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A nanopore array with diameter of ~30 nm was fabricated by use of focused ion beam (FIB) scanning and thin film coating on Si (100). A thin film of SiO 2 with thickness of 200 nm (used as a sacrificial layer) was coated by physical evaporation deposition (PVD) first. Next, the thin films of poly-silicon with thickness of 50 nm were coated on double side of the substrate. A window with an area of 2 × 2 mm 2 was opened by reactive ion etching from bottom side and reached to the thin film of SiO 2. After that, a fine controlled FIB milling with bitmap function (milling according to a designed pattern in a defined area) was used to scan the area. Signal is obtained by a sensor inside the vacuum chamber collecting secondary electrons emitted from the sputtered material when the beam reach the layer of SiO 2. Stopping the milling process at this moment, the nanopore array was derived after removing the sacrificial layer by wet chemical etching. The nanopore arrays were characterized using transmission electron microscopy (TEM) after the FIB drilling.

The development of the ability to machine glass materials to optical tolerances is highly desirable. In this work, cutting tests were carried out on glass to investigate the wear of diamond tools under different cutting conditions, i.e. conventional turning and ultrasonic vibration cutting. The tool wear mechanism was discussed on the basis of the observation of wear zone and machined surface topography. Cleavage and micro-chipping appear to be the dominant wear mechanism under the cutting conditions used in the tests. The cutting performance was found to be improved by applying ultrasonic vibration to the cutting tool. The change in the tribology of the cutting process as well as the alteration of the deformation mechanism of the work material in the cutting zone might be responsible for the reduction in tool wear in vibration cutting.

Recent research and development on the femtosecond laser has shown that it is a powerful tool for high precision micromachining. However, the femtosecond laser-material interaction is fast and complex due to its ultrashort pulse duration. Consequently, it is not an easy task to optimize process parameters and to ensure high-quality fabrication. In this context, we propose an in-line monitoring technique based on plasma plume diagnostics. By analyzing the spectra of the femtosecond laser-induced plasma, which was detected and analyzed using a spectrometer, the plasma temperature of the copper sample was estimated. As drilling holes and cutting lines are two common applications in industry, the relationship between the emission light and the geometry of the fabricated structure was investigated based on the time-varying signals from the photodetector. These results will help us to understand the mechanism of femtosecond laser ablation so as to achieve high quality micromachining.

Microstructures fabricated by use of focused ion beam (FIB) direct scanning is useful for microsystems. However, a new phenomenon was found recently by our experimental results. After the FIB bombardment in the defined area, the microstructures were formed under the competence between the ion sputtering induced surface roughening and surface diffusion induced surface smoothing. The process was called self-organized formation. The generated microstructures were characterized by atomic force microscope (AFM). The measured results show that the dimensions of the microstructures were changed with time. In other word, the measured results were different between the samples just processed and that one finished over one week, and the former with smaller dimensions than the latter. The reason maybe due to the thermal effect induced by the FIB bombardment. We called it a natural annealing. The fabricated microstructures were not in stable state due to the internal stress caused by ion sputtering and thermal diffusion. At initial state, it is in dynamic balance. After the natural annealing with several days, the dynamic balance is changed by the thermal diffusion which caused the dimensions of the microstructures varied continuously. In addition, the surface oxidation is also another factor.

Wavelength tuning of fiber Bragg gratings (FBGs) by virtue of a lateral or transverse load is attractive for a variety of applications in the field of optical sensing. The wavelength response characteristic of the FBG upon application of a lateral load is highly dependent on the pressurizing media, its configuration and the contact conditions. In this paper, the effect of stiffness of the pressurizing media, its thickness and the effect of contact friction on the lateral pressure tuning of FBGs is evaluated using finite element method. It is found that significant enhancement in lateral pressure sensitivity and wavelength tuning range is achievable by optimizing these parameters. Also the stress-induced birefringence could be reduced to an insignificant near-zero value. The present study is thus useful in better utilization of lateral pressure tuning of FBGs for sensing applications.

In this paper, we report the effects of polarization state of individual beams in ablation of surface relief gratings using a two-beam interferometric technique. We have carried out ablation experiments on (111) silicon to form surface relief gratings by interfering two femtosecond laser beams under different polarization combinations. Four combinations of polarization were studied, i.e., s-: s-polarization, s-: p-polarization, p-: p-polarization and circular-: circular-polarization (c-: c-polarization). A novel interferometer was used for the investigation. The grating depths, surface roughness and ablation thresholds have been shown to depend on the polarization state of the interfering beams.

