Control System Of Polarization Imaging Spectrometer Based On AOTF

Polarization imaging spectrometer is a new instrument that uses special optical devices to process polarization and frequency of incident light to study the image and spectral information of target matter at different wavelengths.It is widely applied in modern medical and environmental monitoring.The range of wavelength measurement,resolution and image clarity of the imaging system have been raised more and more in the development of new optical spectrum imaging technology.As a new type of acoustooptic device,Acousto-Optic Tunable Filter is widely used in the field of spectral imaging technology.It has the advantages of small volume,high diffraction efficiency and resolution,arbitrary wavelength switching,flexible tuning and wide tuning range.Therefore,it has been applied in the polarization imaging spectrometer.The imaging quality and performance of polarizing imaging spectrometer is mainly affected by the core component AOTF.The diffraction intensity of AOTF depends on the actual power of AOTF ultrasonic transducer in a certain range,and the power required in different frequency ranges is also different.Based on the research of the frequency characteristics of the transducer impedance,using broadband impedance matching theory to design a wide band,high diffraction efficiency and power efficiency of the AOTF control system,the driving power to maximize the transfer to the transducer to frequency selective filter,and further improve the imaging quality of polarization imaging spectrometer.The system is driven by the high-speed DDS chip and high speed microcontroller,by VC PC control and high frequency to the 180 MHz frequency range in 60 MHz power controllable driving signal through the power amplification and impedance matching network after loading in dual ultrasonic transducer AOTF,acousto-optic interaction provide the necessary conditions for the formation of acoustooptic crystal.It has the highest 36 dBm stable and controllable output power in the 60~180MHz band.It can make AOTF work in the best state and achieve the target material's spectral image acquisition in visible band by automatic control of the upper computer.By further optimizing the impedance matching network of transducer,the spectral diffraction efficiency of AOTF reaches up to 94% in visible band at the end,which makes the diffraction efficiency of AOTF in 421~1151nm band greatly improved.By assembling the prototype of the spectrometer and collecting the object,the image quality can meet the actual requirements.