Ultrafast z-scanning for high-efficiency laser micro-machining

High-throughput laser micro-machining demands precise control of the laser beam position to achieve optimal efficiency,but existing methods can be both time-consuming and cost-prohibitive.In this paper,we demonstrate a new high-throughput micromachining technique based on rapidly scanning the laser focal point along the optical axis using an acoustically driven variable focal length lens.Our results show that this scanning method enables higher machining rates over a range of defocus distances and that the effect becomes more significant as the laser energy is increased.In a specific example of silicon,we achieve a nearly threefold increase in the machining rate,while maintaining sharp side walls and a small spot size.This method has great potential for improving the micro-machining efficiency of conventional systems and also opens the door to applying laser machining to workpieces with uneven topography that have been traditionally difficult to process.

Research and test of the adaptive quadrature demodulation technology for silicon micro-machined gyroscope

A program of adaptive quadrature demodulation is proposed to supply the gaps in the traditional analog detection technology of a silicon micro-machined gyroscope (SMG). This program is suitable for digital phase locked loop (DPLL) drive technology that proposed in other papers. In addition the program adopts an adaptive filtering algorithm, which selects the in-phase and quadrature components that are outputs of the DPLL of the SMG's drive mode as reference signals to update the amplitude of the in-phase and quadrature components of the input signal by iteratively. An objective of the program is to minimize the mean square error of the accurate amplitudes and the estimated amplitudes of SMG's detection mode. The simulation and test results prove the feasibility of the program that lays the foundation for the further improvement of the SMG's system performance and the implementation of the SMG system's self-calibration and self-demarcation in future.

An Intelligent Predictive Model-Based Multi-Response Optimization of EDM Process

Electrical Discharge Machining(EDM)is a popular non-traditional machining process that is widely used due to its ability to machine hard and brittle materials.It does not require a cutting tool and can machine complex geometries easily.However,it suffers from drawbacks like a poor rate of machining and excessive tool wear.In this research,an attempt is made to address these issues by using an intelligent predictive model coupled global optimization approach to predict suitable combinations of input parameters(current,pulse on-time and pulse off-time)that would effectively increase the material removal rate and minimize the tool wear.The predictive models,which are based on the symbolic regression approach exploit the machine intelligence of Genetic Programming(GP).As compared to traditional polynomial response surface(PRS)predictive models,the GP predictive models show compactness as well as better prediction capability.The developed GP predictive models are deployed in conjunction with NSGA-II to predict Pareto optimal solutions.

Bibliometric analysis of micro-nano manufacturing technologies

Manufacturing is the primary industry promoting economic and social development.For the past 30 years,the global trends of preciseness and device miniaturisation have promoted manufacturing to the micro(μ)and nano(η)scale.Identification of themost promising micro-nano manufacturing technologies(MNMT)is of interest to industry,academia and private and national science investing foundations.Considering the exponential broadening of the research area and an enormous volume of literature,providing an overview of the state of the art is far beyond the scope of a technical review paper.This study performs bibliometric analysis of a stream of academic literature devoted toμ-andη-machining.Themain goals of the analysis are to assess the current core and trends in the field ofMNMT.Literature and citation statistics from 1988 were collected from theWeb of Science,Google Scholar,Scopus,Engineering Village,ScienceDirect and SpringerLink databases and were then analysed and illustrated with Microsoft Excel and VOSviewer software.The top keywords,articles,journals,authors,universities and countrieswere identified according to different parameters.The index of normalised influence was offered to evaluate the top element in each category.We observed that the most powerful keywords were present in well-known articles published in prominent journals by authoritative scientists at leading universities in the countries that are most actively engaged in MNMT.The implications of the research outcomes for investors and academicians are summarised in the conclusion.

Advanced Thermopile IR Dual Line Sensor for Smart Home

This article presents all steps between the advanced design and the production of CMOS compatible thermoelectric effect infrared sensors dedicated to smart home applications. It will start by making a comparison between thermopile, bolometer and pyroelectric technologies. Although sensitivity performances available with bolometers appear to be better at first sight, it is found that thermopiles have non-negligible advantages that make them more suitable for this application field. Then the different steps necessary for the design will be described, starting from the thermoelectric model of the sensor (temperature gradient, electrical sensitivity, etc.) and considering all steps up to technological manufacturing in a clean room. The results obtained on the structures produced on a specific computer-controlled measurement bench (temperature regulation with an onboard preamplification card) will be presented. Finally, the results prove that the square structures have better performances (S = 82 V/W and NETD = 208 mK).

A 16-bit sigma–delta modulator applied in micro-machined inertial sensors

A fourth-order low-distortion low-pass sigma-delta （∑△） modulator is presented for micro-machined inertial sensors. The proposed single-loop single-bit feedback modulator is optimized with a feed-forward path to decrease the nonlinearities and power consumption. The IC is implemented in a standard 0.6 μm CMOS technology and operates at a sampling frequency of 3.846 MHz. The chip area is 2.12 mm^2 with 23 pads. The experimental results indicate a signal-to-noise ratio （SNR） of 100 dB and dynamic range （DR） of 103 dB at an oversampling rate （OSR） of 128 with the input signal amplitude of-3.88 dBFS at 9.8 kHz; the power consumption is 15 raW at a 5 V supply.

Scale Factor Determination of Micro-Machined Angular Rate Sensors Without a Turntable

This paper presents a digital readout system to detect small capacitive signals of a micromachined angular rate sensor. The flexible parameter adjustment ability and the computation speed of the digital signal processor were used to develop a new calibration procedure to determine the scale factor of a gyroscope without a turntable. The force of gravity was used to deflect the movable masses in the sensor, which resulted in a corresponding angular rate input. The gyroscope scale factor was then measured without a turntable. Test results show a maximum deviation of about 1.2% with respect to the scale factor determined on a turntable with the accuracy independent of the manufacturing process and property variations The calibration method in combination with the improved readout electronics can minimize the calibration procedure and, thus, reduce the manufacturing costs.

Development of high damage threshold laser-machined apodizers and gain filters for laser applications

We have developed high damage threshold filters to modify the spatial profile of a high energy laser beam. The filters are formed by laser ablation of a transmissive window. The ablation sites constitute scattering centers which can be filtered in a subsequent spatial filter. By creating the filters in dielectric materials, we see an increased laser-induced damage threshold from previous filters created using ‘metal on glass' lithography.