Bit-efficient, sub-millisecond wavefront measurement using a lock-in camera for time-reversal based optical focusing inside scattering media.
Bit-efficient, sub-millisecond wavefront measurement using a lock-in camera for time-reversal based optical focusing inside scattering media.
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DOI：
10.1364/ol.41.001321
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发表时间：
2016-04-01
期刊：
影响因子：
3.6
通讯作者：
Wang LV
中科院分区：
文献类型：
--
作者：
Liu Y;Ma C;Shen Y;Wang LV
逆时超声编码光学聚焦测量超声标记光的波前，然后将标记光相位共轭回超声焦点，从而将光聚焦到散射介质深处。在以往的工作中，波前测量的速度受到传统相机低帧率的限制。此外，当信背景比较低时，这些摄像机使用大部分比特来表示无信息的背景，导致比特的使用效率极低。在这里，我们使用一个锁定摄像机，通过在拒绝背景后仅对信号进行数字化，提高了比特效率并减少了数据传输负载。使用该相机，我们在0.3 ms内获得单帧测量后超声标记光的波前，并将光聚焦在两个漫射器之间。当SBR为6 × 10−4时，相灵敏度达到0.51 rad。
Time-reversed ultrasonically encoded optical focusing measures the wavefront of ultrasonically tagged light, and then phase conjugates the tagged light back to the ultrasonic focus, thus focusing light deep inside the scattering media. In previous works, the speed of wavefront measurement was limited by the low frame rates of conventional cameras. In addition, these cameras used most of their bits to represent an informationless background when the signal-to-background ratio was low, resulting in extremely low efficiencies in the use of bits. Here, using a lock-in camera, we increase the bit efficiency and reduce the data transfer load by digitizing only the signal after rejecting the background. With this camera, we obtained the wavefront of ultrasonically tagged light after a single frame of measurement taken within 0.3 ms, and focused light in between two diffusers. The phase sensitivity has reached 0.51 rad even when the SBR is 6 × 10−4.