Key Engineering Materials Vols. 381-382

Abstract: Nanostructures materials have stimulated broad attention in the past decade because of their potential fundamental characteristics and its promising applications in nano electronic devices. In the present investigation, crystalline boron nanowires (BNWs) were synthesized by vapor liquid solid (VLS) technique and its mechanical properties were studied using a nanomanipulator inside a scanning electron microscope (SEM). Electron beam induced deposition (EBID) method was used to clamp boron nanowire to the AFM tips. The Young’s modulus of the NWs were determined from the buckling instability of NW and computed to be approximately 131.7 ± 14.6GPa. In addition, the nanomanipulation system was used to manipulate nanowire and built a nanoring.

Abstract: In this paper, we applied the contact constant-height mode together with the pre-compensation technique which can realize the capability of high speed as well as faithful topographical image. Before scanning, the slope variation of the micro-structured surface was measured by the capacitance sensor and then stored in a PC. During the surface profile scanning, a piezoelectric actuator is applied which can provide the inconsecutive motion that corresponds to the pre-measured slope variation. As a result, the precision measurement can also be achieved. The validity of the proposed method and its performance are verified by compare the topographical images that were gained by the contact constant-force mode with feedback control. However, the scanning speed of our method is obviously high.

Abstract: We demonstrate a method of displacement measurement based on Nd:YAG laser with birefringence external cavity. The measurement system is composed of Nd:YAG laser, a wave plate with phase retardation of 450 and an external feedback mirror. Due to the birefringence effect, the external cavity modulates the laser output intensities in the two orthogonal directions with a phase difference of 900, which is two times to that of the wave plate. Both the in-quadrature laser intensities vary one period, when the external cavity length changes λ/2. These two channel laser intensities with phase difference of 900 can be subdivided to λ/8 after 4-fold evaluation. The movement direction of external mirror can be distinguished by the lead or lag between these two channel signals. Our method can improve the resolution of displacement measurement 4 times that of conventional optical feedback, and reach 133nm for a laser wavelength of 1.064µm.

Abstract: A new synthetic heterodyne laser Doppler interferometer based on homodyne interferometer is addressed in this work. Interference signal includes the DC offset that is light intensity. The DC offset must be got rid because it does not need to obtain a velocity. The high pass filter is used instead of the subtractor. DC offset having random variation is difficult to get rid as using the subtractor itself. When the vibration amplitude is smaller than at least 1/ 2 of the wavelength of He-Ne laser, a serious problem of incorrect velocity measurement can be caused since there is non-zero crossing interference signal whose DC value can be eliminated in using the HPF. In order to solve this problem of using the HPF in the homodyne interferometer, a synthetic interferometer using a mechanical modulation method is proposed in this work by exciting a reference mirror with the displacement larger than the 1/2 of the wavelength. In this work, the analytical work is presented to show how the synthetic interferometer solves the problem of incorrect velocity measurement using the Fourier-Bessel function description of the interference signals. Simulation and Experimental works are also presented to validate the synthetic heterodyne interferometer proposed in the work.

Abstract: Most of the nano-positioning systems(stage) are accomplished by a flexure hinge mechanism, which is two or three multilayer PZT actuators to realize the high accuracy and long range[1]. In this paper, it can be made by a new nano stage with the bending characteristics of the mechanical cantilever that is composed of the step motor, one multilayer PZT actuator and the displacement sensor unit. The sensor unit consists of semiconductor LD, PD and sensor holder. The displacement of stage is acquired by the bending control of the cantilever between the step motor and the PZT actuator. The basic properties of the positioning stage are presented. From these results, we can know that the new nano stage can be made by only one multilayer PZT actuator .

Abstract: In this paper, we report a novel quasi-common-path laser feedback interferometer (QLFI) for highly stable, high-resolution and non-contact displacement measurement. QLFI measures the displacement of the target by measuring the phase of feedback light. In addition to the target-generated feedback light (frequency shifted by 2#), a reference mirror generates a reference feedback light which is frequency shifted by #. The phase variations of both feedback lights are measured by heterodyne detection simultaneously and their difference offers the phase variations caused only by target displacement. When the optical path lengths of the reference and measuring feedback light are nearly the same, the phase fluctuations caused by the environment and laser instability are effectively removed. The heat-induced deformation of a He-Ne laser tube is successfully in-line measured using QLFI.

Abstract: A novel self-mixing interference signal analysis method is proposed based on the use of an electro-optic modulator (EOM). Self-mixing interference occurs in the laser cavity by reflecting the light from a mirror-like target in front of the laser. Sinusoidal phase modulation of the beam is obtained by an EOM in the external cavity. The phase of the interference signal is calculated by four-bucket integration technique. The interferometer is applied to measure the displacement of a high-precision commercial PZT with an accuracy of a few nanometers.

Abstract: This paper has developed the bimodal USM a novel actuation pattern, which can actuate the bimodal USM in nanometer magnitude with single actuation pattern instead of combination control of AC actuation pattern, pulse actuation pattern and DC actuation pattern. The novel actuation pattern utilizes a single chip micro-computer to produce a kind of wavelet actuation unit which contains several sine voltage waves with different amplitudes, each wavelet actuation unit is exerted on bimodal USM according to the instruction, by which the step control is obtained. Across the two electrodes of bimodal USM, the differential wavelet actuation voltages are applied to reduce the moving distance of each actuation step, thus the nanometer magnitude actuation sensitivity is achieved. The grating is used as position sensor and the subdivision formulae of mutual compensation functions are adopted to promote the real-time response. The experiment indicated that, with the novel wavelet differential actuation pattern, the actuation characteristic of bimodal USM was improved, the micro-nanometer positioning control was easy to be implemented and the important positioning control parameters under every different actuation conditions could be obtained through the study in the process of actuation.

Abstract: Adaptive fiber-optic interferometer which is based on multimode optical fiber as a sensor and diffusion holograms recorded in semiconductor photorefractive crystal CdTe:V without any electric field is developed. The interferometer sensitivity achieved is only 5.7 times less then highest sensitivity which is possible only in non-adaptive lossless classical interferometer. A practical detection limit is equal to Hz W nm 10 0 3 5 − × . , which allows to broadband detecting of an object’s displacement of order 0.2 nm or deformation of order 2 pε with using light sources having only 5 mW optical power.

Abstract: This paper develops a new separated mini-environment to provide a constant temperature chamber for the placement of Micro/Nano-metrology instrument. In this paper, the rule of temperature change with time under natural convection and coercive convection is presented. The measurement and control system is composed of TEC, programmable power source and precise temperature measurement system. The mathematic model of the constant temperature chamber is identified making use of system identification theory and system identification toolkit of MATLAB. The temperature stability is improved by applying auto-adaptive PID method. Experiments show that the temperature fluctuation of a single-point is less than 0.02°C and the whole field is within 0.05°C. The goal of high-precision temperature control is achieved.