Biomedical applications of new technologies in opto-electronics are described.
The first part of this paper describes principle and medical applications of SELFOC. SELFOC is a new type of fibre-optic light guide, where distribution of the refractive index is parabolic in radial direction. SELFOC can transmit not only a single laser beam but also a bundle of laser beams and an image. As a typical example of the medical applications of SELFOC, SELFOC arthroscope is described.
The latter part of this paper describes principle and biomedical applications of holo-graphy. The principle of holography is explained in an elementary way, where wave-front reconstruction property of a hologram is emphasized. Biomedical applications of holographic interferometry and holographic microscopy are described. Holographic storage of medical information is discussed. A graphic input device utilizing holography, Holotablet, is also described.

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Validity of Fourier coefficients as parameters for the electrocardiographic pattern recognition by means of the threshold logic units and the maximum likelihood method was verified. As the traditional methods of Fourier transform required much time, a new method of fast Fourier transform of folding type, which differed from FFT of Cooley and Tukey, was developed. Sampling points used in the present investigations totaled 100. Using scalar ECG of Frank's orthogonal system (X, Y and Z leads) 15 normal subjects, myocardial infarction cases and ostium secundum type of atrial septal defect cases respectively were analyzed by this new method, and the coefficients such as A_n, B_n, √_An²+B_n² and Arctan (A_n/B_n) were obtained.√A_n²+B_n² was considered as the most useful parameter among them, because it is invariant for the parallel shift of amplitude and time axis.
Normals, myocardial infarction and atrial septal defect cases were classified, in 100 per cent success, by threshold logic units and maximum likelihood method in the twelve dimensional information space, respectively using the initial four Fourier coefficients of the X, Y and Z leads as parameters.
Fourier coefficient parameters were estimated by t-tests, and then the effort was made to reduce the numbers of parameters of information space.
Complete separation was also obtained even when the number of dimension were reduced to seven by using the initial seven Fourier coefficients of X lead alone. This suggested that the important diagnostic information was mostly contained in X lead, and also that the lower harmonic components had the greater part of the information of ECG. Nonlinear discriminant function played an important role in the low dimensional information space.

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For successful operation of brain tumors, it is essential to minimize hemorrhage during neurosurgical operation, and to destroy any adjacent tumor cells. A newly developed technique for coagulating brain tumors as an operative procedure by using microwave was investigated. It penetrates a distance and destroys the tumor tissue with its thermal effect.
For successful tissue coagulation, it is required to concentrate microwave energy to a narrow region. For this purpose, a kind of antenna was contrived and the thermal distribution in the vicinity of the antenna was investigated both theoretically and experimentally. It revealed that the near-by field of the antenna could make an adequate thermal distribution for local tissue coagulation. An experimental equipment was made for 2.45 GHz using magnetron as the microwave source.
The desirable local coagulation on a dog's brain tissue was achieved with this experimental equipment. This method of local coagulation by microwave will facilitate more effective operation on tumors without unnecessary bleeding and scattering of tumor cells and will destroy as much tumor tissues as possible This method of tissue coagulation is considered applicable to treating not only brain tumors but also many other tumors and diseases.

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There are many papers on vibratory sensation for vibrations perpendicular to the skin but only a few papers on vibratory sensation for vibrations parallel to the skin. In one of them, it is mentioned that parallel vibrations are better than perpendicular vibrations as a means of information transmission. The reasons are, however, not clear why the difference in sensations for two vibration modes occur.
Parallel vibratory sensations are studied in order to 1) make the difference of sensory characteristics clear between vibration parallel to and vibration perpendicular to the skin, 2) grasp the effect of contact force of stimulator on a threshold curve and 3) estimate the channel capacity in information transmission via amplitude modulated stimuli.
Experiments were carried out by a method of conductor adjustment in a noise-free room with auditory masking by random sound from a headphone and with a stabilizing plate around the stimulator in order to localize vibration on the skin.
The results showed that threshold-frequency characteristics are similar to those of perpendicular vibration except that at around 20 Hz, curves are concave because of the mechanoreceptors which are sensitive to skin stretching. The effect of the contact force on the threshold curves is considered slight. The channel capacities estimated from just noticeable difference are 2. 3 bits to 3. 9 bits for subject K and 5. 2 bits for subject S.

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This paper presents some results of the computer diagnosis of roentgenography of the stomach for the preliminary screening in the mass examination. The authors take up the upright barium-filled picture which is the fundamental picture of a stomach at first, since no less than one third of the organic diseases of the stomach can be detected by this picture using only the contour information.
Some logical programs of the processing system are made for the computer diagnosis. Several methods are presented and exemplified concerning the smoothing of the picture for detecting abnormalities, the recognition of the gastric angle, the determination of the gastric axis, and the choice of the parameters for detecting the irregularity of the gastric contour.
These methods will be improved by studying further examples and by rearranging individual subprograms to constitute an overall diagnostic system.

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Monaural phase effects (MPE's) in steady-state musical tones were experimentally studied for two-and three-component tones. The two types of stimulus pairs used were : {sin 2π·ft+A₂/A₁ sin 2π·2ft, sin 2π·ft+A₂/A₁ sin (2π·2ft+θ); and {sin 2π·ft+A₂/A₁ sin 2π·2ft+A₃/A₁ sin 2π·3ft, sin 2π·ft+A₂/A₁ cos 2π·2ft+A₃/A₁ sin 2π·3ft.
Timbre discrimination between the stimuli of each pair was investigated as a function of f, A₂/A₁, A₃/A₁, and θ at a constant sound pressure level (about 30 dB). The AB method was applied, and the information rates were calculated and used as a measure of discriminability.
The most important findings are :
(1) MPE's can be perceived for two-and three-component steady state musical tones under certain conditions of f, A₂/A₁, A₃/A₁, and θ.
(2) For stimulus pairs with a frequency beyond 1248 Hz, no timbre difference can be heard.
(3) Maximal discriminability of two-component tones with f of 193 Hz is obtained when A₂/A₁ is about 0.5. For three-component tones maximal discriminability is reached at a certain value of A₂/A₁, which increases with A₃/A₁. And a great difference is observed between the stimulus pairs with A₃/A₁>1 and with A₃/A₁<1.
The experimental results suggest that MPE's are related to differences in the waveform of the vibration patterns of the basilar membrane, and are particularly related to the corresponding differences in the temporal patterns of the nerve impulses near the peak point of the envelope of the basilar membrane vibration caused by the higher component of the stimulus.

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Several problems related to the small moving coil phonocardiographic transducer have been investigated. As the damping resistance of the mechanical system of the transducer, oil and air flow resistances are considered, and the characteristics of these are discussed. Especially, the relations between air flow resistance and transducer characteristics are studied in detail simulating by an electrical equivalent circuit.
The equivalent circuit for the measuring system including transducer and chest wall is discussed next, and the design method using the behavior of the cross points is investigated. On the basis of these studies, two sorts of transducers have been made for trial and the characteristics of these are also presented.
These, in comparison with the conventional piezoelectric type, offer the following merits : (1) better stability of characteristics, (2) lower output impedance, (3) possibility of extending the cable without noise generated in moving it, (4) simplified preamplifier and improved signal to noise ratio, (5) lower temperature drifts of damping resistance and smaller weight for the air flow resistance type. On the other hand, demerits include (1) effects of stray magnetic field, (2) drop in response at higher frequencies compared with the piezoelectric transducer, (3) difficulty of miniaturization because of a magnetic circuit needed.

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