Reduction of debris adhesion and increasing the process performance by SF₆ assist laser processing of silicon wafer was investigated. It is observed that debris adhesion was drastically reduced when SF₆ gas was used to compare the case of He gas. Shadow graphic imaging experiments were shown a density contrast region in expanded gases, which would indicate the evaporation of silicon particles by chemical reaction with SF₆ and silicon particles at the plasma-heating region. We found that process performance of SF₆ assist laser processing was higher than the He assist processing, and debris adhesion was suppressed effectively in case where the intense plasma was formed during processing.

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In recent years, attention is paid to diffractive optics which have surface appearance like diffraction grating or Fresnel lens. A variety of machining methods are requested to effectively produce metal mold of diffractive optics, consisting of a number of microgrooves with various shapes. One of them is flat-end microgrooves. Flat-end microgrooves mean microgrooves having no slope at the end. The existence of the slope limits the design of microgrooves and causes unnecessary diffraction lights and losses. Thus, the slope is requested to remove. The study deals with the creation of V-shaped microgrooves with two flat-ends by using 6-axis controll non-rotational cutting tools, that is, curved microgrooves with two flat-ends are created on a curved surface. The proposed method shows the effectiveness to create flat-end curved microgrooves on curved surfaces as well as the method of cutting edge detection to set a cutting edge symply and accurately.

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It is known that vibratory OD-blade slicing, which involves the application of a low-frequency vibration to an OD-blade or a workpiece, exhibits the self-corrective effect of the OD-blade owing to the intermittent repetition of contact and separation between the OD-blade and the workpiece. Moreover, in our previous study, we investigated the mechanism of the self-corrective effect using dynamic numerical simulation, and it was shown that this effect can reduce the blade elastic deformation during slicing and the waviness of the sliced surface. In this paper, we discuss this effect using finite element method (FEM) simulation, and show the dynamical results of blade elastic deformation during vibratory slicing. Furthermore, in this paper, we describe slicing accuracy characteristics, such as the waviness, roughness and sawing marks of the sliced surface obtained experimentally. It is found that the waviness and generation rate of sawing marks on the sliced surface in vibratory slicing are not only reduced compared with those in non-vibratory slicing owing to the OD-blade self-corrective effect brought about by vibration, but also the roughness distribution is not changed between non-vibratory and vibratory slicing, on the basis of a series of experimental and FEM simulation analyses.

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The fabricating methods of nanoscale shapes on Si (100) surface by using atomic force microscope (AFM) and scanning tunneling microscope (STM) were investigated. As a result, nanoscale grooves and faces were fabricated by the scratching methods using AFM. The scratching loads had a major influence on these shapes. Nanoscale pits, grooves and faces were fabricated by STM as a result of controlling the sample bias voltage and the tip curvature radius of tungsten probes. Cross-sectional TEM observations of the nanoscale grooves and faces fabricated by AFM and STM were carried out to study the microstructural changes of Si single crystals. As a result of the TEM observations, it was found that many dislocations and an amorphous phase appeared in the surface of the grooves and faces fabricated by AFM. On the other hand, the single crystalline structure without a dislocation was preserved in the surface of the grooves and faces fabricated by STM. Based on these results, it is considered that the fabricating mechanisms of AFM and STM are a mechanical processing and an electric field evaporation, respectively.

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The study deals with developing a new method to compensate the initial position error of diamond cutting tool in ultraprecision micromachining by use of a 5-axis control ultraprecision machining center. In the ultraprecision machining, various kinds of errors have large influence on the machining accuracy although they are very small. In recent years, the demand is increasing to fabricate complicated microparts accurately and efficiently by means of multi-axis control ultraprecision machining center. However, the accumulation of various kinds of errors due to the increasing number of motion axes and the setting difficulty of small diamond tools deteriorate the form accuracy of machined microparts. To solve these problems, the study proposes a new method to precisely measure the tool radius and to correctly set the tool, and develops the initial tool setting error compensation system. From experimental results, it is found that the method proposed in the study is effective.

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This paper proposes a mirror finishing process using laser-induced periodic surface structures. Grate-shape minute periodic structures can be formed on various kinds of materials by linearly polarized femtosecond laser pulses with low fluence that is slightly above the ablation threshold. The spacing of the periodic structures is about the same as the laser wavelength. Taking advantage of this phenomenon, a multi-edged tool made of sintered tungsten carbide can be easily obtained. A series of mirror finishing experiments using the multi-edged tool has been carried out. As a result, it has been shown that the multi-edged tool with laser-induced periodic surface structures has high performance for mirror finshing. Surface roughness finished by this processing method reaches 5nm Ra.

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In this paper, we describe the performance analysis of the piezoelectric actuator and results of the motion speed of the newly developed micro robot which can be applied for flexible positioning device as well as microscopic operation. In order to provide microscopic operation, the unique locomotion mechanism which is composed of four piezoelectric actuators and two electromagnets is proposed. Here two legs arranged on cross each other are connected by four piezoelectric actuators so that it can move in any directions, i.e. in X and Y directions as well as rotate at the specified point precisely with the manner of an inchworm. However, this robot takes a long time to move long distance because the maximum speed is only a few millimeters. For example, the robot takes over 30 seconds for 10 centimeters. In order to analyze the relationship between the motion speed and parameters of the piezoelectric actuator, we use the simple dynamical model. Then, we have selected the special piezoelectric actuator with amplification mechanism in order to improve the motion speed. In several experiments, we have checked that the robot equipped with the newly selected actuators becomes over 7 times faster than previous one. We have also discussed the influence of the mechanical distortion and the delay time of the electromagnet for more accurate approximation of the motion speed. The possibility of this tiny robot for flexible positioning device is also discussed to open the new field for micro-robotics in precision region.

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