A device for determining a focal position of a laser beam, in particular a processing laser beam in a laser processing head, has an optical decoupling element for decoupling a partial beam from a beam path of the laser beam, a detector for detecting at least one beam parameter of the partial beam, and at least one optical element with an adjustable focal length, which is arranged in a region of the beam path of the partial beam between the optical decoupling element and the detector. Also disclosed is a laser processing head which includes a device of this type, as well as a method for determining a focal position of a laser beam.

We describe an apparatus for producing a three-dimensional workpiece, the apparatus comprising: a process chamber for receiving a material from which the three-dimensional workpiece is producible using an additive layer manufacturing technique, wherein the process chamber comprises a translucent window; an irradiation device for irradiating, through the translucent window, the material for producing the three-dimensional workpiece; and an enclosure arranged between the translucent window of the process chamber and the irradiation device, wherein at least a part of the enclosure is translucent for an irradiation beam stemming from the irradiation device to travel from the irradiation device through the enclosure to the material for producing the three-dimensional workpiece, wherein the enclosure comprises an inlet and an outlet, and wherein the apparatus is configured to control a flow of a fluid through the enclosure via the inlet and the outlet.

We describe a device for calibrating an irradiation system of an apparatus for producing a three-dimensional workpiece, the irradiation system comprising an irradiation unit for selectively irradiating an irradiation beam onto an irradiation plane, wherein the device comprises: a control unit configured to control the irradiation system to irradiate the irradiation beam onto the irradiation plane, and an optical detection unit coupled to the control unit, wherein the optical detection unit comprises an optical detector and an objective lens for optically detecting a portion of the irradiation plane, wherein the optical detection unit is configured to detect a position of a spot of the irradiation beam on the irradiation plane, wherein the objective lens is adapted to be arranged, with respect to an irradiation beam path of the irradiation beam, between the optical detector and an irradiation beam scanner of the irradiation system, wherein the optical detection unit is configured to detect the position of the spot of the irradiation beam in multiple focal planes based on a focal length of the optical detection unit being adjustable, wherein the optical detection unit is configured to output a signal to the control unit in response to the optical detection unit detecting the position of the spot of the irradiation beam on the irradiation plane, and wherein the control unit is configured to control the irradiation system based on the signal output from the optical detection unit to the control unit.

We describe a device for calibrating an irradiation system of an apparatus for producing a three-dimensional workpiece, the irradiation system comprising an irradiation unit for selectively irradiating an irradiation beam onto an irradiation plane, wherein the device comprises: a control unit configured to control the irradiation system to irradiate the irradiation beam onto the irradiation plane, and an optical detection unit coupled to the control unit, wherein the optical detection unit comprises an optical detector and an objective lens for optically detecting a portion of the irradiation plane, wherein the optical detection unit is configured to detect a position of a spot of the irradiation beam on the irradiation plane, wherein the objective lens is adapted to be arranged, with respect to an irradiation beam path of the irradiation beam, between the optical detector and an irradiation beam scanner of the irradiation system, wherein the optical detection unit is configured to detect the position of the spot of the irradiation beam in multiple focal planes based on a focal length of the optical detection unit being adjustable, wherein the optical detection unit is configured to output a signal to the control unit in response to the optical detection unit detecting the position of the spot of the irradiation beam on the irradiation plane, and wherein the control unit is configured to control the irradiation system based on the signal output from the optical detection unit to the control unit.

A laser processing apparatus includes a condensing lens configured to form a condensing point of an applied laser beam and form a focus of a camera; a focus adjusting unit configured to adjust a height of the focus of the camera by moving a base to which the camera and the condensing lens are fixed in a height direction perpendicular to a holding surface of a chuck table; a condensing point adjusting unit disposed between a laser oscillator and the condensing lens, and configured to shift a height of the condensing point of the laser beam without changing a height of the condensing lens; and a control unit including a registering section configured to register the heights of the condensing point and the focus, the control unit being configured to control the focus adjusting unit and the condensing point adjusting unit on the basis of information of the registering section.

A laser lift-off integrated apparatus includes a laser light source configured to perform laser lift-off on a wafer to undergo lift-off, a lift-off chamber configured to bear the wafer to undergo lift-off, a heater configured to provide temperature required by the wafer to undergo lift-off during a lift-off process, a profile measuring device configured to acquire surface profile information of the wafer to undergo lift-off, and a movable device configured to, according to the surface profile information acquired by the profile measuring device, adjust a height of the wafer to undergo lift-off such that a focus of the laser light source is at a position where the wafer to undergo lift-off is to undergo lift-off.

A calculating section of a control unit calculates a vertical position Defocus for a condensing lens using a height value H1 of a modified layer in a wafer that is set by a setting section according to the equation (1) below.
Defocus=(thickness T1 of wafer−height value H1−b)/a  (1) The calculating section calculates an appropriate vertical position for the condensing lens according to the equation (1) depending on the height value H1 of the modified layer that is set by the setting section. Therefore, the vertical position of the condensing lens in laser processing operation can be determined more easily, and a time-consuming and tedious experiment for fine adjustment of the vertical position of the condensing lens does not need to be conducted.

A method for flame cutting of a workpiece, in particular a planar workpiece, with a thickness of at least 10 mm is performed by a laser beam with power of more than 10 kW and with oxygen as a cutting gas. Accordingly, a focal position in the beam direction of the laser beam is located within the workpiece at a depth that is greater than half the thickness of the workpiece. The laser beam emerges from a nozzle opening of a cutting gas nozzle together with the cutting gas, wherein a distance of a workpiece-side nozzle end face from the workpiece surface is at least 2 mm, preferably at least 3 mm, particularly preferably at least 5 mm.

A method of forming an object from a material includes directing a first beam of light toward a first target location of the material to define a first portion of the object. The method also includes, after directing the first beam of light toward the first target location, determining an optical correction to be applied by an optical system. The optical correction is based on an atmospheric change in an atmospheric distortion region proximate the first target location due, at least in part, to interaction of the first beam of light and the material. The method further includes directing a second beam of light toward a second target location of the material to define a second portion of the object. The second beam of light is directed through at least a portion of the atmospheric distortion region while the optical correction is applied.

A method of forming an object from a material includes directing a first beam of light toward a first target location of the material to define a first portion of the object. The method also includes, after directing the first beam of light toward the first target location, determining an optical correction to be applied by an optical system. The optical correction is based on an atmospheric change in an atmospheric distortion region proximate the first target location due, at least in part, to interaction of the first beam of light and the material. The method further includes directing a second beam of light toward a second target location of the material to define a second portion of the object. The second beam of light is directed through at least a portion of the atmospheric distortion region while the optical correction is applied.