structure lines not in a scanning motion but in sections.

The scan regime runs according to the WO 2007/144565 as well as the US 6,559,411 according to the method of the so-called "bow tie scanning". The trajectory described by the laser beam, like a "male fly", is composed of track sections formed by two parallel straight lines with a length dependent on the spacing of the structure lines and two intersecting straight lines connecting the opposite ends of the parallel straight lines.

While the movement along the track sections of the intersecting straights are due to the overlap with the rectilinear feed motion of the substrate two structural lines perpendicular to the advancing movement or structure line sections generated, which are per closed Movement path two structure lines or structure line sections.

While the movement along the track sections of the parallel straight line either the laser is turned off, which has the disadvantage of being set pulse stability is lost or it remains turned on, which is only possible if the entire structure line is created in a scanning motion and additional measures requires that the then emptied laser beam no Damage caused. As such an additional Action comes primarily a laser beam trap in Consider that provided here along the two longitudinal edges of the substrate would have to be.

At the Scanning of only structure line sections is different from Scanning the entire structure line in one additional scan Action required to section the scanner (s) It must be ensured that not only the Ends of the structure line sections are set exactly together, but also that if as suggested several scanners for different sections of a structure line are used, these sections are exactly in alignment. The advantages achieved stand increased adjustment, stability and tax expenditures and the risk of erroneous transitions between adjacent ones Opposite sections.

Of the Prior art shows a development in which the technical effort is increasingly increased to quality high-quality structure lines at a high process speed to create.

Of the Invention is based on the object, a device for structuring of thin-film solar cell modules that comparatively with a device technology low effort structuring high quality.

These The object is achieved by a device having the features of the claim 1 solved.

advantageous Further developments are described in the subclaims.

It is essential to the invention that, unlike the most obvious prior art, by the US 6,559,411 is formed as a scanner Einachsscanner is used, a scanner mirror is tilted about an axis which includes with the transport direction of the transport means an angle of less than 180 ° and greater than 90 ° to the incident laser beam in a scanning direction perpendicular to the axis 23 to be able to scan across the module with changing sense of direction.

Of the Scanner mirror and the transport device each have one Drive on, which are controlled to each other to control the Scan speed of the scanner mirror and the transport speed set the transport device so that the laser beam a generated parallel to the transverse edges of the module structure line.

By doing the laser beam deflection exclusively via The tilting of only one scanner mirror is surprising Way a better straightness of the structure line achieved.

Based In the drawing, the device will be closer in the following example explained.

It demonstrate:

1a - 1b a device in side view with a module to be machined in different positions

2 a plan view of the support plane of a device according to the 1a - 1b

3 a plan view of the transport plane of a device according to the 1a - 1b

4 a second optical device of a device

5 a schematic diagram for explaining the scanning direction

In the 1a and 1b is shown in a simplified schematic representation of an advantageous embodiment of a device according to the invention with its essential features, which does not claim to be a real dimensioning or complete representation raises.

The device has a support plane 5 and a working plane 8th on, of which in each case a plan view in the 2 and 3 is shown, which is reduced to the essential features in the relevant level.

The device comprises at least one optical device 12 which is advantageous as a first optical device 12.1 , presented in the 1a - 1b , or a second optical device 12.2 represented in 4 , can be executed. The 5 serves the easier understanding of the relative position of transport and scanning direction.

With the device should be readily known from the prior art, generic devices thin-film solar cell modules (Modules) are laser structured by placing in a Module, which takes the form of a rectangular plane plate with longitudinal and transverse edges, spaced structure lines be introduced parallel to the transverse edges.

The device comprises a loading station 1 , a processing station 2 , an unloading station 3 and a transport device 4 ,

The loading station 1 and the unloading station 3 each have bearing surfaces 16 for the module to be processed 6 in a support plane 5 on.

The bearing surfaces become advantageous 16 the loading and unloading station 1 . 3 formed by at least two mutually synchronously driven, spaced-apart conveyor belts, whereby the module 6 in the loading station 1 introduced and transported in a predetermined excavation position (s. 1a ) or from the unloading station 3 can be removed from a predetermined Absenkposition.

In addition, the loading and unloading station include 1 . 3 each a lifter 7 with support elements 15 , with which the module 6 on the support elements 15 lying on the support plane 5 in a higher working plane 8th lifted high or from the working plane 8th in the lower lying support level 5 can be lowered.

The support level 5 is a horizontally oriented plane that is either at an ergonomic height to be machined by a worker of the device module 6 to lead or remove from this, or preferably in a matched to the device optionally upstream and / or downstream handling systems height.

