Akiyuki Minamide

Study on Photopyroelectric Signal of Optically Opaque Material Measured by Polyvinylidene Difluoride Film Sensor.

In this paper, we propose a new one-dimensional model to analyze a photopyroelectric signal of optically opaque materials measured by a polyvinylidene difluoride (PVDF) film sensor. This model is considered three layers (sample, air gap and the PVDF film) and the reflections of the thermal wave at the interfaces of each layer. In order to check the validity of the proposed model, we measure the inclination of the frequency dependence of the signal measured by the PVDF film and compare it with a theoretical value. When laser light is irradiated onto a graphite surface on the PVDF film, the measured inclinations are -1.6 for a 9 µm PVDF film, -1.8 for a 28 µm film and -2.0 for a 110 µm film. These inclinations were comparable with the simulated inclinations in the cases of all the film thickness of the PVDF film considered.

Measurement of Thermal Diffusivity of Transparent Adhesives by Photoacoustic Microscope

In this paper, we describe a method by which thermal diffusivity of transparent epoxy adhesive on a substrate can easily be measured from the frequency dependence of a photoacoustic (PA) signal. In order to eliminate the influence of the substrate, the phase difference between a PA signal of the adhesive on the substrate and a PA signal of only the substrate was measured. This method was tested for cases of thermally thin and thick graphite (high thermal conductivity) substrates and a polypropylene (low thermal conductivity) substrate. It has the advantage that the thermal diffusivity of a transparent adhesive on a substrate can be measured regardless of the thickness and the thermal properties of the substrate.

Study of Scanning Photoacoustic Microscopy

The hardware and software of Scanning Photoacoustic Microscope (SPAM) composed of low price parts are described. From the obtained images it is found that our SPAM can be used well to understand fundamental characteristics of a surface flaw on a machinable ceramic, surface and subsurface flaws in epoxy and the distribution of carbon fiber in the CFRP (Carbon Fiber Reinforced Plastic) as an equipment of nondestructive testing.

Study of Models on the Generation and Propagation of Photoacoustic Signals in a Drilled Hole in Epoxy Resin

This paper describes improved models derived from an experiment in generation and propagation of photoacoustic signals in a drilled hole of an epoxy resin with different backing materials, a white polypropylene and a black one. The major difference between the improved and the old models is as follows. The photoacoustic signal at the top edge of the hole was generated not only due to absorbed incident light, but also due to absorbed and scattered light at the top edge of the hole. In addition, we show the propagation paths of the PA signals generated at the top edge of the hole.

Study on Estimation of Metal Film Thickness by Attenuated Total Reflection

The estimation of thin film thickness by attenuated total reflection (ATR) was proposed. This technique is caused by be fitted curve evaluated from Fresnels formula to experimental values of reflectivity in the resonance dip due to surface plasmon. The equation for the thickness, d spr, estimated from ATR and the minimum, R min, of the resonance dip in reflectivity due to surface plasmon resonance is represented by d spr=D+√E(R min-F). The values obtained by this method were compared with those obtained by the surface roughness tester made by the Rank Tayler Hobson Company. From this comparison, the experimental formula d srt=Gd spr+H was proposed, and G and H were obtained as 0.69 and 6.7 respectively for an Ag film, 0.86 and -1.45 respectively for an Au film, and 0.67 and 8.98 respectively for a Cu film, all ranging from about 30 nm to 70 nm in thickness.

Study on Photoacoustic Effect of Epoxy Resin on Backing Material by Scanning Photoacoustic Microscope

Amplitude and phase of a photoacoustic signal generated from an epoxy resin on backings (aluminum, white acrylic resin and black-coated white acrylic resin) were measured by a scanning photoacoustic microscope. The experimental results were as follows. The photoacoustic signals for light-reflective backings (aluminum and white acrylic resin) were generated from the epoxy resin on the backing, while photoacoustic signals for light-absorptive backing (black coated white acrylic resin) were generated from the backing itself.

Development of Scanning Photoacoustic Microscope

The paper describes the advantages of our scanning photoacoustic microscope (SPAM) as a nondestructive equipment for evaluating and imaging surface flaws and subsurface cracks in advanced materials. Hardware and software of the SPAM were discussed. It was found that surface flaws and subsurface drill holes in epoxy resin well analyzed by using the SPAM. This microscope was also effective in imaging the distributions of carbon fiber fluxes in a carbon fiber reinforced plastic.

Material evaluation with new modulation method in photoacoustic technique

The proposed new method partially solves the problem of low signal-to-noise-ratio (SNR) when modulation frequency increases. In this paper, the authors suggest keeping the amplitude of the detected photoacoustic (PA) signal constant by linearly increasing the modulation voltage versus the frequency. This technique decreases the SNR at low frequencies but increases the SNR in the usual noisy band and the PA signal of the sample can be easily estimated by FFT. Furthermore, the technique is demonstrated to effectively detect a subsurface defect in a graphite sample in the 10–100 Hz frequency range.

Development of a handedness exchange support system using tangible devices

This study is aimed toward development of the system which supports early rehabilitation training of upper-limbs paralysis. The form of rehabilitation training covered is handedness exchange. Among rehabilitation for functional impairments to a persons dominant hand, in addition to functional training targeting the affected area, there is also training that aims to enable the person to use their other (non-dominant) hand instead. This handedness exchange rehabilitation training aims to bring out the potential functional capability of the non-dominant hand. This training involves practicing manipulating chopsticks and penmanship practice, and because it requires manipulation of delicate tools, the burden for patients can be significant. We have produced a prototype system that can be carried out with patients enjoying handedness exchange even within medical wards. In this paper, we describe the availability of our system to training program of handedness exchange.

Design of an Environmental Education Material Based on Field Observations

The objective of this study was to develop an environmental education material that is appropriate to Kanazawa. Since 2003, we have been observing the summer ground air temperature in Kanazawa, Japan. The results are effectively applied as teaching materials for environmental education classes. The curriculum contents are used to explain the land use and the heat environment in Kanazawa. This paper contains a description of the teaching materials and the system used for observing the temperature in Kanazawa.