Performance Testing Of Liquid Optical Phase And Focus Devices

The key of optical synthetic aperture imaging technology is to solve the problem of common phase.The phase offset between sub apertures will seriously affect the imaging quality.In engineering,the phase modulation accuracy of 1 / 10 wavelength of optical band is generally required.In recent years,with the birth of the new discipline of microfluidic optics,it provides a new method for single subaperture phase modulation to fabricate phase modulation devices by manipulating the fine deformation of liquid.In this paper,a high-precision liquid phase modulator is fabricated by using piezoelectric ceramics.Through the combination with liquid focusing device,a set of optical platform is designed,which can not only focus and adjust phase,but also test the performance of liquid phase modulator.The main contents of this paper are as follows:1.Based on the principle of microfluidic optics,a high-precision liquid phase modulator is designed and fabricated.The high-precision detection of liquid phase modulator is realized by using optical interferometry and digital image processing technology.In the first step,piezoelectric ceramic is selected as the carrier of the phase modulator,and liquid is injected into the piezoelectric ceramic cavity to prepare the phase modulator;In the second step,the liquid phase modulator is placed on one arm of the interferometer in the optical platform,and the interference fringe images of the liquid phase modulator under different voltages are recorded by CCD;In the third step,after a series of digital image processing,the fringes skeleton of a single pixel is obtained.The fringes marking method is used to track the movement of the skeleton fringes under different voltages and calculate the pixel movement of the skeleton fringes;The fourth step is to analyze the experimental data,and give the phase modulation range and accuracy of the liquid phase modulator through the relationship between voltage and piezoelectric ceramic displacement and pixel displacement.2.Focusing function is added to the platform based on phase modulation.Microfluidic optical technology and dielectric wetting effect are used to control the overall optical path of the platform.In this paper,liquid lens is used to control the focal length,and the liquid lens is driven by software to control the optical path of the platform and the clarity of interference fringes on PC.The experimental results show that the focusing device of the platform can realize the control of the fringe definition.The phase modulation range of the phase modulation device is 0-3.325 π under the voltage of 0-30 V,The phase modulation accuracy can reach 1 / 40 wavelength,and the linearity of phase modulation is good in the voltage range,which meets the phase modulation requirements of single sub aperture in optical synthetic aperture.