Kenichi Harakawa

Temperature Distribution in Circular Space Reconstructed from Sampling Data at Unequal Intervals in Small Numbers Using Acoustic Computerized Tomography (A-CT)

The propagation velocity of sound is often used to measure temperature. The sound probe has the advantage of non-contact sensing and quick response. By combining a sound probe with computerized tomography (CT) and data interpolation, an image of temperature distribution through space can be reconstructed. We have proposed a method for measuring the temperature distribution in two-dimensional space using an acoustic CT (A-CT) method with a very small number of acoustic transducers. The measured object is a circular space with a radius of 1,480 mm. Sixteen transducers are installed on the circular stage. Without a mechanical motion, projection data for the reconstruction is acquired by electronic scanning. We reconstruct the temperature distribution by interpolation from a small number of data set. Electrical heaters create a temperature gradient in space. The temperature profile is measured by 19 thermocouples and used for a computer simulation. Experimentally reconstructed images are in agreement with the simulated images. The measurement system proposed in this paper has advantages for use in atmospheric monitoring, air conditioning and heat management.

Self-Developing Characteristics of Nitrocellulose Exposed to Ion Beams

The self-developing and processing properties of nitrocellulose are investigated in comparison with other resists such as PMMA and PBS. It is found that only the nitrocellulose has the self-developing feature of the three resists, and that the self-developing rate of the nitrocellulose is independent of the polymerization grade of nitrocellulose, but is dependent on the nitrogen content in the nitrocellulose.

CO2 Laser Detection Using a Warm Carrier Device with a Thin Film Antenna

Thin film warm carrier devices have been fabricated by electron beam lithographic methods and demonstrated at 10.6 µm. The devices consisted of a narrow gold antenna, the top of which contacted p-type germanium through a 0.1 µm-diam. pinhole fabricated by focused ion-beam techniques. The device exhibited a distinguished antenna pattern for 10.6 µm wave length radiation.

Effects of Heat Treatment on the Sensitivity of Warm Carrier Devices for CH3OH Laser Radiation

Warm carrier infrared laser detectors, which have 0.1 µm-diameter ohmic contact electrode, were fabricated using a focused ion beam, and the effects of heat treatment on the detection sensitivity of the devices were studied at the CH3OH laser frequency. It was found that the sensitivity of the device increased by 100 times with heat treatment at 450°C.

Fabrication of Submicron Contact Hole with a Focused Ion Beam

In order to obtain reproducibility for fabricating microcontact holes in insulator film on the semiconductor substrate, a method of controlling focused ion beam irradiation by monitoring the absorption current was examined. The holes which penetrated the insulator (SiO2) film and just reached the surface of the semiconductor (Ge) substrate were fabricated by stopping the irradiation of the ion beam just after the absorption current of the sample passed through its maximum value. Using this method, holes with a contact area of the order of 10-10 cm2 were obtained with good reproducibility.

Fabrication and properties of antenna-coupled thin-film warm carrier devices

Abstract A plana type thin-film warm carrier device has been fabricated by electron beam lithographic methods associated with focused ion-beams. The fabricated device has 3μm-wide and 950μm long thin-film antenna on SiO 2 film, and the top of it contacted with p-type germanium through a 0.1μm-diam pinhole which penetrates the SiO 2 film. The device exhibited a distinguishing antenna pattern for 10.6μm CO 2 laser radiation.