WO2024046686A1 - Procédé et dispositif de projection laser - Google Patents

Procédé et dispositif de projection laser Download PDF

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Publication number
WO2024046686A1
WO2024046686A1 PCT/EP2023/071280 EP2023071280W WO2024046686A1 WO 2024046686 A1 WO2024046686 A1 WO 2024046686A1 EP 2023071280 W EP2023071280 W EP 2023071280W WO 2024046686 A1 WO2024046686 A1 WO 2024046686A1
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WIPO (PCT)
Prior art keywords
navigation
laser beam
laser
section
trajectory
Prior art date
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PCT/EP2023/071280
Other languages
German (de)
English (en)
Inventor
Markus Brunk
Martin Greggersen
Original Assignee
Lap Gmbh Laser Applikationen
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Publication date
Application filed by Lap Gmbh Laser Applikationen filed Critical Lap Gmbh Laser Applikationen
Publication of WO2024046686A1 publication Critical patent/WO2024046686A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/101—Scanning systems with both horizontal and vertical deflecting means, e.g. raster or XY scanners
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F19/00—Advertising or display means not otherwise provided for
    • G09F19/12—Advertising or display means not otherwise provided for using special optical effects
    • G09F19/18—Advertising or display means not otherwise provided for using special optical effects involving the use of optical projection means, e.g. projection of images on clouds
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3155—Modulator illumination systems for controlling the light source
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3179—Video signal processing therefor
    • H04N9/3182—Colour adjustment, e.g. white balance, shading or gamut
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1049—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam
    • A61N2005/105—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam using a laser alignment system

Definitions

  • the present invention relates to a method for laser projection using a laser device and to a laser device which is designed to carry out the method according to the invention.
  • Laser projectors are used in a wide variety of technical areas to project outlines and markings onto objects. As a rule, their lines can be projected clearly visibly onto a flat or curved surface, or onto a surface of any other contour, in a single-color projection, for example in a red, green or blue projection, or in a multi-color projection, in particular in a mixed-color projection.
  • the basis for the projection is often CAD data, which is processed into projection data and transmitted to one or more projectors.
  • Industrial laser projection systems create virtual but visible stencils on objects to be processed that do not touch or contaminate the surfaces.
  • the projection is usually carried out using one or more galvanometers, which can be used to change the orientation of a mirror in relation to a laser beam. The laser beam is deflected by the mirror, with the angle of rotation of the mirror determining the direction of deflection. If two or more galvanometers are combined with each other, every accessible point in the room can be illuminated.
  • the invention is based on the object of providing a method and a device for laser projection which allows the intensity of the laser beam to be adjusted to a predeterminable level using simple means.
  • a method for laser projection using a laser device comprising a laser generation unit by means of which a laser beam can be generated, a deflection device by means of which a beam angle of the laser beam can be adjusted for steering the laser beam along a predetermined trajectory, and a control device coupled to the laser generation unit by means of which the power of the Laser beam can be adjusted, wherein in a first step for the navigation of the laser beam along the predetermined trajectory, several navigation angles to be controlled by means of the deflection device are determined, with the navigation angles each being assigned a starting power, which specifies the power of the laser beam when deflecting between two navigation angles , and wherein in a next step, depending on the number of navigation angles to be controlled immediately one after the other, with which the laser beam reaches a navigation section of a reference surface, an expected dwell time of the laser beam in the navigation section is determined and that at least for a subset of the navigation angles with which the Laser beam reaches the navigation section, the respective starting power of the laser beam is set to
  • the present invention makes it possible to provide a laser projector that can be operated in compliance with specified laser safety classes.
  • a laser projector can be provided that meets the specified safety guidelines
  • the removable criteria for laser class 2 and laser class 3B are met. If certain laser classes are met, it can be achieved, for example, that a laser projector according to the invention can also be used without a laser protection officer who is otherwise necessary for operation in the company.
  • Compliance with certain laser classes can be achieved by limiting the total power that can be emitted by the laser projection device. For example, laser class 3B compliance can be achieved if the laser projection device does not exceed a total power of 500 mW.
