The phase distribution of light field at a certain location can be calculated from two close intensities in first-order optical system along the propagation direction, and can be considered as the wavelet transform coefficient of the pupil light field. According to such theory, a new phase retrieval algorithm based on several intensities of different layers is presented in this paper, which can quickly calculate the phase with low frequency, and then gradually increase the resolution by adding more intensity to calculate.
The extended beacon belongs to partially coherent light field, and Phase space optics is an effective
tool for analyzing such light field, especially in calculating the phase of multi-angle and multi-layer.
Due to the lack of directly detection means, the research of this theory is crippled a long time, in this
paper an optical structure to obtain the spectrogram which is a kind of phase space distribution has
been presented, while the resolution problem and an improved method for possible has been
discussed too, and two new methods to get high quality astronomical Image are appearing with such
algorithm.
When laser propagation through atmospheric turbulence, the effect of anisoplanatic error will affect the compensation results of adaptive optics system. Based on the wave optics propagation model, laser propagation through horizontal path atmospheric turbulence with AO compensating simulation system was established to study the anisoplanatic error in turbulence with diffraction effect. Propagation experiments through a 4-km horizontal path outside were conducted. The AO compensating effects in different isoplanatic angles were tested at different turbulence strength. Both simulation results and experimental data show that during the isoplanatic angle with influence of piston and tilt terms removing the AO system possess effective compensation results.
Adaptive optics system can work with beacon produced by illumination the dim target with laser beam. But atmospheric
turbulence distributed over the entire propagation path produces intensity scintillation of the illumination laser beam. The
multi-beam illumination approach can improve the intensity uniformity by adding different intensity distributions
produced by separate illumination beams passing through independent atmospheric paths. A 4 km horizontal propagation
path was established to examine the illumination effect with multi-beam on the target. Individual laser beams were
launched from a separate region of the transmitter telescope. The far-field irradiance profile was received by target-plane
and recorded with a CCD camera operating in 1k Hz placed in front of the target-plane. The uniformity of target area
was determined by the number of the illuminating beams and the turbulence strength. Data were recorded with 1, 3 or 6
incoherence lasers illumination and for a range of R0 parameter. We calculated the irradiance of a 8x8 cm2 area in the
target-plane to characterize uniformity of illumination. Results show a good reduction in intensity variance with number
of illumination beams increasing and that the uniformity of illumination on target turns to worse when the atmosphere
turbulence became worse. The back backscatter from the target-plane was received by another telescope nearby the
transmitter side and imaged by a CCD camera. The images of the rough reflector showed that the image resolution and the
illumination effects improved with the number of illuminating beams increasing.
Solid-state heat-capacity laser (SSHCL) has been developed in recent years. One of the key features of this heat capacity approach is the inversion of the temperature profile through the medium as compared to conditions where the laser is actively cooled while lasing takes place. So the thermal effects in the active medium on the two conditions mentioned above must be different. In this paper, we mostly discuss the contribution of temperature gradients to the effect of the thermal lens in optically pumped cylindrical laser rods operated in heat capacity operation through classical thermal conductivity equation, end effects and birefringence of the material with stress from temperature gradients ignored. Expressions are derived for the focus length of thermal lensing in laser rods for single-shot and repetitively pulsed operations. Programming the computer, we respectively calculate the thermal induced refractive power of the laser rods in the heat capacity operation and on the cooling condition, and compare the double results.
When the laser beam is out of the field of view (FOV) of charge-coupled devices (CCD) camera, part of the laser energy will also reach on the photoactive area because of the scattering and diffraction effects. If the intensity is high enough, CCD will be in saturation. How and to what degree the scattering and diffraction effects will disturb the CCD is analyzed. The results of experiments are given as well. Considering the contribution of the laser out of the FOV, the disturbing range will be enlarged. Estimation has been done.
The compositional quantification analysis for series samples with molecular formula of (PrGdYbBi)3(FeAl)5O12 (multi-substituted epitaxial yttrium iron garnet film on gadolinium gallium garnet substrate) is processed with EPMA. The self-made oxide standard samples are tested and used. During measurement, the influence of the substrate, interference between X-rays emitted from different element and poor uniformity of samples are took into account. The ZAF correction is also processed. The whole error is less than 3.5wt%, and the precision for single element is better than 2wt% comparing with samples with exactly known composition.
A two-dimensional program was applied to simulate the chemical dynamic process, gas dynamic process and lasing process of a combustion-driven CW HF overtone chemical lasers. Some important parameters in the cavity were obtained. The calculated results included HF molecule concentration on each vibration energy level while lasing, averaged pressure and temperature, zero power gain coefficient of each spectral line, laser spectrum, the averaged laser intensity, output power, chemical efficiency and the length of lasing zone.
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