Dual laser high precision interferometer

摘要

An absolute distance measuring device based on laser interferometry may combine coarse, intermediate, and highest resolution measurement techniques to find the absolute distance to a sample surface with high resolution. The device may provide at least two laser wavelengths simultaneously, to allow reduction or elimination of certain common-mode error components, including dynamic error components. The device may scan at least one of the laser wavelengths over a relatively narrow range and may use quadrature detectors to provide enough signal data to allow certain self-corrections to be performed on the resulting scanned signals and measurements. A novel tunable laser and/or quadrature detector may provide advantages in combination with the device.