Research Of Automatically High Resolution Detection Method For LCOPA

With the rapid development of laser technology, liquid crystal optical phased array(LCOPA) have been the representative of that and it is a kind of real-time programmable electronic beam scanning technology with incomparable advantages: low power consumption, light weight, flexible control, etc. But there are some obvious shortages of its maximum deflection angle, efficiency and effective aperture and so on. Currently, phase detection is only for homogeneous phase-control device. The effective detection of the two-dimensional phase for liquid crystal optical phased array can provide the basis for its further development and application.To realize the high-resolution detection of two-dimensional phase for liquid crystal optical phased array, based on the advantages of conventional method of a quarter wave plate, this paper researches data collection technology in the light path of detection and data processing algorithm for sine curve form. Then a method of Fourier quarter wave plate is presented. The tests of 1/4 wave plate, liquid crystal phased array device are analyzed in the experiment, which has realized the two-dimensional phase high resolution detection. Image processing algorithms is innovatively applied to two-dimensional phase matching and fusion process to solve wide-field detection problem for liquid crystal phased array. The main contents of the research are as follows:1) Based on the conventional method of a quarter wave plate, the automatic detection was realized by adding a microscopic lens, CCD, step motor. DFT algorithm was studied to calculate the minimum value for effective frequency component data, and the method of Fourier quarter wave plate is presented. The optical path of detection was designed to improve the detection reliability.2) Fitting method based on the least squares and Fourier algorithm were contrastively analyzed in theory, simulation, detection experiment of liquid crystal phased array, the discrete Fourier transform(DFT) algorithm has higher efficiency and precision. By method of Fourier quarter wave plate, test experiments to 1/4 wave plate, liquid crystal phased array were carried out, the average detection error of 1/4 wave plate is less than 0.3°, the two-dimensional phase detection result of liquid crystal phased array can display the specific effects of phase sag, 3 μm electrodes. That had verified the detection effectiveness of Fourier a quarter wave plate method in high resolution two-dimensional phase detection.3) The Hough algorithm, Radon algorithm, linear regression algorithm of image processing algorithms were studied to solve the slanting problem of two-dimensional phase. The near interpolation algorithm, 2-d interpolation algorithm, double three interpolation algorithm were theoretically analyzed for rotating restoring problem of phase distribution. For stitching problem of two-dimensional phase difference, matching algorithm based on region and matching algorithm based on Harris feature were respectively analyzed to solve the calculation problem of matching location, and then compared the weighted average method and so on to realize the seamless synthesis in the stitching by the weighted average method.