[Estimation of cost-saving for reducing radioactive waste from nuclear medicine facilities by implementing decay in storage (DIS) in Japan].

DIS has not yet been implemented in Japan as of 2011. Therefore, even if risk was negligible, medical institutions have to entrust radioactive temporal waste disposal to Japan Radio Isotopes Association (JRIA) in the current situation. To decide whether DIS should be implemented in Japan or not, cost-saving effect of DIS was estimated by comparing the cost that nuclear medical facilities pay.

Drying process in a solvent-based paint analyzed by phase-shifting digital holography and an estimation of time for tack free.

A technique to study the drying of paints, based on phase-shifting digital holography, is presented. The technique is applied to the drying process of solvent-based paint on a three-dimensional surface at different substrate temperatures. For processing the data, a cross-correlation function and phase change derived from reconstructed complex amplitudes are calculated to visualize and to evaluate the local variations in the dryness of paint.

[Bibliographic consideration of proper management of radioactive waste on short-lived period nuclides that are used in nuclear medicine].

A rational clearance system for medical radioactive waste has not yet been established in Japan. As Europe and USA's ways, the establishment of DIS that medical radioactive waste what are kept in storage room for more than decided period each nuclide except from regulation of radiation's control. The purpose of this report is to clarify the problems with the establishment of DIS in Japan through a literature review of the experience in Europe and the USA and previous research that has been reported in Japan.

Multicolor digital holography with an achromatic phase shifter.

Multiwavelength recording and reconstruction of a three-dimensional object are realized by use of phase-shifting digital holography. Red, green, and blue lines emitted from a white-light He-Cd laser are used for one-step recording of the complex amplitude of the object with a color CCD camera, in which a phase shift is introduced with an achromatic phase shifter based on the geometric phase. Three color images are reconstructed and successfully combined in a computer by use of Fresnel transformation based on a convolution.

Phase-shifting color digital holography.

Digital holography with a three-wavelength laser and a color CCD has been demonstrated. With the phase shifting of the reference beam, in-line holograms for three wavelengths are recorded simultaneously for derivation of the complex amplitude at each wavelength, and then the three monochromatic images are reconstructed and combined into full-color images in the computer. Laser power variation for wavelengths can be compensated for in the reconstruction process.

Surface shape measurement by phase-shifting digital holography with a wavelength shift.

Surface contouring by phase-shifting digital holography is proposed and verified by experiments and numerical simulations. Digital holograms are recorded before and after mode hopping of a laser diode subject to current tuning, and the difference of the reconstructed phases at each wavelength is computed to deliver surface contours of a diffusely reflecting surface. Since normal incidence on the object is employed, the method does not need the removal of the tilt component and is free from the shadowing effect as advantages over the dual-incidence method proposed before by the first author.

Image reconstruction only by phase data in phase-shifting digital holography.

We describe data compression in phase-shifting digital holography. We demonstrate by experimentation that an image of a diffusely reflecting object can be reconstructed only by phase data of the derived complex amplitude. It is shown that reduction of the bit depth of the phase data does not seriously damage the image even down to 1 bit.

Effects of quantization in phase-shifting digital holography.

We discuss quantization effects of hologram recording on the quality of reconstructed images in phase-shifting digital holography. We vary bit depths of phase-shifted holograms in both numerical simulation and experiments and then derived the complex amplitude, which is subjected to Fresnel transformation for the image reconstruction. The influence of bit-depth limitation in quantization has been demonstrated in a numerical simulation for spot-array patterns with linearly varying intensities and a continuous intensity object.

Algorithm for reconstruction of digital holograms with adjustable magnification.

A new algorithm that allows for reconstruction of digital holograms with adjustable magnification is proposed. The algorithm involves two reconstruction steps implemented by a conventional single Fourier-transform algorithm. The advantages of the algorithm lie in its adaptability to various object sizes and recording distances as well as in its capability to maintain the pitch of a reconstructed image, independent of the reconstruction distance and wavelength for objects larger than a CCD.

Digital Hilbert transformation for separation measurement of thicknesses and refractive indices of layered objects by use of a wavelength-scanning heterodyne interference confocal microscope.

A wavelength-scanning heterodyne interference confocal microscope quickly accomplishes the simultaneous measurement of the thickness and the refractive index of a sample by detection of the amplitude and the phase of the interference signal during a sample scan. However, the measurement range of the optical path difference (OPD) that is obtained from the phase changes is limited by the time response of the phase-locked loop circuit in the FM demodulator. To overcome this limitation and to improve the accuracy of the separation measurement, we propose an OPD detection using digital signal processing with a Hilbert transform.

Geometrical tomographic imaging of refractive indices through turbid media by a wavelength-scanning heterodyne interference confocal microscope.

A wavelength-scanning heterodyne interference confocal microscope has proved to provide the tomographic image of the refractive indices of transparent and turbid media on the scale of geometrical depth when weakly reflected light with an optical power as low as of the order of 10(-14) W is used. The refractive indices of the transparent object and the turbid media were measured with accuracies of -0.5% and approximately 3%, respectively.