Abstract:An imaging spectrometer based on a linear variable filter has the features of compact structure, miniaturization and high spatial resolution. Now, it has become the development trend for imaging spectrometers. Firstly, the concepts and principles of the linear variable filter and its corresponding imaging spectrometer are presented. Then, the advantages and application fields of such imaging spectrometers are analyzed. Finally, the related development status at home and abroad is discussed and the future prospects of the imaging spectrometers based on linear variable filters are given.

Abstract:The influence of temperature variation on the imaging effectiveness of a lens is called thermal dispersion. To make a lens have stable imaging quality in a certain temperature range, usually some compensation measures for athermalization should be taken. Normalized coefficients are the important parts of an athermal mathematical model. The concepts of normalized coefficients and their application in athermal technologies are discussed. The development ideas and trends of athermal technologies for infrared optical systems are presented on the basis of the related papers published in China.

Abstract:HgCdTe epitaxial materials are grown on CdZnTe substrates by an Isothermal Vapor Phase Epitaxy (ISOVPE) method. On this base, a HgCdTe photovoltaic detector with an integrated optically immersed lens structure operating in the waveband from 2.5 μm to 3.2 μm at near room temperature is developed. Because the HgCdTe epitaxial material grown by ISOVPE has a greater composition gradient, its cutoff wavelength is located accurately by a method in which wet etching and transmission spectral measurement are carried out for many times. An integrated optically immersed lens with a diameter of 1.5 mm is made on a CdZnTe substrate by a single point diamond turning method. Then, the optical response area of the device before and after the integrated optically immersed lens is made is evaluated by a Laser Beam Induced Current (LBIC) test method. By comparing the current voltage characteristic curves of the device before and after the integrated optically immersed lens is made, the processing of the lens is evaluated. It is found that the zero biased resistance of the device increases slightly after the lens is made,which coincides with the fact that a hyper-semispherical structure may reduce the incident angle of radiation for the device. The blackbody signal and noise of the device are measured before and after the lens is made. The result shows that the signal of the device with an integrated optically immersed lens is increased by a factor of 20 to 30 and its noise is reduced slightly due to the increase of zero biased resistance.

Abstract:The role of a beam splitter for an interference infrared spectrometer is presented. According to the requirement that the peak-to-valley (PV) value variation of a beam splitter should be 0.05λ (λ=632.8 nm) after it is fixed, the supporting method of the beam splitter is determined. By analyzing the PV value variation of the beam splitter when it is in the states of flatness, verticality and zero-gravity by a finite element method, it is derived that the PV value variation of the beam splitter can be controlled by applying different pressure to the tablet used. It is found that when the beam splitter is in the state of verticality, its PV value is varied greatly and the maximum pressure which can be applied is 0.866 MPa. The elastic supporting material is selected, its size is determined and a supporting sample is made. The actual measurements show that the analysis by the finite element method can meet the high precision supporting requirement of the beam splitter fully. This provides the basis for the accuracy improvement of the instrument system.

Abstract:Because of the advantage of all-weather monitoring, the thermal imager for an offshore oil field security system can monitor the pipeline- and cable-buried submarine area effectively whether it is in fog or at night. An offshore oil field security system based on an infrared thermal imager is designed. The components of the system are given. A single infrared thermal imager system and a combined system consisting of an infrared thermal imager and an automatic Identification System (AIS) are designed respectively. The display and control software for the combined system is designed.

Abstract:For an infrared hotbox monitoring system, when its visible image and infrared image have a large difference in resolution, the fusion of the images is not ideal. This is unfavorable for the determination of the hotboxes of a train. To solve this problem, an algorithm for fusing a visible image with a pseudo-color infrared image is proposed. In the algorithm, the gray levels of the pixels in the same part in both a visible image and an infrared image are reproduced firstly and bilinear interpolation is implemented for other parts in the images, so as to match the pixels in the visible image with those in the infrared image. Then, the infrared image is mapped by pseudo-dolor coding, and weighted fusion is implemented for the visible and infrared images in three channels (RGB). The experimental result shows that the fused image is richer in color. The location of the infrared target in the image is more accurate and is more convenient for the manual identification of the position of a hot-axis. The algorithm can meet the need for fusing infrared and visible images in an infrared hotbox monitoring system.

Abstract:To avoid the limitation of wavelet thresholding and the calculation complexity of non-local means filtering when an image is denoised, a more effective wavelet image denoising method based on Non Local Means (NLM) is proposed. Firstly, multi-level wavelet decomposition is carried out for an image containing noises. Then, a new BayesShrink estimation threshold is used to implement thresholding processing of the sub-band coefficients so as to remove the high frequency noise. Finally, to further remove the noise, NLM processing is implemented in part low-level sub-bands. The experimental result shows that compared with the common wavelet threshold denoising and NLM filtering methods, this method can remove the noises in an infrared image more effectively and can obtain a higher Signal-to-Noise Ratio (SNR) and a lower Mean Square Error (MSE). Moreover, the method is relatively simple in calculation and can achieve excellent visual effect.

Abstract:The calculation of exhaust plume's infrared radiation is an important part of the calculation of infrared radiation of an air vehicle. On the basis of an engineering calculation model of flow field in exhaust plume, the calculation of gas component parameters of a nozzle is implemented in terms of the chemical reaction of combustion. A fast calculation method of exhaust plume's infrared radiation is obtained by utilizing the C-G approximation method based on a Malkmus narrow-band model. The simulation result shows that the method can calculate the infrared radiation in exhaust plume fast and accurately. It can provide an effective approach for the calculation of infrared radiation of an aircraft in the simulation of an infrared guided missile.

Abstract:According to the detection requirements of a double-band infrared detection equipment in different wavebands, an unmanned aerial vehicle (UAV) with a flaring light pipe having double band radiation characteristics is selected as a low altitude moving photoelectric target so that the double band test requirement is met with the same target. Through the overall design of the airway distance and heading of the UAV, the demands of several testing projects such as operation distance testing and target data precision testing are met in the same flight. Then, the precision of the true airway of the target is analyzed deeply and the relevant and setting methods of related parameters such as airway, heading and arranging under different conditions are summarized. This work provides sufficient technical support and choosing space for the organization and implementation of the testing projects.