Fast calculation method with saccade suppression for a computer-generated hologram based on Fresnel zone plate limitation.

The computer-generated hologram (CGH) is an ideal 3D technology that can satisfy all the physiological factors of the human eye (such as binocular parallax, focus adjustment and convergence etc.) by simulating the recording part of traditional optical holography with a computer. CGH has a lot of advantages such as being able to be used for animation. However, it also has many disadvantages, and one of them is the large amount of calculation. A saccade is one of a very rapid movement of human eye, and also, it is an ability of the eye to quickly and accurately move from one target to another. This is very critical for reading and involves very precise and specific eye movements. Saccades normally happen at a frequency of 2 - 8 times per second in daily life without our being conscious, and their peak angular speed can reach 900 degrees/second. However, saccades can also be initiated by an expected stimulus such as looking from one object to another, and they last from 20 - 200 ms depending on their amplitude. In addition, our visual information is suppressed while saccade occurs. In this paper, to realize the fast calculation of CGHs, a new method is proposed that uses saccades to reduce the amount of CGH calculation without any negative effects on observers viewing CGH reconstruction images. We increased high-speed calculation by at least 4 times through Fresnel zone plate limitation and 4.64 times through saccade suppression.

Dynamic visual responses of accommodation and vergence to electro-holographic images.

Electro-holography can display images without inducing fatigue and three-dimensional (3D) sickness, i.e., visual discomfort due to viewing a stereoscopic display. Thus, this technology is expected to be applied to 3D media. However, there are no studies that have shown the agreement between the dynamic responses of accommodation and vergence to the reconstructed images of electro-holography and those to the real targets. This paper describes the measurement results of these responses using a developed system that can simultaneously measure the dynamic responses of accommodation and vergence. Moreover, statistical analysis for associating the accommodation and the vergence responses was achieved, and our study confirmed that these responses were in agreement.

Response of accommodation and vergence to electro-holographic images.

Studies on measuring accommodation and vergence responses of human vision are important to evaluate three-dimensional (3D) display technologies. Electro-holography is expected to be an ideal 3D display. However, there has been little research on measuring responses to it. In this study, the static responses to electro-holographic images with a large visual field and correct stimuli were measured. In addition, responses to real objects were measured for comparison with those to displayed images. There were more subjects than in conventional studies for statistical analysis. The experimental results statistically confirmed the equivalence of the responses to electro-holographic images and those to real objects. Therefore, it was experimentally suggested that electro-holography enables human vision to perform correct accommodation and vergence responses in accordance with the depths.

New approach to breast tumor detection based on fluorescence x-ray analysis.

A new technical approach to breast-tumor detection is proposed. The technique is based on fluorescence x-ray analysis, and can identify a miniature malignant tumor within the breast. The primary beam intensity needed in fluorescence x-ray analysis is on a lower order of magnitude than that used in mammography. Thus, the newly-proposed technique would enable detection of a still tiny breast cancer while dramatically lowering the radiation dose. Field-emission x-ray sources might be a key for translating this concept into a medical technique.

Biological effects of field emission-type X-rays generated by nanotechnology.

Thermionic emission (TE)-type X-ray generators have been exclusively used in medicine, but there are many difficulties in making these X-ray sources compact. A field emission (FE)-type X-ray generator using carbon nanotubes is a newly-developed compact system that can be as small as several cm in length. Considering the compactness of the equipment, the FE-type X-ray generator may become a useful tool for endoscopic, intracavitary or intraoperative radiotherapy in the future. The aim of this study was to investigate the biological effects of X-rays generated by the FE-type X-ray source in comparison with those of conventional TE-type X-rays. Mouse thymic lymphoma 3SB cells were irradiated by an FE-type X-ray generator developed by our group and a conventional TE-type X-ray source under identical conditions. DNA damage after radiation was detected by foci formation of phospho-H2AX (gamma-H2AX). Effect on the cell cycle was analyzed by flow cytometry. Activation of the DNA damage checkpoint was analyzed by immunoblotting. Induction of apoptosis was studied using the TUNEL assay. In terms of induction of DNA damage (DNA double-strand breaks), activation of cell cycle checkpoints (p53 stabilization, p21 induction, Chk1 and Chk2 phosphorylations), and induction of apoptotic cell death, FE-type X-rays were as effective as TE-type X-rays, and FE-type X-rays appeared to be applicable to radiation therapy.