Teruo Usami

Modeling and visualization for a pearl-quality evaluation simulator

Visual simulation using CG and VR has attracted wide attention in the machine vision field. This paper proposes a method of modeling and visualizing pearls that will be the central technique of a pearl-quality evaluation simulator. Pearls manifest a very specific optical phenomenon that is not dependent on the direction of the light source. To investigate this feature, we propose a physical model, called an illuminant model for multilayer film interference considering the multiple reflection in spherical bodies. The rendering algorithm has been configured from such representations of physical characteristics as interference, mirroring, and texture, which correspond, respectively, to the sense of depth, brightness, and grain that are the main evaluation factors obtained from psychological experiments. Further, portions of photos of real pearls and the images generated by the present method were evaluated based on a scale of psychological evaluations of pearl-like quality demonstrating, thereby, that not merely the generated images as a whole, but the respective parts of images can present such a pearl-like quality.

Response calculation of a stacked CdZnTe detector for 16N γ-ray measurement

Abstract A stacked CdZnTe semiconductor detector, which is able to detect the 6.13 MeV γ-rays from 16 N, was prototyped and the response calculation was carried out by a Monte-Carlo simulation. The detector response was simulated by using the electron and photon transport code, EGS4 and taking into account the carrier trapping phenomena. The results of the response calculation agreed with the experimental data from the checking source of 137 Cs and 60 Co. The prototypes response and sensitivity to 16 N were calculated by simulating an incident energy of 6.13 MeV . The source spectra were unfolded with the detectors response function obtained by simulation, and it indicated that the incident γ-ray energy and its intensity ratio was identified. We have acquired the potential to measure the γ-ray energy in the high energy region about 6 MeV with the stacked CdZnTe detector.

Micro-optical distance sensor fabricated by the LIGA process

An ultra-miniaturized sensor head for absolute measurement which has a size of less than 5 mm cube is realized. The sensor works by means of the optical triangulation. To achieve the optical function, the sensor consists of a three layer polymer waveguide patterned by X-ray lithography, an incoupling fiber and two detection fibers and micro cylindrical lenses which are also fabricated by X-ray lithography. The fibers and the cylindrical lenses are placed into the waveguide without any active alignment by using waveguide walls as guiding and fixing structures. The ratio of intensity detected in the two detection fibers is a measure for the distance between the object and the sensor. The detection range of the sensor is 1 to 6 mm between the sensor and an object with diffusively reflecting surface.

Micro-optical distance sensor fabricated by deep x-ray lithography

An all optical ultraminiaturized sensor head for displacement measurement that has a size of less than 5 mm in square has been produced. The sensor works by means of optical triangulation. To achieve the optical function, the sensor consists of a three-layer polymer waveguide patterned by deep x-ray lithography (LIGA), a light input fiber, two detection fibers, and microcylindrical lenses, which are also fabricated by deep x-ray lithography. The fibers and the cylindrical lenses are placed into the waveguide without any active alignment by using the waveguide walls as guiding and fixing structures. The ratio of the intensities detected in the two detection fibers is the measure of the distance between the object and the sensor. High resolution of about 10 ?m is achieved in the range of 2 to 3 mm between the sensor and an object with a diffusively reflecting surface.

Effects of metal impuritites on the etch rate selectivity of (110)/(111) in (110) Si anisotropic etching

We have investigated the effects of metal impurities and thermal oxidation process on Si anisotropic KOH etching characteristics for fabricating microsensors and microactuators having precise deep narrow grooves or channels. The effect of metal impurities such as Al, Cr, Fe, Pb and Cu are evaluated using 30 wt percent KOH etchant at 60 degrees C. Al, Cr and Fe have no relation to the etching characteristics, however, Pb and Cu strongly affect the etching characteristics. The etching rate of Si decreases with increasing Pb and Cu concentration. The etch rate selectivity , which is an anisotropy ratio defined by the etch rate ratio of (110) and (111) plane, is not changed by Pb impurity, but extremely decreases with increasing Cu impurity. It dips form 150 to 80 when the Cu concentration is over 50ppb, and saturated over the concentration. With respect to the surface roughness within our evaluated metal impurities, Cu impurity also strongly affects the roughness of the etched surface. In addition to the effect of metal impurities, we have experienced the effect on the etching selectivity by the thermal oxidation process. The selectivity is decreased with repeating thermal oxidation process, and this tendency is more pronounced with higher oxygen concentration of evaluated Si wafers. As a result, controlling Cu impurity concentration and using a low oxygen concentration wafer are crucial considerations when fabricating sensors and actuators with narrow grooves or channels by Si anisotropic KOH etching.

