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US 11,231,375 B2Granted
Apparatus for high-speed surface relief measurement
AssigneeWisconsin Alumni Research Foundation
InventorsSoongyu Yi, Zongfu Yu
Life of this patent
Estimating the term…
Abstract
An apparatus for measurement of surface relief provides a phase sensitive camera and processing to reconstruct a wavefront profile matching the surface when illuminated with a known light source thereby providing noncontact surface relief measurements.
Claims20
An apparatus for surface relief measurement comprising:
- a light source for illuminating a surface to be measured along an illumination axis;
- a wavefront angle sensor comprising an array of sensor elements at multiple locations distributed in two dimensions over a sensor area, each sensor element adapted to measure a wavefront angle of a wavefront received at the sensor element with respect to an axis of the wavefront angle sensor, the wavefront angle sensor positioned to receive light from the light source phase shifted by the surface to be measured to alter the wavefront angle of the wavefront received by the sensor;
- and
- an electronic computer providing a display and a processor executing a program stored in non-transitive media to:
- (a) collect wavefront angles from the sensor elements to compute a continuous surface consistent with the wavefront angles;
- and
- (b) output a relief map of the surface to be measured using the continuous surface, the relief map indicating heights of the surface to be measured along the illumination axis at multiple points distributed in two dimensions over the surface to be measured;
- wherein the wavefront angle sensor further provides:
- an array of light intensity sensing elements tiling the surface area to receive light having a wavefront angle with respect to a surface normal of the array;
- a set of shadow-casters, each shadow-caster associated with a group of at least three sensing elements to selectively shade different sensing elements of that group as a function of the wavefront angle;
- and
- wherein the electronic computer operates to determine light intensity measured by different sensing elements in a group to provide an output signal indicating wavefront angle;
- and
- wherein the sensor elements are distributed over two dimensions of the sensor area at a spacing of less than 20 μm and there are over 20,000 sensor elements.
11 more elements
A method of measuring surface relief of a surface to be measured using a camera system having:
- a light source for illuminating a surface to be measured along an illumination axis;
- a wavefront angle sensor comprising an array of sensor elements at multiple locations distributed in two dimensions over a sensor area, each sensor element adapted to measure a wavefront angle of a wavefront received at the sensor element with respect to an axis of the wavefront angle sensor, the wavefront angle sensor positioned to receive light from the light source phase shifted by the surface to be measured wherein the wavefront angle sensor further provides an array of light intensity sensing elements tiling the surface area to receive light having a wavefront angle with respect to a surface normal of the array and a set of shadow-casters, each shadow-caster associated with a group of at least three sensing elements to selectively shade different sensing elements of that group as a function of the wavefront angle;
- and wherein the electronic computer operates to determine light intensity measured by different sensing elements in a group to provide an output signal indicating wavefront angle and wherein the sensor elements are distributed over two dimensions of the sensor area at a spacing of less than 20 μm and there are over 20,000 sensor elements;
- and
- an electronic computer providing a display and a processor executing a program stored in non-transitive media, the method comprising:
- (a) illuminating the surface to be measured with the light source;
- (b) collecting wavefront angles from the sensor elements and using the computer to compute a continuous surface consistent with the wavefront angles;
- and
- (c) outputting a relief map of the surface to be measured using the continuous surface, the relief map indicating heights of the surface to be measured along the illumination axis at multiple points distributed in two dimensions over the surface to be measured.
6 more elements
Dependencies are inferred from the claim text.