Damping and tracking control of nanopositioning stages with double delayed position feedback.

This paper presents a new damping control scheme for piezoelectric nanopositioning stages with double delayed position feedback (DDPF). The DDPF in the inner loop is proposed to suppress vibration of the nanopositioning stage, which leads to a double time-delay system. A new numerical differential method is proposed to determine the parameters of the DDPF with pole placement.

Study on traceability and suppression method of medium-frequency error for ultra-precision machining optical crystals.

The medium-frequency error on the surface of ultraprecision flycutting has an important effect on the performance of the optical crystal. In this paper, firstly, the characteristic phenomenon of "knife-like grain" in the medium frequency surface of the square and circular optical crystal machined by ultraprecision fly-cutting is revealed. Besides, the error traceability is realized and the results show that the periodic low-frequency fluctuation of 0.

A novel flexure-based vertical nanopositioning stage with large travel range.

This paper presents the design of a novel flexure-based vertical (or Z-axis) nanopositioning stage driven by a piezoelectric actuator (PZT), which is capable of executing large travel range. The proposed stage consists mainly of a hybrid displacement amplification mechanism (DAM), a motion guiding mechanism, and a decoupling mechanism. The hybrid DAM with amplification ratio of 12.

Design of a fine alignment system featuring active orientation adjustment for nano imprint lithography.

The fine alignment between a template with nano patterns and a wafer substrate, especially the parallelism between the two surfaces, is critical to Nano Imprint Lithography. A fine alignment system featuring active orientation adjustment which is composed of an imprint unit and a 6-DOF micromanipulator is proposed in this work. Deformations of a compact flexure layer caused by imprint loads are measured by four identical force sensors embedded in the imprint unit.

Modeling and experimental study on near-field acoustic levitation by flexural mode.

Near-field acoustic levitation (NFAL) has been used in noncontact handling and transportation of small objects to avoid contamination. We have performed a theoretical analysis based on nonuniform vibrating surface to quantify the levitation force produced by the air film and also conducted experimental tests to verify our model. Modal analysis was performed using ANSYS on the flexural plate radiator to obtain its natural frequency of desired mode, which is used to design the measurement system.