Masaharu Komori

Imprinted optical pattern of low-softening phosphate glass

Thermal imprinting of transparent tin phosphate glass was performed at 250 degrees C using a fine-patterned silica mold. The glass sample was prepared by a conventional melt-quenching method and polished with a roughness of < or =10 nm for imprinting experiments. The imprinting temperature is optimized based on experimental viscosity data. Scanning electron microscope and atomic force microscope observations revealed that a square grid pattern has a surface roughness of < or =10 nm and 5 microm x 5 microm squares with ~1 microm intervals and 90-100 nm depth. Diffraction spots due to the micropattern are demonstrated by illuminating He-Ne laser light.

Micro/nanoimprinting of glass under high temperature using a CVD diamond mold

For micro/nanoimprinting of glass, the appropriate combination of glass and mold material was clarified by an adhesion test using chemical vapor deposition (CVD) diamond, silicon, glassy carbon and sintered nitride ceramics as the mold material, and Pyrex, TEMPAX and BK7 as the glass material. The result of the adhesion test shows that CVD diamond is suitable for imprinting with a wide variety of glass materials under various temperature conditions. The method of fabricating the CVD diamond mold using focused ion beam (FIB) was examined, and it was clarified that the grain boundary of CVD diamond has little effect on the surface condition. Glass micro/nanoimprinting was performed using the CVD diamond mold. The effect of the molding conditions, such as the molding temperature and mold-release temperature, on the height of glass transcription was clarified. The effects of pattern size and shape were also investigated. On the basis of the results, a method of selecting the molding conditions to obtain the desired transcript height was developed. In this research, the entire flow of glass micro/nanoimprinting, including mold material selection, the mold fabrication process and molding process, was proposed experimentally, and the selection method of the molding conditions was shown.

Quality-guided phase unwrapping algorithm based on reliability evaluation

For optical interferometry, a new quality-guided phase unwrapping algorithm based on the reliability evaluation of each pixel of the wrapped phase is proposed. First, the parameters used as quality measures in the past quality-guided algorithms are classified into the reliability measure and the quality measure, and the intensity of the object image belongs to the reliability measure. Then, by computing and applying a threshold to the intensity of the object image, the valid region (i.e., the interference region) is distinguished into the reliable region and the doubtful region. The wrapped phase in the reliable region is subsequently unwrapped by the way of multipaths integration, and different paths are guided by separate quality measures. Finally, starting from the reliable region, the doubtful region is unwrapped by the way that each path takes in the reliable region. Experimental results have shown that the proposed algorithm not only performs well, but also computes efficiently.

Design of laser interferometric measuring device of involute profile

The vibration and noise of gears is one of the serious problems for devices, such as vehicles and wind turbines. The characteristics of the vibration and noise of gears are considerably affected by the tooth flank form deviation of micrometer order. The quality of product gears is controlled using a gear measuring instrument and calibrated with an involute artifact. However, the conventional calibration of the involute artifact cannot achieve a sufficient accuracy. In this report, a direct method of measuring the involute artifact using a laser interferometer is proposed. Fundamental experiments are carried out, in which the effects of the surface condition of the measured object and the effect of the driving of the artifact are investigated. It is confirmed that the proposed method enables the measurement of the detailed form of an involute tooth flank and has the potential of accomplishing a highly precise measurement of an involute artifact.

Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact

There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.

Design and Error Analysis of Multiball Artifact Composed of Simple Features to Evaluate Pitch Measurement Accuracy

The strength and vibration/noise of gears are influenced by the pitch deviation of micrometer order and therefore, advanced quality control is needed in gear manufacturing processes using measuring instruments. The accuracy of the pitch measuring instrument is verified using a master gear or artifact, but their accuracy is not sufficiently high. An artifact with higher accuracy for the evaluation and calibration of the pitch measurement is necessary in order to respond to the requirement of gear accuracy. In this research, the multiball artifact, a novel high-precision pitch artifact, is proposed for use in the evaluation of pitch measuring instruments. The multiball artifact is composed of balls, a cylinder, and a plane, where the center cylinder or center ball is surrounded by the balls on the plane. The positions of those elements are decided automatically by the contact among those elements. Balls, cylinders, and planes can be manufactured with accuracy on the order of several tens of nanometers. Therefore, this artifact can realize high accuracy. In addition, this artifact does not need advanced techniques in manufacturing and assembly. This leads to the reduction in manufacturing cost. In this report, the concept and structure of the multiball artifact are proposed, and theoretical analysis on the measurement of the artifact is carried out. Feasible angular pitch is analyzed theoretically. For a cylinder-centered artifact, it is easy to realize the target angular pitch by adjusting the cylinder diameter. Ball-centered types suffer from the limitation of the variation in ball diameter if standard balls are used, but an angular pitch close to the target pitch is possible through the selection of an appropriate combination of balls. The effects of the dimensional deviation of the diameter of the center cylinder, the inclination of the center cylinder, the dimensional deviation of the surrounding ball diameters, the sphericity of balls, and the flatness of the base plane are analyzed. Deviations in the cylinder have a comparatively large effect on angular pitch. On the other hand, the effect of the deviation of the ball or base plane is smaller. The feasible angular pitch is clarified, and it is verified that the concept and structure of the multiball artifact are effective. The effects of deviations in the form and dimension of the composing elements are analyzed, and it is clarified that the accuracy of the cylinder is important. DOI: 10.1115/1.3087535