The working level 8th is located in the focal plane one to the processing station 2 belonging optical device 12 , which is preferred as a first optical device 12.1 or a second optical device 12.2 is executed.

The processing station 2 includes next to a work table 17 in the working plane 8th at least one below the work table 17 arranged optical device 12 ,

According to a first embodiment, two first optical devices 12.1 available, each with a laser 9 , a one-axis scanner downstream in the direction of radiation 10 (X-scanner) and one between the laser 9 and the single axis scanner 10 existing beam widening and focusing optics 11 getting one from the laser 9 coming laser beam depending on the respective deflection angle of the single-axis scanner 10 into the working plane 8th focused.

If according to further embodiments, a plurality of first optical devices 12.1 are provided, the axes must 23 to their scanner level 22 be tilted, aligned in a same direction to produce mutually parallel structure lines.

Because the scanning direction 24 a single-axis scanner 10 through the only one existing axis 23 to the the scanner mirror 22 is tilted, is determined, ie the scanning direction 24 runs perpendicular to the axis 23 , is the scanning direction 24 not adjustable as with a two-axis scanner via a coordinated control of two scanner mirrors.

The scanning direction 24 is solely due to the positioning of the one axis 23 of the single-axis scanner 10 and thus the positioning of the optical device 12 to the transport device 4 that the module 6 in the working plane 8th in the transport direction 13 transported, determined.

To the scanning direction 24 at a selectable scan angle α to the transport direction 13 to set up is the first optical device 12.1 advantageous on a swivel table 14 arranged around an axis 23 cutting, vertical pivot axis is pivotable.

The scan angle α, the scan speed and the transport speed of the transport device 4 while editing the module 6 are coordinated so that the laser beam is perpendicular to the transport direction 13 running structure line generated.

Due to the fact that the course of the generated structure line is determined by the superimposition of the transport movement and the scan movement, ie the course of the structure line is composed of the rectilinear trajectory of the transport device 4 and this perpendicular, also rectilinear trajectory of the laser beam, these two movements must be matched with their speed exactly matched.

As the scanning movement in the scanning direction 24 takes place with changing sense of direction, it has alternately a movement component in the sense of direction of the transport movement (scanning direction 24.1 with sense of direction to the transport movement) and a movement component in the opposite direction sense to the transport movement (scan direction 24.2 with opposite sense of direction of the transport movement).

The transport movement is by its transport direction 13 and the sense of direction from the loading station 1 away, to the unloading station 3 clearly defined.

A structure line perpendicular to the transport direction 13 running, is only generated during the scan movement 24.1 in the direction of the transport movement.

Consequently, the laser becomes 9 only driven to emit a laser beam when the scanner mirror 22 is pivoted in a sense of direction while turning the scanner mirror 22 is turned off in the other direction.

The cycle time can be reduced by using several first optical devices 12.1 are present, which are controlled simultaneously, which are simultaneously generated by means of multiple laser beams structure lines.

Advantageously, instead of two first optical devices 12.1 , each with a laser 9 , a single axis scanner 10 and a beam expanding and focusing optics 11 are equipped, also a second optical device 12.2 used as they are in 4 is shown.

This second optical device 12.2 includes two single-axis scanners 10 , a beam widening and focusing optics 11 and only one laser 9 and one between the laser 9 and the two single-axis scanners 10 positioned, swiveling deflecting mirror 19 ,

The deflection mirror 19 is pivotable between two end positions about a rotation axis, with a speed equal to the scanning speed of the two single-axis scanners 10 , Thus, the laser beam is alternately in the single-axis scanner 10 coupled, which scan at the same scanning speed in the opposite direction. The laser beam is thus, while it is in one of the two end positions, each in the single-axis scanner 10 coupled, the straight in the scanning direction 24.1 scans. It is important for the process accuracy that the two single-axis scanners 10 and the deflection mirror 19 in their movement and speed are precisely matched.

By an arrangement of more than one second optical unit 12.2 the process speed can be further increased.

This results in each second optical unit 12.2 a savings for a laser 9 and there is no need for the permanent switching on and off of the laser 9 ,

The module is used for editing 6 on the worktable 17 so to the transport device 4 positioned that the longitudinal edges of the module 6 in the transport direction 13 aligned so that the structure lines are parallel to the transverse edges.

By the scanning direction 24 by pivoting the swivel table 14 can be changed, at a given scan speed, which should be as high as possible in the interest of a short cycle time, the transport speed is not limited to a predetermined value, but can be selected within a process window. The transport speed can thus be tuned in accordance with the speed of the auxiliary processes, so that for the transport of a module 6 necessary time during processing not greater than the minimum time between the feeding of two successive modules to be processed 6 to the starting position.