The metallographically polished polycrystalline Sn surface was sputtered by 30 kV focused Ga + ions at room temperature. The experiment was carried out using various FIB incidence angles (0°, 15°, 30°, and 45°) over a wide range of doses (10 16 –10 18 ions/cm 2 ). The surface morphology was carefully characterized under the optical microscope, scanning electron microscope (SEM) and atomic force microscope (AFM). Ripples were observed on the irradiated areas even at the normal FIB incidence angle, which is not consistent with the Bradley–Harper (BH) rippling model. The orientation of ripples relies on crystallographic orientation rather than projected ion beam direction as predicted by BH model. The ripple wavelength is independent of ion dose, while ripple amplitude increases with ion dose. It is found that the ripples are formed by self-organization due to anisotropic surface diffusion in the low melting point metal.

Safe and effective laser ophthalmic surgery requires a fine balance between the efficiency of laser delivered and the degree of collateral side damage. The laser-ocular tissue interaction process is reliant on three main variables, namely, wavelength, pulse duration, and deposited energy. A certain amount of energy is needed to achieve ablation, while too much energy can result in unwanted collateral thermal damage. In our work the relationship between energy deposition and ablation effect is studied by an in-vitro experiment using an 800 nm wavelength 150 fs-pulse-duration laser system. This experiment aims to validate the probability of decreasing the supplied energy during glaucoma surgery by femtosecond laser. Our results show that less energy is needed using femtosecond laser than that using a longer pulse laser.

The wavelength tuning of fiber Bragg gratings (FBGs) by virtue of a lateral or transverse load is attractive for a variety of applications in the field of optical sensing. However, the lateral pressure tuning of FBGs suffers from the drawback of low lateral pressure sensitivity, narrow tuning range and stress induced birefringence. In this paper, polymeric package technique is adopted to improve the lateral pressure sensitivity to as high as 0.3 nm/N/mm along with tuning range of nearly 1 nm without considerable pulse broadening and peak splitting. Finite element analysis of the lateral pressure tuning process of polymer packaged FBG corroborated with the experimental results.

Polymeric coatings and packaging are often used to enhance the temperature sensitivity of fiber Bragg grating temperature sensors. The high thermal expansion coefficient of the polymer enhances the thermal sensitivity by improving the wavelength shift due to thermal expansion. The adhesion of the polymeric coatings to the silica based optical fiber plays an important role in the wavelength response characteristics of fiber Bragg gratings with respect to temperature. Experiments are done to qualitatively analyze the influence of adhesion. Three‐dimensional finite element simulations have been carried out. Spring elements are used to interconnect the nodes of the meshed models of optical fiber and coating. The effect of adhesion is studied as a function of spring stiffness.

Ultra-precision machines are widely used to turn aspherical or spherical profiles on mould inserts for the injection moulding of optical lenses. During the turning of a profile on a stainless steel mould insert, the cutting speed reduces significantly to 0 as the cutting tool is fed towards the centre of the machined profile. This paper reports experiments carried out to study the wear of uncoated and PVD-coated carbide tools (carbide tool coated with 2000 alternate layers of AlN and TiN, each layer 1.5 nm and carbide tool coated with 0.5 μm TiN, 5.5 μm TiCN and 0.5 μm TiN) in the ultra-precision machining of STAVAX (modified AISI 420 stainless steel) at low speeds with and without lubricant. A sprayed mixture of compressed air, liquid paraffin oil and cyclomethicone was used as lubricant. Examination of the wear at the rake face of the tool suggests that during machining of the alloy with a hardness of 55 HRC without lubricant, the cutting edge is subjected to high compressive stress, resulting in fracture. Reducing the hardness of the alloy would therefore result in a lower stress acting on the cutting edge, thus rendering the tool less susceptible to fracture. Both the rake and the flank faces of the coated tools exhibited lower wear than the uncoated tools. This was due to the former tools possessing higher fracture resistance owing to the presence of the coating. The lubricant was effective in improving surface finish, preventing surface fracture and reducing flank wear.