Simulation method for interference fringe patterns in measuring gear tooth flanks by laser interferometry

We present a ray-tracing-based method for simulation of interference fringe patterns (IFPs) for measuring gear tooth flanks with a two-path interferometer. This simulation method involves two steps. In the first step, the profile of an IFP is achieved by means of ray tracing within the object path of the interferometer. In the second step, the profile of an IFP is filled with interference fringes, according to a set of functions from an optical path length to a fringe gray level. To examine the correctness of this simulation method, simulations are performed for two spur involute gears, and the simulated IFPs are verified by experiments using the actual two-path interferometer built on an optical platform.

Analysis of General Characteristics of Transmission Error of Gears With Convex Modification of Tooth Flank Form Considering Elastic Deformation Under Load

The vibrationlnoise of power transmission gears is a serious problem for vehicles including automobiles, and therefore many studies on gear vibration have been reported. These studies, however, were carried out by investigation using numerical simulations in which gears with specific dimensions and tooth flank modifications under specific loading were considered. Therefore, the general characteristics of the transmission error of gears have not been clarified theoretically. In this report, a general model for the tooth meshing of gears is proposed; in which a quasi-infinite elastic model composed of springs with stiffness peculiar to the gear is incorporated. The transmission error of gears is formulated by theoretical equations. An investigation on the factors affecting the general characteristics of transmission error is accomplished using the formulated equations. The qualitative characteristic of the transmission error of gears with convex tooth flank form deviation is determined by the actual contact ratio and qualitative elements of gears, i.e., tooth flank form deviation and the distribution of stiffness. Even if the amplitude of torque, the amount of tooth flank form deviation, and other quantitative elements are not determined, the qualitative characteristic of transmission error can be derived. The peak-to-peak value of transmission error increases proportionately to the amount of tooth flank form deviation.

Gear checker analysis and evaluation using a virtual gear checker

The vibration of gears is one of the serious problems for machines. The characteristics of vibration of gears are considerably affected by the tooth flank form deviation of micrometer order; therefore, strict quality control of the tooth flank form is required. However, because the gear checker (a gear-measuring machine) is structurally complex, it is difficult to analyze how the error factors of the gear checkers affect the measurement result. In this research, a virtual gear checker (VGC) is proposed, that is, a computer program that considers the structures, motions and possible error factors of the real gear checkers, such as motion error. The VGC can be used to simulate the gear measurement, and the effects of the error factors on the measurement result can be analyzed. It is possible to evaluate the uncertainty of tooth flank measurement much more easily and quickly with a VGC than with a real gear checker. A VGC can be used to analyze not only the gear measurement but also arbitrary-shaped objects such as a ball artefact, and the theoretical measurement result is output from the VGC. In this paper, we describe the development of a VGC, and the effect of error factors and the uncertainties of gear measurement are analyzed.

Object-image-based method to construct an unweighted quality map for phase extraction and phase unwrapping

A method to construct an unweighted quality map for phase extraction and phase unwrapping is proposed, based on an object image pattern. The object image pattern must be recorded under the same conditions as that of the corresponding interference patterns, except that the lights coming from the reference arm of the interferometer are hidden. An unweighted quality map that can represent the valid and invalid regions in the interference patterns is completed successfully, based on two factors: the fact that the object region in the object image pattern is homologous with the valid region (i.e., the interference region) in the interference patterns, and on distinguishing between the object and background regions in the object image pattern using neighbor window threshold filtering and fitting the boundary of the object image. The application of the proposed method to the real measurement shows its feasibility and correctness. This paper might provide an alternative method for constructing an unweighted quality map for phase extraction and phase unwrapping.