Airbag accelerometer with a simple switched-capacitor readout ASIC

A bulk micromachined capacitive accelerometer for airbag applications based on (110) silicon anisotropic KOH etching is presented. The sensor is a two-chip accelerometer that consists of a glass-silicon-glass stacked sense element and an interface ASIC containing an impedance converter for capacitance detection, an EPROM and DACs for digital trimming, and a self-test feature for diagnosis. A simple switched-capacitor readout circuit with DC offset error cancellation scheme is proposed as the impedance converter. The dependence of narrow gap etching, surface roughness, and uniformity of the groove depth on the KOH concentration are also investigated for the fabrication of the device, and it is shown that the etch rate of the plane intrinsically controls the depth of the narrow gap with a KOH concentration of over 30 wt. percent, and smooth surface and uniformity of groove depth are obtained at 40 wt. percent KOH. The nonlinearity of the output is about 1.5 percent FS. The temperature coefficient of sensitivity and the off-axis sensitivity are 150 ppm/degree C and 2 percent respectively. The dimensions of the sensor are 10.3 X 10.3 X 3 mm.

Shape estimation of radioactive spent resins in a storage tank using the sampled pattern matching

A method for estimating the shape of accumulated radioactive spent resins in a storage tank has been proposed using the sampled pattern matching. In a two-dimensional simulation model, several kinds of the resin shapes are assumed, and the radiation fields outside the tank are calculated. The resin shapes were estimated using the simulated radiation field data and compared to the assumed shapes, resulting in reasonable agreements between them.

Image Analysis and Synthesis Using Physics-Based Modeling for Pearl Quality Evaluation System

Analysis by image synthesis using CG has attracted wide attention in machine vision. This paper proposes a method of modeling and synthesizing pearls that will be the central technique of a pearl quality evaluation system. Pearls manifest a specific optical phenomenon that is not dependent on the direction of the light source. To investigate this feature, we propose a physical model for multilayer film interference called an “illuminant model.” The synthesis algorithm has been configured from such representations of physical characteristics as interference, mirroring and texture which correspond to the main evaluation factors obtained from human experts. Further, portions of photos of real pearls and the synthesized images were analyzed based on a scale of psychological evaluation of “pearl-like quality” demonstrating thereby that the generated images can present such a pearl-like quality.

Multi-electrode circular position-sensitive device (PSD) and its application to angular measurement

Semiconductor position sensitive devices (PSD) enable to measure the position of a light spot using simple construction. A circular PSD, which has a circular photosensitive region, can be used for angular measurement. This paper presents a new type of circular PSD called Multi Electrode Circular PSD (ME-CPSD) and demonstrates its application for angular measurement. This device, constructed on Si substrate, has a photosensitive region, a resistor line and 16 output electrodes. The photosensitive region has the shape of a ring which is formed by a radial arrangement of long and narrow photodiodes. The outer end of the photodiodes are connected to the continuous resistor line. Photoexcited carriers which are generated in the photodiode by the incident light flow to the resistor line and are extracted by the multioutput electrode which divides the resistor into 16 equal parts. To measure the position of the light spot, a pair of electrodes is selected by switches connected to every electrode and the position of the light spot is calculated from the output current of the selected electrodes. Compared to conventional circular PSDs, the reliability of the angular measurement is improved, because the ME-CPSD does not have an undetectable region caused by the unavoidable discontinuity in the structure of conventional circular PSDs. This device can change its measuring range by selecting the pair of electrodes, making it not only capable of measuring any absolute angular position, but allows also a more precise angular measurement by selecting narrower electrode intervals. This device has the capability to realize a high precision noncontact angular measurement system with simple construction.

A Link Beam Driven, Triple Axis Angular Rate Sensor Based on a Double Gimbal Structure

We report a prototype of a triple axis angular rate sensor based on a double gimbal structure with a link beam drive mechanism, which can be operated without vacuum packaging. The principle of this rate sensor is based upon the torsional reference vibration of an outer gimbal generated by a PZT plate through link beams, and triple axis rate detections by piezoresistive four-terminal elements located on the tortional beams supporting each rate-sensitive inertial mass within the outer driven gimbal.