Proc. SPIE. 9142, Selected Papers from Conferences of the Photoelectronic Technology Committee of the Chinese Society of Astronautics: Optical Imaging, Remote Sensing, and Laser-Matter Interaction 2013
Based on the heat transfer theory and finite element method, the macroscopic ablation model of Gaussian beam laser irradiated surface is built and the value of temperature field and thermal ablation development is calculated and analyzed rationally by using finite element software of ANSYS. Calculation results show that the ablating form of the materials in different irritation is of diversity. The laser irradiated surface is a camber surface rather than a flat surface, which is on the lowest point and owns the highest power density. Research shows that the higher laser power density absorbed by material surface, the faster the irritation surface regressed.
Terahertz (THz) technology, as new research topic and technology field which is paid more and
more attention by the researchers and governments, has some unique properties which is different
from other electromagnetic wave. THz wave is regarded to have potential application in many fields.
Existing and emerging applications of terahertz technology in imaging, medicine, biology, space
exploration, covert communications, compact radar ranges, industrial controls, terahertz microscopy,
terahertz tomography, and homeland security have stimulated intensive research effort in photonics
and electronics technologies bracketing the famous terahertz gap from the high and low frequency
sides, respectively. Cutoff frequencies and maximum frequencies of operation of InGaAs-based
Heterostructure Bipolar Transistors and High Electron Mobility Transistors are now approaching or
even exceeding 600 GHz. New ideas of using plasma resonances of two-dimensional electrons for
tunable detection and emission of terahertz radiation are being explored and proven experimentally.
Plasma effects in polarization-induced electrons and holes in granular pyroelectric/semiconductor
heterostructures hold promise of an active THz medium tunable by external electric field or light.
The mechanism of laser cleaning rust deposit on the steel surface was studied experimentally. Especially, the parameters and mechanism of cleaning rust deposit from steel surface with pulsed YAG laser was studied in detail. The practical application of laser cleaning in maintenance was discussed in this paper. A pulsed YAG laser and a continued CO2 laser was used to do some experiment comparatively. The results demonstrated that the effect of pulsed YAG laser is better than continued CO2 laser. The pulsed YAG laser can accomplish complete cleaning by regulating parameters of laser, however, the continued CO2 laser can not. There are cleaning threshold and damage threshold in laser cleaning. Between the initial cleaning threshold and complete cleaning threshold, cleaning percentage of the surface increases with the increasing of laser fluence and pulse number, but does not depend on repetition rate. The mechanism of laser cleaning rust deposit with pulsed YAG laser is suggested: the vibration of deep rust deposit and thermal shock action induced by laser-supported detonation (LSD) to make rust particles sputter is primary, however, the thermal effect of laser irradiation is secondary.