Leijie Wang

Yaw error correction of ultra-precision stage for scanning beam interference lithography systems

The stage yaw error is a key factor affecting the phase distortion of gratings produced by scanning beam interference lithography system. In order to solve this problem, a coarse-fine dual-stage mechanism is proposed, in which an ultra-precision fine positioning stage with yaw error correction function is developed. To achieve nanoscale positioning and sub-microradian yaw motion accuracy, four Lorentz motors are used to drive the fine stage. The internal coupling factors and the mechanism of Lorentz motors motion control are analyzed. Besides, the Abbe error caused by the yaw error is investigated. Positioning and scanning experiments are conducted and the outcomes show that maximum yaw error is 0.33 μrad during constant velocity scanning, which completely meets the grating fabrication requirements.

Sinusoidal phase-modulating laser diode interferometer for wide range displacement measurement

A sinusoidal phase-modulating laser diode interferometer for wide range displacement measurement is proposed. To realize wide range displacement measurement, a signal processing method utilizing a look-up table to estimate the dynamic value of the effective sinusoidal phase-modulating depth is detailed, and the error caused by the residual amplitude modulation and the effective sinusoidal phase-modulating depth in wide range displacement measurement can be eliminated. It is discussed that the extended measurement range depends on the monotone intervals of several specific functions. The simulation and experimental results prove that the sinusoidal phase-modulating laser diode interferometer with the proposed method could realize centimeter level displacement measurement range.