The development, during annealing, of periodic one-dimensional ripple structure has been investigated. The nanoscale ripple array was fabricated on silicon(0 0 1) crystal surface using focused ion beam (FIB). Annealing was performed isothermally in a flowing argon gas ambient at 670 °C. The morphology of the ripple before and after annealing was analyzed by use of atomic force microscope. The height of the ripple decreased after thermal annealing. Furthermore, after annealing, spikes of gallium and/or gallium-rich precipitate were also observed on the surface of the ripples and the FIB milled areas.

The Ga+ focused ion beam (FIB) etching characteristics of TiNi thin films have been investigated. The thin films were deposited on Si(1 0 0) substrates by co-sputtering TiNi and Ti target using magnetron-sputtering system. Optical Microscope and atomic force microscopy (AFM) was used to analyze the etching rate and surface morphology of the TiNi. Experimental results show that the etched depth depends linearly on the ion fluence per area with a slope of 0.28 μm3/nC. But the etching rate decreases with increasing the ion beam current. The surface became smoother after FIB milling. The root-mean-square (rms) surface roughness changes nonlinearly with ion fluence with a minimum rms of about 4.3 nm at a fluence of about 3.1×1017 ions/cm2. The rms surface roughness decreases with increasing the ion beam current and reaches about 3.3 nm as the ion beam current is increased to 2 nA. A periodical ripple topography was observed.

A study was undertaken to investigate the wear characteristics of polycrystalline cubic boron nitride (PCBN) cutting tools and surface integrity during machining of STAVAX (specialised stainless steel) with and without coolant. Plastic deformation and formation of overtempered martensite and white layer (untempered martensite) were the dominant subsurface and surface defects. It was found that decreasing the hardness of the STAVAX from 55 HRC to 40 HRC could result in fracture on the flank face, leading to a deterioration of the surface finish. It was observed that low CBN content tools (60%CBN/40%TiN) exhibited greater fracture resistance than high CBN content tools (85%CBN/15%TiN, 90%CBN/10%Co). Although coolant could not bring about a reduction in the flank wear, it was effective in reducing the subsurface and surface defects, and in preventing chipping of the tool edge, leading to an improved surface finish. A superior surface finish (Ra

Having an excellent shape memory effect, titanium–nickel (TiNi) thin films are often used for fabrication of microactuators in microelectromechanical systems. In this work, the Ga+ focused ion beam (FIB) etching characteristics of TiNi thin films has been investigated. The thin films were deposited on Si(1 1 1) wafers by co-sputtering NiTi and Ti targets using a magnetron-sputtering system. Some patterns have been etched on the surface of the films by FIB. Atomic force microscopy has been used to analyze the surface morphology of the etched areas. It is found that the etched depth depends linearly on the ion dose per area with a slope of 0.259 μm/(nC/μm2). However, the etching depth decreases with increasing the ion beam current. The root-mean-square (RMS) surface roughness changes nonlinearly with ion dose and reaches a minimum of about 5.00 nm at a dose of about 0.45 nC/μm2. The RMS decreases with increasing ion beam current and reaches about 4.00 nm as the ion beam current is increased to 2 nA.

Defects in silicon wafers have been of great scientific and technological interest since before the earliest days of the silicon transistor. Recently much attention has been focused on crystal originated pits on the polished surface of the wafer. These defects have been shown to contribute to gate dielectric breakdown. The present work relates to surface and/or subsurface defect inspection systems for semiconductor industries and particularly to an inspection system for defects such as swirl defects and groups of particles in unpolished silicon wafers before the wafer reclamation and/or the wafer fabrication process using a digital shearography technique. The method described here relates specifically to semiconductor wafers, but may be generalized to any other samples. In the present work, surface or subsurface defects are detected and evaluated by stressing the silicon wafer while looking for defect-induced anomalies in a fringe pattern, generated by the interference of two speckle patterns, in the CCD camera and digital image processing.

By applying ultrasonic vibration to a single-crystal diamond tool-tip, ductile machining of fused silica can be achieved even for 2 μm depth of cut. The increase in the critical depth of cut is significant and is a function of the ratio of vibration speed to cutting speed. Surface roughness Ra of 100 nm was obtained for up to 2 μm depth of cut.

Titanium nitride (TiN) thin films have low electrical resistivity, good chemical and metallurgical stability, and exceptional mechanical properties. As such, we are interested in exploring TiN for use as mold material for micro-and nano replication. Focused ion beam (FIB) technique was successfully used to fabricate sub-micron sized pattern on a TiN/Si(100) wafer. This mask-free fabrication technique takes advantage of the kinetic precision of FIB; the energy of ions used was 40 KeV. The width and depth of each trench in the TiN mold are 390 nm and 280 nm respectively.

