Recent advances in novel technology of ultraweak biophoton emission measurements and analysis are described. Biophoton emission is known to be spontaneous ultraweak photon emission from living organisms and systems originating from various biochemical reactions in the living body, and carries information on physiological and functional states of the living system. For the purpose of characterizing the biophoton emission and extracting of new bio-information, we developed novel techniques for quantum stochastic analysis of ultraweak photon emission field and its spatio-temporal properties. To study the optical field characteristics of the ultraweak biophoton emission we employ a highly sensitive pulse-to-pulse time interval photon counter capable of measuring the arrival time of photons to the order of 12.5ns. Using this system we observed, for the first time, super-Poisson behavior of the photon emission from luminescent bacteria. For the spatio-temporal analysis of biophoton emission we use a two-dimensional photon counting tube and simultaneously measure the position and arrival times of the emitted photons. Then the biophoton emission characteristics of a mechanical injured plant root is measured which leads to the novel knowledge on the information transmission within the plant system.

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Nearinfrared Spectroscopy (NIRS) technique is introduced with a functional brain mapping and a Time Resolved Spectroscopy (TRS). With a five-channel optical monitoring, we succeeded in detecting region-specific changes in both the hemoglobin oxygenation state and blood volume during a mental task. A portable TRS system was constructed by which we could demonstrate the change in muscle deoxygenation quantitatively during a human forearm occlusion.

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Optical diagnostic methodologies for theraperutic control during laser therapy are discussed. Interventional therapy and endoscopic therapy are significantly important to reduce therapeutic invation to improve quality of life of patients. To reduce the risk of serious complication in particular tissue perforation, novel tissue characterization method should be developed. Meanwhile, automatic controlled surgical procedure should be established in precise laser ablation therapy such as photorefractive keratectomy. The real time monitoring laser ablation process/results are necessary to attain feedback control. I review these diagnostic methods during laser therapy in the case of laser angioplasty and photorefractive keratectomy.

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Epifluorescence stereoscope analysis system and diagnostic angioscope analyzer system for photodiagnosis using a photosensitizer (NPe6) and diode laser system was assembled. The fluorescence of NPe6 that accumulated in malignant tissue and atherosclerotic lesion were measured in the mouse tumor model and the atherosclerotic rabbit model by these systems. The fluorescence images of NPe6 in tumors and muscles were captured at 0.25, 1, 2, 3 hours after NPe6 administration to each tumor-bearing mouse. With the lapse of time after administration, the fluorescence intensity decreased but contrast between tumor and muscle became higher. The bared heart of atherosclerotic rabbit was observed. The fluorescence of NPe6 was measured from the coronary arteries, but was not emitted from the coronary veins and the cardiac muscles. The fluorescence spectra of NPe6 were analyzed in the coronary artery of the atherosclerotic rabbit. There was a high correlation between the peak fluorescence intensity and thickness of atheroma.

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The preservation of polarization and coherence of the signal light transmitted through strongly scattering media such as biological tissues have been examined for the feasibility study of optical coherence imaging in tissues. Our experimental results indicate that the multiply scattered and diffused components of transmitted light through scattering medium become not only randomly depolarized, but spatially incoherent, making them insensitive to optical heterodyne detection that is based on the interference of the signal and local oscillator beams.

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The activity of research and development on ultra-short and highly-intense pulse laser systems in Europe is reviewed. The new field of highly-intense laser-matter interaction physics motivates major institutes owing conventional nsec- or p-sec laser facilities to improve theirs to compact f-sec laser systems which can generate TW-level power. The elemental techniques of mode-locked oscillators to generate ultra-short pulses and chirped-pulse amplification are also intensively studied.

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This report compares the laser characteristics of CuBr and CuI. The CuI will yield more power than CuBr at all pumping power. The energy control of Cu atoms is carried out by adding Ag and Zn atoms to the same laser tube. The energy transition of Ag atoms (λ = 328.1nm) shows marked enhancement of the yellow line of copper vapor laser. We suspect that the phenomenon is radiative energy transfer from Ag to Cu atoms. Addition of Zn atoms will broaden the laser pulse to 3ps which is about 790% wider than ordinary laser pulse width. This phenomenon means that Cu atoms in meta-stable state are pumped to higher energy level beyond the upper laser level by radiative energy transfer from Zn atoms (the energy difference between Cu and Zn is 0.5cm^-1). The Cu atoms density of upper laser level is enhanced by cascading decay in Cu atoms from upper energy levels.

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Organic L-Arginine Phosphate Monohydrate (LAP) crystal showed much lower threshold (6mJ/18ns) stimulated Brillouin scattering (SBS) at 1.06μm wavelength than fused silica, and higher SBS reflectivity of approximately 65% (inherently 93%) limited due to its absorbance. The reason why LAP crystal has a high damage threshold at Q-switched pulse operation is explained due to the SBS backward reflectance. We have demostrated the improvement of wavefront distortion induced by thermal effects in solid-state laser materials. Deuterated LAP crystal is very interesting not only as a frequency converter but also as a phase conjugated SBS mirror for all solid-state high-energy lasers because of high SBS gain coefficient and its low absorbance.

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We have developed a compact, lightweight laser range finder system using Q-switched erbium doped fiber laser with peak power of 600W at a repetition frequency of 1kHz. The system can measure the distance between overhead transmission lines and a tree top 300m away with an accuracy of ± 0.2m. This is a commercial version of a system which has been jointly developed by The Kansai Electric Power Inc. and Sumitomo Electric Industries, LTD.

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Oscillation characteristics of a diode-pumped single-frequency Tm:YAG laser have been investigated. Single-frequency operation is induced by using the etalon and/or birefringent filter in the laser cavity. Single-frequency tuning over 50nm wavelength range has been achieved. In addition, CO₂ absorption spectra in the 2μm region have been detected by this laser.

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