Takao Sajima

Effects of irradiance of various wavelengths from light-emitting diodes on the growth of the harmful dinoflagellate Heterocapsa circularisquama and the diatom Skeletonema costatum

We investigated the effects of specific light wavelengths from light-emitting diodes (LEDs) on the growth of the dinoflagellate Heterocapsa circularisquama, which kills bivalves, and the diatom Skeletonema costatum, which is an important food source for bivalves. Growth of H. circularisquama was obviously inhibited at 590 nm and a photon flux density less than 75 μmol quanta/m2/s. However, growth of S. costatum was not suppressed by irradiance from any LEDs tested from near-ultraviolet to near-infrared wavelengths at 75 μmol quanta/m2/s. The growth rate of H. circularisquama in an experimental treatment group with irradiance provided by both cool-white fluorescent lamps (12∶12 h L:D cycle) and a 590-nm LED (continuous irradiance) was 0.43/day. In the control group with irradiance provided only by cool-white fluorescent lamps (12∶12 h L:D cycle), the growth rate was 0.63/day, indicating that growth of H. circularisquama was suppressed by 590 nm (less than 75 μmol quanta/m2/s) irradiance from the LED and the continuous irradiance. The use of 590-nm LEDs in bivalve culture at irradiance levels less than 75 μmol quanta/m2/s might encourage the growth of the useful diatom S. costatum without stimulating growth of the harmful dinoflagellate H. circularisquama.

Study of a vibrating fiber probing system for 3-D micro-structures: performance improvement

This paper presents a system for measuring 3D micro-structures that uses an optical fiber probe equipped with a piezo element that causes the probe to vibrate. The optical fiber probe consists of a stylus shaft with a diameter of 3 µm and a glass ball with a diameter of 5 µm attached to the tip. The stylus is vibrated in a circular motion in a single plane. The vibrator mechanism is introduced to prevent adhesion of the stylus tip to the surface being measured. This adhesion, which adversely affects the accuracy and time of the measurement, is caused by intermolecular, electrostatic, and liquid bridge forces. The measuring principle involves monitoring the vibrational amplitude of the stylus shaft that is required to prevent the adhesion of the stylus tip to the surface being measured, this amplitude being measured optically. In our previous report (Murakami et al 2012 Key Eng. Mater. 523–524 907–12), we found that the stylus shaft actually moves in an elliptical motion when it is set to describe a circular motion in the X-Y plane. Therefore, when a measurement is taken, it is necessary to adjust the motion of the piezoelectric tube to compensate for the difference between the diameter of the perfect circle and the actual elliptical motion of the stylus shaft displacement. In this study, the stylus characteristics were examined and the motion of the stylus shaft was then corrected to attain the desired circular motion. Next, the expansion of the measuring area by using a line laser was investigated. Finally, an experiment involving the measurement of a micro-hole was performed to demonstrate the practicality of the vibrating fiber probe. As a result, it was shown that the displacement between the diameter of the perfect circle and the actual elliptical motion of the stylus tip was about 0.034 µm after compensation. In addition, it was confirmed that the measurement area can be expanded by using an optical slit, but the standard deviation of the repeatability of the point measurement with the slit decreases to about half of that without the slit. In addition, the practicality of this system was confirmed by measuring the shape of a 100 µm diameter micro-hole.

Development of a Deep-Hole Boring Tool Guided by Laser

Summary A laser-guided BTA tool has been developed with the purpose of preventing the axial hole deviation in deep hole boring. To examine the performance of this system, two kinds of experiments were carried out using prebored duralumin work-piece. The first experiment was to examine if the tool can be precisely manipulated by computer. The second was to investigate if the tool can follow the target. The target is located in front of the tool and its position changes in the normal plane to the machining axis. The results show that the tool can turn its course to correct hole deviation.

Development of a high-performance laser-guided deep-hole boring tool : optimal determination of reference origin for precise guiding

Abstract A laser-guided deep-hole boring tool using piezoelectric actuators was developed to prevent hole deviation. To extend the depth of controllable boring further, the following were improved. The tool’s guiding error, caused by misalignment of the corner cube prism and the mirror in the optical head from the spindle axis, was eliminated using an adjustment jig that determined the reference origins of the two position-sensitive detectors (PSDs) precisely. A single-edge counter-boring head is used instead of the double-edge head used up to now. The former was thought to be better in attitude control than the latter. A new boring bar, which was lower in rigidity and better in controllability of tool attitude, was used. Experiments were conducted to examine the performance of the new tool in detail and to determine its practical application, using duralumin (A2017-T4) workpieces with a prebored 108-mm diameter hole. The experiments were performed with a rotating tool–stationary workpiece system. Rotational speed was 270 rpm and feed was 0.125 mm/rev. Tool diameter was 110 mm. As a result, controlled boring becomes possible up to a depth of 700 mm under the stated experimental conditions. 700 mm is the maximum machinable length of the machine tool. The tool can be put to practical use.