The quality of machined optical surfaces is affected by machine tool accuracy, cutting tool quality and dynamic machining effects. This paper investigates the effect of cutting tool conditions and tool set-up error on surface distortion. Controlled cutting tests were performed on a two-axis diamond turning machine. Spherical mirrors with respective pre-set tool offset values and tool height values were turned. The relationship between machined form accuracy and tool offset and tool height was investigated based on experimental and analytical results. Influence of tool wear generated during machining process was studied. A spherical surface with a form accuracy better than λ /10 has been produced.

In this paper, integration of interference phenomenon into femtosecond laser micromachining was reported as the femtosecond laser pulses were reshaped spatially to perform ablation. The generation of circular interference pattern was demonstrated by overlapping infrared femtosecond laser pulses. The interference pattern was subsequently focused on a copper substrate to ablate microstructures of concentric circular rings. The present technique is expected to open up new applications in the areas of rapid fabrication of micro-Fresnel lenses, hybrid microlenses and lens arrays.

Polycrystalline cubic boron nitride (PCBN) cutting tools are widely used in the ultra-precision machining of stainless steel mould inserts for the injection moulding of optical lenses. During the machining of a spherical or an aspherical profile on a mould insert, the cutting speed reduces significantly to approximately 0 as the cutting tool is fed towards the centre of the machined profile. This paper will report on experiments carried out to investigate the wear of various grades of PCBN tool in the ultra-precision machining of STAVAX (modified AISI 420 stainless steel) at low speeds. In the initial stage of machining, fine-scale cavities were formed on the rake face and as such, the damaged surface acted like a chip breaker and thus as a preferential site for crack initiation. Once a crack was initiated, it propagated along the grain boundaries leading to intergranular fracture. The experimental results show that the formation and extent of the surface fracture are greatly dependent on the cutting forces and the severity of abrasion on the rake face which are governed by the cutting temperature. The porosity, ductility and the bonding strength of the grains in the tool, apart from its thermal conductivity appear to have major influences on the fracture resistance of the tool.

A microreplication process, micromolding, was developed to replicate three-dimensional microcomponents. It included modifying a conventional molding machine, developing a thermal control unit to control the mold temperature, and developing a vacuum unit to evacuate the microcavity before filling it with plastic melt. Focused ion beam sputtering, a maskless patterning of material, was used to fabricate a microcavity that was then used as a mold insert. Feasibility of the micromolding process was investigated by simulation, and results were verified with the replication of polymer microcomponents (e.g., microgear, gear-train). Commercial simulation software was used to reveal possible issues in micromolding by integrating the microcomponent with a larger base. The simulations predict the filling time, pressure distribution, volumetric shrinkage, stress distribution, etc., of the microcomponent.

This article presents experimental results of precision machining of steel alloys with polycrystalline diamond tools. Ultrasonic vibration-assisted cutting was tried out for expanding the application of diamond tools for high-precision and high-quality machining of ferrous materials. The experimental results show that compared with conventional turning, the cutting performance, in terms of cutting force, surface finish, and tool life, was improved by applying ultrasonic vibration to the cutting tool. The cutting forces and tool wear measured in vibration cutting are much lower than those in conventional cutting. The tool wear mechanism was discussed on the basis of the observation of wear zone.

Tool wear causes the loss of the original profile accuracy of the cutting edge and degrades the form accuracy of machined surfaces. The purpose of this research is to clarify the tool-wear mechanism and its effect on machining accuracy in ultra-precision diamond cutting with a round-nose tool. Controlled cutting tests of Al 6061 were performed on a two-axis, ultra-precision turning machine. Single-crystal diamond tools were used in the experiment. The tool-wear pattern was studied based on the observation of the wear zone using a scanning electron microscope. The topographic characteristics of the chips were examined and the effect of the micro-cutting geometry on the tool wear was investigated theoretically and experimentally. The mutual effects of crystallographic dependence of wear resistance of diamonds and the change in the cutting velocity during machining are believed to be the main reasons causing uneven wear along the cutting edge. Measures for reducing the effect of tool wear are also discussed.