The processing station 2 and consequently the optical device 12 , are between the loading station 1 and the unloading station 3 both on a base frame 18 are placed arranged. Also advantageous is the optical device 12 , if necessary with the swivel table 14 on the base frame 18 mounted, bringing almost the entire height of the support plane 5 above the base frame 18 can be used for the beam path of the laser beam.

By the working plane 8th regardless of the support level 5 can be provided at a high altitude, the beam path from the laser 9 right up to the processing level 8th , in which the laser beam in each position of the deflection angle of the single-axis scanner 10 focused, mainly in vertical direction. That is, a necessary space for the beam guidance is required in a non-interfering manner in the height of the device, rather than in the width, which would lead to a larger area requirement of the device in a workshop.

As already stated, the loading and unloading stations are 1 . 3 each with a lifter 7 fitted.

A module 6 , which in a predetermined Aushebeposition in the support plane 5 on the bearing surfaces 16 the loading station 1 and the support elements 15 of the lowered lifter 7 is brought to rest, by means of the lifter 7 into the working plane 8th lifted ( 1b ). For this purpose, the lifter 7 vertically in the loading station 1 or the unloading station 3 guided and with a motor driven lifting mechanism 20 fitted.

The support elements 15 the lifter 7 can be stationary or horizontally movable by z. B. equal to the bearing surfaces 16 the loading and unloading station 1 . 3 or particularly advantageous instead of the bearing surfaces so executed 16 are designed as conveyor belts.

In the latter case by means of conveyor belts of the lifter 7 the module 6 both transported to the lifting position when the lifter 7 in a lowered position, as well as the excavated module 6 in the processing station 2 , preferably transported to a starting position for processing, when the lifter 7 is in a raised position.

The start position is reached when the module 6 in the working plane 8th above the optical device 12 is located so that from this position, a first adjacent to a transverse edge structure line can be introduced.

At the latest in this starting position, the module 6 for transport during processing of the transport device 4 accepted.

The transport device 4 has two mutually parallel, horizontally aligned guide rails 21 on, between which the work table 17 is arranged. At the guide rails 21 are each provided a plurality of synchronously driven by a linear motor slide, each with a holder for grasping the longitudinal edges of the module 6 are equipped. The transport device 4 can be designed to be a module 6 transported from the excavated position to the lowered position. However, it is advantageous for the transport of the module 6 in the processing station 2 ie from a start position to a stop position, between which the module 6 is processed, limited, and the support elements 15 the lifter 7 are designed as conveyor belts to the excavated module 6 to transport to the start position and from the stop position.

The work table 17 is preferably a so-called air-vacuum table. Such a known from the prior art table has in its table surface on a plurality of openings, which are usually arranged in a grid. A part of these openings is connected to a Vakuumabsaugeinrichtung, which is why an ausfliegendes module 6 is pulled onto the table surface. The other part of the openings is connected to an air pressure device, which is why an overlying module 6 is pushed away from the table surface. On a suitable vote on the module 6 acting pressures can the module 6 above the table surface are held in suspension and it may also be deformations in the evenness of Mo duls 6 be compensated. There is no direct contact between the table surface and the module 6 is produced, the transport is frictionless and thus extremely gentle for the module 6 ,

So that of the optical devices 12 coming laser beams along the scanning direction 24 in the module 6 can be coupled, there is the work table 17 from several table elements. The table elements are designed and adjusted to each other that between two adjacently arranged table elements in each case a gap is formed, through which a laser beam freely on the module 6 can hit. The columns run in the direction of the scanning direction 24 ,

If necessary, change the column to a changed scanning direction 24 adapt, the table elements can be exchanged for differently designed table elements, or they are adjusted to each other, so that the course of the column of the changed scanning direction 24 can be adjusted.

In 3 are the three table elements of the work table shown here 17 in shape to a predetermined scanning direction 24 customized.

By using a single-axis scanner 10 In addition to the better straightness of the structure lines, which has already been explained, and to a technically simpler executable and controllable scanner compared to a two-axis scanner, further advantages result for generating the structure lines.

Above The scan area must be avoided for safety reasons an uncontrolled radiation emission in principle a laser beam trap will be installed.

In the same area is basically a suction provided, with which the removed material is sucked off. Usually, the extraction hood belonging to the extraction hood 25 designed so that it also takes over the function of a laser beam trap. For two-axis scanner is such a suction hood 25 Basically dimensioned so that it covers the entire possible scan area, which is usually designed as a large area extended hood.

