In this paper, we investigate the effects of auto-tracking subsystem together with different beam divergences on SNR, BER and stability of FSO communication links. For this purpose we compute the values of power, SNR and BER on receiver, based on analytic formula of Gaussian beam on receiver plane. In this computation the atmospheric effects including absorption, scattering and turbulence are c...

The GRACE Follow-On satellites will use, for the first time, a Laser Ranging Interferometer to measure intersatellite distance changes from which fluctuations in Earth's geoid can be inferred. We have investigated the beam steering method that is required to maintain the laser link between the satellites. Although developed for the specific needs of the GRACE Follow-On mission, the beam steerin...

We present a real-time complex amplitude reconstruction method for determining the beam propagation ratio M2 of laser beams based on the transport of intensity equation (TIE). In this work, a synchronous acquisition system consisting of two identical CCDs is established. Once two beam intensity images at different cross-section positions along the optical axis are captured simultaneously by the...

where co is the angular velocity of the chopper, r the distance from the rotating center to the laser beam axis, and t2-t, the time interval for a variation of P(x)/P0 from 0.9 to 0.1. Figure 1 shows the experimental arrangement. In this experiment, we use a He-Ne laser oscillating in the TEMoo mode. The wavelength is 0.63 m. The position of the beam waist is located at the output mirror of the...

Laser additive manufacturing (LAM) is rapidly becoming an important method for the fabrication of both prototype and production metal parts. However, the technology is really just in its infancy, and significant work still needs to be done in the development of new materials and in understanding how various process parameters affect results. In particular, LAM methods typically have a relativel...

The layered manufacturing technique is one of the most effective processes for the manufacture of prototypes, tools and functional end products. Selective Laser Sintering (SLS) and Selective Laser Melting (SLM), in particular, are two of the most versatile techniques, able to cover a wide range of materials such as polymer, ceramic and metal powder. In this study, the monitoring method of proce...

We investigate laser ablation of crystalline silicon induced by a femtosecond optical vortex beam, addressing how beam properties can be obtained by analyzing the ablation crater. The morphology of the surface structures formed in the annular crater surface allows direct visualization of the beam polarization, while analysis of the crater size provides beam spot parameters. We also determine th...

A statistical model for forward stimulated-Brillouin scattering is developed for a spatially incoherent, monochromatic, laser beam propagating in a plasma. The threshold above which the laser beam spatial incoherence cannot prevent the coherent growth of forward stimulated-Brillouin scattering is computed. It is found to be well below the threshold for self-focusing. Three-dimensional simulatio...

In this work Laser wireless video communication system using intensity modualtion direct detection IM/DD over a 1 km range between transmitter and receiver is experimentally investigated and demonstrated. Beam expander and beam collimeter were implemented to collimete laser beam at the transmitter and focus this beam at the receiver respectively. The results show that IM/DD communication sysate...

A microscopic photothermal lensing measurement under two-color continuous-wave laser excitation was performed to investigate a signal enhancement owing to the transient absorption by photoexcited solute molecules in liquid solutions. An intensity-modulated 409 nm laser beam and an un-modulated 532 nm laser beam were used for excitation, and a 670 nm probe beam was used for detecting the modulat...