Research On 48 Gray Linear Scale Acousto-optic Modulator Driving Source And Its Communication System

With the rapid development of laser technology and the continuous development of high-quality of acousto-optical crystal materials,the acousto-optic devices based on the principles of acousto-optic interaction have been widely used in the fields of laser large screen character & document display,laser heterodyne interference technology and other high-precision measurement fields.The Bragg acousto-optic modulator,which has many advantages,such as high diffraction efficiency and high operating frequency,is a kind of acousto-optic device which is widely used at present.In order to make the acousto-optic modulator has good working performance.A 48 gray linear scale acousto-optic modulator driving source is designed for the Bragg acousto-optic modulator to achive the feature that the diffraction light intensity gray value presents a linear corresponding change with the digital modulation voltage.The circuit design of this acousto-optic modulator driving source mainly includes two parts: the digital voltage control circuit and the RF driving circuit.The function of the digital voltage control circuit is to generate 48 grades digital control voltages,these voltages are further converted to 48 grades digital modulation voltages by the level-shifter of the RF driving circuit.And then those modulation voltages are used to modulate the amplitude of the high frequency carrier signal of the RF driving circuit.So the driving source outputs the corresponding RF driving signals and drives the acousto-optic device.Through acousto-optic modulation experiments obtain the corresponding diffraction intensity gray value and display corresponding gray level.The experimental results show that the diffraction intensity gray value has a nonlinear relationship with the digital modulation signal.Due to the inherent nonlinear characteristic ofacousto-optic devices,using linear voltage compensation technique obtains the linear correlation coefficient of diffraction intensity gray value vs.digital modulation voltage is97.73%,increased by 7.06% than uncompensated.And the gray grades increases to 48,increased by 18 grades than uncompensated.Then through the audio-frequency acousto-optic communication experiments to test the transmission performance of the system for the audio signals.The experimental results show that the audio-frequency acousto-optic communication system has a very good linear transmission performance within a certain range of amplitude variation.