Upon the irradiation of UV laser pulses at 193 nm or 248 nm, photodissociation, bimolecular photoreaction, and photodesorption of surface molecules were observed for the deposited molecular solids on a quartz plate at about 100K. The observed translational energy distribution of ejected particles made possible the analyses of the dynamical pathways of the detachment processes. Small molecules such as NH₃ and CS₂ showed photoejection of a hydrogen atom and a sulfur atom, respectively, similar to the gas phase processes, .: although the dissociation was found to occur through the lowest dissociation channel. Acetylene solids showed an addition reaction producing vinylacetylene at 193 nm with a quantum yield of 0.003 at 77K. Vinylacetylene was then converted to diacetylene after the excitation by the second photon through the disproportionation reaction with another acetylene: C₄H^*₄ + C₂ H₂→C₄H₂+C₂H₄.
Butadiene solids covered with submonolayer Co₂ (CO) ₈ produced butene molecules at the interface for the excitation of Co₂ (CO) ₈ at 248 nm. CO fragments were also ejected from the surface, although the translational energy was very low suggesting the dissociation of the Co=CO bond in the interface region between the surface Co₂ (CO) ₈ and the inner butadiene layer. Three different mechanisms have been introduced for the photodesorption induced by UV laser irradiation of molecular solids: 1) Franck-Condon transition to a repulsive potential curve with respect to the surface bond, 2) thermal excitation of localized surface sites initiated by the generationof high energy atomic or diatomic fragments, and 3) optoacoustic shock propagation to the surface ejecting weakly bound molecules, which is induced by the electron-phonon coupling near the impurity sites. The last one was referred as a highly likely mechanism for the solids with the lowest valence excited states.

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This paper describes time evolution of an incident probe pulse in degenerate four-wave mixing with dualwave-front generation. It is shown that the incident pulse transmission results inself-conservation propagation without loss and pulse-form-change. Theoretical analysis is given by parametric propagation equations as a function of space-time. Their transient solutions reveal that interesting propagation effect which is confirmed by the experimental observation using a dye-laser and Na-vapor system.

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This paper describes a method of eliminating the bi-directional ambiguity in measurements of theflow velocity using a lenticular grating. The deflection characteristics of the light passing through the lenticularis studied theoretically and it is shown that the lenticular grating works as a phase grating. In avelocimeter using the lenticular grating and the four photodetecters, the opposite directions of the flow arediscriminated from the phase relation between the two signals combined appropriately from the output signalsof four photodetectors.
The method is used to measure the velocity of a random pattern on the rotating disk. The experimentalresults show the usefulness of this method for eliminating the directional ambiguity.

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This paper describes focusing characteristics of CO₂ laser beam by a plano-convex lens which has beenused in many laser applications. The spot size and the intensity distribitions near the focus are calculated and discussed.

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The results of optical observation of the plume produced with pulsed Nd: YAG laser irradiation are de-scribed. The dynamic behaviors were observed by means of high speed photography, and the structures wereanalized with the aid of spectroscopy and transmission electron microscopy (TEM).
From the above experiments we obtained some conclusions as follows:
1) The plume is mainly composed of the atomic vapor and the ultra fine particle of base materials.
2) The mean moving speed of the plume is proportional to the laser intensity. There is a relation between the intensity (I) and the start time of plume (ts), as I=t_s^-0.58. This relation has been interpreted with simplifiedvapor model.
3) he mean size of particles in the plume is 10-30nm in diameter. The size distribution can be controlled by laser intensity, and gas species and pressure in the atmosphere.

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This paper describes the measurement of RF electromagnetic fields utilizing lasers. The system consists of a sensor in which light is modulated by RF electromagnetic fields to be measured, and a demodulator to detectthe amplitude and phase of the RF fields. Two kinds of sensors are explained and some methods of light detection accompanying the frequency conversion are proposed. A simple model experimentwas made demonstratingthe validity of the system.

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