Remote sensing of ranged-resolved profiles of atmospheric turbulence is necessary and important for many applications in
astronomical and adaptive optics communities. In order to obtain turbulence profiles in atmospheric boundary layer, a
device is developed and experiments has been carried out. In the experiments, laser guide stars are formed at several
successive altitudes by projecting pulsed laser, returned signals are received by two receiving telescopes and the images of
the returned signals are formed by a imaging device. Variance of centroids′ distance is derived from the images with two
spots at the same altitude and ranged-resolved profile of the variance is obtained. So, based on a inversion algorithm,
atmospheric turbulence profiles are retrieved from differential image motion variance of distance of centroids at various
altitudes. The structure constants of refractive index of atmosphere range from 10<sup>-14</sup>m<sup>-2/3</sup> at lower altitudes to 10<sup>-16</sup>m<sup>-2/3</sup> at
higher altitudes are remote sensed experimentally. The results show it is a effective method that combined laser guide stars
with differential image motion method and could sense atmospheric turbulence profiles remotely in real time.
Proc. SPIE. 9796, Selected Papers of the Photoelectronic Technology Committee Conferences held November 2015
KEYWORDS: Optical fibers, Refractive index, Digital signal processing, Optical amplifiers, Sensors, Calibration, Fiber lasers, Time metrology, Turbulence, Temperature sensors, Resistors, Pulsed laser operation, Temperature metrology
Measuring principle of time constant for thin wire thermal resistor was put forward. An 1.07μm fiber laser was used to output a rectangle laser pulse with edges of several tens microns and width of 100ms, and the thermal resistor under test was shined by the laser. As a result, the temperature of the thermal resistor rose and gradually went up to a fixed level with the irradiation. And then the thermal resistor’s temperature dropped and gradually went down to the room temperature with the laser powered off. Time constant of the thermal resistor could be obtained by means of measuring the temperature variation of the thermal resistor due to the laser pulse. A device was designed and experiments were carried out, the time constants of three commonly used thin wire thermal resistors were measured.
The objectives of this tutorial are to introduce an optical method of measuring atmospheric turbulent outer scale. The method utilizes the ratio between the correlation functions of the wandering in two perpendicular planes. A simple relationship to obtain the outer scale from the measured correlation functions is established for a particular model of turbulence, the modified Von Karman model. Base on the rational conclusion, an implementary project of measuring atmospheric turbulent outer scale with optical method is designed. At the same time, the plan of the experiment system is given. By predigesting the model, the calculating program of the measurement is written also.