Method and apparatus for determining flatness characteristic for reflective facet of polygon assembly
US8610901B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 24, 2011 |
| Grant date | Dec 17, 2013 |
| Priority date | — |
| Expiry date | Jan 11, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/306
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining a flatness characteristic for a facet of a polygon assembly includes a) rotating a polygon assembly with facets at a desired speed, b) directing a light beam from a light source toward the polygon assembly so light is reflected by consecutive facets during revolutions of the polygon assembly, reflected light passing through a focusing lens that directs a spot light toward a target with spaced-apart bars arranged in a grating pattern that block a portion of the reflected light and allows another portion to pass through another focusing lens that directs another spot light toward a light sensor, the light sensor detecting intensity of the spot light, and c) measuring the intensity over time during revolutions of the polygon assembly to obtain measurements for each facet. An associated test setup includes a fixture, motor controller, light source, light sensor, two focusing lens, target, and system controller.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.