Robust high-dynamic-range optical roll sensing.

We present a robust optical-roll sensor with a high-dynamic range and high-throughput capabilities. The working principle relies on tracking the amplitude of an optical square wave-encoded light source. After encoding a square wave onto a polarization reference, quadrature demodulation of the polarized light allows us to cancel common-mode noise. Benefits of this sensor include its simplicity, low cost, high-throughput, insensitivity to source amplitude fluctuations, and no inherent drift. In this Letter, we present the working principle and experimentally validate a 43° usable working range with 0.002° resolution. This sensor has the highest reported dynamic range for optical roll sensing.

Development of a compact, fiber-coupled, six degree-of-freedom measurement system for precision linear stage metrology.

A compact, fiber-coupled, six degree-of-freedom measurement system which enables fast, accurate calibration, and error mapping of precision linear stages is presented. The novel design has the advantages of simplicity, compactness, and relatively low cost. This proposed sensor can simultaneously measure displacement, two straightness errors, and changes in pitch, yaw, and roll using a single optical beam traveling between the measurement system and a small target. The optical configuration of the system and the working principle for all degrees-of-freedom are presented along with the influence and compensation of crosstalk motions in roll and straightness measurements. Several comparison experiments are conducted to investigate the feasibility and performance of the proposed system in each degree-of-freedom independently. Comparison experiments to a commercial interferometer demonstrate error standard deviations of 0.33 µm in straightness, 0.14 µrad in pitch, 0.44 µradin yaw, and 45.8 µrad in roll.