A switching-control algorithm is necessary in order to connect the optical paths between input and output ports by using MEMS mirrors in a free-space optical system. We propose a new search algorithm that finds the maximum optical power by using the motion control technique of MEMS mirrors. We apply the algorithm to peak search control for optical path connection with maximum optical power and to the optical power stabilization control in the case of environment changes, such as temperature change. The results confirm that the algorithm is suitable for practical use.

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Chemical Mechanical Polishing (CMP) system is an essential technology to produce the recent high performance electronic devices. One of the problematic point of CMP processes is its high cost. Another is its heavy load to the environment. The principal cause of these two points is that this system needs to be poured and flushed by slurry continuously. One method to solve this problem is to recycle and reuse waste slurry used in this system. This research is targeted on slurry for “Tungsten CMP” which is particularly problematic for its high cost. Untreated slurry from “Tungsten CMP” contains water and metal. These contents will degrade the processing characteristics of slurry. Examinations were conducted to ascertain if recycling waste slurry is possible by eliminating contained water and metals. It was concluded that slurry can be recycled by abstracting water by ceramic filter and metal by ion-exchange. It was also verified that this recycled slurry reserved equivalent processing characteristic as the new slurry.

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This paper describes machining characteristics of high spindle speed micro electrical discharge machining (EDM) using the electrostatic induction feeding method. In this method, non-contact electric feeding allows the tool electrode to be rotated at high speed up to fifty thousand rpm. In micro EDM, it is considered that higher spindle speed is more useful in flushing debris particles from the gap and cooling the tool electrode. In addition, since the heat spot generated by each discharge is separated by a sufficiently long distance on the periphery of the rotating tool electrode due to the relative motion between electrodes, the locally elevated temperature can be lowered. Thus an experimental setup for high spindle speed micro EDM using the electrostatic induction feeding method was newly developed. Machining results showed that machining speed and surface roughness can be improved, and that tool wear rate can be lowered. In micro drilling, deeper micro-holes, smaller gaps and better straightness were obtained due to the high flushing efficiency at the high spindle speed.

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The luminous efficiency of light-emitting diodes (LEDs) improves and approaches that of fluorescent lamps. However, a significant portion of the light generated in the InGaN luminous layer of the LED chip is lost by total internal reflection and thus cannot be used for lighting purposes. We have developed a method of improving the light extraction efficiency from LED chips by strongly reducing these losses. The sapphire substrate is lifted off from the LED chip and a relief structure is created on the surface of the InGaN layer by direct ablation using a femto-second excimer laser with a wavelength of 248 nm and a pulse duration of 500 fs. This laser enables precise sub-μm structuring of the semiconductor layer with minimum thermal damage. As a result, light from the luminous layer diffracts at the solid / air interface and is not reflected back inside the film. In this way, the light extraction efficiency could be improved by a factor of two. After covering the structured InGaN surface with a protective resin, the light extraction efficiency could further be improved by an additional factor of 1.65 resulting in a total enhancement of more than a factor of three.

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This paper proposes a new method of evaluating the accuracies of the 5-axis control machining centers by using the machining test. Concretely, a set of rectangular grooves arrayed like a matrix are machined on the workpiece changing the inclination or the rotation angle of the tilting rotary table. The grooves are machined to the upper and four side surfaces of the workpiece mounted on the table. From the created groove-matrix, the influences of the geometric errors inherent to the five-axis machines, the geometrical profile of cutting edge of ball end mill and the tool length compensation errors on the machined surfaces are visible. Moreover, the influence of these errors on the surface of the workpiece is investigated, and it is compared with the simulation results.

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This study deals with the design method of automatic discharge gap controller (ADGC) installed on a microrobot which can create long, complicated curved holes by means of electrical discharge machining (EDM). The microrobot has to make a curved hole by both performing stable EDM and moving along a curved trajectory in a workpiece. To realize the stable EDM, the microrobot must be equipped with a function in which its electrode is always kept in an appropriate position autonomously and automatically to maintain suitable discharge gap. The function is accomplished by ADGC. It was proven that ADGC has the ability of achieving the function. However, a design method of ADGC is not established since the relationship between the structures of ADGC, the movement of ADGC, and EDM conditions is not enough revealed. As a first step to solve this problem, this study proposes the ADGC design method based on a simple mathematical model of ADGC and develops a new measurement method to evaluate the performance of ADGC doing EDM. The results obtained in the verification experiments using the measurement method show that the ADGC design method proposed is effective.

