Curvature/tilt metrology tool with closed loop feedback control
US7391523B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 2004 |
| Grant date | Jun 24, 2008 |
| Priority date | — |
| Expiry date | Jun 25, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2522
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for quantitatively measuring the curvature and/or relative tilt of large surfaces wherein a small array of parallel laser beams, each separated by a known distance, reflect from the surface of a sample and fall upon a feedback controlled front-surface steering mirror to a detector that measures both the change in separation of the reflected beams and the spatial translation of the entire array on the detector. The sample surface is translated beneath or in front of the fixed laser array by means of a computer controlled stage or other apparatus to create a 1-dimensional line scan or 2-dimensional map of both bow and relative tilt of the sample surface. A computer-driven, feedback-controlled steering mirror compensates for varying sample tilt by precisely realigning the reflected laser array onto the detector as the sample is translated. The apparatus also utilizes a laser with intensity feedback control to continuously optimize the reflected laser power for varying surface reflectivity as the sample is translated. This combination provides a means to quantitatively measure curvature and relative tilt of sample areas much larger than the actual laser beam array size.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.