With the rise in demand for miniaturized features with better acute edge acuity and negligible thermal damage zone, one of the key vital areas lies in the refinement of the quality of the laser beam itself. Spatial filter is routinely used in optical micromachining systems to smoothen the Gaussian profile of the machining spot in order to obtain a feature of the desired quality. However, its profile smoothening effect has never been investigated for femtosecond pulsed laser micromachining process since the extremely high peak power of femtosecond pulses will cause damage on the filtering aperture of spatial filter. During the development of an acousto-optical micromachining system using femtosecond pulses, we found that if the damage of the filtering aperture can be circumvented, spatial filter can improve the machining quality of femtosecond pulse ablation, especially when ablation is conducted at low-fluency range (just above the ablation threshold fluency). In this paper, we investigate and demonstrate both the improvement and potential that beam refinement can bring about. In our experiment, a series of test patterns were ablated with a 400 nm second-harmonic Ti:Sapphire femtosecond laser of 150 fs duration at varying pulse energy ranging from 31 to 39 nJ. The specimen used in the experiment is a platinum- (Pt) sputtered coating of 100 nm thickness on a quartz substrate. The results show a significant improvement in the constancy of the shape as well as the size of ablated feature, revealing an improved beam profile and beam energy distribution due to spatial filtering.

Laser Doppler vibrometer (LVD) has been the most favorite instrument for precision dynamics measurement due to its non-contact, high accuracy and high resolution. However, LDV can only give the dynamic data of a particular location on the entire feature. In order to get the whole field data, a laser beam-scanning mechanism has to be implemented. Currently, motor-driven scanning mirror is used to move the measurement probe from one point to another. The mechanical vibrations of the scanning mirror will reduce the measurement accuracy. This paper introduces a novel scanning LDV optical system embodied in an acousto-optic deflector scanning mechanism. It can improve the measurement accuracy since there is no mechanical motion involved. One main advantage of this system is that it generates a laser scanning beam in parallel that is different from the beam scanning in the conventional scanning laser Doppler vibrometer (SLDV). The new system has a board scanning range. The measurement target size ranges from few tens of millimeters down to 10 μm. We have demonstrated the capability of the novel system on scanning measurements of features as big as ultra-precision cutting tool to features as tiny as AFM cantilever. We believe that the novel SLDV will find profound potential applications in the precision engineering field.

The formation mechanism of atomic force microscope (AFM) Moire is explained using the transmittance function. The technique for preparing the AFM Moire specimen grating is described. The sensitivity and accuracy of this method is analyzed. AFM Moire method is used to measure the thermal deformation ball grid array (BGA) electronic package. The shear strain at the different solders in the BGA package is measured. The result is compared with that from electron beam Moire method. The consistent comparison result verifies the AFM Moire method is reliable and effective in the micro-deformation measurement in the electronic package.

Photomasks are the backbone of microfabrication industries. Currently they are fabricated by a lithographic process, which is very expensive and time consuming since it is a multi-step process. These issues can be addressed by fabricating photomasks by direct femtosecond laser writing, which is a single-step process and comparatively cheaper and faster than lithography. In this paper we discuss our investigations on the effect of two types of laser writing techniques, namely front- and rear-side laser writing, with regard to the feature size and the edge quality of a feature. It is proved conclusively that for the patterning of masks, front-side laser writing is a better technique than rear-side laser writing with regard to smaller feature size and better edge quality. Moreover the energy required for front-side laser writing is considerably lower than that for rear-side laser writing.

Laser micromachining on 1000 nm -thick gold film using femtosecond laser has been studied. The laser pulses that are used for this study are 400 nm in central wavelength, 150 fs in pulse duration, and the repetition rate is 1 kHz . Plano-concave lens with a focal length of 19 mm focuses the laser beam into a spot of 3 μm (1/e2 diameter). The sample was translated at a linear speed of 400 μm / s during machining. Grooves were cut on gold thin film with laser pulses of various energies. The ablation depths were measured and plotted. There are two ablation regimes. In the first regime, the cutting is very shallow and the edges are free of molten material. While in the second regime, molten material appears and the cutting edges are contaminated. The results suggest that clean and precise microstructuring can be achieved with femtosecond pulsed laser by controlling the pulse energy in the first ablation regime.

