A calibration algorithm for the voltage-phase characteristic of a liquid crystal optical phased array

Liquid crystal optical phased array (LCOPA) is a kind of spatial light modulator(SLM) which is now widely studied in the field of laser radar, adaptive optics, optical information processing, etc. The calibration of the voltage-phase characteristic of a LCOPA is an important step which will seriously affect the performance of a LCOPA. Firstly, derived the relationship between the phase distribution of the emergent light and light intensity in the far-field. Designed an optic path to calibrate the voltage-phase characteristic. And built up a observation equation. Introduced a weight matrix to reduce the errors caused by the impact of phenomena such as the fly-back. Proposed a new calibration algorithm based on the measurement of light intensity. A checkerboard pattern with a period of M pixels per check was used in the calibration routine. Fix the control voltage of one region, and change the voltage in another region. The light pattern in the far-field changes with the control voltage. Measure the intensity of the light beam at the center of the far-field. Then, obtain the raw data. Filter and normalize the raw data. And calculate the phase difference between two regions. Use weighted least square method to get the relationship between the control voltage and the phase retardation. Lastly, using this method to calibrate a LCOPA which is produced by BNS corp.