Study Of Weak Photo-electric Signal Detection Based On Chaotic Oscillator

At the infrared physics field, emissivity is an important property parameter of the materials. There is a significant meaning to measure it. However because there is a mathematic problem not to be solved very well in physics field, the emissivity and true temperature of the target can't be separated from radiation signal. In recent years multi-spectrum method is developed to solve the problem. But it is needed to split the radiation photo-electric signal according to wave length. When there are a lot of the splitted wavelength numbers, the precision is higher in processing results. However the radiation energy is very weak in every working waveband. These signals are submerged in strong noise. The traditional detection method can't meet the requirements. So the weak signal detection technology in strong noise background must be researched. Moreover high spectral satellite is being researched in our country. It also needs to study on weak photo-electric signal detection.In the high precision detection system of weak photo-electric signal, chopper weel is used in order to decrease zero drift influence to constant weak photo-electric signal. At first, the weak photo-electric signal is modulated periodic signal. Then the signal is received in sensor. Of course the signal is submerged in strong noise.The results show that chaos system has a very strong immunity to noise but it is sensitive to the periodic signal. So chaos theory can solve the difficult problem very well in weak photo-electric signal detection system.The mathematic model and dynamic property of typical chaos system is analyzed firstly and the influence of the amplitude and frequency of weak photo-electric signal to chaos dynamic property is researched. It is known that the typical chaos system is sensitive to the amplitude and the frequency of weak photo-electric signal. So the optimal chaos model is established in the detection system of weak photo-electric signal.On the basis of optimal chaos model, the dynamic property of optimal chaos model is analyzed deeply. And the method is proposed that lyapunov exponent method is introduced to optimal chaos model to calculate the chaos threshold quantitatively. So the amplitude of weak photo-electric signal is detected precisely. Then the lowest signal-noise ratio in weak photo-electric signal detection system can be determined.To detect the unknown frequency of weak photo-electric signal, the frequency detection method based on proportional differential control of R(o|¨)ssler chaos system is proposed. It can detect unknown frequency through controlling the chaos state to big periodic state of R(o|¨)ssler system firstly and using spectrum analysis. On the basis of the method, adaptive frequency detection method based on chaos model is proposed. It can solve the problem of the order number high of R(o|¨)ssler system and complex control. The frequency diviation between the frequency of Duffing system and the detected frequency is controlled to choose the chaos model adaptively. Thus the frequency of weak photo-eletric signal can be detected accurately.Finally, on the basis of the amplitude and the frequency detection methods of weak photo-electric signal based on optimal chaos model the experiment system of weak photo-electric signal is developed. And the the amplitude and the frequency of weak photo-electric signal is detected in the experiment. The experiment results verified that it is right and effective to the detection method of weak photo-electric signal based on chaos oscillator. Meanwhile the detection system based on chaos oscillator is used in bidirectional reflectance distribution function measurement system and the weak photo-electric signal in the bidirectional reflectance distribution function system is detected precisely.