High efficiency mirror surface machining of brittle materials such as glasses and ceramics has become more important as these materials have become used more widely in optical and electronic devices. In this work, the ultrasonic vibration diamond cutting of glasses was performed in order to investigate the effect of tool vibration on the brittle–ductile transition mechanism. The effect of cutting speed on the critical depth of cut was studied by groove cutting experiments. The value of critical depth of cut has been found to vary with the ratio of vibration speed to cutting speed. The characteristics of the surface generated in the ductile mode have been examined and the measures for minimizing the influence of tool vibration on surface finish are suggested. The reason for the increase in the critical depth of cut is discussed based on the analysis of the ultrasonic vibration cutting process and the measured data of cutting force.

With the growing importance of micro machining, it has become important to characterise the profile of slot surfaces in order to understand the machining process in detail. In this paper, a novel optical layout adapting the concept of Mirau interferometry to polarization optics, in combination with instantaneous phase shifting interferometry, for measurement of slot surfaces is described. Experiments were carried out with this setup on a wafer surface with slot and the results were compared with that of a commercial surface profiler to demonstrate the applicability of the principle. The results obtained, were discussed with reference to the beam spot size, positioning of the object and the vertical resolution of the measurement setup, and compared with that of the commercial surface profiler.

CBN cutting tools are widely used in ultra-precision machining of STAVAX (specialized stainless steel) mould inserts for injection moulding of optical lenses. This paper will report on experiments carried out to investigate the wear of CBN tools with different grain sizes and various CBN/TiN ratios in ultra-precision machining of STAVAX. The tool-wear characteristics were observed to be greatly dependent on the tool type, hardness of the STAVAX and cutting parameters used. In the machining of STAVAX with a hardness of 55 HRC, fine-scale cavities were formed on the rake face and as such the surface damage acted like a chip breaker resulting in formation of cracks. While the flank faces of all tool types showed a similar wear resistance, it was observed that a combination of a higher percentage of TiN binder and smaller grain size led to greater wear resistance on the rake face. It was found that the formation of cracks on the rake faces could be prevented by means of either increasing the cutting speed or reducing the hardness of the machined workpiece.

Sophistication in materials applications is the basis of technological progress and therefore there is a continuous search for new materials: i.e. materials that are light in weight, strong, tough, corrosion resistant, durable, wear resistant, resistant to various hazards of nature, safe for our health, etc. The new generation of materials with improved properties pose problems during machining because of their material structure, and hence they require new machining processes. The interactions between the tool and workpiece and also between the various micromechanisms involved in material removal during ductile regime machining of new materials, such as glasses, ceramics, and semiconductors, are discussed in this paper.

Silicon single crystals are not amenable to conventional machining operations because of their inherent low fracture toughness. This paper deals with an investigation of brittle-ductile transition in diamond cutting of silicon from the viewpoint of material response and tool geometry. Micro indentation and scribing tests were conducted in order to investigate the influence of applied loads on the deformation characteristics. The transition of material removal from brittle to ductile was observed by continuously changing the cutting depth. The effect of tool rake angle on the machined surface quality was studied by actual diamond turning. A mirror surface, with a roughness of 5 nm R a, was produced using a tool with a −25° rake angle. The reason for the difference in the machined surface quality is discussed based on the analysis of stress distribution in the microcutting process.

Modern-day products are characterised by high-precision components. A wide range of materials, including metals and their alloys, ceramics, glasses and semiconductors, are finished to a given geometry, finish, accuracy and surface integrity to meet the service requirements. For advanced technology systems, demands for higher fabrication precision are complicated by the use of brittle materials. For efficient and economical machining of these materials, an understanding of the material removal mechanism is essential. This paper focuses on the different material removal mechanisms involved in machining of brittle materials.

In the machining of mirror-like surfaces, a typical cutting depth of a few micrometers is common. With such a small depth of cut, chip formation takes place within individual grains of polycrystalline materials. In this article, orthogonal cutting of single copper crystals was performed in order to investigate the dependency of cutting deformation and surface quality on the crystallographic orientation of the substrate material. The experimental results show that the crystallographic orientation of the workpiece exerts a significant influence on the shear angle and the machined surface roughness. Cutting force variation with crystallographic orientation was analyzed on the basis of a microplasticity model. The trend in the variation of theoretical values of an effective Taylor factor (the shear strength) compares well with that of published experimental data on cutting forces.