  • Laser class 2 could also be achieved by selecting laser diodes with a maximum emitted power of 1 mW.
  • the power of 1 mW is unsuitable for use in a projector, as the projection would not be bright enough for its intended purpose due to the usual distance to the projection surface and the high speeds at which the laser beam is usually deflected.
  • a safety area can be defined, whereby predeterminable criteria outside the safety area, such as the criteria for laser class 2, are met and within the safety area other criteria are met that require classification in a higher laser class.
  • the method according to the invention is based on the idea of using safety criteria for pulsed beam sources, in particular regardless of whether a pulsed or an unpulsed radiation source is used to generate the laser beam. For example, based on currently valid safety guidelines, the energy of the laser beam when crossing an aperture of 7 mm can now be considered instead of the power to ensure compliance with the criteria necessary for a specific laser class.
  • the energy of the laser beam when sweeping over a specific area section can be determined by knowing the emitting power of the laser generation unit depending on the residence time of the laser beam within the area section determine.
  • the trajectory to be swept by the laser beam is usually determined by the sequential control of individual predetermined navigation angles using the deflection device.
  • the navigation angles are controlled one after the other at a short time interval from one another.
  • Each navigation angle is usually also assigned a laser power, which determines the laser power for this navigation angle.
  • the duration of the laser beam in a specific navigation section can be determined, for example, by multiplying the number of navigation angles to be controlled one after the other, with which the navigation section is reached, and the time interval.
  • the time interval between two navigation angles controlled one after the other can be 2 ps.
  • the time interval can be specified by a time constant that a controller uses as process time between individual control steps.
  • a curve to be projected with the laser device it can be provided in a first step to provide vector graphics, for example in SVG or DXF format. These vector graphics are usually processed using a computer processing method set up for this purpose and broken down into individual elements such as circle sections, lines and splines. This data is then transmitted to the laser projection device.
  • the laser projection device receives the data and processes it using a control device in such a way that an angle phi, an angle theta and a specific laser power are assigned in predeterminable time intervals of, for example, 2 ps.
  • the solid angle to be controlled by the deflection device consisting of the angle Phi and the angle Theta, can also be referred to as the navigation angle. This processing is called trajectoryization.
  • the data can be transferred to a controller, which uses the galvanometer drives and the laser drivers to cyclically and in real time follow the specified trajectory based on the navigation angles.
  • the rotation frequencies i.e. the repetition rates of a trajectory, are typically between 30 - 50 Hz.
  • the output power emitted by the laser generation unit is adjusted.
  • the laser powers of the individual sources are preferably adjusted in order not to exceed an expected energy in a navigation section resulting from the power of the laser beam and the dwell time.
  • an expected actual energy to be applied by means of the laser beam in the navigation section of the reference surface is determined on the basis of the predetermined starting powers of the laser beam and, if exceeded the actual energy over a first predeterminable limit energy, the starting powers are reduced to target powers in such a way that an expected actual energy is achieved which is less than or equal to the limit energy.
  • the setting of the starting powers assigned to the navigation angles to the target powers can be carried out in such a way that all starting powers to be set are reduced or increased by a specific factor.
  • each starting power to be adjusted is reduced or increased by a certain factor.
  • the setting of the starting power to the target power takes place before the activation of the laser, so that the laser does not exceed the predeterminable power or energy limit values when activated and thus immediately upon activation of the laser Compliance with certain laser classes is guaranteed.
  • increasing the starting power can also be considered.
  • An increase can be carried out, for example, if the actual energy of the laser beam to be expected in a navigation section is lower than a predeterminable limit energy. If the duration of the laser beam in the navigation section does not exceed a certain level, so that a predetermined limit energy or limit power of the laser beam in the navigation section under consideration is already undershot without adjustment, provision can also be made to leave the starting powers unchanged .