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This paper describes the influence of Na₂SO₄ electrolyzed oxidizing water on the surface of pure nickel. First, the etching characteristic of Na₂SO₄ electrolyzed oxidizing water on the surface of pure nickel was made clear by the comparative immersion experiments with NaCl electrolyzed oxidizing water and H₂SO₄ solution. The results show that as for the etching effects on pure nickel, Na₂SO₄ electrolyzed oxidizing water is same as the NaCl electrolyzed oxidizing water and becomes stronger than H₂SO₄ solution. Next, we threw light on the influence of Na₂SO₄ electrolyzed oxidizing water on the surface shape of pure nickel, by the observation using the SEM and the AFM image. The results indicated that Na₂SO₄ electrolyzed oxidizing water did not have a big influence on the surface shape of pure nickel. Lastly, by analyzing the surface, we made it clear that Na₂SO₄ electrolyzed oxidizing water can remove the surface oxidation film of the pure nickel. Na₂SO₄ electrolyzed oxidizing water does not have chloride ion, unlike NaCl electrolyzed oxidizing water. Therefore, Na₂SO₄ electrolyzed oxidizing water is wide in the application scope, compared with NaCl electrolyzed oxidizing water.

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Our main purposes were to establish ultraviolet-ray aided machining and clarify the chemical and mechanical polishing mechanism. The specific goals were to lessen the deformities in the machined surface, to make the crystal grains on the machined surface appear, and to apply this machining at the micrometer level instead of at the nanometer level. The present study targets the development of a polishing technique that uses a photocatalyst and a cathilon (a luminous dye : Cathilon Brilliant Flavine; hereafter referred to as Cathilon) excited by an ultraviolet ray. Nickel (hereafter referred to as Ni) was polished chemically and mechanically at the sub-micrometer level under an ultraviolet-ray irradiation. Measurements clarified that TiO₂ of 0.1-μm grain size mechanically polished the Ni, and Cathilon chemically polished Ni. A flat surface was attained on the Ni by chemical and mechanical polishing using both the TiO₂ and Cathilon, when they were irradiated by an ultraviolet ray. Further measurements indicated that the corrosion of Ni surface became large under an ultraviolet-ray excitation. The eroded trace was large when Cathilon is rich. Though much TiO₂ tends to roughen Ni surface, the flat surface was obtained in the case of much TiO₂ and much Cathilon due to both equivalent influences.

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Based on a knife-edge optical displacement sensor, the intensity distribution in a detector plane reflected from an irradiated surface spot with micro-geometry was theoretically analyzed using the point spread function. Then the digitized height maps obtained by an AFM for electrical discharge machined surfaces and ground surfaces were used to calculate the reflection intensity distributions in order to investigate the infl uences of optical confi guration, surface micro-geometry and spot shape. It is revealed that the focus signal varies significantly with the irradiation position for both surfaces under test and the displacement signal of the sensor is strongly affected by the micro-geometry on an irradiated spot. We also demonstrated that the signal variation due to surface micro-geometry can be reduced up to 70% by employing an elliptical rather than a circular irradiation spot.

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In recent years, the size of plane substrates and semiconductor wafers has increased. As conventional contact transportation systems composed of, for example, carrier rollers, belt conveyers, and robot hands carry these longer and wider substrates, the increased weight of substrate results in increased potential for fracture. A non-contact transportation system is required to solve this problem. I propose a new non-contact transportation system combining acoustic viscous and aerostatic forces to provide damage-free transport. In this system, substrates are supported by aerostatic force and transported by acoustic viscous streaming induced by traveling wave deformation of a disk-type stator. Two non-contact guiding techniques to avoid substrates drop off from the transporter. One is hybrid type consists of stators, which have transportation and guiding function, set on the both side of transporter. The other is discrete type consists of stators and guide units separately. The guide unit has a plate oscillates with a standing wave of fundamental mode to excite non-contact holding/ guiding force. We constructed a non-contact transport apparatus for polycrystalline silicon wafers (150(W) × 150(L) × 0.3(t)). The stator with piezoelectric actuators for hybrid type performs holding thrust force of 0.37mN. On the other hand, one guide unit produces the holding force of 20mN

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