Abstract: Apparatus for producing an object by means of additive manufacturing, comprising: a process chamber for receiving on a build surface of a build plate a bath of powdered material which can be solidified; a support for positioning said build plate in relation to a surface level of said bath of powdered material; a solidifying device for solidifying a selective part of said material; and a homing device for moving said build surface, by said support, to a home position such that said object can be build on said build surface of said build plate, wherein said homing device comprises a homing member which can be displaced along said build surface of said build plate, wherein said homing device is designed for moving said build surface to said home position until a measured force for displacing said homing member is within a pre-determined range. Method for producing an object by means of additive manufacturing.

Abstract: Apparatus for producing an object by means of additive manufacturing, comprising: a process chamber for receiving on a build surface of a build plate a bath of powdered material which can be solidified; a support for positioning said build plate in relation to a surface level of said bath of powdered material; a solidifying device for solidifying a selective part of said material; and a homing device for moving said build surface, by said support, to a home position such that said object can be build on said build surface of said build plate, wherein said homing device comprises a homing member which can be displaced along said build surface of said build plate, wherein said homing device is designed for moving said build surface to said home position until a measured force for displacing said homing member is within a pre-determined range. Method for producing an object by means of additive manufacturing.

Abstract: Apparatus for producing an object by means of additive manufacturing, comprising: a process chamber for receiving on a build surface of a build plate a bath of powdered material which can be solidified; a support for positioning said build plate in relation to a surface level of said bath of powdered material in said process chamber; a solidifying device for solidifying a selective part of said material; and a homing device for moving said build surface, by said support, to a home position. Method of producing an object by means of additive manufacturing on a build surface of a build plate.

Abstract: An encoder-type measurement system is configured to measure a position dependent signal of a movable object. The measurement system includes a light source and a sensor. The light source and the sensor are mounted on one of the movable object or a substantially stationary frame. The measurement system also includes a reference object that includes a grating or grid mounted on the other of the movable object or the substantially stationary frame. The light source is configured to emit a light beam towards the reference object. The sensor is configured to detect light of the light source reflected by the reference object. The measurement system also includes an error detector capable of detecting errors in or on the grating or grid of the sensor target object during a continuous production process.

Abstract: A lithographic apparatus includes a positioner configured to position a first part of the apparatus relative to a second part of the apparatus, the positioner including a motor having a motor position dependent motor constant defining a relation between a motor input and a motor output, and a control system to drive the motor, the control system including a set-point generator to provide a reference signal based on a desired position of the first part relative to the second part, and a controller to provide a drive signal to the motor based on the reference signal, wherein the controller includes a compensator which is configured to at least partially compensate the drive signal for the motor position dependent motor constant. The invention further relates to a positioner, a method to optimize the positioning system, and a method to derive a motor position dependent motor constant.

Abstract: In an embodiment, a stage system calibration method includes moving the stage relative to an encoder grid in response to a setpoint signal and measuring a position of the stage by a sensor head cooperating with the encoder grid. The position of the stage is controlled by a stage controller. A signal representative of a difference between the setpoint signal and the position of the stage as measured by the sensor head is registered. The stage system is calibrated from the registered signal representative of the difference.

Abstract: A lithographic apparatus includes a positioner configured to position a first part of the apparatus relative to a second part of the apparatus, the positioner including a motor having a motor position dependent motor constant defining a relation between a motor input and a motor output, and a control system to drive the motor, the control system including a set-point generator to provide a reference signal based on a desired position of the first part relative to the second part, and a controller to provide a drive signal to the motor based on the reference signal, wherein the controller includes a compensator which is configured to at least partially compensate the drive signal for the motor position dependent motor constant. The invention further relates to a positioner, a method to optimize the positioning system, and a method to derive a motor position dependent motor constant.

Abstract: In an embodiment, a stage system calibration method includes moving the stage relative to an encoder grid in response to a setpoint signal and measuring a position of the stage by a sensor head cooperating with the encoder grid. The position of the stage is controlled by a stage controller. A signal representative of a difference between the setpoint signal and the position of the stage as measured by the sensor head is registered. The stage system is calibrated from the registered signal representative of the difference.

Abstract: An encoder-type measurement system is configured to measure a position dependent signal of a movable object. The measurement system includes a light source and a sensor. The light source and the sensor are mounted on one of the movable object or a substantially stationary frame. The measurement system also includes a reference object that includes a grating or grid mounted on the other of the movable object or the substantially stationary frame. The light source is configured to emit a light beam towards the reference object. The sensor is configured to detect light of the light source reflected by the reference object. The measurement system also includes an error detector capable of detecting errors in or on the grating or grid of the sensor target object during a continuous production process.