  • the expected actual energy to be applied by means of the laser beam in the navigation section of the reference surface can be calculated, for example, using the equation Eq. n
  • Equation Eq the actual energy; is the time interval between a previous and the considered navigation angle i; j is the starting power of the laser source of the laser beam assigned to the navigation angle i under consideration; S t is a scaling factor of the laser source; a is the first navigation angle considered and n is the last navigation angle considered.
  • the sum is formed for a number of consecutive navigation angles a to n, whereby the time duration is multiplied by the laser power P t and a scaling factor of the laser source. If there is more than one source, the equation must be expanded accordingly to include the laser power P xl and the scaling factor S xi of the other sources.
  • the actual energy can be determined using equation G2 when using a laser generation unit with two laser sources.
  • the time period t £ between two navigation angles i is usually the same.
  • the time period is therefore formed, for example, by a time constant t K , in particular a controller constant.
  • the time constant t K can be 2ps.
  • the limit energy can be determined for different laser power classes to be achieved.
  • a limit energy for laser class 2 can be determined using equation G3.
  • E limit is the limit energy
  • T is the dwell time of the laser beam in the navigation section under consideration
  • C 6 is a rating factor for the degree of focusing of the laser beam.
  • a value of 1 can be selected for the design factor C 6 , for example.
  • this expansion is taken into account in the design factor.
  • the method uses a collimated laser beam with a beam diameter of less than 7 mm.
  • the limit energy for laser class 3R can be determined, for example, using equation G4.
  • the dwell time T results from the sum of the time intervals between the navigation angles i considered. If the time intervals are the same, i.e. are present as a time constant, the dwell time T can be formed by multiplying the time constant by the number of navigation angles to be controlled immediately one after the other with which the laser beam reaches the navigation section of the reference surface under consideration.
  • the determined actual energy is higher than the limit energy to be undercut, it is considered to multiply the starting powers of the navigation angles under consideration by a correction factor in order to adjust the expected actual energy of the laser in the navigation section under consideration reduce that is at or below the limit energy.
  • the correction factor can be determined, for example, using equation G5.
  • an expected section power to be emitted by means of the laser beam in a navigation section of the first reference surface is determined on the basis of the target powers of the laser beam, and the section power is compared with a predeterminable limit power, and whereby if the expected section performance exceeds the limit performance at least for a subset of the Navigation angle with which the laser beam reaches the navigation section, the target powers are reduced in such a way that the expected section power is less than or equal to the limit power.
  • a section energy to be expected to be applied in the navigation section is first determined and linked to a repetition rate of the predetermined trajectory.
  • the section energy can be determined, for example, using equation Eq, or when using multiple laser sources using an adapted equation such as equation G2, where the actual energy corresponds to the section energy.
  • the section power can be determined, for example using equation G6, by multiplying the section energy by the repetition rate of the trajectory.
  • trajectory segments of the predetermined trajectory for which the laser beam reaches this navigation section are identified for at least one navigation section of the reference surface. By identifying trajectory segments with which the laser beam reaches the navigation section under consideration, it can first be recognized whether more than one trajectory section lies within the navigation section under consideration. In the following, a total energy of different combinations of these trajectory segments can be taken into account in order to determine whether a predeterminable limit energy is exceeded.
  • the trajectory segments are sections of the predetermined trajectory, each of which is composed of immediately successive navigation angles with which the laser beam reaches the navigation section under consideration.
  • a number of navigation angles assigned to the combination the trajectory section of the predetermined trajectory comprising the trajectory segments is determined, starting with a first navigation angle of the first trajectory segment of the combination and ending with a last navigation angle of the last trajectory segment of the combination along the trajectory section.
  • the number of possible combinations of different trajectory segments, each of which lies in the navigation section under consideration, increases with the number of identified segments.
  • the number of combinations can be found using equation G7.
  • the area of the predetermined trajectory, which includes identified trajectory segments of a combination, is a trajectory section assigned to the navigation section.
  • a trajectory section is assigned to each combination of trajectory segments.
  • a Trajectory section begins with a first navigation angle of a first trajectory segment lying within the navigation section
  • Such a trajectory section therefore includes all immediately successive navigation angles starting with a first navigation angle of a first trajectory segment and ending with a last navigation angle of a last trajectory segment of the combination.
