Yongyue Qi

Study on a Positioning and Measuring System With Nanometer Accuracy

The process of developing a nanopositioning and nanomeasuring system is described. The piezoelectric micro-motion stage is based on the principle of inchworm motion. The traditional single actuator is updated to the double actuators. With the novel principle of push-pull relay movement the stage can move continuously and smoothly. In order to achieve nano-measurement a new method called coupled differential interferometry is proposed. An optical system with 8 times optical path difference is adopted. The new interferometer is simple in concept, without optical paths and easy to set up. In addition the real time error compensation of the interferential signals is accomplished by the Heydemann model. The experiment results show: the minimum step of the micro-motion stage is 18nm, the accuracy of the interferometry is 10–12nm.Copyright

Research on improving the measuring accuracy of laser autocollimator used over long distance

The methods of how to improve the measuring accuracy of the autocollimator used over long outside distance are introduced in this paper. Pulse diode laser is adopted as a light source and CCD is used as signal receiver. By the optical design of common-path and the signal processing such as smoothing filtering, interpolating image center, eliminating anomaly data and identifying false points, a higher stability of 2.5” and a better repeatability of 5.6” are achieved in the positioning measurement over ten meters. The principle of auto-collimation, the optical system design, the signal processing and the experimental results are expatiated in this paper.

Measuring system for micro force based on electrostatic theory

The micro force measuring technology is widely used in the area of micro friction test, liquid surface tension analysis, organism micro-structure force test, measurement and calibration of MEMS and NEMS, etc. In view of measurement and realization approach of micro force value, a micro measuring system is proposed. A control electrostatic force generator is adopted to reproduce micro force. The basic working principle is an exact designed cylindrical capacitor with the characteristics of long measurement range, fine linearity and faint border effect. A linear axletree with high precision and linearity is used to ensure concentricity of movement. In order to eliminate the interference from parasitical capacitance a hermetical shield is designed. By means of measuring the voltage between electrodes and capacitance change gradient, the micro force test at μN~nN degree could be realized.

Study on Digital Music Electrotherapy Instrument

A new music doctor with digital music source is designed in view of the shortcoming of traditional musical doctor such as low tone quality and serious distortion. The hardware of the digital music electrotherapy instrument consists of three parts: music source control system, music signal adjusting module and therapeutic signal monitoring system. With pre-amplifier and power magnification the signal is adjusted. The digital music source is designed based on MCU C51 with MP3 decoder, audio file storage system based on USB interface with FLASH memory. At last the functions of data saving and display are realized by monitoring system. The experimental results show the fine cadence consistency between remedial signal and music signal. Keywords-music doctor; digital music source; music electrotherapy instrument

The high accuracy data processing system of laser interferometry signals based on MSP430

Generally speaking there are two orthogonal signals used in single-frequency laser interferometer for differentiating direction and electronic subdivision. However there usually exist three errors with the interferential signals: zero offsets error, unequal amplitude error and quadrature phase shift error. These three errors have a serious impact on subdivision precision. Based on Heydemann error compensation algorithm, it is proposed to achieve compensation of the three errors. Due to complicated operation of the Heydemann mode, a improved arithmetic is advanced to decrease the calculating time effectively in accordance with the special characteristic that only one item of data will be changed in each fitting algorithm operation. Then a real-time and dynamic compensatory circuit is designed. Taking microchip MSP430 as the core of hardware system, two input signals with the three errors are turned into digital quantity by the AD7862. After data processing in line with improved arithmetic, two ideal signals without errors are output by the AD7225. At the same time two original signals are turned into relevant square wave and imported to the differentiating direction circuit. The impulse exported from the distinguishing direction circuit is counted by the timer of the microchip. According to the number of the pulse and the soft subdivision the final result is showed by LED. The arithmetic and the circuit are adopted to test the capability of a laser interferometer with 8 times optical path difference and the measuring accuracy of 12-14nm is achieved.