1 Center of Applied Laser, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China ; 2 University of Chinese Academy of Sciences, Beijing 100190, China
Abstract Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix (TM) of a scattering medium. We report a simple but powerful method, direct digital frequency synthesis (DDS) technology to modulate the phase front of the laser and measure the TM. By judiciously modulating the phase front of a He-Ne laser beam, we experimentally generate a high quality focus at any targeted location through a 2 mm thick 120 grit ground glass diffuser, which is commercially used in laser display and laser holographic display for improving brightness uniformity and reducing speckle. The signal to noise ratio (SNR) of the clear round focus is ∼ 50 and the size is about 44 μ m. Our study will open up new avenues for enhancing light energy delivery to the optical engine in laser TV to lower the power consumption, phase compensation to reduce the speckle noise, and controlling the lasing threshold in random lasers.
Fund: Project supported by the National Key Research and Development Program of China (Grant Nos. 2016YFB0401902 and 2016YFB0402001) and Key-Area Research and Development Program of GuangDong Province, China (Grant No. 2019B010926001).
Yuan Yuan(袁园), Min-Yuan Sun(孙敏远), Yong Bi(毕勇), Wei-Nan Gao(高伟男), Shuo Zhang(张硕), and Wen-Ping Zhang(张文平) Controlling the light wavefront through a scattering medium based on direct digital frequency synthesis technology 2021 Chin. Phys. B 30 014209
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