  • N K is the possible number of combinations, which results from the number n TS of trajectory segments lying within the navigation section under consideration.
  • a first trajectory segment and one or more further trajectory segments immediately following one another are taken into account.
  • Immediately successive trajectory segments are those segments of the trajectory that follow one another directly in the direction of the temporal sequence of the navigation angle to be controlled or in the direction of movement of the laser along the trajectory, i.e. without skipping over segments in between, and also lie in the navigation section under consideration.
  • a combination can therefore consist of two or more than two trajectory segments located within the navigation section under consideration. It goes without saying that only a single run of the trajectory within a period is considered here. The trajectory segments that lie within a navigation section under consideration are therefore each different segments of a single run of the trajectory.
  • a reference duration is determined depending on the number of navigation angles assigned to the combination, a combination limit energy assigned to the combination being determined depending on the reference duration, and where An expected actual combination energy for the combination is determined from the sum of segment energies, each of which corresponds to the expected energy of the trajectory segments of the combination, and the actual combination energy is compared with the combination limit energy , and whereby when the combination actual energy exceeds the combination limit energy, at least for a subset of the navigation angles of the trajectory section, the starting power or target power of the laser beam assigned to the navigation angles is reduced in such a way that the expected combination -Actual energy is less than or equal to the combination limit energy.
  • the combination limit energy can also be determined for different laser power classes to be achieved. Analogous to equation G3, the combination limit energy can be determined for laser class 2, for example, using equation G8.
  • E KGE is the combination limit energy
  • RD is the reference duration for the combination under consideration
  • C 6 is the design factor to take into account the degree of focusing of the laser beam, which, as explained above, can be 1, for example.
  • the combination limit energy for laser class 3R can be determined, for example, using equation G4 analogously.
  • the reference duration RD can be determined from the sum of the time intervals between the individual navigation angles of the combination under consideration, starting with a first navigation angle of the first trajectory segment of the combination and ending with a last navigation angle of the last trajectory segment of the combination along the trajectory section. So not only the navigation angles of the individual trajectory segments of the combination are taken into account, but also those between two immediately successive trajectory segments.
  • the reference duration RD can therefore be determined, for example, using equation G9.
  • RD is the reference duration for the combination under consideration
  • t t is the time interval between a previous and the considered navigation angle i
  • a is the first navigation angle considered
  • n is the last navigation angle considered.
  • the reference duration can be determined from multiplying the time constant t K by the number of navigation angles n considered, i.e. in particular using equation G10.
  • the segment energies can be determined using equation Gi l. Equation Eq Equation G2 can be applied. To avoid repetition, further explanations are therefore omitted.
  • E SE is the segment energy of a trajectory segment under consideration
  • t t is the time interval between a previous and the considered navigation angle i
  • P[ is the starting power assigned to the navigation angle i under consideration or the target power of the laser source of the laser beam adjusted after previous method steps have been applied
  • Si is a scaling factor of the laser source
  • a is the first navigation angle and n is the last navigation angle of the trajectory segment under consideration.
  • the time duration for laser projectors of the generic type is analogous to the explanations for equations Gl and G2 between two navigation angles i preferably the same.
  • the laser power previously assigned to the navigation angles considered i.e. the starting or target power set up to this method step
  • the power setting can be done, for example, using equation Eq. 2.
  • P new is the set new power assigned to a navigation angle under consideration
  • P att is the old power associated with a navigation angle under consideration
  • E KGE is the combination limit energy
  • E KIE is the combination-actual energy.
  • the power of the laser beam is adjusted using pulse width modulation.
  • a distance from objects detected in the detection range of the distance sensor to the laser device is monitored by means of a distance sensor. This makes it possible to recognize that an object is within a predetermined safety distance.
  • the priority is to use the distance sensor to detect people, in particular the head of a person, who are within a safe distance.
  • the distance sensor only detects when an object is within a set safety distance. It is therefore not necessary to record the actual distance.
