In this paper, a calibration method of LVF-based spectroradiometer is summarize, including spectral calibration and radiometric calibration. The spectral calibration process as follow: first, the relationship between stepping motor’s step number and transmission wavelength is derivative by theoretical calculation, including a non-linearity correction of LVF;second, a line-to-line method was used to corrected the theoretical wavelength; Finally, the 3.39 μm and 10.69 μm laser is used for spectral calibration validation, show the sought 0.1% accuracy or better is achieved.A new sub-region multi-point calibration method is used for radiometric calibration to improving accuracy, results show the sought 1% accuracy or better is achieved.
Narrow linewidth and high stability of frequency are extremely necessary in modern precision experiments. The frequency of a free running semiconductor laser will drift several GHz per day, far too much to fulfill the demands in atomic and laser physics. In order to overcome this disadvantage, a variety of technologies for frequency stabilization are researched. The experimental realizations of frequency stabilization based on 780nm semiconductor laser are described in detail. Meanwhile, the performance and capabilities of the various frequency stabilization technologies are analyzed.
The dual-band image fusion algorithm is presented based on infrared radiation characteristics. It is a more accuracy solution, in terms of the spectral, than the wavelet-based image fusion. The fusion algorithm and quality assessment is then applied to demonstrate its performance. Firstly, the gray value of thermal image is converted into corresponding radiation extiance. Secondly, the relationship between the radiation exitance and temperature in 8μm~12μm is fitted by applications of least square method. Combined with Planck blackbody radiation theory, the temperature value of different Pixel of the thermal image is obtained by calculating the radiation. Then the radiation of LWIR image scene in MWIR spectral range is derived through Planck's Formula. Thirdly, the deduced radiation, which reflects the details of the LWIR scene, is quantified and introduced into the MWIR image. Finally, the simulation of dual-band image fusion is obtained by Matlab. The results show that the objectives of image fusion not only retain the abundant spectral information of the original images, but also gain additional information by processing the dual-band data. Thus the dual-band image fusion can increase detection, recognition and identification ranges compared with the original MWIR and LWIR data.
The spectral radiation of extended area blackbody source is widely used to provide a reference for absolute temperature in infrared test and calibration. Thus the temperature accuracy of extended area blackbody is a critical parameter to determine the performance of test and calibration system. The temperature of emissive surface is measured and controlled by Platinum resistance temperature sensor. A variety of techniques have been developed for improving the temperature accuracy of extended area blackbody. In order to overcome nonlinear error caused by the Platinum resistance temperature sensor, a calibration method based on two-point multi-section linear correction algorithm is proposed. The tests verify that the method enhances the calibration accuracy of temperature accuracy of extended area blackbody and satisfies the requirements of high precision tests on metrological quality.
In order to evaluate the performance of themal image system, an infrared simulation method of 4-bar
target is put forward based on blackbody radiation characteristics. These simulated targets are efficient
inputs for performance testing and evaluating the minimum resolvable temperature difference and
spatial resolution of the infrared computer simulating system. Finally, the infrared simulation images of
standard 4 bars target, which have tunable spectral band, adjustable temperature difference and
different spatial frequency, are realized by utilizing Matlab.