A 400 nm second harmonic Ti : sapphire femtosecond laser was applied to structure silicon base on a direct-write process in air. A series of lines were ablated with pulses of 300-fs duration at varying power densities ranging from 50 to 100 nJ of energy on 2″ silicon (1 1 1) wafers. In this event, we investigate and report extensive laser induced thermal damage and redeposition encompassing the ablated lines at high energy levels above the damage threshold of the silicon. In addition, the effect of polarisation on the direction of micromachining is also observed and discussed. The resolution and quality of these lines were also found to hold a linear relationship to the laser energy up to its thermal threshold limit.

In this article, the feasibility of atomic force microscope (AFM) scanning moire on a cross-line diffraction grating has been studied. The AFM scanning moire technique has been applied to measure the thermal deformation of electronic packages successfully. This technique is convenient to perform the mismatch method, also it could obtain a higher resolution than any other moire method.

Phase shifting interferometry is a well-established technique for non-contact surface profile measurement. Though phase shifting technique has many advantages, it is marred by a few inaccuracies due to the vibration and mechanical movement of the phase shifter itself. Significant amount of work is reported to theoretically compensate these error sources. But for a few works, prominent achievements have not been reported in eliminating these error sources in phase shifting interferometry. In this paper, a novel optical layout, in combination with instantaneous phase shifting interferometry is described. Experiments were carried out with this setup on a super mirror with a λ/20 surface roughness, to demonstrate the validity of the principle.

Diamond turning technology has gained great importance in high-precision optical component fabrication. The quality of machined optical surfaces is mainly affected by the machine tool's accuracy, cutting tool's quality, and dynamic machining effects. This study investigated the effects of cutting tool conditions and tool set-up error on the surface distortion. Controlled cutting tests were performed on a two-axis diamond turning machine. Spherical mirrors with preset tool offset values and tool height values were turned. The relationship among machined form accuracy, tool offset, and tool height was investigated based on experimental and analytical results. The influence of tool wear on machined surface quality was studied. Factors governing uneven wear along the cutting edge in contour machining were analyzed. A spherical surface with a form accuracy better than λ/10 was produced. Methods for minimizing the effect of tool wear are also discussed.

Silicon wafers are used world-wide for the production of microchips. Silicon is a hard and brittle material. Conversion of silicon ingots into polished wafers requires much processing including machining and chemical processing. The machining is critical to high-quality standards. With the development of new components, the electronic industries require higher standards for total thickness variation and also wafer warp. This paper focuses on the different machining methods available for silicon processing.

Form errors are deviations of the machined surface from the geometrical surface excluding position errors, waviness and roughness. From a functional point of view, as for surface roughness, form error characterisation is also important. In the present work, an optical profiler is used to measure and numerically characterise form errors such as roundness and cylindricity of cylindrical surfaces. A double orientation method using mean value analysis has been applied to separate the workpiece error from the spindle error during roundness measurement. Software is developed for data generation, fitting the reference data for assessing form errors in terms of statistical and functional parameters including new parameters. An optical profiler measures all the surface irregularities and hence can be used to study both micro and macro errors of the profile measured. A study of both roughness and roundness parameters along the circumferential direction is made for the unfiltered signal using different filter cut-off values. It is known that filtering greatly affects the value of the form error parameters measured. The form measurements obtained by the optical profiler are compared with the stylus profiler and the results are presented.

Measurement of vibration is a vital factor that limits the precision and accuracy of machining of micro and macro components. In this paper, a novel technique for measurement of vibration is proposed using an acousto-optic modulator, which highlights an improved approach in measuring vibration in the subnanometre range. An experimental comparison was made with a laser Doppler vibrometer. This novel concept is proposed for application to a precision machine tool to measure the vibration on the machine bed induced during the machining process and by the external environment, which can be compensated for by in-process techniques. This novel measurement technique can also be applied for the precision measurement of the stage movement in ultra-precision machines to a subnanometre resolution.

Many of today's products require high precision and operate in extreme environments. To meet these demands, new types of high-performance materials and machining techniques have been developed. The use of these machining techniques, enables these materials to achieve nanometric tolerances. Ceramics are one group of such materials, which can be used in high-performance applications because of their high stiffness. dimensional and temperature stability, and resistance to chemical environments. The brittleness of these materials poses problems during machining, but the demand for precision parts made of these materials are increasing at a fast rate. Experiments have shown that plastic flow can occur in ceramic materials, so they can be ductile machined. However, much needs to be determined in respect of the cutting conditions to enable this ductile behaviour to be successfully maintained throughout the machining processes such as turning or grinding.