  • a suitable distance sensor could therefore be set up to detect an object located in the security area based on a threshold value being exceeded.
  • the distance sensor is designed and set up to determine a distance from a detected object or to generate a signal by means of which a distance to the object can be determined.
  • the power of the laser beam depends on the distance monitored by the distance sensor is set, the laser generation unit being deactivated, in particular if the safety distance falls below a predeterminable safety distance.
  • the reference surface is calculated as a virtual surface which extends over an angular range, in particular over the entire angular range, of a navigation range that can be reached by the laser beam.
  • the navigation area that can be reached by the laser beam is essentially determined based on the exit opening of the laser device of the solid angle that can be reached with the deflection device.
  • the virtual reference surface has a spherical shape and extends at a distance from the laser projection device, the distance of the virtual reference surface corresponding in particular to the safety distance.
  • the distance of the virtual reference surface can be selected, for example, according to local conditions and/or according to predeterminable safety criteria.
  • the reference area is divided into a grid comprising several grid cells, with each grid cell corresponding to a navigation section that can be reached by the laser beam.
  • a navigation section can, for example, have a rectangular outer contour.
  • the outer contour of a navigation section is square.
  • any value can be selected in the navigation section, for example a value based on certain standardized specifications.
  • the edge length can be a value between 4 mm, or less than 4 mm, and 10 mm, or more than 10 mm.
  • a square outer contour with an edge length of 7 mm is considered.
  • the laser generating unit has two or more than two laser beam sources, with the beams generated by the two or more than two laser beam sources being superimposed to generate the laser beam.
  • a red laser with a starting power assigned to the navigation angles of 100% of its maximum power is used together with a green laser with a starting power assigned to the navigation angles of 50% of its maximum power.
  • a different power setting of the laser sources enables the projection of different mixed colors.
  • both sources can be reduced proportionally, for example the red laser to 50% and the green laser to 25% of their respective maximum power.
  • the individual sources must be individually adjusted, for example using individually adjustable pulse width modulation.
  • the deflection device has at least one movable mirror, in particular at least one galvanometer mirror, by means of which the laser beam can be deflected to adjust the beam angle.
  • a safety problem can arise if the deflection device unintentionally remains inoperative or does not reach the desired deflection speed due to malfunctions.
  • the actual duration of the laser beam in a specific navigation section can be longer than the calculated one Length of stay.
  • a predetermined speed of a drive unit of the deflection device is monitored by means of a monitoring device.
  • This monitoring can, for example, be intended to determine whether the actual angle of the deflection device corresponds to the intended target angle. Deviations between the actual angle and the target angle are also called “following errors”.
  • provision can be made to check the resulting speed from both mirror movements against a limit speed. With this monitoring, mirrors that remain completely non-functional, i.e. “sticky” mirrors, can be detected.
  • a laser device for laser projection comprising a laser generation unit by means of which a laser beam can be generated, a deflection device by means of which a beam angle of the laser beam can be adjusted for steering the laser beam along a predeterminable trajectory, and a control device coupled to the laser generation unit by means of which the power of the laser beam is controlled is adjustable, the laser device being designed and set up to carry out a method according to the invention according to one of the previously explained embodiments.
  • FIG. 1 is a schematic view of a laser device according to the invention
  • FIG. 2 shows a schematic representation of navigation angles to be controlled by means of a laser device according to the invention
  • FIG. 3 shows a detail of a reference area with navigation sections in a schematic representation
  • FIG. 4 shows a navigation section of the reference area from FIG. 3 in a schematic representation
  • FIG. 5a shows a navigation section of a reference surface with a trajectory section intersecting the navigation section in a schematic representation
  • Fig. 5b is a schematic representation of individual trajectory segments that lie within the navigation section from Fig. 5a.
  • FIG. 1 shows a laser device 10, also generally referred to as a projector, with a laser generating unit 12 which generates a laser beam 14.
  • the laser beam 14 is directed by means of a deflection device 16 in such a way that the laser beam 14 sweeps over a predeterminable trajectory 18 in space.
