The infrared imaging system represents the culmination of modern science and technology, finding extensive applications in aerospace, weapon electronics, security, industrial testing, and other fields. Target detection probability is a crucial parameter for evaluating the performance of an infrared imaging system and is closely linked to its design. While the Johnson criterion considers minimum resolvable temperature difference (MTRD) to assess the performance of infrared imaging systems, there exists an issue regarding low accuracy when applying infrared focal plane array (FPA) detectors. This paper proposes utilizing the targeting task performance (TTP) metric, that incorporates system sensitivity by considering a partial weighted integral of target background contrast exceeding the system contrast threshold function as a measure of information quantity within the system for simulating target detection performance in an infrared photoelectric system. In this study, we selected an uncooled infrared FPA detector and employed night vision integrated performance model (NV-IPM) software, along with control variable analysis to investigate how changing various system parameters affects the imaging performance of our proposed infrared photoelectric system. The purpose of this study to provide fundamental parameters for infrared imaging system optimizing future designs before research and development.
Aiming at the requirements of optical detection and recognition for wide-area and continuous monitoring of aircraft targets, the influence of micro-scanning on the imaging and recognition performance of aircraft target is discussed in this article. This paper proposes a statistical method for aircraft target recognition threshold based on human vision. On the basis of analyzing the imaging principle of micro-scanning, the edge feature of the aircraft target is extracted using the Canny algorithm. Then the main axis direction of the aircraft target is determined based on the principal component analysis (PCA). Sampling is performed at equal intervals along the vertical direction of the main axis of the aircraft, and the characteristic parameters of the contour edge of the aircraft target are extracted. The matching algorithm of Spearman rank correlation coefficient is used to judge whether the target is recognizable. Research results show that the influence of sampling phase on target imaging can be eliminated by micro-scanning. The recognition distance of the target is significantly improved with the increase of scanning times. A smaller optical system aperture can be selected to achieve the task of target recognition when the micro-scanning imaging mode is used.
Silicon nitride ceramics were irradiated by a solid-state Nd3+: YAG pulsed laser with an output wavelength of 1064nm. The plasma characteristic spectral lines were obtained by changing the laser energy. According to the National Institute of Standards and Technology (NIST) standard atomic spectroscopy database, the spectral lines were identified. The full width at half maximum parameters of Si I 252.27nm and Si I 288.60nm neutral atom characteristic lines of the spectral lines were obtained by Lorenz and Gauss fitting, respectively. Using the Stark broadening method to calculate the electron density, it was found that as the laser energy increases, the electron density gradually decreases. When the laser energy was increased to 156mJ and reached the minimum value, the electron density began to increase as the laser energy continued to increase. The reason for conducting the analysis is that as the plasma shielding effect increases with the increase of laser energy, the plasma absorbs the laser energy by reverse bremsstrahlung and resonance absorption mechanism. The decrease in energy irradiated onto the target, which excites the amount of plasma to reduce the plasma density. When the laser energy is raised to 156mJ, the energy irradiated to the target and the energy of the plasma shield are dynamically balanced. At this point in time, the electron density reaches a minimum, and the electron density increases with increasing laser energy.
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