Development of a High-Performance Deep-Hole Laser-Guided Boring Tool: Guiding Characteristics

A laser-guided BTA tool using piezoelectric actuators was developed to prevent hole deviation. Three kinds of experiments were conducted to examine the performance of this tool using a duralumin workpiece with a prebored hole. The first experiment was performed to examine the conditions of the hole deviation in normal deep hole boring. The second was to examine whether the tool could go straight through without shifting toward a thin wall on one side of the workpiece. The third was to examine whether the tool could go straight through without advancing along an obliquely prebored hole. The results showed that the tool could be guided to go straight through despite the disturbances.

Development of a deep-hole, laser-guide boring tool: the boring of workpieces with a thin wall and an inclined prebored hole

Abstract A laser-guided BTA tool has been developed to prevent axial hole deviations. Four kinds of experiments were conducted to examine the performance of this tool in detail and to determine its practical application using a duralumin (A2017-T4) workpiece with a prebored 108-mm diameter hole. The first experiment was performed to examine the conditions of the hole deviation in the case of normal deep-hole boring. The second was to examine whether the tool corrects for the stated hole deviation. The third was to examine whether the tool can go straight through to the target without shifting toward a thin wall ( t = 0.7 mm ) on one side of the workpiece. The fourth was to examine whether the tool can be guided toward the target without affecting a prebored hole, which was inclined to radial direction at 100 μm for a hole length of 100 mm. The experiments were performed with a rotating tool-stationary workpiece system. Rotational speed was 270 rpm and feed ws 0.125 mm/rev. Tool diameter was 110 mm. The results show that the tool can be guided to go straight through toward the target despite the disturbances.

Development of an Optical Hole-Diameter Measuring Instrument

An optical hole-diameter measuring instrument has been developed. The instrument, which consists of two laser diodes, a photo sensitive detector, two condenser lenses and some mirrors, is intended to measure, based on trigonometry, the distances to the hole wall on two sides alternately. The fundamental analysis and experiment showed that it was possible to measure the distances to the object having not only a mirror-like plane surface but also a rough cylindrical surface. Using the instrument, which was manufactured on trial, it was found that the hole-diameter between 9.5 and 11.0 mm could be measured within accuracy of 23 μm.

Position sensing with magic gas mixture in the transition region from the proportional to the self-quenching streamer mode

Using a single-wire gas counter filled with magic gas mixtures, position sensing was performed in the region of the transition from the proportional to the self-quenching-streamer (SQS) mode. The gas mixtures used were Ar-iso-C/sub 4/H/sub 10/-Freon-13B1, known as the original magic gas mixture, and Ar-CH/sub 4/-Freon-13B1. Both mixtures were used with different concentrations of Freon 13B1, i.e. 0, 0.15, 0.45, 0.90 and 1.1%. It is shown that by adding a small amount of Freon vapor, the generation of the SQS mode becomes more stable. The iso-C/sub 4/H/sub 10/-based gas is shown to be more stable with respect to high anode voltage than the CH/sub 4/ based gas. >

Development of Mechanical Actuator for Deep-Hole Measurement System

This paper presents a new type of mechanical actuator which is used to help in measuring deep holes that carry up to a load of 26kg during measurement. Often the measurement probe‘s attitude is misaligned due to acting force on it. Actuator prevents or controls the misalignment of such probe during measurement. In this research, the complete measurement system consists of a servo motor, a laser diode, a laser interferometer, an optical system as well as the integrated computer system. The main purpose of this research is to develop the new type of actuator which can control the attitude (position and inclination) of a measurement probe. The experimental results show that it is possible to carry mechanically the loads up to 26kg of the measurement probe during measurement of deep-holes. In this paper, the developed actuator’s mechanical function and its performance have been discussed with the experimental results.

Analysis and Evaluation of Surface Force Effects in Vibrating Fiber Probing System for 3-D Micro Structure Measurements

This paper presents a measurement system for 3-D micro structure using an optical fiber probe equipped with a piezo element generating vibration. The optical fiber probe consists of a stylus shaft with a diameter of 3 µm and a glass ball with a diameter of 5 µm attached to the tip. The stylus is set so as to circularly move in a plane. The measurement principle involves the monitoring of the vibrational amplitude of the stylus to prevent adhesion of the stylus tip to the measured surface due to the surface force, and this amplitude is measured optically. In this research, the stylus characteristics are examined. The effects of the relative humidity and the surface roughness on the surface force are then evaluated. As a result, it is shown that the surface force increases remarkably when the relative humidity is greater than 40%, and there is no adhesion of the stylus tip to the measured surface due to the surface force in case of the stylus vibrational amplitude of over 0.5 µm. Also, the adhesion of the stylus tip cannot be observed in the 0.2 - 0.8 µm surface roughness range.