The damage threshold of CCD’s black and white screen has been effectively measured in this paper. The visible array CCD is a type of photoelectric detector used at the visible wavelengths. The black and white screen of visible array CCD had been observed when it was irradiated by 532nm pulsed laser with low repetition frequency and high energy from a distance of 30m. The measurement method was proposed for the damage threshold of laser power density at the photosensitive surface when the black and white screen came into being. The gain of optical system was firstly designed to measure as 4.4×10<sup>3</sup> by changing the repetition frequency of incident laser and adding the right attenuation slices in light path, and finally the damage threshold of CCD’s black and white screen was calculated as 4.5W/cm<sup>2</sup>. The research fruit can provide the theoretical basis and data reference for carrying out the jamming and blinding photoelectric detector of high power laser.
According to the demands of laser energy control and test in Hardware-in-the Loop (HWIL) simulation systems for laser jamming CCD sensors effects applications, the laser propagation regulars in the system and the ways to describe laser energy simulations are provided. The basic theoretical analysis to calculate the laser energy distribution in far field and the method to achieve the simulation equipment are also discussed. Based on the Virtual Instrument (VI) technology, the ways for random phase screens formed by multiple layers of atmospheric turbulence as while as wave fronts retrieval based on a spatial Light Modulators(SLMs) set are derived. In the CCD sensors’ jamming effects experiments with different laser parameters such as repeat frequency, the lasers and their energy control equipment were utilized so as to form the distributions of laser light random phase and the undulations of laser beam intension in far field. By using the simulations system, the realization to generate different far field laser propagation effects at real time and to prove the efficiency of the laser energy control and test based on the platform of Windows+ LabVIEW+IMAQ Vision technology in simulations were experienced for CVIs. The analysis of error factors in simulation system was also provided. It is shown that the rhetorical method, devices and the analysis to simulation dynamic effects for laser propagation, which can provide the specialties of real-time, dynamic control, expansibility and can also be applied to beam quality, energy control and test in the HWIL simulation systems for laser jamming CCD sensors experiments.
Owing to the high temporal coherence and spatial coherence of laser, it has been considered as the perfect source to study light’s interference effect so far. The simulation method of multi-beam interference effect was proposed based on the maturity Gaussian optics in this paper. The simulation result and stripe’s equidistant distribution of the dual-beam interference effect agreed with that of Yang’s double slit interference well. The agreement strongly proved that the simulation method was right and feasible. The simulation results have showed that the triple-beam interference effect was hexagonal arrangement’s lattice distribution; the quadruple-beam interference effect was foursquare arrangement’s lattice distribution; the pentuple-beam interference effect was radially symmetrical lattice distribution; and the hextuple-beam interference effect was regularly hexagonal arrangement’s lattice distribution. Every lattice around the center spot was all circular in the quadruple-beam and hextuple-beam interference effect.
The CMOS Image Sensor (CIS) is photoelectricity image device which focused the photosensitive array, amplifier, A/D transfer, storage, DSP, computer interface circuit on the same silicon substrate. It has low power consumption, high integration,low cost etc. With large scale integrated circuit technology progress, the noise suppression level of CIS is enhanced unceasingly, and its image quality is getting better and better. It has been in the security monitoring, biometrice, detection and imaging and even military reconnaissance and other field is widely used. CIS is easily disturbed and damaged while it is irradiated by laser. It is of great significance to study the effect of laser irradiation on optoelectronic countermeasure and device for the laser strengthening resistance is of great significance. There are some researchers have studied the laser induced disturbed and damaged of CIS. They focused on the saturation, supersaturated effects, and they observed different effects as for unsaturation, saturation, supersaturated, allsaturated and pixel flip etc. This paper research 1064nm laser interference effect in a typical before type CMOS, and observring the saturated crosstalk and half the crosstalk line. This paper extracted from cmos devices working principle and signal detection methods such as the Angle of the formation mechanism of the crosstalk line phenomenon are analyzed.
Owing to the limitation of optoelectric imaging systems’ pupil, it is inevitable to generate the diffraction effect in laser propagation; however, the laser energy distribution causing by the diffraction effect can directly affect the jamming effect to optoelectric imaging systems. First of all, we began with the basal Huygens-Fresnel principle and Fresnel-Kirchhoff diffraction formula in this paper, and deduced the laser energy distribution formula on the optoelectric imaging systems’ detector causing by the rectangular pupil, circular pupil and annulus pupil. Secondly, we simulated the laser energy distribution causing by the diffraction effect under the different pupil shapes, laser launch parameters, optical system’s parameters and optoelectric detector’s parameters, and investigated the laser energy distribution rule under the different conditions. The simulation results indicated that the range of intensity distribution increased with laser wavelength, laser incident energy, focal length and the size of pupil that also can affect the pattern of intensity distribution. The research fruits can provide the theoretical basis and technical support for evaluating laser jamming effect to optoelectric imaging systems.
The dazzling phenomena such as point saturation, line crosstalk present successively when laser irradiates on the CCD camera. We use CW laser at 532 nm and 1064 nm to irradiate the interline transfer area array CCD, CCD emerges lattice spots under the lens focusing. Based on geometrical optics, we use theoretical analysis and numerical simulation to study the mechanization of lattice spots. Laser jamming effects to the same CCD are different between 532 nm and 1064 nm. This is because the 532 nm laser diffracts with the chip, while 1064 nm laser interferences with its reflected light in the transmission process. Meanwhile, the mechanization of the ring surrounding the main spot is analyzed.
