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A method that uses two quadrant detectors (QDs) for sensing wave-front tilt is described. The detectors are set at the front and back of the focal plane of the focusing optics. When the intensity distribution at the aperture of a telescope is not uniform because of atmospheric turbulence, the wave-front tilt can be measured more accurately with our two-QD method than with a conventional single-focal-plane QD. We proved this method to be effective by using it for fixed-star observation. Application of the method to a ground-to-satellite laser beam pointing system showed that it increases the intensity of the laser beam that is transmitted to a satellite. OCIS codes: 010.1080, 010.3310, 010.7350.

The far-field pattern of an onboard laser transmitter was measured with a transatmospheric optical link with a distance of [approximately]33,000 km between the satellite and the optical ground station. The far-field pattern was acquired with a new method used to analyze statistically downlink irradiance data obtained at the ground station. The statistical tracking and pointing characteristics of the transmitter were taken into account in estimating downlink irradiance, assuming that there were no atmospheric scintillation effects. The peak directive gain of the downlink laser beam was 104.3 dB. The beam width (full width at half-maximum) was 28.5 x 17.5 [micro]rad. These results were consistent with the results from a laboratory test undertaken before launch of the satellite.

We conducted Goldberg's 30-item General Health Questionnaire (GHQ) on 1,216 Japanese general population aged 40-92. Among them, 9.8% of males and 13.7% of females scored over the cut-off point which is used to indicate minor psychiatric disorders. Factor analysis was carried out using the Likert method and eight factors labelled as follows were selected: depression, anxiety and tension, anergia, interpersonal dysfunction, difficulty in coping, insomnia, anhedonia and social avoidance. The mean value of the standardized scores for each age-sex group indicated that changes in sex-age social roles with age affect the mental health of the general population.

A technique for transmitting a narrow laser beam from a ground station to a satellite has been developed. The principle of pointing a laser beam to a distant target in a scattering medium by use of a backscattered laser beam image is described. We calculated the intensity distribution of the image by using a typical model of atmospheric coefficients. The method was applied to transmit a laser beam from a ground station to Engineering Test Satellite-VI. The accuracy of pointing the laser beam to the satellite was approximately 10 [micro] rad in this experiment. OCIS codes: 010.1310, 010.3310.

Temporal natures for a variance of turbulence-induced log-intensity fluctuations are obtained. The variance of the optical fluctuation is reduced when the optical signals are integrated in a photodetector, and we express the index of reduction (called the time-averaging factor) by using an autocovariance function of the optical fluctuation. The optical fluctuations for a ground-to-satellite path are caused by both atmospheric turbulence and the beam-pointing jitter error of the optical transmitter. The turbulence-induced optical scintillation can be discriminated from the fluctuation that is due to the beam-pointing jitter error. The compared result from the probability density function of the optical signal reveals good agreement. The temporal autocovariance functions of optical scintillation are obtained and used to calculate the time-averaging factor. The analytically expected effects of time averaging are verified by the experimental results. The estimations contribute to the link budget design for the optical tracking channel through atmospheric turbulence. OCIS codes: 010.0010, 010.1300, 010.1330, 010.3310, 060.0060, 060.4510.