Machining without the use of any cutting fluid (dry or green machining) is becoming increasingly more popular due to concern regarding the safety of the environment. Most industries apply cutting fluids/coolants when their use is not necessary. The coolants and lubricants used for machining represents 16–20% of the manufacturing costs, hence the extravagant use of these fluids should be restricted. However, it should also be noted that some of the benefits of cutting fluids are not going to be available for dry machining and also dry machining will be acceptable only whenever the part quality and machining times achieved in wet machining are equalled or surpassed. This paper presents recent developments in the dry machining operation.

In this paper, a new scanning moire method is developed to measure the in-plane deformation of mica using an atomic force microscope (AFM). Moire patterns are formed by the scanning line of the CRT in the AFM system, and the atomic lattice of the mica or high-orientated pyrolytic graphite (HOPG). The measurement principle and the techniques employed for grating preparation are described in detail. This new method is used to measure the residual deformation of a mica plate after irradiation by a Nd-YAG laser, and to determine the residual strain of HOPG under a tensile load. Some interesting results are obtained. The successful results verify the feasibility of this method for measuring deformation in the nanometre range using the lattice of the material as the model grid.

This paper describes a method called the Nexus method used for evaluating tolerance stack problems with position, circular runout, total runout and concentricity tolerances. The method constructs a graphical representation of features termed the Nexus cell. The cell contains all the geometric information of the feature in numerical values. After each feature is represented by a Nexus cell, the cells are linked up to form the Nexus model for the part. Once the model is completed, it can be used to evaluate GDT problems associated with the part. The method is capable of arriving at accurate results when dealing with several special cases of position tolerances. Applications of the proposed method have been illustrated and possible uses of such a method were discussed.

The shape control of beams by piezoelectric actuators is addressed analytically. Solutions are presented for a beamsubjectedto differentboundaryconditions.Thesolutionsshowhowandhowmuchthepiezoelectricactuators can ine uence the shape of a beam. Several case studies arealso presented to show the applications of the analytical solutions in the various analyses relevant to shape control of beams by piezoelectric actuators. The limitation of the actuation forces produced by piezoelectric actuators makes it dife cult to realize global and local precise shape control. In this application, the actuation forces produced by piezoelectric actuators are used to change the shapes of e exible structures. Some work has been reported on the shape control of beams, plates, and shells during the past few years. Some numerical methods, includ- ing the Ritz method, 3,4 e nite difference method, 5 and e nite element method 6i 10 have been used to model and analyze the problems rel- evant to shape control of e exible structures by piezoelectric actua- tors. However, due to the approximation of the numerical methods, the reported results can only give rough information of the global shape changes of the structures induced by piezoelectric actuators. Theycannot showthe detailed localshapechange information,such as information on the slope or curvature change of a structure at one point. The detailed local shape change information induced by piezoelectricactuators,whichshowshowthepiezoelectricactuators can change the shape of a structure or what types of shape change the piezoelectric actuators can make to a structure, is important for the design and analysis of such a piezoelectric smart structure. To obtain this information, one needs to analytically solve the problem of shape control. In general, it is very dife cult and complicated to solveanalyticallytheproblemforatwo-dimensionalplate;however, a one-dimensional beam is another case, and an analytical solution can be possibly obtained with acceptable complexity. The conclu- sions for a two-dimensional plate can be drawn from those for a one-dimensional beam. Thispaperwillpresenttheanalyticalsolutionsofthedee ectionof a beam induced by both piezoelectric actuators and external forces. In accordance with the solutions, the detailed local shape change information induced by piezoelectric actuators will be addressed. Using the solutions, one can analytically perform various analyses relevant to the shape control of beams by piezoelectric actuators. Case studies will also be carried out to show the applications of the solution.

Laser Doppler vibrometry is a well-established technique for non-contact vibration measurement. The necessity to monitor the vibration of the whole surface rather than a single point leads to the appearance of laser scanning vibrometer. However, current scanning vibrometers are applied only to larger structures. Scanning vibrometer for micro-components whose feature size is in region of millimeters and microns is still under development, and no prominent achievement obtained until now. In this paper, a novel scanning laser vibrometry using the combination of acousto-optical deflector and telecentric lens for micro-components is described and the advantages and limitations of the system are discussed. A scanning vibrometer especially applicable to micro-components can be developed based on the technique described here. Experiments carried out on a diamond-cutting tool and high speed rotating rigid disc successfully demonstrate the principle of the system.