Laser active suppressing jamming is one of the most effective technologies to cope with optoelectric imaging systems. In the process of carrying out laser disturbing experiment, regular circular fringes often appeared on the detector, besides laser spot converging by optical system. First of all, the formation of circular fringes has been experimentally investigated by using a simple converging lens to replace the complex optical system. Moreover, circular fringes have been simulated based on the interference theory of coherent light. The coherence between the experimental phenomena and the simulated results showed that the formation mechanism of regular circular fringes was the interference effect between reflected light by back surface of lens and directly refractive light on the detector. At last, the visibility of circular fringes has been calculated from 0.05 to 0.22 according to the current plating standard of lens surface and manufacture technique of optoelectric detector.
Due to influence of atmosphere turbulence, distribution characteristics of laser speckles vary with propagation distances. In this paper, numerical calculation using a multiple-phase screen method is performed to simulate the propagation of laser beam in the turbulence. The distributions of intensity at different distances are calculated. A characteristic factor σ<sup> 2</sup> is proposed to quantify the degree of turbulence induced intensity spatial fluctuation compared with the same beam propagating in vacuum. The results show that, at the same distance, mean σ<sup> 2</sup> of the beam propagating perpendicularly is smaller than the beam propagating horizontally. For a perpendicularly transmitted Gaussian beam, mean σ<sup> 2</sup> decreases gradually after it reaches its maximum value, and tends to be stable if the propagation distance is long enough.
Laser active suppressing jamming is one of the most important technologies in the domain of electro-optical countermeasures. The propagation direction of laser is not always in the same line with the principal axis of electro-optical imaging system, so it is necessary to investigate laser energy distribution on detector under the different incident angle. This paper toke optical system with wide field of view for example. We firstly analyzed the system’s structure based on the inverting prism and evaluated image quality. Laser energy distribution caused by diffraction effect of optical system was secondly simulated based on Kirchhoff ’s diffraction theory. Thirdly, we built the system’s analysis model of stray light, traced a large number of light propagation, and obtained laser energy distribution on detector caused by scattering effect. At last, combine the above two kinds of energy distribution into total laser energy distribution on detector. According to the detector’s saturated threshold, we can count up the saturated number and evaluate laser disturbing effect. The research results can provide theoretical reference and technical support for evaluating laser disturbing effect of electro-optical imaging system.
The laser-induced damage of GaAs/Ge single heterojunction solar cells is investigated. The solar cells were irradiated by a continuous wave laser at the wavelength of 532 nm. Results indicate that the GaAs/Ge solar cells would mostly be damaged when laser is focused on its grid lines. Theoretically, the continuous wave laser at the wavelength of 532 nm is absorbed at the surface of solar cells. The continual temperature rise decomposed the material GaAs and melted the material Ge. The melted metal Ge connected the solar cells grid lines and the rear electrode, the solar cell became completely invalid. The major damage of continuous wave mainly comes from both the thermal melting and the thermal stress effects. The huge temperature gradient on the surface of the solar cells generated the crack, and even rupture. Concentric iridescent ring appeared on the damaged surfaces when observed with an optical microscope(OM) of broad spectrum. The damaged surface film was characterized by X-ray photoelectron spectroscopy(XPS) and the Contour Meter. The component of the concentric iridescent is GeO<sub>2</sub> film, when the light irradiated on the film and interfered, the concentric iridescent generated. The different ring indicated the thickness of oxide was different. When the film was corroded by HCl, the iridescent disappeared. The formation mechanism of the film and the cause of the concentric iridescent ring were analyzed. These experimental conclusions are tested and verified by scanning electron microscope with energy dispersive spectroscopy and X-ray photoelectron spectroscopy.
A new approach is presented to reduce turbulence-induced scintillation by use of a phase-locked beams array composed of linearly polarized beams with different polarization angles. The noninterference of orthogonal polarizations suggests that the beams array mentioned above can act effectively as a two-mode partially coherent beam, and the percentage of a single mode is controllable by changing the polarization angles of the beams. Numerical calculation using a multiple-phase screen method is performed to analyze the on-axis scintillation index σ<sub>I</sub><sup>2</sup> and mean received intensity ⟨I⟩ for the beams array propagating through weak, moderate, and strong turbulence. The effects of different polarization angles on σ<sub>I</sub><sup>2</sup> and ⟨I⟩ at the receiver are studied. When the turbulence is weak, numerical calculations show that both σ<sub>I</sub><sup>2</sup> and ⟨I⟩ are closely related to the polarization angles of the beams. And there will be a smaller scintillation index for a phase-locked beams array comprising beams with different polarization angles as compared to a uniformly polarized beams array. As the beams are phase-locked, the mean received intensity provided by them is larger than that provided by an incoherent beams array. For it is quite easy to change the polarization angles, phase-locked beams array comprising beams with different polarization angles can be a promising source in the applications that need a balance between scintillation and mean received intensity in weak turbulence conditions. When the turbulence is moderately strong, incoherent beams array is actually a better choice, because the scintillation index is smaller and the mean received intensity is as much, compared to a phase-locked beams array.