Method and apparatus for wafer-level measurement of volume holographic gratings

摘要

The invention describes a system for the measurement of volume holograms on a wafer scale that permits high-resolution and high throughput measurement of grating parameters. The invention uses a collimated beam of a fixed wavelength light source that is transmitted through the wafer to be tested. The transmitted beam is imaged with a lens onto a sensor. The sensor is used to measure the beam power under a variety of conditions, including without a wafer in place, so that the various measurements can be used to determine grating characteristics. The measurement data produced includes values for grating spacing, tilt angle, and diffraction efficiency with a high spatial resolution.