  • the power setting of the laser generation unit can be carried out by means of a control device 20 coupled to the laser generation unit 12.
  • the control device 20 and/or a further control device provided for this purpose can control the deflection device 16 in such a way that a predetermined navigation angle X (FIG. 2) is controlled.
  • a distance sensor 30 can be provided to detect objects in a detection range of the distance sensor 30.
  • the deflection device 16 can be set up to direct the laser beam 14 into any navigation angle X located in a navigation area 28.
  • the navigation area 28 can be in Radiation area of the laser device 10 may be conical.
  • the detection range of the distance sensor 30 is preferably larger or at least as large as the navigation range 28 that can be reached with the laser beam 14.
  • the laser generating device 12, the control device 20 and the deflection device 16 can be arranged in a common housing 26.
  • the distance sensor can also be arranged inside, but also on or outside of the housing.
  • a reference surface 24 is formed - here shaped spherically to the deflection point of the laser beam 14 on the deflection device 16.
  • This reference surface 24 can in particular be arranged at a safety distance that corresponds to a safety area monitored by the distance sensor 30.
  • the reference surface 24 is a virtually generated spatial surface that serves to adjust the power of the laser device 10 according to the invention.
  • a first criterion 1 to adjust the power of the laser sources of the laser device by two mechanisms.
  • a diode current of a laser diode on the laser driver the maximum laser power that should be emitted can be specified.
  • This value is preferably set once and is preferably unchangeable.
  • a largely linear adjustment of the emitted power can be achieved by pulse width modulation of the signal at the laser diode.
  • This intensity value which can be adjusted using a power value, is determined for each point of the trajectory and is used, for example, to make the projected figure appear equally bright.
  • the power setting can be influenced in order to avoid any violation of the laser class.
  • the basic frequency of this pulse width modulation is, for example, 20 MHz and therefore has a period of 50 ns, which in turn can be divided into 271 stages of 184 ps each.
  • This Pulses therefore have a minimum length of 184 ps and a maximum length of 50 ns. They therefore fall under this criterion 1.
  • FIG. 2 shows purely schematically a simple example of a spatial trajectory 18 to be controlled with the laser beam 14 of a laser device 10.
  • the trajectory 18 is formed by controlling several navigation angles X.
  • the navigation angles Xi to Xi shown in FIG. 2 for purposes of illustration are controlled one after the other by means of the deflection device 16. Since the navigation angles
  • the navigation angle X is formed from two angle information phi and theta. With this pair of angles phi and theta, any solid angle within the navigation area 28 of the laser device 10 can be controlled.
  • the angle information phi and theta are used to set the deflection device 16.
  • Figure 3 shows a virtual reference surface 24 in a schematic representation.
  • the reference surface 24 is divided into a grid with square grid cells 32 in the present example, each grid cell 32 corresponding to a navigation section 22 that can be reached by the laser beam 14.
  • 3 also shows purely schematically a trajectory 18 swept over by the laser beam 14.
  • the laser beam 14 reaches different navigation sections 22 when controlling the navigation angles X of the trajectory 18.
  • Figure 4 shows a navigation section 22 from Figure 3 in detail.
  • successively controlled navigation angles X of a segment of the trajectory 18 lying within the navigation section 22 are shown.
  • the area of the trajectory 18 that lies within the navigation section 22 is referred to as the trajectory segment TS.
  • eleven navigation angles X lie within the navigation section 22.
  • the dwell time is 22 ps (11 x 2 ps).
  • a trajectory projection 18 in the projection area 28 onto a grid 32 of a reference surface 24 is divided by a second criterion 2, as already explained above, to divide a trajectory projection 18 in the projection area 28 onto a grid 32 of a reference surface 24.
  • this grid 32 is preferably at the distance of the security area from the projector 10 and more preferably has a spherical shape.
  • the entire theoretically reachable area 28 of the projector 10 is covered by the sphere.
  • the preferably square cells of the grid 32 of the sphere preferably have an edge length of 7 mm in both directions on the spherical surface.
