Aiming at the urgent need of infrared radiation characteristics of different types of targets of interest under typical sea conditions in the development of high-precision missile infrared imaging guidance weapons, a model data-driven infrared radiation modeling method was developed. Firstly, by studying the influence factors of the system's full link in the Marine environment, the atmospheric radiative transfer model is constructed, and the theoretical values of the target and background parameters are calculated. Secondly, through the consistency comparison between the measured results and the theoretical model, the simulation target model is iterated to improve the system accuracy. Finally, the measured radiation luminance data of different bands and the theoretical modeling data of the same ship target in head-on and side-head-on attitude are compared and analyzed. The results show that the model prediction is in good agreement with the measured results, and the error is less than 15%. The proposed model is reliable and feasible, which can lay a model foundation for the follow-up development of infrared imaging guidelines, and provide technical support for the detection and recognition of sea surface targets.
The vibration environment of the internal opto-machinal system of the electro-optical pod is different from the external vibration environment and needs to be accurately defined. Based on the detailed analysis of the vibration source distribution and response bandwidth of the airborne electro-optical system, the Cassegrain Opto-mechanical System is taken as the research object, and the complete analysis process is established from the original environmental excitation. The equivalent vibration algorithm is used to determine the micro-vibration conditions. The finite element detail model of the connection method is used for dynamic response. At the same time, based on the simulation model optomechanical system, an optical axis drift analysis method based on feature point correlation and response extremum judgment is proposed. The relationship between the displacement mode and the amount of drift of the optical axis is obtained.
With applications ranging from the desktop to remote sensing, the long wave infrared (LWIR) interferometric spectral imaging system is always with huge volume and large weight. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, wedge angle of interferometric cavity, f-number of the imaging lens and the relationship between the wedge angle and the modulation of the interferogram. A prototype is developed and a good experimental result of a uniform radiation source, a monochromatic source, is obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.
Fourier transform spectroscopy is a widely employed method for obtaining spectra, with applications ranging from the desktop to remote sensing. The long wave infrared (LWIR) interferometric spectral imaging system is always with huge volume and large weight. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, the reflectivity of the two interferometric cavity surfaces, field of view (FOV) and f-number of the imaging lens. A prototype is developed and a good experimental result of CO2 laser is obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.
Overall structure of the infrared target simulator system and the principle of DMD are introduced. When DMD is on “open” state, all of the incidence light can rip into the pupil of the projection system. In addition, when it is on “close” state or “flat” state, all of the incident light can’t rip into the pupil of the projection system. Based on this principle, with a specific infrared target simulator, TIR prism with BaF2 as material is designed. And then, this design is improved by ZnSe material instead of BaF2. ZnSe transmission rate is very well in the range of 0.6 microns to 14 microns and the infrared target simulator in this project requires 3 to 5 microns and 8 to 14 microns wavelength. This material is hard and easy to be processed. The design idea and design process are introduced in details in this paper and angle parameters are obtained. To improve light utilization and image quality in infrared target simulator system, two types of thin film on TIR prism different surfaces are designed. One is high transmittance with incidence angle of 0° and 24°,the other is 55°. Finally, this scheme is simulated and optimized by Tracepro software. Approving results were acquired.
The design of the collimator for dynamic infrared (IR) scene simulation based on the digital micro-mirror devices (DMD) is present in this paper. The collimator adopts a reimaging configuration to limit in physical size availability and cost. The aspheric lens is used in the relay optics to improve the image quality and simplify the optics configuration. The total internal reflection (TIR) prisms is located between the last surface of the optics and the DMD to fold the raypaths of the IR light source. The optics collimates the output from 1024×768 element DMD in the 8~10.3μm waveband and enables an imaging system to be tested out of 8° Field Of View (FOV). The long pupil distance of 800mm ensures the remote location seekers under the test.
