A gas temperature and pressure measurement method based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) detecting linewidth of gas absorption line was proposed in this paper. Combined with Lambert-Beer Law and ideal gas law, the relationship between temperature, pressure and gas linewidth with Lorentzian line shape was investigated in theory. Taking carbon monoxide (CO) at 1567.32 nm for example, the linewidths of gas absorption line in different temperatures and pressures were obtained by simulation. The relationship between the linewidth of second harmonic and temperature, pressure with the coefficient 0.025 pm/K and 0.0645 pm/kPa respectively. According to the relationship of simulation results and detected linewidth, the undefined temperature and pressure of CO gas were measured. The gas temperature and pressure measurement based on linewidth detection, avoiding the influence of laser intensity, is an effective temperature and pressure measurement method. This method also has the ability to detect temperature and pressure of other gases with Lorentzian line shape.
In traditional Fourier transform profilometry, the conversion from phase to height is deduced depending on the
supposition that not only are the projector and the camera at the same height above the reference plane, but also their
axes must cross at the same point on the reference plane. When these conditions are too strict to be satisfied, a large
measurement error will be introduced. An improved optical geometry of the projected-fringe technique is discussed and
phase-height mapping formula is deduced in this paper. Employing the new optical geometry, a simple calibration model
is developed based on absolute phase extraction and space mapping techniques, which make the environmental
parameters is not as critical as before. Furthermore, a virtual space pattern is used to provide the reference points for
camera calibration based on Zhang's calibration method. The calibration can be accomplished merely with a planar
pattern, which extremely reduce the cost of device and make the process of measurement more convenient. The
experiment result shows the good accuracy of the system.
Potential effects were analyzed after incidence of signal wave firstly. Based on the electromagnetic theory and combined with the nonlinear effect of Stimulated Raman Scattering (SRS) of optical fiber, correlative equations were set up for the Raman amplifying Pump wave of optical fiber, Stokes wave and signal wave and the conditional expression which made system gain form positive feedback was given at the same time. It comes to the conclusion that under the condition that system gain positive feedback is satisfied by optical fiber parameters, the input signal wave is amplified when the SRS gain corresponds to unsaturated gain state; the higher is the SRS gain the more is amplification times; the correlation degree is relatively increased when the SRS gain is relatively low in some region.
A dual-wave Quasi-CW Nd:YAG laser has been demonstrated at the wavelengths of 1319 nm and 660nm. The radiation energy level of the 1319nm transition was analyzed. The critical technology of restraining resonance of 1064nm so as to improve that of 660nm was discussed. Sophisticated optical coating and cavity structure was studied. And a maximum CW Output power of 43W at 1319nm was acquired. Based 1319nm laser, an intracavity frequency-doubling laser of 660nm was also demonstrated by using KTP crystal and an acousto-optically Q-switch. And a Quasi-CW red light output power of 2W at 660nm was acquired, accordingly, dual-wave output was realized.
A novel three-dimensional human head modeling method on laser technology, using the CCD camera to receive the scanning information, based on the theory of aerial photography surveying, is reported here. We introduce the mode integration of human head, its mathematical model and the principle of human head feature identifying. The laser scanning human head three-dimensional modeling system is established.