  • Each point of the trajectory 18 is assigned to a cell or a navigation section 22 of the grid or the reference surface 24 based on its coordinates or navigation angle X.
  • FIG. 4 schematically shows, for example, a single cell or a single navigation section 22 from the example in Figure 3.
  • the sub-area of the trajectory 18 is symbolized by points representing navigation angle ps of trajectory 18 represents.
  • the energy for each 2 ps step is determined from the known maximum laser power of the sources and the adjustable power using pulse width modulation.
  • the sum of all 2 ps steps in this pulse is the pulse energy.
  • the permissible limit value is obtained, for example, using equation G3, with the time being determined by the number of pulses multiplied by 2ps.
  • compliance with laser class 2 can be made possible in a certain safety area.
  • compliance with laser class 3R can be made possible for the distance of, for example, 100 mm in front of the projector.
  • a grid with an edge length of 7 mm can be used, which leads to different pulse lengths of the trajectory segments TS and power setting values for the navigation angles X under consideration.
  • the power values for the navigation angles when the calculated limit values are exceeded, the power values for the navigation angles
  • a third criterion 3 provision can be made in a third criterion 3 to re-evaluate the power settings of the navigation angle X corrected, for example, after taking criterion 2 into account.
  • this criterion 3 the sum of the energies for all pulses or trajectory segments TS is considered, which are in a grid cell or in a navigation section 22 within a certain time, of, for example, 0.25 seconds. This also includes the repetitions of the pulses or trajectory segments TS, which occur within the navigation section 22 under consideration due to the projection frequency of, for example, 25 to 50 Hz.
  • the total power of a cell or a navigation section 22 may not be greater than 1 mW at a distance from the protected area and not more than 5 mW at a distance of 100 mm (cf. laser class 2 or 3R). If the limit is exceeded, a correction is carried out for the entire cell, i.e. for all navigation angles X with which the laser beam 14 reaches the navigation section 22. For this purpose, all power values of the navigation angles
  • FIG. 5a shows a schematic representation of another example of a navigation section 22 with a section of a trajectory 18, with four sub-segments TS1 to TS4 lying within the navigation section.
  • Figure 5b shows schematically the compilation of various combinations of sub-segments TS1 to TS4 from Figure 5a located within the navigation section 22. Between the sub-segments TS1 to TS4, intermediate pieces ZI to Z3 are indicated, which represent the trajectory areas which lie along the trajectory 18 between the first trajectory segment TS1 reaching the navigation section 22 and the last trajectory segment TS4 reaching the navigation section 22 and thus outside the navigation section 22.
  • trajectory section TAI includes, for example, all navigation angles are defined accordingly.
  • a fourth criterion 4 to consider multiple pulses, i.e. several trajectory segments TS occurring in a navigation section 22 within a period T. This occurs, for example, when the trajectory 18 intersects itself.
  • An example of a cell or a navigation section 22 with several trajectory segments TS within a period T is - as mentioned - shown in Figure 5a.
  • Figure 5b the time course of the four trajectory segments TS1 to TS4 within this cell or the navigation section 22 is indicated schematically. All four trajectory segments TS are passed through within a period T of a trajectory 18. This can be seen in the time sequence in the diagram in FIG. 5b.
  • the diagram shows purely schematically the power P of the trajectory segments TS over time. First, the navigation angle X of the trajectory segment TS1 is controlled, then the trajectory segments TS2 to TS4 follow. Then the period T ends and a new run begins.
  • the four individual pulses TS1 to TS4 can already be taken into account in criterion 2. However, since the pulses can occur irregularly in number, length and distance within a periodic cycle, additional virtual pulses must also be included Trajectory sections called TA, against which limits from criterion 2 are checked. This can be done for different laser classes, for example for both laser class 2 and laser class 3R.
  • the virtual pulses or trajectory sections TA are defined by considering several consecutive pulses together.
  • the successive pulses or trajectory segments TS of a virtual pulse are also referred to here as combination K. This can be seen specifically in Figure 5b. In this example cell with four pulses TS1 to TS4, six additional virtual pulses or trajectory sections TAI to TA6 are defined.