Infrared scene simulation system can simulate multifold objects and backgrounds to perform dynamic test and evaluate EO detecting system in the hardware in-the-loop test. The basic structure of a dual-waveband dynamic IR scene projector was introduced in the paper. The system’s core device is an IR Digital Micro-mirror Device (DMD) and the radiant source is a mini-type high temperature IR plane black-body. An IR collimation optical system which transmission range includes 3~5μm and 8~12μm is designed as the projection optical system. Scene simulation software was developed with Visual C++ and Vega soft tools and a software flow chart was presented. The parameters and testing results of the system were given, and this system was applied with satisfying performance in an IR imaging simulation testing.
With unique working principle and spectral characteristic, the long wave infrared (LWIR) interferometric spectral imaging is a popular technology with wide application in many fields. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, the reflectivity of the two interferometric cavity surfaces and the wedge angle of interferometric cavity. A prototype is developed and good experimental results of blackbody and polypropylene film are obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.
During the research of hyper-spectral imaging spectrometer, how to process the huge amount of image data is a difficult problem for all researchers. The amount of image data is about the order of magnitude of several hundreds megabytes per second. With the development of multi-core computer, parallel computing on multi-core computer is increasingly applied in large-scale data processing. In this paper, we give a detailed discussion of parallel computing technology, we also apply this technology to the data processing of hyper-spectral image data. Experimental results show that the speed of data processing is apparently improved. Our research has significant meaning for the engineering application of hyper-spectral imaging spectrometer.
Spectral calibration and radiometric calibration is an important part in the data processing of the windowing Fourier transform imaging spectrometer, it can ensure that the spectral curve output from spectrometer are more closely to target spectrum. The main idea of spectral calibration is using a monochromatic source whose wavelength is known, in the same way, radiometric calibration can be achieved by using radiation source whose radiation characteristic is known.
In this paper, we propose a set of methods of spectral calibration and radiometric calibration. In order to carry out spectral calibration, we use monocharomator to scan several sample points near the position of every spectral channel of imaging spectrometer, and then we employ Gaussian fitting function to determine the central wavelength and bandwidth of every spectral channel. In order to carry out radiometric calibration, we employ panchromatic light source and integrating sphere, at the position of every spectral channel of imaging spectrometer, we measure the response ability of spectrometer to radiation. The calibration accuracy is carefully analyzed. Experimental results show that calibration accuracy meet the given requirements.
KEYWORDS: Imaging systems, Modulation transfer functions, Mathematical modeling, Signal processing, Visual process modeling, Image intensifiers, Visualization, Contrast transfer function, Signal to noise ratio, Transmittance
To estimate the view range of low light level (LLL) imaging system,
analyze the key factors influencing the system performance, and optimize the system
design parameters, we have established mathematical models for each module
(objective lens, image intensifier, electronic sub-system, displayer, human visual
sub-system), according to the transmission process of signals from the target and
background. Finally, the performance evaluation software for LLL imaging system
has been programmed, with the detection and recognition criterion. The software has
been verified by the field experiment of a specific LLL imaging system, with the
confidence coefficient higher than 80%.
We have to make the integral sphere source trace to the standard lamp, when we calibrate the
imaging spectrometer. But the standard lamp need to be calibrated by the blackbody firstly. In this
paper, we have the integral sphere source trace to the blackbody directly, using the exclusive
spectral response of a spectrometer. During the experiments, two spectral responses of the
spectrometer (200nm~1100nm) within 700nm~900nm are obtained separately by measuring the
spectral radiances of the blackbody at 1000°C and the integral sphere source at some color
temperature. We get the equivalent color temperature of the integral sphere source, making use of
the consistency of the two spectral responses in theory. After that, we can compute the spectral
radiance at the exit of integral sphere by Plank formula. So we not only complete the calibration of
the integral sphere source, but also have the integral sphere source trace to the blackbody
simultaneously. From the result analysis,we think this method is exact enough for the calibration
about the spectral radiation of the integral sphere source.
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