An overlay measurement device measures an error between a first overlay mark and a second overlay mark respectively formed on different layers formed on a wafer. The device is configured to detect a height of the first overlay mark based on a change in the signal of the first detector according to a change in the relative position of the objective lens with respect to the wafer in the optical axis direction and detect a height of the second overlay mark based on a change in the signal of the second detector according to a change in the relative position of the objective lens with respect to the wafer in the optical axis direction.

An overlay measurement device measures an error between a first overlay mark and a second overlay mark respectively formed on different layers formed on a wafer. The device is configured to detect a height of the first overlay mark based on a change in the signal of the first detector according to a change in the relative position of the objective lens with respect to the wafer in the optical axis direction and detect a height of the second overlay mark based on a change in the signal of the second detector according to a change in the relative position of the objective lens with respect to the wafer in the optical axis direction.

Overlay is determined for a device using signals measured from the device and a signal response to overlay determined from a plurality of calibration targets. Each calibration target has the same design as the device, but includes a known overlay shift. The calibration targets may be located in a scribe line, within a product area on the wafer, or on a separate calibration wafer. Each calibration target may have a different overlay shift, including zero overlay shift. The device may serve as a calibration target with zero overlay shift. The overlay shift may be in two orthogonal directions. The signal response to overlay may be determined based on a set of signals obtained from the calibration targets. A second set of signals may then be obtained from the device and the overlay determined based on the second set of signals and the determined signal response to overlay.

Overlay is determined for a device using signals measured from the device and a signal response to overlay determined from a plurality of calibration targets. Each calibration target has the same design as the device, but includes a known overlay shift. The calibration targets may be located in a scribe line, within a product area on the wafer, or on a separate calibration wafer. Each calibration target may have a different overlay shift, including zero overlay shift. The device may serve as a calibration target with zero overlay shift. The overlay shift may be in two orthogonal directions. The signal response to overlay may be determined based on a set of signals obtained from the calibration targets. A second set of signals may then be obtained from the device and the overlay determined based on the second set of signals and the determined signal response to overlay.

Aspects for active alignment for assembling optical imaging systems are described herein. As an example, the aspects may include aligning an optical detector with an optical component. The optical component is configured to alter a direction of one or more light beams emitted from an image displayed by an optical engine. The aspects may further include detecting, by the optical detector, a virtual image generated by the one or more light beams emitted by the optical engine; and adjusting, by a multi-axis controller, an optical path of the one or more light beams based on one or more parameters of the virtual image collected by the optical detector.

A lithographic process is used to form a plurality of target structures distributed at a plurality of locations across a substrate and having overlaid periodic structures with a number of different overlay bias values distributed across the target structures. At least some of the target structures comprising a number of overlaid periodic structures (e.g., gratings) that is fewer than said number of different overlay bias values. Asymmetry measurements are obtained for the target structures. The detected asymmetries are used to determine parameters of a lithographic process. Overlay model parameters including translation, magnification and rotation, can be calculated while correcting the effect of bottom grating asymmetry, and using a multi-parameter model of overlay error across the substrate.

A lithographic process is used to form a plurality of target structures distributed at a plurality of locations across a substrate and having overlaid periodic structures with a number of different overlay bias values distributed across the target structures. At least some of the target structures comprising a number of overlaid periodic structures (e.g., gratings) that is fewer than said number of different overlay bias values. Asymmetry measurements are obtained for the target structures. The detected asymmetries are used to determine parameters of a lithographic process. Overlay model parameters including translation, magnification and rotation, can be calculated while correcting the effect of bottom grating asymmetry, and using a multi-parameter model of overlay error across the substrate.

The invention relates to a method and an apparatus for ascertaining a positional deviation of a brake disc (30) relative to a caliper seat (11). According to the invention, an angular deviation (34) from the parallel between the brake disc (30) and the caliper seat (11) is measured in that an apparatus (1) for ascertaining the positional deviation of the brake disc (30) is connected to the caliper seat (11), the apparatus (1) comprising at least two distance sensors (20, 22) that are stationary with respect to the caliper seat (11) and take measurements in the direction of a first flat face of the brake disc (30), the distance sensors (20, 22) transmitting distances (A, A′) between the first flat face of the brake disc (30) and the distance sensors (20, 22) measured at different radii (R, R′) of the brake disc (30) to an evaluation device, the angular deviation (34) of the brake disc (30) being ascertained by the evaluation device from the distances.

The invention relates to a method and an apparatus for ascertaining a positional deviation of a brake disc (30) relative to a caliper seat (11). According to the invention, an angular deviation (34) from the parallel between the brake disc (30) and the caliper seat (11) is measured in that an apparatus (1) for ascertaining the positional deviation of the brake disc (30) is connected to the caliper seat (11), the apparatus (1) comprising at least two distance sensors (20, 22) that are stationary with respect to the caliper seat (11) and take measurements in the direction of a first flat face of the brake disc (30), the distance sensors (20, 22) transmitting distances (A, A′) between the first flat face of the brake disc (30) and the distance sensors (20, 22) measured at different radii (R, R′) of the brake disc (30) to an evaluation device, the angular deviation (34) of the brake disc (30) being ascertained by the evaluation device from the distances.

A system and method of calibrating an ADAS sensor of a vehicle by aligning a target with the sensor, where the vehicle is initially nominally positioned in front of a target adjustment stand that includes a stationary base frame and a movable target mount configured to support a target, with the target adjustment stand including one or more actuators for adjusting the position of the target mount. A computer system is used to determine an orientation of the vehicle relative to the target adjustment stand, with the position of the target mount being adjusted based on the determined orientation of the vehicle relative to the target adjustment stand. Upon properly orienting the target mount, and the target supported thereon, a calibration routine is performed whereby the sensor is calibrated using the target.