  • equations G3 and G4 from criterion 2 can, for example, be used to determine the limit value for the respective virtual pulse or the respective trajectory section TA.
  • the virtual pulses or trajectory sections TAI to TA6 are each shown in Figure 5b as an arrow under the diagram.
  • the first virtual pulse TAI the sum of the energies of the first two individual pulses TS1 and TS2 of the combination Kl is determined as well as the length, i.e. the reference duration RD, of the trajectory section TAI from the beginning of the trajectory segment TS1 to the end of the trajectory segment TS2.
  • the sum of the energies of the first three individual pulses TS1 to TS3 is determined as well as the length, i.e. the reference duration RD, of the trajectory section TA2 from the beginning of the trajectory segment TS1 to the end of the trajectory segment TS3.
  • the other virtual pulses TA3 to TA6 are considered accordingly.

Abstract

L'invention concerne un procédé de projection laser et un dispositif laser (10) pour mettre en œuvre de ce procédé. Selon l'invention, le procédé comprend l'utilisation d'un dispositif laser (10) comprenant une unité de production de laser (12) au moyen de laquelle un faisceau laser (14) peut être produit, un appareil de déviation (16) au moyen duquel un angle d'émission du faisceau laser (14) peut être ajusté afin de diriger le faisceau laser (14) le long d'une trajectoire spécifiée (18), et un appareil de commande (20), couplé à l'unité de production de laser (12), au moyen duquel la puissance du faisceau laser (14) peut être ajustée, dans lequel dans une première étape pour la navigation du faisceau laser (14) le long de la trajectoire spécifiée (18), une pluralité d'angles de navigation à atteindre au moyen de l'appareil de déviation (16) sont déterminés, une puissance de démarrage étant attribuée aux angles de navigation, laquelle puissance de démarrage spécifie la puissance du faisceau laser (14) pendant la déviation entre deux angles de navigation, et dans lequel dans une étape suivante en fonction du nombre d'angles de navigation à atteindre directement successivement et avec laquelle le faisceau laser (14) atteint une section de navigation (22) d'une surface de référence (24), un temps de séjour attendu du faisceau laser (14) dans la section de navigation (22) est déterminé et au moins pour un sous-ensemble des angles de navigation avec lesquels le faisceau laser (14) atteint la section de navigation (22), la puissance de démarrage respective du faisceau laser (14) est ajustée à une puissance cible dépendant du temps de séjour déterminé.
PCT/EP2023/071280 2022-09-01 2023-08-01 Procédé et dispositif de projection laser WO2024046686A1 (fr)

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DE102022122155.5A DE102022122155B3 (de) 2022-09-01 2022-09-01 Verfahren und Vorrichtung zur Laserprojektion

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080106654A1 (en) * 2004-11-05 2008-05-08 Benner William R Audience scanning light projector and associated methods
WO2018036688A1 (fr) * 2016-08-25 2018-03-01 Robert Bosch Gmbh Procédé et dispositif de balayage d'une surface de projection à l'aide d'un faisceau laser
US20200159009A1 (en) * 2018-11-19 2020-05-21 Virtek Vision International Ulc System and method for limiting laser exposure of arbitrary laser template projection

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102018201508B4 (de) 2018-02-01 2021-03-18 Robert Bosch Gmbh Verwendung in einem LiDAR-System eines Verfahrens zum Betrieb eines LiDAR-Systems durch Aussenden von Laserlicht in Form von Laserpulsen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080106654A1 (en) * 2004-11-05 2008-05-08 Benner William R Audience scanning light projector and associated methods
WO2018036688A1 (fr) * 2016-08-25 2018-03-01 Robert Bosch Gmbh Procédé et dispositif de balayage d'une surface de projection à l'aide d'un faisceau laser
US20200159009A1 (en) * 2018-11-19 2020-05-21 Virtek Vision International Ulc System and method for limiting laser exposure of arbitrary laser template projection

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