Three dimensional autocollimator is based on a precise angular measurement method which has been proposed in our previous papers. Optimal design for the three dimensional autocollimator is one of the most important problem for the application of this method. Considering that the parameters and the properties of the optical system interact with each other, we analysis the relationships between the parameters and the properties in detail. It is indicated that there are four restrictions which should be considered during the design for the optical system. Then, an optimal design for the parameters of the optical system is proposed, and all the parameters of the optical system can be determined according to the properties of the autocollimator.
Laser transmission is influenced by environment particularly large, especially in fog, rain, snow and other complex weather conditions.This article mainly from two aspects of theory research and Modtran software simulation discussed the laser transmission characteristics in the rain.Different laser is theoretically discussed mainly in a variety of transmission attenuation degree of rainfall conditions.Using Modtran simulation software to get the theoretical calculation results of simulation and error analysis.
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) radiation, which occupies a large portion of the electromagnetic spectrum between infrared and microwave bands, offers innovations imaging and sensing technologies that can provide information not available through conventional methods such as microwave, X-ray imaging and NMR(nuclear magnetic resonance). T-ray imaging can give not only the density picture but also the phase information within the frequency domain. T-ray imaging has several advantages over other sensing and imaging techniques, so it has many important scientific, industrial and medical applications. In this paper, we study the feasibility of using THz sensing and imaging for mine detection. The principal features of THz radiation and its unique advantage in mine detection are investigated. Some difficult issues, which are not resolved yet, are discussed. The military applications and development trend of the THz spectroscopy are briefly forecasted.
Laser Ultrasonics is a new branch in Ultrasonics, which is based on the generation of ultrasonic by a laser and the detection of stress wave with laser interferometer, and is an ideal combination of laser and ultrasonic for non-destructive testing. It is a noncontact, remote and precise technique for nondestructive testing of materials and products. Firstly, this paper introduces the principles of laser ultrasonic generation, and the ablation excitation theory. And then optical detection method of laser-induced ultrasonic with the confocal Fabry-Perot interferometer is introduced. Based on the principles of laser-induced ultrasonic generation and detection, the integrated structure of the laser ultrasonic induced by laser line source and detected by a confocal Fabry-Perot interferometer is presented to detect multilayer structure such as solid propellant rocket motor structures in weaponry. Considering how laser ultrasonics would be used in the field and some mostly effects to the results. The laser system, accepting its present limitations, was optimized and developed for the inspection of the multilayer structure of solid propellant rocket motor as the experimental program progressed.
Smoke interference is an economy and practical way of electro-optical countermeasure. In this paper, the mechanism, characteristic, technology and result evaluation of smokes screening laser is discussed to find more effect way of smoke interference. Smoke screen mechanism, characteristic, experiment device and method are discussed experimentally. Especially the smoke screening laser of 0.53μm, 1.06μm and 1.54μm is discussed in detail. On this foundation, an experiment with titanium tetrachloride is designed to detect the effect of smoke screening. Experiment show that titanium tetrachloride and water reaction can generate a great deal of smoke. The smoke is very thick and last out long time. It has good interference effect of laser of 0.53μm, 1.06μm, 1.54μm. But the smoke presents acidic, strong causticity and stimulative. So ammonia was added. In order to improve the interference effect with the parameter change, a great deal experiments were been done at different concentration of ammonia and different dosage of ammonia. The attenuation performance tables of same concentration different dosage and same dosage different concentration were painted. Analyzing these tables, we can get a series of conclusion for smoke screening laser of 0.53μm, 1.06μm, 1.54μm. And also the best parameters are presented for smoke screening.
The principles of laser ultrasonic generation and measurements with pulsed laser are presented. There are two kinds of means to actuate ultrasonic pulse: elasticity actuating and ablation actuating. The progress in laser ultrasonic about laser ultrasound generation, detection, propagation and its applications is introduced briefly. Applications in the field of Non-Destructive Testing (NDT) are reviewed. In the field of Non-Destructive Testing, according to the principle, the laser ultrasonic testing system consists of laser system, laser interferometer, photoelectric detector and receiving system with signal amplifier. Thus, long-range and non-contact on-line detection of ultrasonic testing system was realized. In view of some of the problems, the developing trends of such techniques are analyzed.
In this paper, the principle of radiation sensor is introduced, the quantitative model for the relation of radiation & fiber loss was derived, and the relations among output-power loss were tested in variance circumstances.