Abstract:According to the spectral response curves and dark current of a near infrared two-dolor detector in two different operation wavebands, a signal acquisition system based on the near infrared two-color detector is designed. The system has many current-voltage conversion levels, voltage amplification levels and filter circuit bandwidth levels. It can amplify signals and control bandwidth quickly. Moreover, it provides zero analog signals for four amplify circuits via a Digital-to-Analog (D/A) convertor. This can effectively eliminate the noises caused by the stray light and the dark current of the detector itself. The system has the features of high speed, low noise and high resolution. By using this signal acquisition system, many parameters of the optical system, such as signal-to-noise ratio, dynamic range and minimum measurable power, can be improved.

Abstract:For a diffuser which is used as the light source carrier for in-orbit calibration of an optical remote sensor, to use a ratioing radiometer to monitor the variation of its reflection performance in orbit is an effective means. In order to meet the inversion requirement of quantitative products, the absolute radiation in-orbit calibration system for a new generation of spaceborne High Resolution Imaging Spectrometer (HRIS) should be designed to use the sun as its light source. The long-term tracking measurement results of a foreign in-orbit calibrator show that the reflectance of the diffuser is changing all the time. Moreover, the shorter the wavelength is, the greater the change is. However, the remote sensing of ocean color elements just concentrates on the wavelength region close to UV. To solve this problem, a spectrum ratioing radiometer is designed. Its radiation detection performance is analyzed theoretically and measured experimentally. The results show that its linear correlation coefficient is better than 0.9991 in the whole dynamic measurement range and its spectrum signal-to-noise ratio under the in-orbit irradiation input condition is better than 100. It can meet the calibration precision requirement of the reflection performance of the spaceborne diffuser for a spaceborne HRIS.

Abstract:The interferogram acquisition principle and process of infrared Fourier spectrometers were presented. On the basis of MATLAB, modeling and calculation of the characteristics of interferograms were carried out by combining numerical integration with discrete Fourier transform for the first time. The interferograms corresponding to different temperature blackbody radiation were obtained and their direct component, maximum value and relative minimum value were analyzed. The linear relationship between the relative minimum value and the direct component was given quantitatively and was verified by comparing experimental data. The background noise of an atmospheric vertical detector system was analyzed in terms of the characteristics of interferograms for the first time in China. Then, the feasibility of using the subtraction circuit in CTIA to improve the dynamic range of the detector was analyzed. The result showed that the method was not feasible.

Abstract:For a high resolution wide waveband infrared spectroradiometer based on linear variable filters, a wavelength calibration method is proposed. Firstly, the initial wavelength is derived theoretically and the linearity of the linear variable filter used is corrected. Then, the wavelength correction is carried out by the characteristic peak matching based on wavelength reference source so as to complete wavelength calibration. Finally, the calibration accuracy is checked by using a laser. The result shows that the calibration accuracy of the proposed method is better than 1%.

Abstract:The accuracy of wavelength calibration is one of the important specifications for measuring a spectrometer. Because of its importance, the wavelength calibration of a Charge Coupled Device (CCD) array UV spectrometer is studied. A new wavelength calibration method containing noise deduction, spectrum peak location and wavelength fitting is given. To reduce the influence of dark noise on spectral signals, a method for deducting dark noise by using non-exposure pixels is proposed. To solve the problem of spectrum-peak drift, a spectrum-peak location method based on weight narrow-window difference is proposed. For the lacking of spectrum line of a single light source, a multiband wavelength fitting method is proposed. The experimental results show that the proposed method has its wavelength calibration accuracy less than 0.6 nm. Its calibration accuracy at key wavelength points is less than 0.01 nm. Because of the advantages of high calibration accuracy and low complexity etc, it can be used for the wavelength calibration of UV spectrometers.

Abstract:An aluminous flat plate heat pipe prototype was manufactured and a test device was built for the prototype. The properties of the prototype were experimentally investigated by using the test device. The experimental results showed that the heat pipe had quick response to temperature and could realize temperature equilibrium rapidly. For the power of 200 W, the temperature differences on cooling surface and heating surface were only 0.87℃ and 1.37℃ respectively. With the increase of heat flux, the advantages of temperature evenness of the heat pipe became more evident. Its thermal resistance was only 0.100℃/W. This heat pipe prototype had excellent starting performance, temperature evenness and heat transfer performance.

Abstract:To verify the capability of infrared guided missiles against infrared decoy at less cost, the ability of infrared hardware-in-the-loop simulation should be improved. The infrared hardware-in-the-loop simulation based on MOS resistor arrays is one of the most effective simulation methods in many means. Infrared decoy is simulated by using a MOS resistor array and an infrared decoy model. Particularly, an infrared decoy motion model is established. Then, the theoretical model of infrared decoy established after the correction of the trajectory of infrared decoy is measured in the fields. The result shows that the realistic simulation of infrared decoy trajectory is the key to the effective verification and improvement of the capability of infrared guided missiles against infrared decoy.

Abstract:To remove the influences of system error and electro-optical modulation on the measurement result in the infrared detector S parameter measurement based on a lightwave component analyzer, a calibration method based on 12-term error coefficient is proposed. On the basis of the network modeling of both electro-optical modulation and S parameters of an infrared detector, the DFD of the measurement system is designed. The S parameter correction formula is derived. The S21 parameters of the infrared detector are measured in the range from 10 MHz to 20 GHz. The Pearson Product-moment Correlation Coefficient (PPMCC) between the data obtained by the proposed method and the data measured by using a N4375D-type analyzer is 0.997. The result shows that the data are in good agreement and the validity of the proposed method is verified.