A single axis scanner 10 is limited to one line in its scanning area, which is why a suction hood 25 can be designed accordingly as a narrow shaft, which is above the work table 17 , Advantageously fixed in its position changeable.

1

loading

2

processing station

3

unloading

4

transport means

5

support plane

6

module

7

Lifters

8th

machining plane

9

laser

10

Single-axis scanner

11

Strahlaufweitungs- and focusing optics

12

optical Facility

12.1

first optical device

12.2

second optical device

13

transport direction

14

Rotary table

15

support elements

16

bearing surface

17

worktable

18

base frame

19

deflecting

20

lifting mechanism

21

guide rail

22

scanner mirror

23

axis

24

scanning direction

24.1

scanning direction with sense of direction to the transport movement

24.2

scanning direction with opposite sense of direction of the transport movement

25

exhaust hood scan angle

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 6559411 B2 [0001, 0010, 0016]
• US 6300593 [0014]
• - WO 2007/144565 [0016, 0018]
• US 6559411 [0017, 0018, 0026]

Claims (8)

Device for structuring thin-film solar cell modules (modules ( 6 )), whereby in a module ( 6 ) are introduced with a rectangular shape parallel to the transverse edges of the structure lines by means of laser, with a loading station ( 1 ), an unloading station ( 3 ) and an intermediate processing station ( 2 ), a work desk ( 17 ) in a working plane ( 8th ) and at least one below the work table ( 17 ) arranged optical device ( 12 ) with a laser ( 9 ), at least one laser ( 9 ) in the radiation direction downstream scanner and one in the beam path between the laser ( 9 ) and the working level ( 8th ) existing beam widening and focusing optics ( 11 ), one from the laser ( 9 ) laser beam depending on the respective deflection angle of the scanner in the working plane ( 8th ) and a transport device ( 4 ), which is designed to be the module ( 6 ) in the processing level ( 8th ) via a work table (here 17 ) in a transport direction ( 13 ) in the direction of its longitudinal edges, characterized in that the scanner is a single-axis scanner ( 10 ), with a scanner mirror ( 22 ) around an axis ( 23 ) is tiltable to the incident laser beam perpendicular to the axis ( 23 ) in a scanning direction ( 24 ) with changing sense of direction ( 24.1 . 24.2 ) scanning through the module ( 6 ) to be able to cause the axis ( 23 ) with the transport direction ( 13 ) includes a scan angle (α) less than 180 ° and greater than 90 °, and that the scanner mirror ( 22 ) and the transport device ( 4 ) are controllable such that the scanning speed and the transport speed are coordinated with each other as a function of the scan angle (α), so that the laser beam is aligned with the transverse edges of the module ( 6 ) generates parallel structure line. Device according to claim 1, characterized in that the loading station ( 1 ) and the unloading station ( 3 ) each bearing surfaces ( 16 ) in a support level ( 5 ) in relation to the processing level ( 8th ) is lower, and in each case a lifter ( 7 ), with supporting elements ( 15 ) on which an overlying module ( 6 ) between the support level ( 5 ) and the working level ( 8th ) can be raised or lowered. Apparatus according to claim 2, characterized in that the support elements ( 15 ) of the lifter ( 7 ) are designed as conveyor belts to the excavated module ( 6 ) into the processing station ( 2 ) preferably to transport to a start position for processing. Device according to claim 1, characterized in that the work table ( 17 ) is formed from a plurality of table elements, which are designed and set to each other, that between two adjacently arranged table elements in each case a gap is formed, which in the direction of the scan direction ( 24 ) and through which a laser beam passes unhindered onto the module ( 6 ). Apparatus according to claim 4, characterized in that the table elements are mutually adjustable, whereby the course of the column of an optionally changed scanning direction ( 24 ) can be adjusted. Device according to claim 1, characterized in that the optical device ( 12 ) a first optical device ( 12.1 ), which is exactly one laser ( 9 ), a beam widening and focusing optics ( 11 ) and a single-axis scanner ( 10 ) and mounted on a swivel table ( 14 ) is arranged, which is pivotable about a vertical pivot axis to a scanning direction ( 24 ). Apparatus according to claim 6, characterized in that a plurality of first optical devices ( 12.1 ) whose axes ( 23 ) are aligned in the same direction to produce mutually parallel structure lines. Device according to claim 1, characterized in that the optical device ( 12 ) a second optical device ( 12.2 ), which is exactly one laser ( 9 ), a beam widening and focusing optics ( 11 ) and two single-axis scanners ( 10 ), and one of the beam widening and focusing optics ( 11 ) downstream deflecting mirror ( 19 ), which is pivotable in two end positions, in order to move the laser beam alternately into one or the other single-axis scanner ( 10 ).